National Library of Energy BETA

Sample records for te rm te

  1. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    N u n a v u t O n t a r i o A l b e r t a Te x a s N o r t h w e s t Te r r i t o r i e s M a n i t o b a B r i t i s h C o l u m b i a S a s k a t c h e w a n Y u k o n M o n t a n a U t a h I d a h o C a l i f o r n i a N e v a d a O r e g o n A r i z o n a I o w a K a n s a s C o l o r a d o W y o m i n g S o n o r a N e w M e x i c o M i n n e s o t a N e b r a s k a O h i o C h i h u a h u a I l l i n o i s M i s s o u r i F l o r i d a G e o r g i a O k l a h o m a W a s h i n g t o n S o

  2. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    A l a s k a N u n a v u t O n t a r i o A l b e r t a Te x a s N o r t h w e s t Te r r i t o r i e s M a n i t o b a B r i t i s h C o l u m b i a S a s k a t c h e w a n Y u k o n M o n t a n a U t a h I d a h o C a l i f o r n i a N e v a d a O r e g o n A r i z o n a I o w a K a n s a s C o l o r a d o W y o m i n g S o n o r a N e w M e x i c o M i n n e s o t a N e b r a s k a O h i o C h i h u a h u a I l l i n o i s M i s s o u r i F l o r i d a G e o r g i a O k l a h o m a W a s h i n

  3. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    D u N o r d - O u e s t Te r r e - N e u v e - e t - L a b r a d o r Q u é b e c Í l e - d u - P r i n c e - É d o u a r d N o u v e l l e - É c o s s e N o u v e a u - B r u n s w i c k C o l o m b i e - B r i t a n n i q u e B a f f i n I s l a n d Í l e d u B a f f i n E l l e s m e r e I s l a n d Í l e d u E l l e s m e r e V i c t o r i a I s l a n d Í l e d u V i c t o r i a N e w f o u n d l a n d a n d L a b r a d o r Te r r e - N e u v e - e t - L a b r a d o r A l a s k a N u n

  4. A search for an excited muon decaying to a muon and two jets in pp collisions at $$\\sqrt{s}\\;=\\;8\\;{\\rm{TeV}}$$ with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; et al

    2016-07-11

    In this study, a new search signature for excited leptons is explored. Excited muons are sought in the channelmore » $${pp}\\to \\mu {\\mu }^{* }\\to \\mu \\mu \\ {\\rm{jet}}\\;{\\rm{jet}}$$, assuming both the production and decay occur via a contact interaction. The analysis is based on 20.3 fb–1 of pp collision data at a centre-of-mass energy of $$\\sqrt{s}\\;=\\;8\\;{\\rm{TeV}}$$ taken with the ATLAS detector at the large hadron collider. No evidence of excited muons is found, and limits are set at the 95% confidence level on the cross section times branching ratio as a function of the excited-muon mass $${m}_{{\\mu }^{* }}$$. For $${m}_{{\\mu }^{* }}$$ between 1.3 and 3.0 TeV, the upper limit on $$\\sigma B({\\mu }^{* }\\to \\mu q\\bar{q}$$) is between 0.6 and 1 fb. Limits on $$\\sigma B$$ are converted to lower bounds on the compositeness scale Λ. In the limiting case $${\\rm{\\Lambda }}={m}_{{\\mu }^{* }}$$, excited muons with a mass below 2.8 TeV are excluded. With the same model assumptions, these limits at larger $${\\mu }^{* }$$ masses improve upon previous limits from traditional searches based on the gauge-mediated decay $${\\mu }^{* }\\to \\mu \\gamma $$.« less

  5. 125Te NMR chemical-shift trends in PbTeGeTe and PbTeSnTe alloys

    SciTech Connect (OSTI)

    Njegic, Bosiljka; Levin, Evgenii M.; Schmidt-Rohr, Klaus

    2013-10-08

    Complex tellurides, such as doped PbTe, GeTe, and their alloys, are among the best thermoelectric materials. Knowledge of the change in 125Te NMR chemical shift due to bonding to dopant or solute atoms is useful for determination of phase composition, peak assignment, and analysis of local bonding. We have measured the 125Te NMR chemical shifts in PbTe-based alloys, Pb1?xGexTe and Pb1?xSnxTe, which have a rocksalt-like structure, and analyzed their trends. For low x, several peaks are resolved in the 22-kHz MAS 125Te NMR spectra. A simple linear trend in chemical shifts with the number of Pb neighbors is observed. No evidence of a proposed ferroelectric displacement of Ge atoms in a cubic PbTe matrix is detected at low Ge concentrations. The observed chemical shift trends are compared with the results of DFT calculations, which confirm the linear dependence on the composition of the first-neighbor shell. The data enable determination of the composition of various phases in multiphase telluride materials. They also provide estimates of the 125Te chemical shifts of GeTe and SnTe (+970 and +400150 ppm, respectively, from PbTe), which are otherwise difficult to access due to Knight shifts of many hundreds of ppm in neat GeTe and SnTe.

  6. A measurement of the ratio of inclusive cross sections $\\sigma(p\\bar{p}\\rightarrow Z+b{\\rm\\, jet})/ \\sigma(p\\bar{p}\\rightarrow Z+{\\rm jet})$ at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D.; Alkhazov, Georgiy D.; Alton, Andrew K.; Alverson, George O.; Alves, Gilvan Augusto; Ancu, Lucian Stefan; /Nijmegen U. /Fermilab

    2010-10-01

    The ratio of the cross section for p{bar p} interactions producing a Z boson and at least one b quark jet to the inclusive Z+jet cross section is measured using 4.2 fb{sup -1} of p{bar p} collisions collected with the D0 detector at the Fermilab Tevatron collider at {radical}s = 1.96 TeV. The Z {yields} {ell}{sup +}{ell}{sup -} candidate events with at least one b jet are discriminated from Z+ charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is 0.0193 {+-} 0.0027 for events having a jet with transverse momentum p{sub T} > 20 GeV and pseudorapidity |{eta}| {le} 2.5, which is the most precise to date and is consistent with theoretical predictions.

  7. Study of B meson production in pPb collisions at $\\sqrt{s_{ \\rm{NN}}} =$ = 5.02 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-08-26

    The production cross sections of the B+, B0, and B0s mesons, and of their charge conjugates, are measured via exclusive hadronic decays in pPb collisions at the center-of-mass energy √sNN = 5.02 TeV with the CMS detector at the CERN LHC. We used the dataset for this analysis and it corresponds to an integrated luminosity of 34.6 nb-1. The production cross sections are measured in the transverse momentum range between 10 and 60 GeV/c. No significant modification is observed compared to proton-proton perturbative QCD calculations scaled by the number of incoherent nucleon-nucleon collisions. Furthermore, these results provide a baseline for the study of in-medium b quark energy loss in PbPb collisions.

  8. Study of Vector Boson Plus $D^{*}(2010)^+$ Meson Production in $\\bar{p}p$ Collisions at $\\sqrt{s}=1.96\\, {\\rm TeV}$

    SciTech Connect (OSTI)

    Aaltonen, T.

    2015-08-27

    Our study of vector boson (V ) production in conjunction with a D*(2010)+ meson is presented. Using a data sample correponding to 9.7 fb-1 p of proton-antiproton collisions at center-of-mass energy √s = 1:96 TeV produced by the Fermilab Tevatron, we reconstruct V +D*+ samples with the CDF II detector. The D*+ is fully reconstructed in the D*(2010)+ → D0(→ K- π++ decay mode. This technique is sensitive to the associated production of vector boson plus charm or bottom mesons. We measure the ratio of production cross sections σ(W +D*)/ σ(W) = [1.75±0.13(stat)±0:09(syst)]% and σ(Z +D*)/ σ(Z) = [1:5±0:4(stat)_0:2(syst)]%. Event properties are utilized to determine the fraction of V +D*(2010)+ events originating from different production processes. Our results are in agreement with the predictions obtained with the pythia program, limiting possible contribution from non-standard-model physics processes.

  9. Measurement of Vector Boson Plus $$D^{*}(2010)^+$$ Meson Production in $$\\bar{p}p$$ Collisions at $$\\sqrt{s}=1.96\\, {\\rm TeV}$$

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.

    2016-03-21

    Our study of vector boson (V ) production in conjunction with a D*(2010)+ meson is presented. Using a data sample correponding to 9.7 fb-1 p of proton-antiproton collisions at center-of-mass energy √s = 1:96 TeV produced by the Fermilab Tevatron, we reconstruct V +D*+ samples with the CDF II detector. The D*+ is fully reconstructed in the D*(2010)+ → D0(→ K- π+)π+ decay mode. This technique is sensitive to the associated production of vector boson plus charm or bottom mesons. We measure the ratio of production cross sections σ(W +D*)/ σ(W) = [1.75±0.13(stat)±0:09(syst)]% and σ(Z +D*)/ σ(Z) = [1:5±0:4(stat)_0:2(syst)]%. Eventmore » properties are utilized to determine the fraction of V +D*(2010)+ events originating from different production processes. Our results are in agreement with the predictions obtained with the pythia program, limiting possible contribution from non-standard-model physics processes.« less

  10. Neutron capture of /sup 122/Te, /sup 123/Te, /sup 124/Te, /sup 125/Te, and /sup 126/Te

    SciTech Connect (OSTI)

    Macklin, R.L.; Winters, R.R.

    1989-07-01

    Isotopically enriched samples of the tellurium isotopes from mass 122 to mass 126 were used to measure neutron capture in the energy range 2.6 keV to 600 keV at the Oak Ridge Electron Linear Accelerator pulsed neutron source. Starting at 2.6 keV, over 200 Breit-Wigner resonances for each isotope were used to describe the capture data. Least-squares adjustment gave parameters and their uncertainties for a total of 1659 resonances. Capture cross sections averaged over Maxwellian neutron distributions with temperatures ranging from kT = 5 keV to kT = 100 keV were derived for comparison with stellar nucleosynthesis calculations. For the three isotopes shielded from the astrophysical r-process, /sup 122/Te, /sup 123/Te and /sup 124/Te at kT = 30 keV the respective values were (280 /plus minus/ 10) mb, (819 /plus minus/ 30) mb and (154 /plus minus/ 6) mb. The corresponding products of cross section and solar system abundance are nearly equal in close agreement with s-process nucleosynthesis calculations. 26 refs., 8 figs., 10 tabs.

  11. TE Connectivity Finds Answers in Tomography

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TE Connectivity Finds Answers in Tomography TE Connectivity Finds Answers in Tomography Print Thursday, 22 August 2013 10:50 TE Connectivity is a world leader in connectivity-the...

  12. Optical phonons in PbTe/CdTe multilayer heterostructures

    SciTech Connect (OSTI)

    Novikova, N. N.; Yakovlev, V. A.; Kucherenko, I. V.; Karczewski, G.; Aleshchenko, Yu. A.; Muratov, A. V.; Zavaritskaya, T. N.; Melnik, N. N.

    2015-05-15

    The infrared reflection spectra of PbTe/CdTe multilayer nanostructures grown by molecular-beam epitaxy are measured in the frequency range of 20–5000 cm{sup −1} at room temperature. The thicknesses and high-frequency dielectric constants of the PbTe and CdTe layers and the frequencies of the transverse optical (TO) phonons in these structures are determined from dispersion analysis of the spectra. It is found that the samples under study are characterized by two TO phonon frequencies, equal to 28 and 47 cm{sup −1}. The first frequency is close to that of TO phonons in bulk PbTe, and the second is assigned to the optical mode in structurally distorted interface layers. The Raman-scattering spectra upon excitation with the radiation of an Ar{sup +} laser at 514.5 nm are measured at room and liquid-nitrogen temperatures. The weak line at 106 cm{sup −1} observed in these spectra is attributed to longitudinal optical phonons in the interface layers.

  13. TE Connectivity Finds Answers in Tomography

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TE Connectivity Finds Answers in Tomography TE Connectivity Finds Answers in Tomography Print Thursday, 22 August 2013 10:50 TE Connectivity is a world leader in connectivity-the $13 billion global company designs and manufactures more than 500,000 different electronic connectivity products for the automotive, energy, industrial, broadband communications, consumer device, healthcare, aerospace, and defense industries. TE Connectivity has a long-standing commitment to innovation and engineering

  14. TE Connectivity Finds Answers in Tomography

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TE Connectivity Finds Answers in Tomography TE Connectivity Finds Answers in Tomography Print Thursday, 22 August 2013 10:50 TE Connectivity is a world leader in connectivity-the $13 billion global company designs and manufactures more than 500,000 different electronic connectivity products for the automotive, energy, industrial, broadband communications, consumer device, healthcare, aerospace, and defense industries. TE Connectivity has a long-standing commitment to innovation and engineering

  15. Recycling of CdTe photovoltaic waste

    DOE Patents [OSTI]

    Goozner, Robert E.; Long, Mark O.; Drinkard, Jr., William F.

    1999-01-01

    A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate and electrolyzing the leachate to separate Cd from Te, wherein the Te is deposits onto a cathode while the Cd remains in solution.

  16. TE Connectivity Finds Answers in Tomography

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    healthcare, aerospace, and defense industries. TE Connectivity has a long-standing commitment to innovation and engineering excellence. Their products help address challenges...

  17. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    " ' & ( &1; &25; 6 &26; &24; ( & &30; &24; &30; ( 2&3; &1; 2& &30; % ) &26; &1; &25; ) &1; &19; & &25; O c a n P a c i f i q u e P a c i f i c O c e a n O c a n o P a c f i c o O c a n A t l a n t i q u ...

  18. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    ... Refineras Refineries Refinera Raffinerie Asphalt ... Usine de valorisation United States Estados Unidos ... Ltd 71 Marathon Petroleum Co LP 106 Silver Eagle ...

  19. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    4 3 2 1 9 8 7 6 5 4 3 2 1 20 19 18 17 16 15 14 13 12 11 10 10°W 20°W 30°W 40°W 50°W 60°W 70°W 70°W 80°W 80°W 90°W 90°W 100°W 100°W 110°W 110°W 120°W 120°W 130°W 130°W 140°W 140°W 150°W 150°W 160°W 170°W 180° 170°E 160°E 150°E 140°E 70°N 70°N 60°N 60°N 50°N 50°N 40°N 40°N 30°N 30°N 20°N 20°N 10°N 10°N 0 250 500 750 1,000 125 Miles / Millas / Milles 1:12 000 000 Border Crossings of Liquids Pipelines, North America Cruces Fronterizos de Ductos de

  20. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    9 8 7 6 5 4 3 2 1 9 8 7 6 5 4 3 2 1 15 14 13 12 11 10 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 10°W 20°W 30°W 40°W 50°W 60°W 70°W 70°W 80°W 80°W 90°W 90°W 100°W 100°W 110°W 110°W 120°W 120°W 130°W 130°W 140°W 140°W 150°W 150°W 160°W 170°W 180° 170°E 160°E 150°E 140°E 70°N 70°N 60°N 60°N 50°N 50°N 40°N 40°N 30°N 30°N 20°N 20°N 10°N 10°N Border Crossings of Natural Gas Pipelines, North America Cruces Fronterizos de Ductos de Gas Natural,

  1. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    10°W 20°W 30°W 40°W 50°W 60°W 70°W 70°W 80°W 80°W 90°W 90°W 100°W 100°W 110°W 110°W 120°W 120°W 130°W 130°W 140°W 140°W 150°W 150°W 160°W 170°W 180° 170°E 160°E 150°E 140°E 70°N 70°N 60°N 60°N 50°N 50°N 40°N 40°N 30°N 30°N 20°N 20°N 10°N 10°N 0 250 500 750 1,000 125 Miles / Millas / Milles 1:12 000 000 Coal Carbón Charbon Petroleum Petrolíferos Pétrole Geothermal Geotérmica Géothermie Hydroelectric Hidroeléctrica Hydroélectrique Natural Gas Gas

  2. Te

    U.S. Energy Information Administration (EIA) Indexed Site

         + + 2 )  3 " /  $ "     ( % * !  6      / , * " ! & ,   + 2 )    ( % * ! <       , 6" + + "   + + 2" ))"     ( % * '/   , ) /   " 0, 2/ " 0      & / " 1   , / *  )

  3. Te

    U.S. Energy Information Administration (EIA) Indexed Site

         - - 4 +   5 $ 1 & $     * ' , # 8       1. , $ # (.   - 4 +     * ' , # >      . 8 $ - - $   - - 4 $ + + $     * ' , )1  . + 1  $ 2. 4 1" $ 2      + . ! +   . 1(9 . - 3 +   11 # ( - " $   $ " 4 12.   . + 1  

  4. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    0&1; &27; , )&30; & " 0&6; &1; &25; &27; &23;&1; &19; + 0, )" & ))" * " + 1 &1; &24; , * &30; )&1; &18; & " 1 &5; O c a n P a c i f i q u e P a c i f i c O c e a n O c a n o P a c f i c o O c a n A t l ...

  5. Te

    U.S. Energy Information Administration (EIA) Indexed Site

    &29; . + (1 2&6; &1; &27; &29; &25;&1; &19; - 2. + (+ + , - 3 &1; &21; . 1(9 . - 3 + &1; &20; + . + &5; O c a n P a c i f i q u e P a c i f i c O c e a n O c a n o P a c f i c o O c a n A t l ...

  6. CdTe devices and method of manufacturing same

    SciTech Connect (OSTI)

    Gessert, Timothy A.; Noufi, Rommel; Dhere, Ramesh G.; Albin, David S.; Barnes, Teresa; Burst, James; Duenow, Joel N.; Reese, Matthew

    2015-09-29

    A method of producing polycrystalline CdTe materials and devices that incorporate the polycrystalline CdTe materials are provided. In particular, a method of producing polycrystalline p-doped CdTe thin films for use in CdTe solar cells in which the CdTe thin films possess enhanced acceptor densities and minority carrier lifetimes, resulting in enhanced efficiency of the solar cells containing the CdTe material are provided.

  7. High performance Zintl phase TE materials with embedded nanoparticles...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Zintl phase TE materials with embedded nanoparticles High performance Zintl phase TE materials with embedded nanoparticles Performance of zintl phase thermoelectric ...

  8. Recycling of CdTe photovoltaic waste

    DOE Patents [OSTI]

    Goozner, Robert E.; Long, Mark O.; Drinkard, Jr., William F.

    1999-04-27

    A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base.

  9. Recycling of CdTe photovoltaic waste

    DOE Patents [OSTI]

    Goozner, R.E.; Long, M.O.; Drinkard, W.F. Jr.

    1999-04-27

    A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base. 3 figs.

  10. Nonlinear terahertz response of HgTe/CdTe quantum wells

    SciTech Connect (OSTI)

    Chen, Qinjun; Sanderson, Matthew; Zhang, Chao

    2015-08-24

    Without breaking the topological order, HgTe/CdTe quantum wells can have two types of bulk band structure: direct gap type (type I) and indirect gap type (type II). We report that the strong nonlinear optical responses exist in both types of bulk states under a moderate electric field in the terahertz regime. Interestingly, for the type II band structure, the third order conductivity changes sign when chemical potentials lies below 10 meV due to the significant response of the hole excitation close to the bottom of conduction band. Negative nonlinear conductivities suggest that HgTe/CdTe quantum wells can find application in the gain medium of a laser for terahertz radiation. The thermal influences on nonlinear optical responses of HgTe/CdTe quantum wells are also studied.

  11. Thermodynamic and Transport Properties of YTe3, LaTe3 and CeTe3

    SciTech Connect (OSTI)

    Ru, N.

    2011-08-19

    Measurements of heat capacity, susceptibility, and electrical resistivity are presented for single crystals of the charge density wave compounds YTe{sub 3}, LaTe{sub 3}, and CeTe{sub 3}. The materials are metallic to low temperatures, but have a small density of states due to the charge density wave gapping large portions of the Fermi surface. CeTe{sub 3} is found to be a weak Kondo lattice, with an antiferromagnetic ground state and T{sub N} = 2.8 K. The electrical resistivity of all three compounds is highly anisotropic, confirming the weak dispersion perpendicular to Te planes predicted by band structure calculations.

  12. GaTe semiconductor for radiation detection

    DOE Patents [OSTI]

    Payne, Stephen A.; Burger, Arnold; Mandal, Krishna C.

    2009-06-23

    GaTe semiconductor is used as a room-temperature radiation detector. GaTe has useful properties for radiation detectors: ideal bandgap, favorable mobilities, low melting point (no evaporation), non-hygroscopic nature, and availability of high-purity starting materials. The detector can be used, e.g., for detection of illicit nuclear weapons and radiological dispersed devices at ports of entry, in cities, and off shore and for determination of medical isotopes present in a patient.

  13. Efficiency, Cost and Weight Trade-off in TE Power Generation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    TE Materials with Embedded Particles High performance Zintl phase TE materials with embedded nanoparticles High performance Zintl phase TE materials with embedded nanoparticles

  14. Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Zhao, Xin-Hao; Campbell, Calli M.; DiNezza, Michael J.; Liu, Shi; Zhao, Yuan; Zhang, Yong-Hang

    2014-12-22

    The bulk Shockley-Read-Hall carrier lifetime of CdTe and interface recombination velocity at the CdTe/Mg{sub 0.24}Cd{sub 0.76}Te heterointerface are estimated to be around 0.5??s and (4.7??0.4)??10{sup 2?}cm/s, respectively, using time-resolved photoluminescence (PL) measurements. Four CdTe/MgCdTe double heterostructures (DHs) with varying CdTe layer thicknesses were grown on nearly lattice-matched InSb (001) substrates using molecular beam epitaxy. The longest lifetime of 179?ns is observed in the DH with a 2??m thick CdTe layer. It is also shown that the photon recycling effect has a strong influence on the bulk radiative lifetime, and the reabsorption process affects the measured PL spectrum shape and intensity.

  15. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals...

    Office of Scientific and Technical Information (OSTI)

    temperature gradient, we observed the migration of Te inclusions from a low-temperature ... These results show that the migration, diffusion, and reaction of Te with Cd in the matrix ...

  16. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals...

    Office of Scientific and Technical Information (OSTI)

    Nuclear Radiation Detectors Citation Details In-Document Search Title: Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear ...

  17. Effect and optimization of CdS/CdTe interdiffusion on CdTe electrical properties and CdS/CdTe cell performance

    SciTech Connect (OSTI)

    Song, W.; Mao, D.; Kaydanov, V.; Ohno, T.R.; Trefny, J.V.; Levi, D.H.; Johnston, S. McCandless, B.E.

    1999-03-01

    We have investigated the effect of the CdS/CdTe interdiffusion on the properties of the CdTe films and the CdS/CdTe cell performance. Sulfur (S) diffusion into the CdTe films leads to a decreased defect density in the films, improvement of cell performance, and possibly to the increase of the carrier lifetime in the films. Cell performance is improved with the increase of the amount of S in the CdTe films. S diffusion into CdTe also deteriorates the uniformity of the CdS window layers, resulting in worse cell performance. Based on this study, we propose a processing method to improve cell performance. {copyright} {ital 1999 American Institute of Physics.}

  18. New chalcogenide glasses in the CdTe-AgI-As{sub 2}Te{sub 3} system

    SciTech Connect (OSTI)

    Kassem, M.; Le Coq, D.; Boidin, R.; Bychkov, E.; ULCO, LPCA, EA 4493, F-59140 Dunkerque

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Determination of the glass-forming region in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system. Black-Right-Pointing-Pointer Characterization of macroscopic properties of the new CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Characterization of the total conductivity of CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Comparison between the selenide and telluride equivalent systems. -- Abstract: Chalcogenide glasses in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system were synthesized and the glass-forming range was determined. The maximum content of CdTe in this glass system was found to be equal to 15 mol.%. The macroscopic characterizations of samples have consisted in Differential Scanning Calorimetry, density, and X-ray diffraction measurements. The cadmium telluride addition does not generate any significant change in the glass transition temperature but the resistance of binary AgI-As{sub 2}Te{sub 3} glasses towards crystallisation is estimated to be decreasing on the base of {Delta}T = T{sub x} - T{sub g} parameter. The total electrical conductivity {sigma} was measured by complex impedance spectroscopy. First, the CdTe additions in the (AgI){sub 0.5}(As{sub 2}Te{sub 3}){sub 0.5} host glass, (CdTe){sub x}(AgI){sub 0.5-x/2}(As{sub 2}Te{sub 3}){sub 0.5-x/2} lead to a conductivity decrease at x {<=} 0.05. Then, the behaviour is reversed at 0.05 {<=} x {<=} 0.15. The obtained results are discussed by comparison with the equivalent selenide system.

  19. Surveying The TeV Sky With Milagro

    SciTech Connect (OSTI)

    Walker, G. P.

    2006-11-17

    A wide field of view, high duty factor TeV gamma-ray observatory is essential for studying TeV astrophysical sources, because most of these sources are either highly variable or are extended. Milagro is such a TeV detector and has performed the deepest survey of the Northern Hemisphere sky. In addition to detecting the Crab Nebula and Mrk 421, which are known TeV sources, Milagro has made the first detection of diffuse TeV emission from the Galactic plane. The Milagro data has been searched for unknown point sources and extended sources. A new extended TeV source is seen and is coincident with an EGRET unidentified source. Based on the success of Milagro, a second generation water Cherenkov gamma-ray observatory is planned which will give an increase in sensitivity of more than an order of magnitude.

  20. Astrophysics and Cosmology with TeV Gamma Rays

    SciTech Connect (OSTI)

    Aharonian, Felix

    2005-07-13

    I will discuss the astrophysical and cosmological implications of recent exciting discoveries of TeV gamma-rays from objects representing several Galactic and Extragalactic source populations.

  1. Luminosity goals for a 100-TeV pp collider

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hinchliffe, Ian; Kotwal, Ashutosh; Mangano, Michelangelo L.; Quigg, Chris; Wang, Lian-Tao

    2015-08-20

    We consider diverse examples of science goals that provide a framework to assess luminosity goals for a future 100-TeV proton-proton collider.

  2. High Performance Zintl Phase TE Materials with Embedded Particles...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Presents results from embedding nanoparticles in magnesium silicide alloy matrix ... Zintl Phase Materials with Embedded Nanoparticles High performance Zintl phase TE ...

  3. Battle Mountain Band - Te-Moak: Solar Energy Park

    Energy Savers [EERE]

    Battle Mountain Band - Te-Moak Chairman Joseph Holley and Vice-chairman Mark Oppenhein, Members Donna Hill, Delbert Holley, Lydia Johnson, and Lydell Oppenhein Solar Energy Park ...

  4. Luminosity goals for a 100-TeV pp collider

    SciTech Connect (OSTI)

    Hinchliffe, Ian; Kotwal, Ashutosh; Mangano, Michelangelo L.; Quigg, Chris; Wang, Lian-Tao

    2015-04-23

    We consider diverse examples of science goals that provide a framework to assess luminosity goals for a future 100-TeV proton-proton collider.

  5. Pressure dependence of the charge-density-wave and superconducting states in GdTe3, TbTe3, and DyTe3

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zocco, D. A.; Hamlin, J. J.; Grube, K.; Chu, J. -H.; Kuo, H. -H.; Fisher, I. R.; Maple, M. B.

    2015-05-14

    Here, we present electrical resistivity and ac-susceptibility measurements of GdTe3, TbTe3 and DyTe3 performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of dTCW,1/dP~ –85K/GPa. For TbTe3 and DyTe3, a second CDW below TCDW,2 increases with pressure until it reaches the TCDW,1(P) line. For GdTe3, the lower CDW emerges as pressure is increased above ~1GPa. As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on TbTe3 provide compelling evidence for bulk SC in the low-pressure region of the phase diagram. We provide measurements ofmore » superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.« less

  6. Copper migration in CdTe heterojunction solar cells

    SciTech Connect (OSTI)

    Chou, H.C.; Rohatgi, A.; Jokerst, N.M.; Thomas, E.W.; Kamra, S.

    1996-07-01

    CdTe solar cells were fabricated by depositing a Au/Cu contact with Cu thickness in the range of 50 to 150A on polycrystalline CdTe/CdS/SnO{sub 2} glass structures. The increase in Cu thickness improves ohmic contact and reduces series resistance (R{sub s}), but the excess Cu tends to diffuse into CdTe and lower shunt resistance (R{sub sh}) and cell performance. Light I-V and secondary ion mass spectroscopy (SIMS) measurements were performed to understand the correlations between the Cu contact thickness, the extent of Cu incorporation in the CdTe cells, and its impact on the cell performance. The CdTe/CdS/SnO{sub 2} glass, CdTe/CdS/GaAs, and CdTe/GaAs structures were prepared in an attempt to achieve CdTe films with different degrees of crystallinity and grain size. A large grain polycrystalline CdTe thin film solar cell was obtained for the first time by selective etching the GaAs substrate coupled with the film transfer onto a glass substrate. SIMS measurement showed that poor crystallinity and smaller grain size of the CdTe film promotes Cu diffusion and decreases the cell performance. Therefore, grain boundaries are the main conduits for Cu migration and larger CdTe grain size or alternate method of contact formation can mitigate the adverse effect of Cu and improve the cell performance. 15 refs., 1 fig.,6 tabs.

  7. High performance Zintl phase TE materials with embedded nanoparticles |

    Broader source: Energy.gov (indexed) [DOE]

    Department of Energy Performance of zintl phase thermoelectric materials with embedded particles are evaluated shakouri.pdf (2.3 MB) More Documents & Publications High performance Zintl phase TE materials with embedded nanoparticles High Performance Zintl Phase TE Materials with Embedded Particles Thermoelectrics Partnership: High Performance Thermoelectric Waste Heat Recovery System Based on Zintl Phase Materials with Embedded Nanoparticles

  8. ETA-NAC007 - Control of Measuring and Test Equipment (M&TE)

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Control of Measuring and Test Equipment (M&TE) Prepared by Electric Transportation ... of calibration standards and Measuring and Test Equipment (M&TE) used for measuring, ...

  9. ETA-UAC07 - Control of Measuring and Test Equipment (M&TE)

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    "Control of Measuring and Test Equipment (M&TE)" Prepared by Electric Transportation ... of calibration standards and Measuring and Test Equipment (M&TE) used for measuring, ...

  10. Thermoelectric device including an alloy of GeTe and AgSbTe as the P-type element

    DOE Patents [OSTI]

    Skrabek, Emanuel Andrew; Trimmer, Donald Smith

    1976-01-01

    Improved alloys suitable for thermoelectric applications and having the general formula: (AgSbTe.sub.2).sub.1.sub.-x + (GeTe).sub.x wherein x has a value of about 0.80 and 0.85, have been found to possess unexpectedly high thermoelectric properties such as efficiency index, as well as other improved physical properties.

  11. Multiband Te p Based Superconductivity of Ta4Pd3Te16

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Singh, David J.

    2014-10-06

    We recently discovered that Ta4Pd3Te16 is a superconductor that has been suggested to be an unconventional superconductor near magnetism. Here, we report electronic structure calculations showing that despite the layered crystal structure the material is an anisotropic three-dimensional (3D) metal. The Fermi surface contains prominent one-dimensional (1D) and two-dimensional (2D) features, including nested 1D sheets, a 2D cylindrical section, and a 3D sheet. Moreover, the electronic states that make up the Fermi surface are mostly derived from Te p states with small Ta d and Pd d contributions. This places the compound far from magnetic instabilities. The results are discussedmore » in terms of multiband superconductivity.« less

  12. Use of separate ZnTe interface layers to form OHMIC contacts to p-CdTe films

    DOE Patents [OSTI]

    Gessert, Timothy A.

    1999-01-01

    A method of improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurim-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact.

  13. Use of separate ZnTe interface layers to form ohmic contacts to p-CdTe films

    DOE Patents [OSTI]

    Gessert, T.A.

    1999-06-01

    A method of is disclosed improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurium-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact. 11 figs.

  14. Surveying the TeV Sky with Milagro

    SciTech Connect (OSTI)

    Lansdell, C. P.

    2006-07-11

    A wide field of view, high duty factor, TeV gamma-ray observatory is essential for studying TeV astrophysical sources, because most of these sources are either highly variable or are extended. Milagro is such a TeV detector and has performed the deepest survey of the Northern Hemisphere sky. In addition to detecting the known TeV sources of the Crab Nebula and Markarian 421, Milagro has made the first detection of diffuse TeV emission from the Galactic plane. The Milagro data has been searched for unknown point sources and extended sources. Evidence for a new extended TeV source is seen and is coincident with an EGRET unidentified source. The Milagro data has also been searched for the predicted TeV emitters of gamma-ray bursts, galaxy clusters, and EGRET unidentified sources. Based on the success of Milagro, a second generation water Cherenkov gamma-ray observatory is planned which will give an increase in sensitivity of more than an order of magnitude.

  15. Electrochemically deposited BiTe-based nanowires for thermoelectric applications

    SciTech Connect (OSTI)

    Ng, Inn-Khuan; Kok, Kuan-Ying; Rahman, Che Zuraini Che Ab; Saidin, Nur Ubaidah; Ilias, Suhaila Hani; Choo, Thye-Foo

    2014-02-12

    Nanostructured materials systems such as thin-films and nanowires (NWs) are promising for thermoelectric power generation and refrigeration compared to traditional counterparts in bulk, due to their enhanced thermoelectric figures-of-merit. BiTe and its derivative compounds, in particular, are well-known for their near-room temperature thermoelectric performance. In this work, both the binary and ternary BiTe-based nanowires namely, BiTe and BiSbTe, were synthesized using template-assisted electrodeposition. Diameters of the nanowires were controlled by the pore sizes of the anodised alumina (AAO) templates used. Systematic study on the compositional change as a function of applied potential was carried out via Linear Sweep Voltanmetry (LSV). Chemical compositions of the nanowires were studied using Energy Dispersive X-ray Spectrometry (EDXS) and their microstructures evaluated using diffraction and imaging techniques. Results from chemical analysis on the nanowires indicated that while the Sb content in BiSbTe nanowires increased with more negative deposition potentials, the formation of Te{sup 0} and Bi{sub 2}Te{sub 3} were favorable at more positive potentials.

  16. Cu Migration in Polycrystalline CdTe Solar Cells

    SciTech Connect (OSTI)

    Guo, Da; Akis, Richard; Brinkman, Daniel; Sankin, Igor; Fang, Tian; Vasileska, Dragica; Ringhofer, Christian

    2014-03-12

    An impurity reaction-diffusion model is applied to Cu defects and related intrinsic defects in polycrystalline CdTe for a better understanding of Cu’s role in the cell level reliability of CdTe PV devices. The simulation yields transient Cu distributions in polycrystalline CdTe during solar cell processing and stressing. Preliminary results for Cu migration using available diffusivity and solubility data show that Cu accumulates near the back contact, a phenomena that is commonly observed in devices after back-contact processing or stress conditions.

  17. Process Development for High Voc CdTe Solar Cells

    SciTech Connect (OSTI)

    Ferekides, C. S.; Morel, D. L.

    2011-05-01

    This is a cumulative and final report for Phases I, II and III of this NREL funded project (subcontract # XXL-5-44205-10). The main research activities of this project focused on the open-circuit voltage of the CdTe thin film solar cells. Although, thin film CdTe continues to be one of the leading materials for large-scale cost-effective production of photovoltaics, the efficiency of the CdTe solar cells have been stagnant for the last few years. This report describes and summarizes the results for this 3-year research project.

  18. Ba2TeO: A new layered oxytelluride

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J. B.; Tokumoto, T. D.; McGill, S. A.; Singh, D. J.; Siegrist, T.

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

  19. Modeling Copper Diffusion in Polycrystalline CdTe Solar Cells

    SciTech Connect (OSTI)

    Akis, Richard; Brinkman, Daniel; Sankin, Igor; Fang, Tian; Guo, Da; Vasileska, Dragica; Ringhofer, Christain

    2014-06-06

    It is well known that Cu plays an important role in CdTe solar cell performance as a dopant. In this work, a finite-difference method is developed and used to simulate Cu diffusion in CdTe solar cells. In the simulations, which are done on a two-dimensional (2D) domain, the CdTe is assumed to be polycrystalline, with the individual grains separated by grain boundaries. When used to fit experimental Cu concentration data, bulk and grain boundary diffusion coefficients and activation energies for CdTe can be extracted. In the past, diffusion coefficients have been typically obtained by fitting data to simple functional forms of limited validity. By doing full simulations, the simplifying assumptions used in those analytical models are avoided and diffusion parameters can thus be determined more accurately

  20. Extracting Cu Diffusion Parameters in Polycrystalline CdTe

    SciTech Connect (OSTI)

    Akis, Richard; Brinkman, Daniel; Sankin, Igor; Fang, Tian; Guo, Da; Dragica, Vasileska; Ringhofer, Christian

    2014-06-13

    It is well known that Cu plays an important role in CdTe solar cell performance as a dopant. In this work, a finite-difference method is developed and used to simulate Cu diffusion in CdTe solar cells. In the simulations, which are done on a two-dimensional (2D) domain, the CdTe is assumed to be polycrystal-line, with the individual grains separated by grain boundaries. When used to fit experimental Cu concentration data, bulk and grain boundary diffusion coefficients and activation energies for CdTe can be extracted. In the past, diffusion coefficients have been typically obtained by fitting data to simple functional forms of limited validity. By doing full simulations, the simplifying assumptions used in those analytical models are avoided and diffusion parameters can thus be determined more accurately.

  1. CdTe Solar Cells: The Role of Copper

    SciTech Connect (OSTI)

    Guo, Da; Akis, Richard; Brinkman, Daniel; Sankin, Igor; Fang, Tian; Vasileska, Dragica; Ringhofer, Christain

    2014-06-06

    In this work, we report on developing 1D reaction-diffusion solver to understand the kinetics of p-type doping formation in CdTe absorbers and to shine some light on underlying causes of metastabilities observed in CdTe PV devices. Evolution of intrinsic and Cu-related defects in CdTe solar cell has been studied in time-space domain self-consistently with free carrier transport and Poisson equation. Resulting device performance was simulated as a function of Cu diffusion anneal time showing pronounced effect the evolution of associated acceptor and donor states can cause on device characteristics. Although 1D simulation has intrinsic limitations when applied to poly-crystalline films, the results suggest strong potential of the approach in better understanding of the performance and metastabilities of CdTe photovoltaic device.

  2. PVA TePla AG | Open Energy Information

    Open Energy Info (EERE)

    search Name: PVA TePla AG Place: Asslar, Germany Zip: 35614 Product: Supplier of plants and equipment for vacuum systems, crystal-growing systems and plasma systems, some of...

  3. Summary of the TeV33 working group

    SciTech Connect (OSTI)

    Bagley, P.P.; Bieniosek, F.M.; Colestock, P.

    1996-10-01

    This summary of the TeV33 working group at Snowmass reports on work in the areas of Tevatron store parameters, the beam-beam interaction, Main Injector intensity (slip stacking), antiproton production, and electron cooling.

  4. Native defects in MBE-grown CdTe

    SciTech Connect (OSTI)

    Olender, Karolina; Wosinski, Tadeusz; Makosa, Andrzej; Tkaczyk, Zbigniew; Kolkovsky, Valery; Karczewski, Grzegorz

    2013-12-04

    Deep-level traps in both n- and p-type CdTe layers, grown by molecular-beam epitaxy on GaAs substrates, have been investigated by means of deep-level transient spectroscopy (DLTS). Four of the traps revealed in the DLTS spectra, which displayed exponential kinetics for capture of charge carriers into the trap states, have been assigned to native point defects: Cd interstitial, Cd vacancy, Te antisite defect and a complex formed of the Te antisite and Cd vacancy. Three further traps, displaying logarithmic capture kinetics, have been ascribed to electron states of treading dislocations generated at the mismatched interface with the substrate and propagated through the CdTe layer.

  5. Extreme solid state refrigeration using nanostructured Bi-Te alloys.

    SciTech Connect (OSTI)

    Lima Sharma, Ana L.; Spataru, Dan Catalin; Medlin, Douglas L.; Sharma, Peter Anand; Morales, Alfredo Martin

    2009-09-01

    Materials are desperately needed for cryogenic solid state refrigeration. We have investigated nanostructured Bi-Te alloys for their potential use in Ettingshausen refrigeration to liquid nitrogen temperatures. These alloys form alternating layers of Bi{sub 2} and Bi{sub 2}Te{sub 3} blocks in equilibrium. The composition Bi{sub 4}Te{sub 3} was identified as having the greatest potential for having a high Ettingshausen figure of merit. Both single crystal and polycrystalline forms of this material were synthesized. After evaluating the Ettingshausen figure of merit for a large, high quality polycrystal, we simulated the limits of practical refrigeration in this material from 200 to 77 K using a simple device model. The band structure was also computed and compared to experiments. We discuss the crystal growth, transport physics, and practical refrigeration potential of Bi-Te alloys.

  6. Substrate CdTe Efficiency Improvements - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Substrate CdTe Efficiency Improvements National Renewable Energy Laboratory Contact NREL About This Technology Publications: PDF Document Publication 11-28PCT Application as-published (984 KB) Technology Marketing Summary Thin film solar cells have been the focus of many research facilities in recent years that are working to decrease manufacturing costs and increase cell efficiency. Cadmium telluride (CdTe) has been well recognized as a promising photovoltaic material for thin film solar cells

  7. High-quality CdTe films from nanoparticle precursors

    SciTech Connect (OSTI)

    Schulz, D.L.; Pehnt, M.; Urgiles, E.

    1996-05-01

    In this paper the authors demonstrate that nanoparticulate precursors coupled with spray deposition offers an attractive route into electronic materials with improved smoothness, density, and lower processing temperatures. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25-75 {Angstrom} diameter) onto substrates at elevated temperatures (T = 280-440{degrees}C) with no further thermal treatment. These films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD, with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C and substantial O. AFM gave CdTe grain sizes of {approx}0.1-0.3 {mu}m for film sprayed at 400{degrees}C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed.

  8. Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics

    SciTech Connect (OSTI)

    Li, Chen [ORNL] [ORNL; Ma, Jie [ORNL] [ORNL; May, Andrew F [ORNL] [ORNL; Cao, Huibo [ORNL] [ORNL; Christianson, Andrew D [ORNL] [ORNL; Ehlers, Georg [ORNL] [ORNL; Singh, David J [ORNL] [ORNL; Sales, Brian C [ORNL] [ORNL; Delaire, Olivier A [ORNL] [ORNL

    2014-01-01

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase-space for three-phonon scattering processes, rather than just the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optical ferroelectric mode.

  9. Effects of Cu Diffusion from ZnTe:Cu/Ti Contacts on Carrier Lifetime of CdS/CdTe Thin Film Solar Cells: Preprint

    SciTech Connect (OSTI)

    Gessert, T. A.; Metzger, W. K.; Asher, S. E.; Young, M. R.; Johnston, S.; Dhere, R. G.; Duda, A.

    2008-05-01

    We study the performance of CdS/CdTe thin film PV devices processed with a ZnTe:Cu/Ti contact to investigate how carrier lifetime in the CdTe layer is affected by Cu diffusion from the contact.

  10. Local composition and carrier concentration in Pb0.7Ge0.3Te and Pb0.5Ge0.5Te alloys from 125Te NMR and microscopy

    SciTech Connect (OSTI)

    Levin, E M; Kramer, M J; Schmidt-Rohr, K

    2014-11-01

    Pb0.7Ge0.3Te and Pb0.5Ge0.5Te alloys, (i) quenched from 923 K or (ii) quenched and annealed at 573 K for 2 h, have been studied by 125Te NMR, X-ray diffraction, electron and optical microscopy, as well as energy dispersive spectroscopy. Depending on the composition and thermal treatment history, 125Te NMR spectra exhibit different resonance frequencies and spin-lattice relaxation times, which can be assigned to different phases in the alloy. Quenched and annealed Pb0.7Ge0.3Te alloys can be considered as solid solutions but are shown by NMR to have components with various carrier concentrations. Quenched and annealed Pb0.5Ge0.5Te alloys contain GeTe- and PbTe-based phases with different compositions and charge carrier concentrations. Based on the analysis of non-exponential 125Te NMR spin-lattice relaxation, the fractions and carrier concentrations of the various phases have been estimated. Our data show that alloying of PbTe with Ge results in the formation of chemically and electronically inhomogeneous systems. 125Te NMR can be used as an efficient probe to detect the local composition in equilibrium as well as non-equilibrium states, and to determine the local carrier concentrations in complex multiphase tellurides.

  11. Heterojunctions of model CdTe/CdSe mixtures

    SciTech Connect (OSTI)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-03-18

    We report on the strain behavior of compound mixtures of model group IIVI semiconductors. We use the StillingerWeber Hamiltonian that we recently introduced, specifically developed to model binary mixtures of group IIVI compounds such as CdTe and CdSe. We also employ molecular dynamics simulations to examine the behavior of thin sheets of material, bilayers of CdTe and CdSe. The lattice mismatch between the two compounds leads to a strong bending of the entire sheet, with about a 0.5 to 1 deflection between neighboring planes. To further analyze bilayer bending, we introduce a simple one-dimensional model and use energy minimization to find the angle of deflection. The analysis is equivalent to a least-squares straight line fit. We consider the effects of bilayers which are asymmetric with respect to the thickness of the CdTe and CdSe parts. We thus learn that the bending can be subdivided into four kinds depending on the compressive/tensile nature of each outer plane of the sheet. We use this approach to directly compare our findings with experimental results on the bending of CdTe/CdSe rods. To reduce the effects of the lattice mismatch we explore diffuse interfaces, where we mix (i.e. alloy) Te and Se, and estimate the strain response.

  12. Heterojunctions of model CdTe/CdSe mixtures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-03-18

    We report on the strain behavior of compound mixtures of model group II-VI semiconductors. We use the Stillinger-Weber Hamiltonian that we recently introduced, specifically developed to model binary mixtures of group II-VI compounds such as CdTe and CdSe. We also employ molecular dynamics simulations to examine the behavior of thin sheets of material, bilayers of CdTe and CdSe. The lattice mismatch between the two compounds leads to a strong bending of the entire sheet, with about a 0.5 to 1° deflection between neighboring planes. To further analyze bilayer bending, we introduce a simple one-dimensional model and use energy minimization tomore » find the angle of deflection. The analysis is equivalent to a least-squares straight line fit. We consider the effects of bilayers which are asymmetric with respect to the thickness of the CdTe and CdSe parts. We thus learn that the bending can be subdivided into four kinds depending on the compressive/tensile nature of each outer plane of the sheet. We use this approach to directly compare our findings with experimental results on the bending of CdTe/CdSe rods. To reduce the effects of the lattice mismatch we explore diffuse interfaces, where we mix (i.e. alloy) Te and Se, and estimate the strain response.« less

  13. Heterojunctions of model CdTe/CdSe mixtures

    SciTech Connect (OSTI)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-03-18

    We report on the strain behavior of compound mixtures of model group II-VI semiconductors. We use the Stillinger-Weber Hamiltonian that we recently introduced, specifically developed to model binary mixtures of group II-VI compounds such as CdTe and CdSe. We also employ molecular dynamics simulations to examine the behavior of thin sheets of material, bilayers of CdTe and CdSe. The lattice mismatch between the two compounds leads to a strong bending of the entire sheet, with about a 0.5 to 1° deflection between neighboring planes. To further analyze bilayer bending, we introduce a simple one-dimensional model and use energy minimization to find the angle of deflection. The analysis is equivalent to a least-squares straight line fit. We consider the effects of bilayers which are asymmetric with respect to the thickness of the CdTe and CdSe parts. We thus learn that the bending can be subdivided into four kinds depending on the compressive/tensile nature of each outer plane of the sheet. We use this approach to directly compare our findings with experimental results on the bending of CdTe/CdSe rods. To reduce the effects of the lattice mismatch we explore diffuse interfaces, where we mix (i.e. alloy) Te and Se, and estimate the strain response.

  14. The half-life of {sup 131g,m}Te

    SciTech Connect (OSTI)

    Ruivo, J. C.; Zamboni, C. B.; Oliveira, J. R. B.; Heder Medina, Nilberto

    2013-05-06

    In this work, the half-lives of {sup 131m}Te and {sup 131g}Te were measured. Radioactive sources of {sup 131}Te were obtained using the {sup 130}Te(n,{gamma}){sup 131}Te nuclear reaction. These nuclear parameters have been determined with a better confidence and accuracy than previously available: 18.89 {+-} 0.11 min and 33.18 {+-} 0.13 h, respectively. These results are quite helpful for new calculations that attempt to describe the low-lying levels in {sup 131}I from the decay of {sup 131g,m}Te.

  15. Growth, steady-state, and time-resolved photoluminescence study of CdTe/MgCdTe double heterostructures on InSb substrates using molecular beam epitaxy

    SciTech Connect (OSTI)

    DiNezza, Michael J.; Liu, Shi; Kirk, Alexander P.; Zhang, Yong-Hang; School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 ; Zhao, Xin-Hao; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287

    2013-11-04

    CdTe/MgCdTe double heterostructures (DHs) are grown on InSb substrates using molecular beam epitaxy and reveal strong photoluminescence with over double the intensity of a GaAs/AlGaAs DH with an identical layer structure design grown on GaAs. Time-resolved photoluminescence of the CdTe/MgCdTe DH gives a Shockley-Read-Hall recombination lifetime of 86 ns, which is more than one order of magnitude longer than that of typical polycrystalline CdTe films. These findings indicate that monocrystalline CdTe/MgCdTe DHs effectively reduce surface recombination, have limited nonradiative interface recombination, and are promising for solar cells that could reach power conversion efficiencies similar to that of GaAs.

  16. Resetting the Defect Chemistry in CdTe

    SciTech Connect (OSTI)

    Metzger, Wyatt K.; Burst, James; Albin, David; Colegrove, Eric; Moseley, John; Duenow, Joel; Farrell, Stuart; Moutinho, Helio; Reese, Matt; Johnston, Steve; Barnes, Teresa; Perkins, Craig; Guthrey, Harvey; Al-Jassim, Mowafak

    2015-06-14

    CdTe cell efficiencies have increased from 17% to 21% in the past three years and now rival polycrystalline Si [1]. Research is now targeting 25% to displace Si, attain costs less than 40 cents/W, and reach grid parity. Recent efficiency gains have come largely from greater photocurrent. There is still headroom to lower costs and improve performance by increasing open-circuit voltage (Voc) and fill factor. Record-efficiency CdTe cells have been limited to Voc <; 880 mV, whereas GaAs can attain Voc of 1.10 V with a slightly smaller bandgap [2,3]. To overcome this barrier, we seek to understand and increase lifetime and carrier concentration in CdTe. In polycrystalline structures, lifetime can be limited by interface and grain-boundary recombination, and attaining high carrier concentration is complicated by morphology.

  17. Current enhancement of CdTe-based solar cells

    SciTech Connect (OSTI)

    Paudel, Naba R.; Poplawsky, Jonathan D.; More, Karren Leslie; Yan, Yanfa

    2015-07-30

    We report on the realization of CdTe solar cell photocurrent enhancement using an n-type CdSe heterojunction partner sputtered on commercial SnO2/SnO2:F coated soda-lime glass substrates. With high-temperature close-space sublimation CdTe deposition followed by CdCl2 activation, this thin-film stack allows for substantial interdiffusion at the CdSe/CdTe interface facilitating a CdSexTe1-x alloy formation. The bowing effect causes a reduced optical bandgap of the alloyed absorber layer and, therefore, leads to current enhancement in the long-wavelength region and a decrease in open-circuit voltage (VOC). To overcome the VOC loss and maintain a high short-circuit current (JSC), the CdTe cell configuration has been modified using combined CdS:O/CdSe window layers. The new device structure has demonstrated enhanced collection from both short-and long-wavelength regions as well as a VOC improvement. With an optimized synthesis process, a small-area cell using CdS:O/CdSe window layer showed an efficiency of 15.2% with a VOC of 831 mV, a JSC of 26.3 mA/cm2, and a fill factor of 69.5%, measured under an AM1.5 illumination without antireflection coating. Furthermore, the results provide new directions for further improvement of CdTe-based solar cells.

  18. Indication of Te segregation in laser-irradiated ZnTe observed by in situ coherent-phonon spectroscopy

    SciTech Connect (OSTI)

    Shimada, Toru; Kamaraju, N.; Frischkorn, Christian; Wolf, Martin; Kampfrath, Tobias

    2014-09-15

    We irradiate a ZnTe single crystal with 10-fs laser pulses at a repetition rate of 80 MHz and investigate its resulting gradual modification by means of coherent-phonon spectroscopy. We observe the emergence of a phonon mode at about 3.6 THz whose amplitude and lifetime grow monotonously with irradiation time. The speed of this process depends sensitively on the pump-pulse duration. Our observations strongly indicate that the emerging phonon mode arises from a Te phase induced by multiphoton absorption of incident laser pulses. A potential application of our findings is laser-machining of microstructures in the bulk of a ZnTe crystal, a highly relevant electrooptic material.

  19. CsBi4Te6: A High-Performance Thermoelectric Material for Low...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    thermoelectric properties of CsBi(4)Te(6) appear to match or exceed those of Bi(2-x)Sb(x)Te(3-y)Se(y) alloys. URL: Link to article - National Center for Biotechnology Information

  20. Current enhancement of CdTe-based solar cells (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Current enhancement of CdTe-based solar cells This content will become publicly available on July 30, 2016 Prev Next Title: Current enhancement of CdTe-based solar cells We ...

  1. Current enhancement of CdTe-based solar cells (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    CdTe-based solar cells Citation Details In-Document Search This content will become publicly available on July 30, 2016 Title: Current enhancement of CdTe-based solar cells We ...

  2. Energy Sources for Yotta-TeV Iceberg Showers (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Energy Sources for Yotta-TeV Iceberg Showers Citation Details In-Document Search Title: Energy Sources for Yotta-TeV Iceberg Showers In late February of 2002, warming climate along ...

  3. First-principles study of roles of Cu and Cl in polycrystalline CdTe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Ji -Hui; Yin, Wan -Jian; Park, Ji -Sang; Metzger, Wyatt; Wei, Su -Huai

    2016-01-25

    In this study, Cu and Cl treatments are important processes to achieve high efficiency polycrystalline cadmium telluride (CdTe) solar cells, thus it will be beneficial to understand the roles they play in both bulk CdTe and CdTe grain boundaries (GBs). Using first-principles calculations, we systematically study Cu and Cl-related defects in bulk CdTe. We find that Cl has only a limited effect on improving p-type doping and too much Cl can induce deep traps in bulk CdTe, whereas Cu can enhance ptype doping of bulk CdTe. In the presence of GBs, we find that, in general, Cl and Cu willmore » prefer to stay at GBs, especially for those with Te-Te wrong bonds, in agreement with experimental observations.« less

  4. CdTe Thin Film Solar Cells and Modules Tutorial; NREL (National Renewable Energy Laboratory)

    SciTech Connect (OSTI)

    Albin, David S.

    2015-06-13

    This is a tutorial presented at the 42nd IEEE Photovoltaics Specialists Conference to cover the introduction, background, and updates on CdTe cell and module technology, including CdTe cell and module structure and fabrication.

  5. Pressure-induced Phase Transition in Thiol-capped CdTe Nanoparticles

    SciTech Connect (OSTI)

    Wu, F; Zaug, J; Young, C; Zhang, J Z

    2006-11-29

    Phase transitions for CdTe nanoparticles (NPs) under high pressure up to 37.0 GPa have been studied using fluorescence measurements. The phase transition from cinnarbar to rocksalt phase has been observed in CdTe NPs solution at 5.8 GPa, which is much higher than the phase transition pressure of bulk CdTe (3.8 GPa) and that of CdTe NPs in solid form (0.8 GPa). CdTe NPs solution therefore shows elevated phase transition pressure and enhanced stability against pressure compared with bulk CdTe and CdTe NPs in solid forms. The enhanced stability of CdTe NPs solution has been attributed to possible shape change in the phase transition and/or inhomogeneous strains in nanoparticle solutions.

  6. Energy Sources for Yotta-TeV Iceberg Showers (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Energy Sources for Yotta-TeV Iceberg Showers Citation Details In-Document Search Title: Energy Sources for Yotta-TeV Iceberg Showers You are accessing a document from the ...

  7. Resonant Level Enhancement of the Thermoelectric Power of Bi2Te3...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Resonant Level Enhancement of the Thermoelectric Power of Bi2Te3 with Tin Resonant Level Enhancement of the Thermoelectric Power of Bi2Te3 with Tin Application to practical p-type...

  8. ETA-HIAC07 - Control of Measuring and Test Equipment (M&TE)

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Control of Measuring and Test Equipment (M&TE) Prepared by Electric Transportation ... The objective of this procedure is to assure that Measuring and Test Equipment (M&TE) used ...

  9. ETA-HAC07 - Control of Measuring and Test Equipment (M&TE)

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Control of Measuring and Test Equipment (M&TE) Prepared by Electric Transportation ... The objective of this procedure is to assure that Measuring and Test Equipment (M&TE) used ...

  10. Probing TeV physics in the structure of the neutron (Technical...

    Office of Scientific and Technical Information (OSTI)

    Probing TeV physics in the structure of the neutron Citation Details In-Document Search Title: Probing TeV physics in the structure of the neutron You are accessing a document ...

  11. APT mass spectrometry and SEM data for CdTe solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Chen; Paudel, Naba R.; Yan, Yanfa; Pennycook, Stephen J.; Poplawsky, Jonathan D.; Guo, Wei

    2016-03-16

    Atom probe tomography (APT) data acquired from a CAMECA LEAP 4000 XHR for the CdS/CdTe interface for a non-CdCl2 treated CdTe solar cell as well as the mass spectrum of an APT data set including a GB in a CdCl2-treated CdTe solar cell are presented. Scanning electron microscopy (SEM) data showing the evolution of sample preparation for APT and scanning transmission electron microscopy (STEM) electron beam induced current (EBIC) are also presented. As a result, these data show mass spectrometry peak decomposition of Cu and Te within an APT dataset, the CdS/CdTe interface of an untreated CdTe solar cell, preparationmore » of APT needles from the CdS/CdTe interface in superstrate grown CdTe solar cells, and the preparation of a cross-sectional STEM EBIC sample.« less

  12. TeV gamma rays from blazars beyond z = 1 ? (Journal Article)...

    Office of Scientific and Technical Information (OSTI)

    TeV gamma rays from blazars beyond z 1 ? Citation Details In-Document Search Title: TeV gamma rays from blazars beyond z 1 ? Authors: Aharonian, Felix ; Essey, Warren ; ...

  13. Junction Evolution During Fabrication of CdS/CdTe Thin-film PV Solar Cells (Presentation)

    SciTech Connect (OSTI)

    Gessert, T. A.

    2010-09-01

    Discussion of the formation of CdTe thin-film PV junctions and optimization of CdTe thin-film PV solar cells.

  14. TeVeS gets caught on caustics

    SciTech Connect (OSTI)

    Contaldi, Carlo R.; Wiseman, Toby; Withers, Benjamin

    2008-08-15

    TeVeS uses a dynamical vector field with timelike unit-norm constraint to specify a preferred local frame. When matter moves slowly in this frame--the so-called quasistatic regime--modified Newtonian dynamics results. Theories with such vectors (such as Einstein-Aether) are prone to the vector dynamics forming singularities that render their classical evolution problematic. Here, we analyze the dynamics of the vector in TeVeS in various situations. We begin by analytically showing that the vacuum solution of TeVeS forms caustic singularities under a large class of physically reasonably initial perturbations. This shows the classical evolution of TeVeS appears problematic in the absence of matter. We then consider matter by investigating black hole solutions. We find large classes of new black hole solutions with static geometries, where the curves generated by the vector field are attracted to the black hole and may form caustics. We go on to consider the full dynamics with matter by numerically simulating, assuming spherical symmetry, the gravitational collapse of a scalar, and the evolution of an initially nearly static boson star. We find that in both cases our initial data evolves so that the vector field develops caustic singularities on a time scale of order the gravitational in-fall time. Having shown singularity formation is generic with or without matter, Bekenstein's original formulation of TeVeS appears dynamically problematic. We argue that by modifying the vector field kinetic terms to the more general form used by Einstein-Aether, this problem may be avoided.

  15. Reverse Monte Carlo simulation of Se{sub 80}Te{sub 20} and Se{sub 80}Te{sub 15}Sb{sub 5} glasses

    SciTech Connect (OSTI)

    Abdel-Baset, A. M.; Rashad, M.; Moharram, A. H.

    2013-12-16

    Two-dimensional Monte Carlo of the total pair distribution functions g(r) is determined for Se{sub 80}Te{sub 20} and Se{sub 80}Te{sub 15}Sb{sub 5} alloys, and then it used to assemble the three-dimensional atomic configurations using the reverse Monte Carlo simulation. The partial pair distribution functions g{sub ij}(r) indicate that the basic structure unit in the Se{sub 80}Te{sub 15}Sb{sub 5} glass is di-antimony tri-selenide units connected together through Se-Se and Se-Te chain. The structure of Se{sub 80}Te{sub 20} alloys is a chain of Se-Te and Se-Se in addition to some rings of Se atoms.

  16. Superconducting Bi2Te: Pressure-induced universality in the (Bi2)m(Bi2Te3)n series

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stillwell, Ryan L.; Jeffries, Jason R.; Jenei, Zsolt; Weir, Samuel T.; Vohra, Yogesh K.

    2016-03-09

    Using high-pressure magnetotransport techniques we have discovered superconductivity in Bi2Te, a member of the infinitely adaptive (Bi2)m(Bi2Te3)n series, whose end members, Bi and Bi2Te3, can be tuned to display topological surface states or superconductivity. Bi2Te has a maximum Tc = 8.6 K at P = 14.5 GPa and goes through multiple high pressure phase transitions, ultimately collapsing into a bcc structure that suggests a universal behavior across the series. High-pressure magnetoresistance and Hall measurements suggest a semi-metal to metal transition near 5.4 GPa, which accompanies the hexagonal to intermediate phase transition seen via x-ray diffraction measurements. In addition, the linearitymore » of Hc2 (T) exceeds the Werthamer-Helfand-Hohenberg limit, even in the extreme spin-orbit scattering limit, yet is consistent with other strong spin-orbit materials. Furthermore, considering these results in combination with similar reports on strong spin-orbit scattering materials seen in the literature, we suggest the need for a new theory that can address the unconventional nature of their superconducting states.« less

  17. Surfactant-Free Synthesis of Bi?Te?-Te Micro-Nano Heterostructure with Enhanced Thermoelectric Figure of Merit

    SciTech Connect (OSTI)

    Zhang, Yichi; Wang, Heng; Kraemer, Stephan; Shi, Yifeng; Zhang, Fan; Snedaker, Matt; Ding, Kunlun; Moskovits, Martin; Snyder, G. Jeffrey; Stucky, Galen D.

    2011-01-01

    An ideal thermoelectric material would be a semiconductor with high electrical conductivity and relatively low thermal conductivity: an electron crystal, phonon glass. Introducing nanoscale heterostructures into the bulk TE matrix is one way of achieving this intuitively anomalous electron/phonon transport behavior. The heterostructured interfaces are expected to play a significant role in phonon scattering to reduce thermal conductivity and in the energy-dependent scattering of electrical carriers to improve the Seebeck coefficient. A nanoparticle building block assembly approach is plausible to fabricate three-dimensional heterostructured materials on a bulk commercial scale. However, a key problem in applying this strategy is the possible negative impact on TE performance of organic residue from the nanoparticle capping ligands. Herein, we report a wet chemical, surfactant-free, low-temperature, and easily up-scalable strategy for the synthesis of nanoscale heterophase Bi?Te?-Te via a galvanic replacement reaction. The micro-nano heterostructured material is fabricated bottom-up, by mixing the heterophase with commercial Bi?Te?. This unique structure shows an enhanced zT value of ~0.4 at room temperature. This heterostructure has one of the highest figures of merit among bismuth telluride systems yet achieved by a wet chemical bottom-up assembly. In addition, it shows a 40% enhancement of the figure of merit over our lab-made material without nanoscale heterostructures. This enhancement is mainly due to the decrease in the thermal conductivity while maintaining the power factor. Overall, this cost-efficient and room-temperature synthesis methodology provides the potential for further improvement and large-scale thermoelectric applications.

  18. Diameter dependent thermoelectric properties of individual SnTe nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowiremore » diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.« less

  19. Diameter dependent thermoelectric properties of individual SnTe nanowires

    SciTech Connect (OSTI)

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowire diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.

  20. Quantum oscillations in a two-dimensional electron gas at the rocksalt/zincblende interface of PbTe/CdTe (111) heterostructures.

    SciTech Connect (OSTI)

    Zhang, Bingpo; Lu, Ping; Liu, Henan; Jiao, Lin; Ye, Zhenyu; Jaime, M.; Balakirev, F. F.; Yuan, Huiqiu; Wu, Huizhen; Pan, Wei; Zhang, Yong

    2015-06-05

    Quantum oscillations are observed in the 2DEG system at the interface of novel heterostructures, PbTe/CdTe (111), with nearly identical lattice parameters (aPbTe = 0.6462 nm, aCdTe = 0.648 nm) but very different lattice structures (PbTe: rock salt, CdTe: zinc blende). The 2DEG formation mechanism, a mismatch in the bonding configurations of the valence electrons at the interface, is uniquely different from the other known 2DEG systems. The aberration-corrected scanning transmission electron microscope (AC-STEM) characterization indicates an abrupt interface without cation interdiffusion due to a large miscibility gap between the two constituent materials. As a result, electronic transport measurements under magnetic field up to 60 T, with the observation of Landau level filling factor ν = 1, unambiguously reveal a π Berry phase, suggesting the Dirac Fermion nature of the 2DEG at the heterostructure interface, and the PbTe/CdTe heterostructure being a new candidate for 2D topological crystalline insulators.

  1. Quantum oscillations in a two-dimensional electron gas at the rocksalt/zincblende interface of PbTe/CdTe (111) heterostructures

    SciTech Connect (OSTI)

    Zhang, Bingpo; Lu, Ping; Liu, Henan; Jiao, Lin; Ye, Zhenyu; Jaime, M.; Balakirev, F. F.; Yuan, Huiqiu; Wu, Huizhen; Pan, Wei; Zhang, Yong

    2015-06-05

    Quantum oscillations are observed in the 2DEG system at the interface of novel heterostructures, PbTe/CdTe (111), with nearly identical lattice parameters (aPbTe = 0.6462 nm, aCdTe = 0.648 nm) but very different lattice structures (PbTe: rock salt, CdTe: zinc blende). The 2DEG formation mechanism, a mismatch in the bonding configurations of the valence electrons at the interface, is uniquely different from the other known 2DEG systems. The aberration-corrected scanning transmission electron microscope (AC-STEM) characterization indicates an abrupt interface without cation interdiffusion due to a large miscibility gap between the two constituent materials. As a result, electronic transport measurements under magnetic field up to 60 T, with the observation of Landau level filling factor ν = 1, unambiguously reveal a π Berry phase, suggesting the Dirac Fermion nature of the 2DEG at the heterostructure interface, and the PbTe/CdTe heterostructure being a new candidate for 2D topological crystalline insulators.

  2. Quantum oscillations in a two-dimensional electron gas at the rocksalt/zincblende interface of PbTe/CdTe (111) heterostructures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Bingpo; Lu, Ping; Liu, Henan; Jiao, Lin; Ye, Zhenyu; Jaime, M.; Balakirev, F. F.; Yuan, Huiqiu; Wu, Huizhen; Pan, Wei; et al

    2015-06-05

    Quantum oscillations are observed in the 2DEG system at the interface of novel heterostructures, PbTe/CdTe (111), with nearly identical lattice parameters (aPbTe = 0.6462 nm, aCdTe = 0.648 nm) but very different lattice structures (PbTe: rock salt, CdTe: zinc blende). The 2DEG formation mechanism, a mismatch in the bonding configurations of the valence electrons at the interface, is uniquely different from the other known 2DEG systems. The aberration-corrected scanning transmission electron microscope (AC-STEM) characterization indicates an abrupt interface without cation interdiffusion due to a large miscibility gap between the two constituent materials. As a result, electronic transport measurements under magneticmore » field up to 60 T, with the observation of Landau level filling factor ν = 1, unambiguously reveal a π Berry phase, suggesting the Dirac Fermion nature of the 2DEG at the heterostructure interface, and the PbTe/CdTe heterostructure being a new candidate for 2D topological crystalline insulators.« less

  3. Dynamic conductivity of the bulk states of n-type HgTe/CdTe quantum well topological insulator

    SciTech Connect (OSTI)

    Chen, Qinjun; Sanderson, Matthew; Cao, J. C.; Zhang, Chao

    2014-11-17

    We theoretically studied the frequency-dependent current response of the bulk state of topological insulator HgTe/CdTe quantum well. The optical conductivity is mainly due to the inter-band process at high frequencies. At low frequencies, intra-band process dominates with a dramatic drop to near zero before the inter-band contribution takes over. The conductivity decreases with temperature at low temperature and increases with temperature at high temperature. The transport scattering rate has an opposite frequency dependence in the low and high temperature regime. The different frequency dependence is due to the interplay of the carrier-impurity scattering and carrier population near the Fermi surface.

  4. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Egarievwe, Stephen U.; Yang, Ge; Egarievwe, Alexander; Okwechime, Ifechukwude O.; Gray, Justin; Hales, Zaveon M.; Hossain, Anwar; Camarda, Guiseppe S.; Bolotnikov, Aleksey E.; James, Ralph B.

    2015-02-11

    Bridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that limit their performances as X-ray- and gamma-ray-detectors. We present here the results of post-growth thermal annealing aimed at reducing and eliminating Te inclusions in them. In a 2D analysis, we observed that the sizes of the Te inclusions declined to 92% during a 60-h annealing of CZT at 510 °C under Cd vapor. Further, tellurium inclusions were eliminated completely in CMT samples annealed at 570 °C in Cd vapor for 26 h, whilst their electrical resistivity fell by an ordermore » of 102. During the temperature-gradient annealing of CMT at 730 °C and an 18 °C/cm temperature gradient for 18 h in a vacuum of 10-5 mbar, we observed the diffusion of Te from the sample, causing a reduction in size of the Te inclusions. For CZT samples annealed at 700 °C in a 10 °C/cm temperature gradient, we observed the migration of Te inclusions from a low-temperature region to a high one at 0.022 μm/s. During the temperature-gradient annealing of CZT in a vacuum of 10-5 mbar at 570 °C and 30 °C/cm for 18 h, some Te inclusions moved toward the high-temperature side of the wafer, while other inclusions of the same size, i.e., 10 µm in diameter, remained in the same position. These results show that the migration, diffusion, and reaction of Te with Cd in the matrix of CZT- and CMT-wafers are complex phenomena that depend on certain conditions.« less

  5. A W' boson near 2 TeV: Predictions for run 2 of the LHC

    SciTech Connect (OSTI)

    Dobrescu, Bogdan A.; Liu, Zhen

    2015-11-20

    We present a renormalizable theory that includes a W' boson of mass in the 1.8–2 TeV range, which may explain the excess events reported by the ATLAS Collaboration in a WZ final state, and by the CMS Collaboration in e+e jj, Wh0, and jj final states. The W' boson couples to right-handed quarks and leptons, including Dirac neutrinos with TeV-scale masses. This theory predicts a Z' boson of mass in the 3.4–4.5 TeV range. The cross section times branching fractions for the narrow Z' dijet and dilepton peaks at the 13 TeV LHC are 10 and 0.6 fb, respectively, for MZ'=3.4 TeV, and an order of magnitude smaller for MZ'=4.5 TeV.

  6. A W' boson near 2 TeV: Predictions for run 2 of the LHC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dobrescu, Bogdan A.; Liu, Zhen

    2015-11-20

    We present a renormalizable theory that includes a W' boson of mass in the 1.8–2 TeV range, which may explain the excess events reported by the ATLAS Collaboration in a WZ final state, and by the CMS Collaboration in e+e– jj, Wh0, and jj final states. The W' boson couples to right-handed quarks and leptons, including Dirac neutrinos with TeV-scale masses. This theory predicts a Z' boson of mass in the 3.4–4.5 TeV range. The cross section times branching fractions for the narrow Z' dijet and dilepton peaks at the 13 TeV LHC are 10 and 0.6 fb, respectively, formore » MZ'=3.4 TeV, and an order of magnitude smaller for MZ'=4.5 TeV.« less

  7. Charge transfer and mobility enhancement at CdO/SnTe heterointerfaces

    SciTech Connect (OSTI)

    Nishitani, Junichi; Yu, Kin Man; Walukiewicz, Wladek

    2014-09-29

    We report a study of the effects of charge transfer on electrical properties of CdO/SnTe heterostructures. A series of structures with variable SnTe thicknesses were deposited by RF magnetron sputtering. Because of an extreme type III band offset with the valence band edge of SnTe located at 1.5?eV above the conduction band edge of CdO, a large charge transfer is expected at the interface of the CdO/SnTe heterostructure. The electrical properties of the heterostructures are analyzed using a multilayer charge transport model. The analysis indicates a large 4-fold enhancement of the CdO electron mobility at the interface with SnTe. The mobility enhancement is attributed to reduction of the charge center scattering through neutralization of the donor-like defects responsible for the Fermi level pinning at the CdO/SnTe interface.

  8. The Effect of Structural Vacancies on the Thermoelectric Properties of (Cu2Te)1-x(Ga2Te3)x

    SciTech Connect (OSTI)

    Ye, Zuxin; Cho, Jung Y; Tessema, Misle; Salvador, James R.; Waldo, Richard; Wang, Hsin; Cai, Wei

    2013-01-01

    We have studied the effects of structural vacancies on the thermoelectric properties of the ternary compounds (Cu2Te)1-x(Ga2Te3)x (x = 0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75), which are solid solutions found in the pseudo-binary phase diagram for Cu2Te and Ga2Te3. This system possesses tunable structural vacancy concentrations. The x= 0.5 phase, CuGaTe2, is nominally devoid of structural vacancies, while the rest of the compounds contain varying amounts of these features, and the volume density of vacancies increases with Ga2Te3 content. The sample with x = 0.5, 0.55, 0.571, 0.6, 0.625 crystallize in the chalcopyrite structure while the x = 0.667 and 0.75 adopt the Ga2Te3 defect zinc blende structure. Strong scattering of heat carrying phonons by structural defects, leads to the reduction of thermal conductivity, which is beneficial to the thermoelectric performance of materials. On the other hand, these defects also scatter charge carriers and reduce the electrical conductivity. All the samples investigated are p-type semiconductors as inferred by the signs of their respective Hall (RH) and Seebeck (S) coefficients. The structural vacancies were found to scatter phonons strongly, while a combination of increased carrier concentration, and vacancies decreases the Hall mobility ( H), degrading the overall thermoelectric performance. The room temperature H drops from 90 cm2/V s for CuGaTe2 to 13 cm2/V s in Cu9Ga11Te21 and 4.6 cm2/V s in CuGa3Te5. The low temperature thermal conductivity decreases significantly with higher Ga2Te3 concentrations (higher vacancy concentration) due to increased point defect scattering which dominate thermal resistance terms. At high temperatures, the dependence of thermal conductivity on the Ga2Te3 content is less significant. The presence of strong Umklapp scattering leads to low thermal conductivity at high temperatures for all samples investigated. The highest ZT among the samples in this study was found for the defect-free CuGaTe

  9. High Efficiency Single Crystal CdTe Solar Cells: November 19, 2009 - January 31, 2011

    SciTech Connect (OSTI)

    Carmody, M.; Gilmore, A.

    2011-05-01

    The goal of the program was to develop single crystal CdTe-based top cells grown on Si solar cells as a platform for the subsequent manufacture of high efficiency tandem cells for CPV applications. The keys to both the single junction and the tandem junction cell architectures are the ability to grow high quality single-crystal CdTe and CdZnTe layers on p-type Si substrates, to dope the CdTe and CdZnTe controllably, both n and p-type, and to make low resistance ohmic front and back contacts. EPIR demonstrated the consistent MBE growth of CdTe/Si and CdZnTe/Si having high crystalline quality despite very large lattice mismatches; epitaxial CdTe/Si and CdZnTe/Si consistently showed state-of-the-art electron mobilities and good hole mobilities; bulk minority carrier recombination lifetimes of unintentionally p-doped CdTe and CdZnTe grown by MBE on Si were demonstrated to be consistently of order 100 ns or longer; desired n- and p-doping levels were achieved; solar cell series specific resistances <10 ?-cm2 were achieved; A single-junction solar cell having a state-of-the-art value of Voc and a unverified 16.4% efficiency was fabricated from CdZnTe having a 1.80 eV bandgap, ideal for the top junction in a tandem cell with a Si bottom junction.

  10. Crystal chemistry peculiarities of Cs{sub 2}Te{sub 4}O{sub 12}

    SciTech Connect (OSTI)

    Hamani, David; Mirgorodsky, Andrei; Masson, Olivier; Merle-Mejean, Therese; Colas, Maggy; Smirnov, Mikhael; Thomas, Philippe

    2011-03-15

    The Raman and IR-absorption spectra of the Cs{sub 2}Te{sub 4}O{sub 12} lattice are first recorded and interpreted. Extraordinary features observed in the structure and Raman spectra of Cs{sub 2}Te{sub 4}O{sub 12} are analyzed by using ab initio and lattice-dynamical model calculations. This compound is specified as a caesium-tellurium tellurate Cs{sub 2}Te{sup IV}(Te{sup VI}O{sub 4}){sub 3} in which Te{sup IV} atoms transfer their 5p electrons to [Te{sup VI}O{sub 4}]{sub 3}{sup 6-} tellurate anions, thus fulfilling (jointly with Cs atoms) the role of cations. The Te{sup VI}-O-Te{sup VI} bridge vibration Raman intensity is found abnormally weak, which is reproduced by model treatment including the Cs{sup +} ion polarizability properties in consideration. -- Graphical abstract: Two versions of the BPM estimations of the Raman intensity for the Cs{sub 2}Te{sub 4}O{sub 12} lattice vibrations: (a) without including effects of the Cs-O bonds and (b) including the above mentioned effects. Experimentally observed peaks are characterized by their frequency positions. Display Omitted Research highlights: > Extraordinary features observed in the structure and Raman spectra of Cs{sub 2}Te{sub 4}O{sub 12}. > Ab initio and lattice-dynamical model calculations. > Abnormally weak Raman intensities of the symmetric Te{sup VI}-O-Te{sup VI} bridge. > The monovalent Cs{sup +} cations profoundly influence the polarizability properties.

  11. Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 2, February 1-April 30, 1981

    SciTech Connect (OSTI)

    Bube, R H

    1981-01-01

    The design, construction and testing of the hot-wall vacuum evaporation system is proceeding on schedule. The vacuum system, a Varian 3118 diffusion pump system, has been installed and tested. A calculation of the optimum possible efficiency for an n-p CdTe homojunction indicates a value of 14%. A complete background is given on the growth of over fifty CdTe single crystals at Stanford, the last four of which were grown as part of this program. Use of crystal regrowth and vibration during growth both increase crystal quality. Higher electrical activity of phosphorus acceptors in CdTe is achieved when 0.1% excess Te is used in place of 0.5% excess Te. Careful characterization of boules grown for this program are underway, using Hall effect or capacitance-voltage data on selected samples. Initial investigation of the properties of grain boundaries in p-type CdTe : P crystals indicates a grain boundary height of 0.44 eV unaffected by illumination. These results suggest that grain boundaries are more strongly pinned in p-type than in n-type CdTe.

  12. PROJECT PROFILE: Interface Science and Engineering for Reliable, High Efficiency CdTe

    Broader source: Energy.gov [DOE]

    While crystalline silicon accounted for two thirds of the PV market in 2014, cadmium telluride (CdTe) photovoltaic (PV) modules are becoming increasingly competitive with continued improvements in efficiency and reduction in price. This project will contribute to enabling 24% efficient CdTe cells by improving surface and interface recombination in the devices. Surface and interface recombination, which is the loss of photo-generated carriers before they are collected, becomes more detrimental to CdTe device performance as carrier lifetime increases. This project will develop effective surface passivation for CdTe and carrier selective contacts for higher efficiency, improved reproducibility, and increased stability.

  13. Nanoscale imaging of photocurrent and efficiency in CdTe solar...

    Office of Scientific and Technical Information (OSTI)

    cells The local collection characteristics of grain interiors and grain boundaries in thin film CdTe polycrystalline solar cells are investigated using scanning photocurrent...

  14. Analysis of Surface Chemistry and Detector Performance of Chemically Process CdZnTe crystals

    SciTech Connect (OSTI)

    HOSSAIN A.; Yang, G.; Sutton, J.; Zergaw, T.; Babalola, O. S.; Bolotnikov, A. E.; Camarda. ZG. S.; Gul, R.; Roy, U. N., and James, R. B.

    2015-10-05

    The goal is to produce non-conductive smooth surfaces for fabricating low-noise and high-efficiency CdZnTe devices.

  15. Characterization and Analysis of CIGS and CdTE Solar Cells: December 2004 - July 2008

    SciTech Connect (OSTI)

    Sites, J. R.

    2009-01-01

    The work reported here embodies a device-physics approach based on careful measurement and interpretation of data from CIGS and CdTe solar cells.

  16. ON THE ENERGY SPECTRA OF GeV/TeV COSMIC RAY LEPTONS (Journal...

    Office of Scientific and Technical Information (OSTI)

    The models rely on either dark matter annihilationdecay or specific nearby astrophysical ... is the Klein-Nishina suppression of the electron cooling rate around TeV energies. ...

  17. On the Energy Spectra of GeV/TeV Cosmic Ray Leptons (Journal...

    Office of Scientific and Technical Information (OSTI)

    The models rely on either dark matter annihilationdecay or specific nearby astrophysical ... is the Klein-Nishina suppression of the electron cooling rate around TeV energies. ...

  18. Probing TeV physics in the structure of the neutron (Technical...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Probing TeV physics in the structure of the neutron Citation Details ... Sponsoring Org: LDRD; USDOE Country of Publication: United States Language: English ...

  19. Scandium resonant impurity level in PbTe

    SciTech Connect (OSTI)

    Skipetrov, E. P. Skipetrova, L. A.; Knotko, A. V.; Slynko, E. I.; Slynko, V. E.

    2014-04-07

    We synthesize a scandium-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties of Pb{sub 1-y}Sc{sub y}Te alloys in weak magnetic fields (4.2?K???T???300?K, B???0.07?T) upon varying the scandium content (y???0.02). We find that all investigated samples are single-phase and n-type. The distribution of scandium impurities along the axis of the ingot is estimated to be exponential. An increase of scandium impurity content leads to a monotonous growth of the free electron concentration by four orders of magnitude (approximately from 10{sup 16}?cm{sup ?3} to 10{sup 20}?cm{sup ?3}). In heavily doped alloys (y?>?0.01), the free electron concentration at the liquid-helium temperature tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant impurity level located on the background of the conduction band. Using the two-band Kane and six-band Dimmock dispersion relations for IV-VI semiconductors, dependences of the Fermi energy measured from the bottom of the conduction band E{sub c} on the scandium impurity content are calculated and the energy of the resonant scandium level is estimated to be E{sub Sc}???E{sub c}?+?280?meV. Diagrams of electronic structure rearrangement of Pb{sub 1-y}Sc{sub y}Te alloys upon doping are proposed.

  20. Radiative leptogenesis at the TeV scale

    SciTech Connect (OSTI)

    Choudhury, Debajyoti; Mahajan, Namit; Patra, Sudhanwa; Sarkar, Utpal E-mail: nmahajan@prl.res.in E-mail: utpal@prl.res.in

    2012-04-01

    We construct an explicit model implementing leptogenesis proceeding via the radiative decay of heavy right handed neutrino. In a simple extension of the Standard Model, a discrete symmetry forbids the usual decays of the right-handed neutrinos, while allowing for an effective coupling between the left-handed and right-handed neutrinos through the dipole moment operator. This generates correct leptogenesis with resonant enhancement and also the required neutrino mass via a TeV scale seesaw mechanism. The model is consistent with low energy phenomenology and would have distinct signals in the next generation colliders, and, perhaps even the LHC.

  1. High-Efficiency, Commercial Ready CdTe Solar Cells

    SciTech Connect (OSTI)

    Sites, James R.

    2015-11-19

    Colorado State’s F-PACE project explored several ways to increase the efficiency of CdTe solar cells and to better understand the device physics of those cells under study. Increases in voltage, current, and fill factor resulted in efficiencies above 17%. The three project tasks and additional studies are described in detail in the final report. Most cells studied were fabricated at Colorado State using an industry-compatible single-vacuum closed-space-sublimation (CSS) chamber for deposition of the key semiconductor layers. Additionally, some cells were supplied by First Solar for comparison purposes, and a small number of modules were supplied by Abound Solar.

  2. Mr. John E. Kieling, Chief Hazardous Was te Bureau

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    John E. Kieling, Chief Hazardous Was te Bureau Depa rtment of Energy Carlsbad Field Office P. O. Box 3090 Carlsbad , New Mexico 88221 NOV 0 5 2013 New Mexico Environment Department 2905 Rodeo Park Drive East. Building 1 Santa Fe, New Mexico 87505-6303 Subject: Panel 6 Closure and Final Waste Emplacement Notifications Dear Mr. Kieling : The purpose of this leiter is 1 0 notify th e New Mexico Environment Department (NMEO) that the Permittees intend to commence closure of Hazardous Waste Disposa

  3. Purification of CdZnTe by Electromigration

    SciTech Connect (OSTI)

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of the electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.

  4. Extending Higgs inflation with TeV scale new physics

    SciTech Connect (OSTI)

    He, Hong-Jian; Xianyu, Zhong-Zhi

    2014-10-10

    Higgs inflation is among the most economical and predictive inflation models, although the original Higgs inflation requires tuning the Higgs or top mass away from its current experimental value by more than 2σ deviations, and generally gives a negligible tensor-to-scalar ratio r∼10{sup −3} (if away from the vicinity of critical point). In this work, we construct a minimal extension of Higgs inflation, by adding only two new weak-singlet particles at TeV scale, a vector-quark T and a real scalar S . The presence of singlets (T, S) significantly impact the renormalization group running of the Higgs boson self-coupling. With this, our model provides a wider range of the tensor-to-scalar ratio r=O(0.1)−O(10{sup −3}) , consistent with the favored r values by either BICEP2 or Planck data, while keeping the successful prediction of the spectral index n{sub s}≃0.96 . It allows the Higgs and top masses to fully fit the collider measurements. We also discuss implications for searching the predicted TeV-scale vector-quark T and scalar S at the LHC and future high energy pp colliders.

  5. Extending Higgs inflation with TeV scale new physics

    SciTech Connect (OSTI)

    He, Hong-Jian; Xianyu, Zhong-Zhi E-mail: xianyuzhongzhi@gmail.com

    2014-10-01

    Higgs inflation is among the most economical and predictive inflation models, although the original Higgs inflation requires tuning the Higgs or top mass away from its current experimental value by more than 2? deviations, and generally gives a negligible tensor-to-scalar ratio r?10{sup -3} (if away from the vicinity of critical point). In this work, we construct a minimal extension of Higgs inflation, by adding only two new weak-singlet particles at TeV scale, a vector-quark T and a real scalar S. The presence of singlets (T,S) significantly impact the renormalization group running of the Higgs boson self-coupling. With this, our model provides a wider range of the tensor-to-scalar ratio r=O(0.1)-O(10{sup -3}), consistent with the favored r values by either BICEP2 or Planck data, while keeping the successful prediction of the spectral index n{sub s}?0.96. It allows the Higgs and top masses to fully fit the collider measurements. We also discuss implications for searching the predicted TeV-scale vector-quark T and scalar S at the LHC and future high energy pp colliders.

  6. Advanced CdTe Photovoltaic Technology: September 2007 - March 2009

    SciTech Connect (OSTI)

    Barth, K.

    2011-05-01

    During the last eighteen months, Abound Solar (formerly AVA Solar) has enjoyed significant success under the SAI program. During this time, a fully automated manufacturing line has been developed, fabricated and commissioned in Longmont, Colorado. The facility is fully integrated, converting glass and semiconductor materials into complete modules beneath its roof. At capacity, a glass panel will enter the factory every 10 seconds and emerge as a completed module two hours later. This facility is currently undergoing trials in preparation for large volume production of 120 x 60 cm thin film CdTe modules. Preceding the development of the large volume manufacturing capability, Abound Solar demonstrated long duration processing with excellent materials utilization for the manufacture of high efficiency 42 cm square modules. Abound Solar prototype modules have been measured with over 9% aperture area efficiency by NREL. Abound Solar demonstrated the ability to produce modules at industry leading low costs to NREL representatives. Costing models show manufacturing costs below $1/Watt and capital equipment costs below $1.50 per watt of annual manufacturing capacity. Under this SAI program, Abound Solar supported a significant research and development program at Colorado State University. The CSU team continues to make progress on device and materials analysis. Modeling for increased device performance and the effects of processing conditions on properties of CdTe PV were investigated.

  7. Purification of CdZnTe by Electromigration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of themore » electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.« less

  8. Thermodynamic properties of model CdTe/CdSe mixtures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-02-20

    We report on the thermodynamic properties of binary compound mixtures of model groups II–VI semiconductors. We use the recently introduced Stillinger–Weber Hamiltonian to model binary mixtures of CdTe and CdSe. We use molecular dynamics simulations to calculate the volume and enthalpy of mixing as a function of mole fraction. The lattice parameter of the mixture closely follows Vegard's law: a linear relation. This implies that the excess volume is a cubic function of mole fraction. A connection is made with hard sphere models of mixed fcc and zincblende structures. We found that the potential energy exhibits a positive deviation frommore » ideal soluton behaviour; the excess enthalpy is nearly independent of temperatures studied (300 and 533 K) and is well described by a simple cubic function of the mole fraction. Using a regular solution approach (combining non-ideal behaviour for the enthalpy with ideal solution behaviour for the entropy of mixing), we arrive at the Gibbs free energy of the mixture. The Gibbs free energy results indicate that the CdTe and CdSe mixtures exhibit phase separation. The upper consolute temperature is found to be 335 K. Finally, we provide the surface energy as a function of composition. Moreover, it roughly follows ideal solution theory, but with a negative deviation (negative excess surface energy). This indicates that alloying increases the stability, even for nano-particles.« less

  9. Photoconductivity of CdTe Nanocrystal-Based Thin Films. Te2- Ligands Lead To Charge Carrier Diffusion Lengths Over 2 Micrometers

    SciTech Connect (OSTI)

    Crisp, Ryan W.; Callahan, Rebecca; Reid, Obadiah G.; Dolzhnikov, Dmitriy S.; Talapin, Dmitri V.; Rumbles, Garry; Luther, Joseph M.; Kopidakis, Nikos

    2015-11-16

    We report on photoconductivity of films of CdTe nanocrystals (NCs) using time-resolved microwave photoconductivity (TRMC). Spherical and tetrapodal CdTe NCs with tunable size-dependent properties are studied as a function of surface ligand (including inorganic molecular chalcogenide species) and annealing temperature. Relatively high carrier mobility is measured for films of sintered tetrapod NCs (4 cm2/(V s)). Our TRMC findings show that Te2- capped CdTe NCs show a marked improvement in carrier mobility (11 cm2/(V s)), indicating that NC surface termination can be altered to play a crucial role in charge-carrier mobility even after the NC solids are sintered into bulk films.

  10. Thermoelectric properties of Sn- and Pb-doped Tl{sub 9}BiTe{sub 6} and Tl{sub 9}SbTe{sub 6}

    SciTech Connect (OSTI)

    Guo, Quansheng; Chan, Meghan; Kuropatwa, Bryan A.; Kleinke, Holger

    2014-11-14

    A variety of substitutions in Tl{sub 9}BiTe{sub 6} and Tl{sub 9}SbTe{sub 6} with Sn and Pb, amounting to 14 different samples, were performed by melting the stoichiometric amounts of elements at 923 K, followed by slow cooling. The pulverized powders were sintered using the hot-pressing technique. All samples were of single phase according to the powder X-ray diffraction patterns. Thermoelectric property measurements were performed to investigate the effects of Sn- and Pb-doping on the electrical conductivity, Seebeck coefficient, and thermal conductivity. Increasing the concentration of the dopants caused increases in electrical and thermal conductivity, while decreasing the Seebeck coefficient. Tl{sub 9}Bi{sub 0.90}Pb{sub 0.10}Te{sub 6} and Tl{sub 9}Bi{sub 0.85}Pb{sub 0.15}Te{sub 6} exhibited the highest power factor. The changes in lattice thermal conductivity were minor and did not follow a clear trend. Competitive ZT values were obtained for Tl{sub 9}Bi{sub 0.95}Sn{sub 0.05}Te{sub 6}, Tl{sub 9}Bi{sub 0.95}Pb{sub 0.05}Te{sub 6}, Tl{sub 9}Sb{sub 0.97}Sn{sub 0.03}Te{sub 6}, and Tl{sub 9}Sb{sub 0.95}Pb{sub 0.05}Te{sub 6}, namely 0.95, 0.94, 0.83, and 0.71 around 500 K, respectively. Higher dopant concentrations led to lower ZT values.

  11. ZnTeO{sub 3} crystal growth by a modified Bridgman technique

    SciTech Connect (OSTI)

    Nawash, Jalal M. Lynn, Kelvin G.

    2014-12-15

    Highlights: • ZnTeO{sub 3} single crystals were grown for the first time by a modified Bridgman method. • The growth is still possible in a system that lacks congruent melting. • A growth is best when melt is exposed to a steeper axial thermal gradient. • Optical and electrical properties were investigated for the grown crystals. - Abstract: Zinc Tellurite (ZnTeO{sub 3}) crystals were grown for the first time using a modified Bridgman method with a 2.5 kHz radio frequency (RF) furnace. Single crystal growth of ZnTeO{sub 3} was hindered by many complicating factors, such as the evaporation of TeO{sub 2} above 700 °C and the formation of more than one phase during crystal growth. While there were several successful runs that produced ZnTeO{sub 3} single crystals, it was found that large (≥10 cm{sup 3}) single ZnTeO{sub 3} crystals resulted when the crucible was exposed to a steeper vertical thermal gradient and when the temperature of the melt was raised to at least 860 °C. The results of powder X-ray diffraction (XRD) patterns were in accordance with the X-ray powder diffraction file (PDF) for ZnTeO{sub 3}. Some optical, electrical and structural properties of ZnTeO{sub 3} single crystals were reported in this paper.

  12. Fabrication and Physics of CdTe Devices by Sputtering: Final Report, 1 March 2005 - 30 November 2008

    SciTech Connect (OSTI)

    Compaan, A.; Collins, R.; Karpov, V.; Giolando, D.

    2009-04-01

    Work to understand CdS/CdTe solar cell device physics; increase magnetron sputtering rate (while keeping high device quality); reduce thickness of CdTe layers (while keeping voltage and fill factor).

  13. Improving Energy Efficiency by Developing Components for Distributed Cooling and Heating Based on Thermal Comfort Modeling[Thermoelectric (TE) HVAC

    Broader source: Energy.gov [DOE]

    Discusses results from TE HVAC project to add detail to a human thermal comfort model and further allow load reduction in the climate control energy through a distributed TE network

  14. Growth of CdTe thin films on graphene by close-spaced sublimation method

    SciTech Connect (OSTI)

    Jung, Younghun; Yang, Gwangseok; Kim, Jihyun, E-mail: hyunhyun7@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Chun, Seungju; Kim, Donghwan [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2013-12-02

    CdTe thin films grown on bi-layer graphene were demonstrated by using the close-spaced sublimation method, where CdTe was selectively grown on the graphene. The density of the CdTe domains was increased with increasing the number of the defective sites in the graphene, which was controlled by the duration of UV exposure. The CdTe growth rate on the bi-layer graphene electrodes was 400?nm/min with a bandgap energy of 1.451.49?eV. Scanning electron microscopy, micro-Raman spectroscopy, micro-photoluminescence, and X-ray diffraction technique were used to confirm the high quality of the CdTe thin films grown on the graphene electrodes.

  15. Ba{sub 2}TeO: A new layered oxytelluride

    SciTech Connect (OSTI)

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J.B.; Tokumoto, T.D.; McGill, S.A.; Singh, D.J.; Siegrist, T.

    2015-02-15

    Single crystals of the new semiconducting oxytelluride phase, Ba{sub 2}TeO, were synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba{sub 2}TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. The optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba{sub 2}TeO is highly insulating. - Graphical abstract: Starting from a simple stacking of rocksalt layers, the final structure of Ba{sub 2}TeO can be obtained by accommodation of structural strain via atom displacements. Density of states calculations and optical absorbance measurements show that Ba{sub 2}TeO has a band gap of 2.93 eV, indicative of semiconductor behavior. - Highlights: • Single crystal synthesis of a new layered oxytelluride, Ba{sub 2}TeO. • The structure features inverse PbO-type BaO layers and NaCl-type BaTe layers. • Optical absorbance show Ba{sub 2}TeO to be a semiconductor with a 2.93 eV gap. • Density of states indicate a small hybridization between Te 5p and Ba 5d states. • The BaTe (BaO) layers dominate the heat capacity at low (high) temperatures.

  16. The effect of structural vacancies on the thermoelectric properties of (Cu?Te){sub 1x}(Ga?Te?)x

    SciTech Connect (OSTI)

    Ye, Zuxin; Young Cho, Jung; Tessema, Misle M.; Salvador, James R.; Waldo, Richard A.; Wang, Hsin; Cai, Wei

    2013-05-01

    We have studied the effects of structural vacancies on the thermoelectric properties of the ternary compounds (Cu?Te)1x(Ga?Te?)x (x=0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75), which are solid solutions found in the pseudo-binary phase diagram for Cu?Te and Ga?Te?, and possesses tunable structural vacancy concentrations. This materials system is not suitable due to the cost and scarcity of the constituent elements, but the vacancy behavior is well understood and will provide a valuable test case for other systems more suitable from the standpoint of cost and abundance of raw materials, which also possesses these vacancy features, but whose structural characterization is lacking at this stage. We find that the nominally defect free phase CuGaTe? possess the highest ZT (ZT=ST/??, where S is the Seebeck coefficient and ? is the electrical resistivity ? is the thermal conductivity and T is the absolute temperature) which approaches 1 at 840 K and seems to continuously increase above this temperature. This result is due to the unexpectedly low thermal conductivity found for this material at high temperature. The low thermal conductivity was caused by strong Umklapp (thermally resistive scattering processes involving three phonons) phonon scattering. We find that due to the coincidentally strong scattering of carriers by the structural defects that higher concentrations of these features lead to poor electrical transport properties and decreased ZT. - Graphical abstract: Thermal conductivity and zT as a function of temperature for a series of compounds of the type (Cu?Te)1x(Ga?Te?)x (x=0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75). Highlights: All the samples show p-type semiconducting behavior in the temperature dependence of the Seebeck and Hall coefficients. The increased carrier concentration and the introduction of vacancies diminish the carrier mobility and power factor. The low temperature k decreases significantly as

  17. NuTeV Anomaly Helps Shed Light on Physics of the Nucleus | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    NuTeV Anomaly Helps Shed Light on Physics of the Nucleus NuTeV Anomaly Helps Shed Light on Physics of the Nucleus NEWPORT NEWS, VA, June 29, 2009 - A new calculation clarifies the complicated relationship between protons and neutrons in the atomic nucleus and offers a fascinating resolution of the famous NuTeV Anomaly. The calculation, published in the journal Physical Review Letters on June 26, was carried out by a collaboration of researchers from the Department of Energy's Thomas Jefferson

  18. Evidence for charge Kondo effect in superconducting Tl-doped PbTe (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Evidence for charge Kondo effect in superconducting Tl-doped PbTe Citation Details In-Document Search Title: Evidence for charge Kondo effect in superconducting Tl-doped PbTe We report results of low-temperature thermodynamic and transport measurements of Pb{sub 1-x}Tl{sub x}Te single crystals for Tl concentrations up to the solubility limit of approximately x = 1.5%. For all doped samples, we observe a low-temperature resistivity upturn that scales in magnitude

  19. Chapter 1.19: Cadmium Telluride Photovoltaic Thin Film: CdTe

    SciTech Connect (OSTI)

    Gessert, T. A.

    2012-01-01

    The chapter reviews the history, development, and present processes used to fabricate thin-film, CdTe-based photovoltaic (PV) devices. It is intended for readers who are generally familiar with the operation and material aspects of PV devices but desire a deeper understanding of the process sequences used in CdTe PV technology. The discussion identifies why certain processes may have commercial production advantages and how the various process steps can interact with each other to affect device performance and reliability. The chapter concludes with a discussion of considerations of large-area CdTe PV deployment including issues related to material availability and energy-payback time.

  20. CdTe portfolio offers commercial ready high efficiency solar - Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Innovation Portal Find More Like This Return to Search CdTe portfolio offers commercial ready high efficiency solar National Renewable Energy Laboratory Contact NREL About This Technology Publications: PDF Document Publication MktgSummary CdTe.pdf (117 KB) Schematic illustration of a typical CdTe superstrate thin-film PV device. In this design, the layers of the device are deposited onto a glass &quot;superstrate&quot; that allows sunlight to enter. The sunlight passes through the

  1. Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.

    2014-11-04

    This article presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy ofmore » $$\\sqrt{s}=7\\;{\\rm Te}{\\rm V}$$ and correspond to an integrated luminosity of $$4.6\\;{\\rm f}{{{\\rm b}}^{-1}}$$. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum $${{p}_{{\\rm T}}}\\gt 320\\;{\\rm Ge}{\\rm V}$$ and pseudorapidity $$|\\eta |\\lt 1.9$$, is measured to be $${{\\sigma }_{W+Z}}=8.5\\pm 1.7$$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques.« less

  2. Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2014-11-04

    This article presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of $\\sqrt{s}=7\\;{\\rm Te}{\\rm V}$ and correspond to an integrated luminosity of $4.6\\;{\\rm f}{{{\\rm b}}^{-1}}$. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum ${{p}_{{\\rm T}}}\\gt 320\\;{\\rm Ge}{\\rm V}$ and pseudorapidity $|\\eta |\\lt 1.9$, is measured to be ${{\\sigma }_{W+Z}}=8.5\\pm 1.7$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques.

  3. Magnetic anisotropy induced by crystal distortion in Ge{sub 1−x}Mn{sub x}Te/PbTe//KCl (001) ferromagnetic semiconductor layers

    SciTech Connect (OSTI)

    Knoff, W. Łusakowski, A.; Domagała, J. Z.; Minikayev, R.; Taliashvili, B.; Łusakowska, E.; Pieniążek, A.; Szczerbakow, A.; Story, T.

    2015-09-21

    Ferromagnetic resonance (FMR) study of magnetic anisotropy is presented for thin layers of IV-VI diluted magnetic semiconductor Ge{sub 1−x}Mn{sub x}Te with x = 0.14 grown by molecular beam epitaxy on KCl (001) substrate with a thin PbTe buffer. Analysis of the angular dependence of the FMR resonant field reveals that an easy magnetization axis is located near to the normal to the layer plane and is controlled by two crystal distortions present in these rhombohedral Ge{sub 1−x}Mn{sub x}Te layers: the ferroelectric distortion with the relative shift of cation and anion sub-lattices along the [111] crystal direction and the biaxial in-plane, compressive strain due to thermal mismatch.

  4. Intrinsic Rashba-like splitting in asymmetric Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} heterogeneous topological insulator films

    SciTech Connect (OSTI)

    Liu, Xiaofei; Guo, Wanlin

    2014-08-25

    We show by density functional theory calculations that asymmetric hetero-stacking of Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} films can modulate the topological surface states. Due to the structure inversion asymmetry, an intrinsic Rashba-like splitting of the conical surface bands is aroused. While such splitting in homogeneous Bi{sub 2}Te{sub 3}-class topological insulators can be realized in films with more than three quintuple layers under external electric fields, the hetero-stacking breaks the limit of thickness for preserving the topological nature into the thinnest two quintuple layers. These results indicate that the hetero-stacking can serve as an efficient strategy for spin-resolved band engineering of topological insulators.

  5. Efficiency, Cost and Weight Trade-off in TE Power Generation System for Vehicle Exhaust Applications

    Broader source: Energy.gov [DOE]

    It contains a detailed co-optimization of the thermoelectric module with the heat sink and a study of the tradeoff between the material cost and efficiency for the TE module and the heat sink. An optimum design is found.

  6. V-183: Cisco TelePresence TC and TE Bugs Let Remote Users Deny...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Remote Users Deny Service and Remote Adjacent Authenticated Users Gain Root Shell Access V-183: Cisco TelePresence TC and TE Bugs Let Remote Users Deny Service and Remote Adjacent...

  7. THE EI'IVIRONMENTAL QUALITY COMPANY CORPCl~V\\TE OFFICE

    Office of Environmental Management (EM)

    EI'IVIRONMENTAL QUALITY COMPANY CORPClVTE OFFICE Ill 36255 MICI*at:l;1 '1 J.VENIJE * WAYNE , IVICHICA148 '184 te800-5925489 tit fax 800-592-5329 February 20, 2013 Yia ...

  8. Structural analysis of Cr aggregation in ferromagnetic semiconductor (Zn,Cr)Te

    SciTech Connect (OSTI)

    Kobayashi, H.; Yamawaki, K.; Nishio, Y.; Kanazawa, K.; Kuroda, S.; Mitome, M.; Bando, Y.

    2013-12-04

    The Cr aggregation in a ferromagnetic semiconductor (Zn,Cr)Te was studied by performing precise analyses using TEM and XRD of microscopic structure of the Cr-aggregated regions formed in iodine-doped Zn{sub 1?x}Cr{sub x}Te films with a relatively high Cr composition x ? 0.2. It was found that the Cr-aggregated regions are composed of Cr{sub 1??}Te nanocrystals of the hexagonal structure and these hexagonal precipitates are stacked preferentially on the (111)A plane of the zinc-blende (ZB) structure of the host ZnTe crystal with its c-axis nearly parallel to the (111){sub ZB} plane.

  9. Giant and tunable valley degeneracy splitting in MoTe 2 (Journal...

    Office of Scientific and Technical Information (OSTI)

    This content will become publicly available on September 7, 2016 Title: Giant and tunable valley degeneracy splitting in MoTe 2 Authors: Qi, Jingshan ; Li, Xiao ; Niu, Qian ; Feng, ...

  10. Ultrathin nanosheets of CrSiTe3. A semiconducting two-dimensional...

    Office of Scientific and Technical Information (OSTI)

    As a result, the ferromagnetic mono- and few-layer 2D CrSiTe3 indicated here should enable ... Type: Accepted Manuscript Journal Name: Journal of Materials Chemistry. C Additional ...

  11. Shape-controlled narrow-gap SnTe nanostructures: From nanocubes to nanorods and nanowires

    SciTech Connect (OSTI)

    Guo, Shaojun; Andrew F. Fidler; He, Kai; Su, Dong; Chen, Gen; Lin, Qianglu; Pietryga, Jeffrey M.; Klimov, Victor I.

    2015-11-06

    In this study, the rational design and synthesis of narrow-gap colloidal semiconductor nanocrystals (NCs) is an important step toward the next generation of solution-processable photovoltaics, photodetectors, and thermoelectric devices. SnTe NCs are particularly attractive as a Pb-free alternative to NCs of narrow-gap lead chalcogenides. Previous synthetic efforts on SnTe NCs have focused on spherical nanoparticles. Here we report new strategies for synthesis of SnTe NCs with shapes tunable from highly monodisperse nanocubes, to nanorods (NRs) with variable aspect ratios, and finally to long, straight nanowires (NWs). Reaction at high temperature quickly forms thermodynamically favored nanocubes, but low temperatures lead to elongated particles. Transmission electron microscopy studies of reaction products at various stages of the synthesis reveal that the growth and shape-focusing of monodisperse SnTe nanocubes likely involves interparticle ripening, while directional growth of NRs and NWs may be initiated by particle dimerization via oriented attachment.

  12. Thermoelectric Enhancement in PbTe with K or Na codoping from...

    Office of Scientific and Technical Information (OSTI)

    Thermoelectric Enhancement in PbTe with K or Na codoping from tuning the interaction of the light- and heavy-hole valence bands Citation Details In-Document Search Title: ...

  13. A comparison of NNLO QCD predictions with 7 TeV ATLAS and CMS...

    Office of Scientific and Technical Information (OSTI)

    with 7 TeV ATLAS and CMS data for V+jet processes Authors: Boughezal, Radja ; Liu, Xiaohui ; Petriello, Frank Publication Date: 2016-09-01 OSTI Identifier: 1258296 Grant...

  14. Atomic-force microscopy and photoluminescence of nanostructured CdTe

    SciTech Connect (OSTI)

    Babentsov, V.; Sizov, F.; Franc, J.; Luchenko, A.; Svezhentsova, E. Tsybrii, Z.

    2013-09-15

    Low-dimensional CdTe nanorods with a diameter of 10-30 nm and a high aspect ratio that reaches 100 are studied. The nanorods are grown by the physical vapor transport method with the use of Bi precipitates on the substrates. In addition, thin films of closely packed CdTe nanorods with the transverse dimensions {approx}(100-200) nm are grown. Atomic-force microscopy shows that the cross sections of all of the nanorods were hexagonally shaped. By photoluminescence measurements, the inference about the wurtzite structure of CdTe is supported, and the structural quality, electron-phonon coupling, and defects are analyzed. On the basis of recent ab initio calculations, the nature of defects responsible for the formation of deep levels in the CdTe layers and bulk crystals are analyzed.

  15. Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials...

    Office of Scientific and Technical Information (OSTI)

    Title: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials ... Resource Relation: Journal Name: Appl. Phys. Lett.; Journal Volume: 104; Journal Issue: 25 Research ...

  16. Connecting thermoelectric performance and topological-insulator behavior: Bi2Te3 and Bi2Te2Se from first principles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shi, Hongliang; Parker, David S.; Du, Mao-Hua; Singh, David J.

    2015-01-20

    Thermoelectric performance is of interest for numerous applications such as waste-heat recovery and solid-state energy conversion and will be seen to be closely connected to topological-insulator behavior. In this paper, we here report first-principles transport and defect calculations for Bi2Te2Se in relation to Bi2Te3. The two compounds are found to contain remarkably different electronic structures in spite of being isostructural and isoelectronic. We also discuss these results in terms of the topological-insulator characteristics of these compounds.

  17. Deformation and shape transitions in hot rotating neutron deficient Te isotopes

    SciTech Connect (OSTI)

    Aggarwal, Mamta; Mazumdar, I.

    2009-08-15

    Evolution of the nuclear shapes and deformations under the influence of temperature and rotation is investigated in Te isotopes with neutron number ranging from the proton drip line to the stability valley. Spin dependent critical temperatures for the shape transitions in Te nuclei are computed. Shape transitions from prolate at low temperature and spin to oblate via triaxiality are seen with increasing neutron number and spin.

  18. NREL Collaboration Boosts Potential for CdTe Solar Cells - News Releases |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    NREL NREL Collaboration Boosts Potential for CdTe Solar Cells February 29, 2016 A critical milestone has been reached in cadmium telluride (CdTe) solar cell technology, helping pave the way for solar energy to directly compete with electricity generated by conventional energy sources. Scientists at the Energy Department's National Renewable Energy Laboratory (NREL) collaborated with researchers at Washington State University and the University of Tennessee to improve the maximum voltage

  19. Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Journal Article: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials Citation Details In-Document Search Title: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials Authors: Shu, Michael J. ; Zalden, Peter ; Chen, Frank ; Weems, Ben ; Chatzakis, Ioannis ; Xiong, Feng ; Jeyasingh, Rakesh ; Hoffmann, Matthias C. ; Pop, Eric ; Wong, H.-S.Philip ; Wuttig, Matthias ; Lindenberg, Aaron M. Publication Date: 2014-07-08 OSTI

  20. Spin glass in semiconducting KFe1.05Ag0.88Te2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, H.; Lei, H.; Klobes, B.; Warren, J. B.; Hermann, R. P.; Petrovic, C.

    2015-05-26

    We report discovery of KFe1.05Ag0.88Te2 single crystals with semiconducting spin glass ground state. Composition and structure analysis suggest nearly stoichiometric I4/mmm space group but allow for the existence of vacancies, absent in long range semiconducting antiferromagnet KFe1.05Ag0.88Te2. The subtle change in stoichometry in Fe/Ag sublattice changes magnetic ground state but not conductivity, giving further insight into the semiconducting gap mechanism.

  1. PbTe/TAGS RTG Mars Environmental Survey (MESUR) mission

    SciTech Connect (OSTI)

    Schock, A. )

    1993-01-10

    The paper describes the results of studies on an RTG option for powering the global network of unmanned landers for NASA's Mars Environmental Survey (MESUR) mission. RTGs are essentially unaffected by diurnal and seasonal variations, Martian sandstorms, and landing site latitudes, and their waste heat can stabilize the temperatures of the landers and their payload. The RTG designs described in this paper are based on PbTe/TAGS thermoelectric elements, in contast to the SiGe-based RTGs the author described in previous publications. The presently described RTGs differ not only in the choice of thermoelectric materials but also in the use of much lower operating temperatures, conductive rather than radiative heat transfer, an inert cover gas instead of vacuum in the RTG's converter, and fibrous instead of multifoil thermal insulation. As in a previous Teledyne design, the Fairchild designs described in this paper employ flight-proven General Purpose Source modules and Close-Pack Arrays of thermoelectric converter modules. Illustrative point designs of RTGs producing 41 and 51 watts(e) at 28 volts are presented. The presented performance parameters were derived by detailed thermal, thermoelectric, and electrical analyses (including radiator geometry optimization) described in the paper. The Fairchild study showed that, with appropriate modifications, the Teledyne design can be scaled up to higher power levels, and it identified solutions to ensure adequate fuel clad ductility at launch temperatures and adequate thermal conductance from the thermoelectric cold ends to the RTG housing.

  2. Chiral magnetic effect in ZrTe5

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Q.; Kharzeev, D. E.; Zhang, C.; Huang, Y.; Pletikosic, I.; Fedorov, A. V.; Zhong, R. D.; Schneeloch, J. A.; Gu, G. D.; Valla, T.

    2016-02-08

    The chiral magnetic effect is the generation of electric current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum anomaly in relativistic field theory of chiral fermions (massless spin 1/2 particles with a definite projection of spin on momentum) - a dramatic phenomenon arising from a collective motion of particles and antiparticles in the Dirac sea. The recent discovery of Dirac semimetals with chiral quasi-particles opens a fascinating possibility to study this phenomenon in condensed matter experiments. Here we report on the measurement of magneto-transport in zirconium pentatelluride, ZrTe5 that providesmore » a strong evidence for the chiral magnetic effect. Our angleresolved photoemission spectroscopy experiments show that this material’s electronic structure is consistent with a 3D Dirac semimetal. We observe a large negative magnetoresistance when magnetic field is parallel with the current. The measured quadratic field dependence of the magnetoconductance is a clear indication of the chiral magnetic effect. The observed phenomenon stems from the effective transmutation of Dirac semimetal into a Weyl semimetal induced by the parallel electric and magnetic fields that represent a topologically nontrivial gauge field background. We expect that chiral magnetic effect may emerge in a wide class of materials that are near the transition between the trivial and topological insulators.« less

  3. DEGREE-SCALE GeV 'JETS' FROM ACTIVE AND DEAD TeV BLAZARS

    SciTech Connect (OSTI)

    Neronov, A.; Semikoz, D.; Kachelriess, M.; Ostapchenko, S.; Elyiv, A.

    2010-08-20

    We show that images of TeV blazars in the GeV energy band should contain, along with point-like sources, degree-scale jet-like extensions. These GeV extensions are the result of electromagnetic cascades initiated by TeV {gamma}-rays interacting with extragalactic background light and the deflection of the cascade electrons/positrons in extragalactic magnetic fields (EGMFs). Using Monte Carlo simulations, we study the spectral and timing properties of the degree-scale extensions in simulated GeV band images of TeV blazars. We show that the brightness profile of such degree-scale extensions can be used to infer the light curve of the primary TeV {gamma}-ray source over the past 10{sup 7} yr, i.e., over a time scale comparable to the lifetime of the parent active galactic nucleus. This implies that the degree-scale jet-like GeV emission could be detected not only near known active TeV blazars, but also from 'TeV blazar remnants', whose central engines were switched off up to 10 million years ago. Since the brightness profile of the GeV 'jets' depends on the strength and the structure of the EGMF, their observation provides additional information about the EGMF.

  4. Ion-beam treatment to prepare surfaces of p-CdTe films

    DOE Patents [OSTI]

    Gessert, Timothy A.

    2001-01-01

    A method of making a low-resistance electrical contact between a p-CdTe layer and outer contact layers by ion beam processing comprising: a) placing a CdS/CdTe device into a chamber and evacuating the chamber; b) orienting the p-CdTe side of the CdS/CdTe layer so that it faces apparatus capable of generating Ar atoms and ions of preferred energy and directionality; c) introducing Ar and igniting the area of apparatus capable of generating Ar atoms and ions of preferred energy and directionality in a manner so that during ion exposure, the source-to-substrate distance is maintained such that it is less than the mean-free path or diffusion length of the Ar atoms and ions at the vacuum pressure; d) allowing exposure of the p-CdTe side of the device to said ion beam for a period less than about 5 minutes; and e) imparting movement to the substrate to control the real uniformity of the ion-beam exposure on the p-CdTe side of the device.

  5. Enhanced thermoelectric performance in Cd doped CuInTe{sub 2} compounds

    SciTech Connect (OSTI)

    Cheng, N.; Liu, R.; Bai, S.; Shi, X. Chen, L.

    2014-04-28

    CuIn{sub 1?x}Cd{sub x}Te{sub 2} materials (x?=?0, 0.02, 0.05, and 0.1) are prepared using melting-annealing method and the highly densified bulk samples are obtained through Spark Plasma Sintering. The X-ray diffraction data confirm that nearly pure chalcopyrite structures are obtained in all the samples. Due to the substitution of Cd at In sites, the carrier concentration is greatly increased, leading to much enhanced electrical conductivity and power factor. The single parabolic band model is used to describe the electrical transport properties of CuInTe{sub 2} and the low temperature Hall mobility is also modeled. By combing theoretical model and experiment data, the optimum carrier concentration in CuInTe{sub 2} is proposed to explain the greatly enhanced power factors in the Cd doped CuInTe{sub 2}. In addition, the thermal conductivity is reduced by extra phonon scattering due to the atomic mass and radius fluctuations between Cd and In atoms. The maximum zTs are observed in CuIn{sub 0.98}Cd{sub 0.02}Te{sub 2} and CuIn{sub 0.9}Cd{sub 0.1}Te{sub 2} samples, which are improved by over 100% at room temperature and around 20% at 600?K.

  6. Oxygen Incorporation During Fabrication of Substrate CdTe Photovoltaic Devices: Preprint

    SciTech Connect (OSTI)

    Duenow, J. N.; Dhere, R. G.; Kuciauskas, D.; Li, J. V.; Pankow, J. W.; DeHart, C. M.; Gessert, T. A.

    2012-06-01

    Recently, CdTe photovoltaic (PV) devices fabricated in the nonstandard substrate configuration have attracted increasing interest because of their potential compatibility with flexible substrates such as metal foils and polymer films. This compatibility could lead to the suitability of CdTe for roll-to-roll processing and building-integrated PV. Currently, however, the efficiencies of substrate CdTe devices reported in the literature are significantly lower ({approx}6%-8%) than those of high-performance superstrate devices ({approx}17%) because of significantly lower open-circuit voltage (Voc) and fill factor (FF). In our recent device development efforts, we have found that processing parameters required to fabricate high-efficiency substrate CdTe PV devices differ from those necessary for traditional superstrate CdTe devices. Here, we investigate how oxygen incorporation in the CdTe deposition, CdCl2 heat treatment, CdS deposition, and post-deposition heat treatment affect device characteristics through their effects on the junction. By adjusting whether oxygen is incorporated during these processing steps, we have achieved Voc values greater than 860 mV and efficiencies greater than 10%.

  7. Ultrathin nanosheets of CrSiTe3. A semiconducting two-dimensional ferromagnetic material

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lin, Ming -Wei; Zhung, Houlong L.; Yan, Jiaqiang; Ward, Thomas Zac; Puretzky, Alexander A.; Rouleau, Christopher M.; Gai, Zheng; Liang, Liangbo; Meunier, Vincent; Ganesh, Panchapakesan; et al

    2015-11-27

    Finite range ferromagnetism and antiferromagnetism in two-dimensional (2D) systems within an isotropic Heisenberg model at non-zero temperature were originally proposed to be impossible. However, recent theoretical studies using an Ising model have recently shown that 2D magnetic crystals can exhibit magnetism. Experimental verification of existing 2D magnetic crystals in this system has remained elusive. In this work we for the first time exfoliate the CrSiTe3, a bulk ferromagnetic semiconductor, to mono- and few-layer 2D crystals onto a Si/SiO2 substrate. The Raman spectra show the good stability and high quality of the exfoliated flakes, consistent with the computed phonon spectra ofmore » 2D CrSiTe3, giving a strong evidence for the existence of 2D CrSiTe3 crystals. When the thickness of the CrSiTe3 crystals is reduced to few-layers, we observed a clear change in resistivity at 80~120 K, consistent with the theoretical calculations on the Curie temperature (Tc) of ~80 K for the magnetic ordering of 2D CrSiTe3 crystals. As a result, the ferromagnetic mono- and few-layer 2D CrSiTe3 indicated here should enable numerous applications in nano-spintronics.« less

  8. Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement

    SciTech Connect (OSTI)

    Wu, Lihua; Yang, Jiong; Chi, Miaofang; Wang, Shanyu; Wei, Ping; Zhang, Wenqing; Chen, Lidong; Yang, Jihui

    2015-09-23

    The low weighted carrier mobility has long been considered to be the key challenge for improvement of thermoelectric (TE) performance in BiTeI. The Rashba-effect-induced two-dimensional density of states in this bulk semiconductor is beneficial for thermopower enhancement, which makes it a prospective compound for TE applications. In this report, we show that intercalation of minor Cu-dopants can substantially alter the equilibria of defect reactions, selectively mediate the donor-acceptor compensation, and tune the defect concentration in the carrier conductive network. Consequently, the potential fluctuations responsible for electron scattering are reduced and the carrier mobility in BiTeI can be enhanced by a factor of two to three between 10 K and 300 K. The carrier concentration can also be optimized by tuning the Te/I composition ratio, leading to higher thermopower in this Rashba system. Cu-intercalation in BiTeI gives rise to higher power factor, slightly lower lattice thermal conductivity, and consequently improved figure of merit. Compared with pristine BiTe0.98I1.02, the TE performance in Cu0.05BiTeI reveals a 150% and 20% enhancement at 300 and 520 K, respectively. Ultimately, these results demonstrate that defect equilibria mediated by selective doping in complex TE and energy materials could be an effective approach to carrier mobility and performance optimization.

  9. Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wu, Lihua; Yang, Jiong; Chi, Miaofang; Wang, Shanyu; Wei, Ping; Zhang, Wenqing; Chen, Lidong; Yang, Jihui

    2015-09-23

    The low weighted carrier mobility has long been considered to be the key challenge for improvement of thermoelectric (TE) performance in BiTeI. The Rashba-effect-induced two-dimensional density of states in this bulk semiconductor is beneficial for thermopower enhancement, which makes it a prospective compound for TE applications. In this report, we show that intercalation of minor Cu-dopants can substantially alter the equilibria of defect reactions, selectively mediate the donor-acceptor compensation, and tune the defect concentration in the carrier conductive network. Consequently, the potential fluctuations responsible for electron scattering are reduced and the carrier mobility in BiTeI can be enhanced by amore » factor of two to three between 10 K and 300 K. The carrier concentration can also be optimized by tuning the Te/I composition ratio, leading to higher thermopower in this Rashba system. Cu-intercalation in BiTeI gives rise to higher power factor, slightly lower lattice thermal conductivity, and consequently improved figure of merit. Compared with pristine BiTe0.98I1.02, the TE performance in Cu0.05BiTeI reveals a 150% and 20% enhancement at 300 and 520 K, respectively. Ultimately, these results demonstrate that defect equilibria mediated by selective doping in complex TE and energy materials could be an effective approach to carrier mobility and performance optimization.« less

  10. Structural characterization of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} as a function of temperature using neutron powder diffraction and extended X-ray absorption fine structure techniques

    SciTech Connect (OSTI)

    Mansour, A. N.; Wong-Ng, W.; Huang, Q.; Tang, W.; Thompson, A.; Sharp, J.

    2014-08-28

    The structure of Bi{sub 2}Te{sub 3} (Seebeck coefficient Standard Reference Material (SRM™ 3451)) and the related phase Sb{sub 2}Te{sub 3} have been characterized as a function of temperature using the neutron powder diffraction (NPD) and the extended X-ray absorption fine structure (EXAFS) techniques. The neutron structural studies were carried out from 20 K to 300 K for Bi{sub 2}Te{sub 3} and from 10 K to 298 K for Sb{sub 2}Te{sub 3}. The EXAFS technique for studying the local structure of the two compounds was conducted from 19 K to 298 K. Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} are isostructural, with a space group of R3{sup ¯}m. The structure consists of repeated quintuple layers of atoms, Te2-M-Te1-M-Te2 (where M = Bi or Sb) stacking along the c-axis of the unit cell. EXAFS was used to examine the bond distances and static and thermal disorders for the first three shells of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} as a function of temperature. The temperature dependencies of thermal disorders were analyzed using the Debye and Einstein models for lattice vibrations. The Debye and Einstein temperatures for the first two shells of Bi{sub 2}Te{sub 3} are similar to those of Sb{sub 2}Te{sub 3} within the uncertainty in the data. However, the Debye and Einstein temperatures for the third shell of Bi-Bi are significantly lower than those of the third shell of Sb-Sb. The Einstein temperature for the third shell is consistent with a soft phonon mode in both Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3}. The lower Einstein temperature of Bi-Bi relative to Sb-Sb is consistent with the lower value of thermal conductivity of Bi{sub 2}Te{sub 3} relative to Sb{sub 2}Te{sub 3}.

  11. Carrier lifetimes and interface recombination velocities in CdTe/Mg{sub x}Cd{sub 1−x}Te double heterostructures with different Mg compositions grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Liu, Shi; Lassise, Maxwell B.; Zhao, Yuan; Zhang, Yong-Hang; Zhao, Xin-Hao; Campbell, Calli M.

    2015-07-27

    The interface recombination velocities of CdTe/Mg{sub x}Cd{sub 1−x}Te double heterostructure (DH) samples with different CdTe layer thicknesses and Mg compositions are studied using time-resolved photoluminescence measurements. A lowest interface recombination velocity of 30 ± 10 cm/s has been measured for the CdTe/Mg{sub 0.46}Cd{sub 0.54}Te interface, and a longest carrier lifetime of 0.83 μs has been observed for the studied DHs. These values are very close to the best reported numbers for GaAs/AlGaAs DHs. The impact of carrier escape through thermionic emission over the MgCdTe barrier on the recombination process in the DHs is also studied.

  12. Disorder-induced anomalously signed Hall effect in crystalline GeTe/Sb{sub 2}Te{sub 3} superlattice-like materials

    SciTech Connect (OSTI)

    Tong, H.; Yu, N. N.; Yang, Z.; Cheng, X. M.; Miao, X. S.

    2015-08-21

    Opposite to the almost persistent p-type conductivity of the crystalline chalcogenides along the GeTe-Sb{sub 2}Te{sub 3} tie line, n-type Hall mobility is observed in crystalline GeTe/Sb{sub 2}Te{sub 3} superlattice-like material (SLL) with a short period length. We suggest that this unusual carrier characteristic originates from the structural disorder introduced by the lattice strain and dangling bonds at the SLL interfaces, which makes the crystalline SLLs behave like the amorphous chalcogenides. Detailed structural disorder in crystalline SLL has been studied by Raman scattering, X-ray photoelectron spectroscopy, as well as Variable-energy positron annihilation spectroscopy measurements. First-principles calculations results show that this structural disorder gives rise to three-site junctions that dominate the charge transport as the period length decreases and result in the anomalously signed Hall effect in the crystalline SLL. Our findings indicate a similar tetrahedral structure in the amorphous and crystalline states of SLLs, which can significantly reduce the entropy difference. Due to the reduced entropy loss and increased resistivity of crystalline phase introduced by disorder, it is not surprising that the SLLs exhibit extremely lower RESET current and power consumption.

  13. The role of oxygen in CdS/CdTe solar cells deposited by close-spaced sublimation

    SciTech Connect (OSTI)

    Rose, D.H.; Levi, D.H.; Matson, R.J.

    1996-05-01

    The presence of oxygen during close-spaced sublimation (CSS) of CdTe has been previously reported to be essential for high-efficiency CdS/CdTe solar cells because it increases the acceptor density in the absorber. The authors find that the presence of oxygen during CSS increases the nucleation site density of CdTe, thus decreasing pinhole density and grain size. Photoluminescence showed that oxygen decreases material quality in the bulk of the CdTe film, but positively impacts the critical CdS/CdTe interface. Through device characterization the authors were unable to verify an increase in acceptor density with increased oxygen. These results, along with the achievement of high-efficiency cells (13% AM1.5) without the use of oxygen, led the authors to conclude that the use of oxygen during CSS deposition of CdTe can be useful but is not essential.

  14. Development of a Total Energy, Environment and Asset Management (TE2AM tm) Curriculum

    SciTech Connect (OSTI)

    2012-12-31

    The University of Wisconsin Department of Engineering Professional Development (EPD) has completed the sponsored project entitled, Development of a Total Energy, Environment and Asset Management (TE2AM™) Curriculum. The project involved the development of a structured professional development program to improve the knowledge, skills, capabilities, and competencies of engineers and operators of commercial buildings. TE2AM™ advances a radically different approach to commercial building design, operation, maintenance, and end-­‐of-­‐life disposition. By employing asset management principles to the lifecycle of a commercial building, owners and occupants will realize improved building performance, reduced energy consumption and positive environmental impacts. Through our commercialization plan, we intend to offer TE2AM™ courses and certificates to the professional community and continuously improve TE2AM™ course materials. The TE2AM™ project supports the DOE Strategic Theme 1 -­‐ Energy Security; and will further advance the DOE Strategic Goal 1.4 Energy Productivity. Through participation in the TE2AM™ curriculum, engineers and operators of commercial buildings will be eligible for a professional certificate; denoting the completion of a prescribed series of learning activities. The project involved a comprehensive, rigorous approach to curriculum development, and accomplished the following goals: 1. Identify, analyze and prioritize key learning needs of engineers, architects and technical professionals as operators of commercial buildings. 2. Design and develop TE2AM™ curricula and instructional strategies to meet learning needs of the target learning community. 3. Establish partnerships with the sponsor and key stakeholders to enhance the development and delivery of learning programs. 4. Successfully commercialize and sustain the training and certificate programs for a substantial time following the term of the award. The project team was

  15. First-epoch VLBA imaging of 20 new TeV blazars

    SciTech Connect (OSTI)

    Piner, B. Glenn; Edwards, Philip G.

    2014-12-10

    We present Very Long Baseline Array (VLBA) images of 20 TeV blazars not previously well studied on the parsec scale. All 20 of these sources are high-frequency peaked BL Lac objects (HBLs). Observations were made between August and December of 2013 at a frequency of 8.4 GHz. These observations represent the first epoch of a VLBA monitoring campaign on these blazars, and they significantly increase the fraction of TeV HBLs studied with high-resolution imaging. The peak very long baseline interferometry (VLBI) flux densities of these sources range from ∼10 to ∼100 mJy bm{sup –1}, and parsec-scale jet structure is detected in all sources. About half of the VLBI cores are resolved, with brightness temperature upper limits of a few times 10{sup 10} K, and we find that a brightness temperature of ∼2 × 10{sup 10} K is consistent with the VLBI data for all but one of the sources. Such brightness temperatures do not require any relativistic beaming to reduce the observed value below commonly invoked intrinsic limits; however, the lack of detection of counterjets does place a modest limit on the bulk Lorentz factor of γ ≳ 2. These data are thus consistent with a picture where weak-jet sources like the TeV HBLs develop significant velocity structures on parsec scales. We also extend consideration to the full sample of TeV HBLs by combining the new VLBI data with VLBI and gamma-ray data from the literature. By comparing measured VLBI and TeV fluxes to samples with intrinsically uncorrelated luminosities generated by Monte Carlo simulations, we find a marginally significant correlation between the VLBI and TeV fluxes for the full TeV HBL sample.

  16. Vibrational properties of epitaxial Bi{sub 4}Te{sub 3} films as studied by Raman spectroscopy

    SciTech Connect (OSTI)

    Xu, Hao; Pan, Wenwu; Chen, Qimiao; Wu, Xiaoyan; Song, Yuxin E-mail: shumin@chalmers.se; Gong, Qian; Lu, Pengfei; Wang, Shumin E-mail: shumin@chalmers.se

    2015-08-15

    Bi{sub 4}Te{sub 3}, as one of the phases of the binary Bi–Te system, shares many similarities with Bi{sub 2}Te{sub 3}, which is known as a topological insulator and thermoelectric material. We report the micro-Raman spectroscopy study of 50 nm Bi{sub 4}Te{sub 3} films on Si substrates prepared by molecular beam epitaxy. Raman spectra of Bi{sub 4}Te{sub 3} films completely resolve the six predicted Raman-active phonon modes for the first time. Structural features and Raman tensors of Bi{sub 4}Te{sub 3} films are introduced. According to the wavenumbers and assignments of the six eigenpeaks in the Raman spectra of Bi{sub 4}Te{sub 3} films, it is found that the Raman-active phonon oscillations in Bi{sub 4}Te{sub 3} films exhibit the vibrational properties of those in both Bi and Bi{sub 2}Te{sub 3} films.

  17. An Experiment to Locate the Site of TeV Flaring in M87

    SciTech Connect (OSTI)

    Harris, D.E.; /Harvard-Smithsonian Ctr. Astrophys.; Massaro, F.; /Harvard-Smithsonian Ctr. Astrophys. /KIPAC, Menlo Park /SLAC; Cheung, C.C.; /Natl. Acad. Sci. /Naval Research Lab, Wash., D.C.; Horns, D.; Raue, M.; /Hamburg U.; Stawarz, L.; /JAXA, Sagamihara /Jagiellonian U., Astron. Observ.; Wagner, S.; /Heidelberg Observ.; Colin, P.; /Munich, Max Planck Inst.; Mazin, D.; /Barcelona, IFAE; Wagner, R.; /Munich, Max Planck Inst.; Beilicke, M.; /McDonnell Ctr. Space Sci.; LeBohec, S.; Hui, M.; /Utah U.; Mukherjee, R.; /Barnard Coll.

    2012-05-18

    We describe a Chandra X-ray target-of-opportunity project designed to isolate the site of TeV flaring in the radio galaxy M87. To date, we have triggered the Chandra observations only once (2010 April) and by the time of the first of our nine observations, the TeV flare had ended. However, we found that the X-ray intensity of the unresolved nucleus was at an elevated level for our first observation. Of the more than 60 Chandra observations we have made of the M87 jet covering nine years, the nucleus was measured at a comparably high level only three times. Two of these occasions can be associated with TeV flaring, and at the time of the third event, there were no TeV monitoring activities. From the rapidity of the intensity drop of the nucleus, we infer that the size of the emitting region is of order a few light days x the unknown beaming factor; comparable to the same sort of estimate for the TeV emitting region. We also find evidence of spectral evolution in the X-ray band which seems consistent with radiative losses affecting the non-thermal population of the emitting electrons within the unresolved nucleus.

  18. Intergalactic magnetic fields and gamma-ray observations of extreme TeV blazars

    SciTech Connect (OSTI)

    Arlen, Timothy C.; Vassilev, Vladimir V.; Weisgarber, Thomas; Wakely, Scott P.; Shafi, S. Yusef

    2014-11-20

    The intergalactic magnetic field (IGMF) in cosmic voids can be indirectly probed through its effect on electromagnetic cascades initiated by a source of teraelectronvolt (TeV) gamma-rays, such as active galactic nuclei (AGNs). AGNs that are sufficiently luminous at TeV energies, 'extreme TeV blazars', can produce detectable levels of secondary radiation from inverse Compton scattering of the electrons in the cascade, provided that the IGMF is not too large. We review recent work in the literature that utilizes this idea to derive constraints on the IGMF for three TeV-detected blazars, 1ES 0229+200, 1ES 1218+304, and RGB J0710+591, and we also investigate four other hard-spectrum TeV blazars in the same framework. Through a recently developed, detailed, three-dimensional particle-tracking Monte Carlo code, incorporating all major effects of QED and cosmological expansion, we research the effects of major uncertainties, such as the spectral properties of the source, uncertainty in the ultraviolet and far-infrared extragalactic background light, undersampled very high energy (energy ≥100 GeV) coverage, past history of gamma-ray emission, source versus observer geometry, and the jet AGN Doppler factor. The implications of these effects on the recently reported lower limits of the IGMF are thoroughly examined to conclude that the presently available data are compatible with a zero-IGMF hypothesis.

  19. Static atomic displacements in a CdTe epitaxial layer on a GaAs substrate

    SciTech Connect (OSTI)

    Horning, R.D.; Staudenmann, J.

    1987-05-25

    A (001)CdTe epitaxial layer on a (001)GaAs substrate was studied by x-ray diffraction between 10 and 360 K. The CdTe growth took place at 380 /sup 0/C in a vertical gas flow metalorganic chemical vapor deposition reactor. Lattice parameters and integrated intensities of both the substrate and the epitaxial layer using the (00l) and (hhh) Bragg reflections reveal three important features. Firstly, the GaAs substrate does not exhibit severe strain after deposition and it is as perfect as a bulk GaAs. Secondly, the CdTe unit cell distorts tetragonally with a/sub perpendicular/>a/sub parallel/ below 300 K. The decay of the (00l) reflection intensities as a function of the temperature yields a Debye temperature of 142 K, the same value as for bulk CdTe. Thirdly, a temperature-dependent isotropic static displacement of the Cd and the Te atoms is introduced to account for the anomalous behavior of the (hhh) intensities.

  20. Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation

    SciTech Connect (OSTI)

    Simonds, Brian J.; Kheraj, Vipul; Palekis, Vasilios; Ferekides, Christos; Scarpulla, Michael A.

    2015-06-14

    Laser processing of polycrystalline CdTe is a promising approach that could potentially increase module manufacturing throughput while reducing capital expenditure costs. For these benefits to be realized, the basic effects of laser irradiation on CdTe must be ascertained. In this study, we utilize surface photovoltage spectroscopy (SPS) to investigate the changes to the electronic properties of the surface of polycrystalline CdTe solar cell stacks induced by continuous-wave laser annealing. The experimental data explained within a model consisting of two space charge regions, one at the CdTe/air interface and one at the CdTe/CdS junction, are used to interpret our SPS results. The frequency dependence and phase spectra of the SPS signal are also discussed. To support the SPS findings, low-temperature spectrally-resolved photoluminescence and time-resolved photoluminescence were also measured. The data show that a modest laser treatment of 250 W/cm{sup 2} with a dwell time of 20 s is sufficient to reduce the effects of Fermi level pinning at the surface due to surface defects.

  1. Experimental Realization of a Three-Dimensional Topological Insulator, Bi 2Te3

    SciTech Connect (OSTI)

    Siemons, W.

    2010-02-24

    Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi{sub 2}Te{sub 3} with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi{sub 2}Te{sub 3} is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi{sub 2}Te{sub 3} also points to promising potential for high-temperature spintronics applications.

  2. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect (OSTI)

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  3. Role of polycrystallinity in CdTe and CuInSe sub 2 photovoltaic cells

    SciTech Connect (OSTI)

    Sites, J.R. )

    1991-01-01

    The polycrystalline nature of thin-film CdTe and CuInSe{sub 2} solar cells continues to be a major factor in several individual losses that limit overall cell efficiency. This report describes progress in the quantitative separation of these losses, including both measurement and analysis procedures. It also applies these techniques to several individual cells to help document the overall progress with CdTe and CuInSe{sub 2} cells. Notably, CdTe cells from Photon Energy have reduced window photocurrent losses to 1 mA/Cm{sup 2}; those from the University of South Florida have achieved a maximum power voltage of 693 mV; and CuInSe{sub 2} cells from International Solar Electric Technology have shown a hole density as high as 7 {times} 10{sup 16} cm{sup {minus}3}, implying a significant reduction in compensation. 9 refs.

  4. Effects of Stoichiometry in Undoped CdTe Heteroepilayers on Si

    SciTech Connect (OSTI)

    Gessert, Timothy A.; Colegrove, Eric; Stafford, Brian; Gao, Wei; Sivananthan, Siva; Kuciauskas, Darius; Moutinho, Helio; Farrell, Stuart; Barnes, Teresa

    2015-06-14

    Crystalline CdTe layers have been grown heteroepitaxially onto crystalline Si substrates to establish material parameters needed for advanced photovoltaic (PV) device development and related simulation. These studies suggest that additional availability of the intrinsic anion (i.e., Te) during molecular beam epitaxy deposition can improve structural and optoelectronic quality of the epilayer and the interface between Si substrate and the epilayer. This is seen most notably for thin CdTe epitaxial films (<; ~10 micrometers). Although these observations are foundationally important, they are also relevant to envisioned high-performance multijunction II-VI alloy PV devices-where thin layers will be required to achieve production costs aligned with market constraints.

  5. Ba2TeO as an optoelectronic material: First-principles study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Siegrist, Theo; Singh, David J.

    2015-05-21

    The band structure, optical and defects properties of Ba2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of themore » donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.« less

  6. Ba2TeO: A new layered oxytelluride

    SciTech Connect (OSTI)

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J. B.; Tokumoto, T. D.; McGill, S. A.; Singh, D. J.; Siegrist, T.

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

  7. Systematic study of doping dependence on linear magnetoresistance in p-PbTe

    SciTech Connect (OSTI)

    Schneider, J. M.; Chitta, V. A.; Oliveira, N. F.; Peres, M. L. Castro, S. de; Soares, D. A. W.; Wiedmann, S.; Zeitler, U.; Abramof, E.; Rappl, P. H. O.; Mengui, U. A.

    2014-10-20

    We report on a large linear magnetoresistance effect observed in doped p-PbTe films. While undoped p-PbTe reveals a sublinear magnetoresistance, p-PbTe films doped with BaF{sub 2} exhibit a transition to a nearly perfect linear magnetoresistance behaviour that is persistent up to 30?T. The linear magnetoresistance slope ?R/?B is to a good approximation, independent of temperature. This is in agreement with the theory of Quantum Linear Magnetoresistance. We also performed magnetoresistance simulations using a classical model of linear magnetoresistance. We found that this model fails to explain the experimental data. A systematic study of the doping dependence reveals that the linear magnetoresistance response has a maximum for small BaF{sub 2} doping levels and diminishes rapidly for increasing doping levels. Exploiting the huge impact of doping on the linear magnetoresistance signal could lead to new classes of devices with giant magnetoresistance behavior.

  8. Ba{sub 2}TeO as an optoelectronic material: First-principles study

    SciTech Connect (OSTI)

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Singh, David J.; Siegrist, Theo

    2015-05-21

    The band structure, optical, and defects properties of Ba{sub 2}TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba{sub 2}TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical bandgap [Besara et al., J. Solid State Chem. 222, 60 (2015)]. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba{sub 2}TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.

  9. Superconducting thin films of (100) and (111) oriented indium doped topological crystalline insulator SnTe

    SciTech Connect (OSTI)

    Si, W.; Zhang, C.; Wu, L.; Ozaki, T.; Gu, G.; Li, Q.

    2015-09-01

    Recent discovery of the topological crystalline insulator SnTe has triggered a search for topological superconductors, which have potential application to topological quantum computing. The present work reports on the superconducting properties of indium doped SnTe thin films. The (100) and (111) oriented thin films were epitaxially grown by pulsed-laser deposition on (100) and (111) BaF2 crystalline substrates respectively. The onset superconducting transition temperatures are about 3.8 K for (100) and 3.6 K for (111) orientations, slightly lower than that of the bulk. Magneto-resistive measurements indicate that these thin films may have upper critical fields higher than that of the bulk. With large surface-to-bulk ratio, superconducting indium doped SnTe thin films provide a rich platform for the study of topological superconductivity and potential device applications based on topological superconductors.

  10. Superconducting thin films of (100) and (111) oriented indium doped topological crystalline insulator SnTe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Si, W.; Zhang, C.; Wu, L.; Ozaki, T.; Gu, G.; Li, Q.

    2015-09-01

    Recent discovery of the topological crystalline insulator SnTe has triggered a search for topological superconductors, which have potential application to topological quantum computing. The present work reports on the superconducting properties of indium doped SnTe thin films. The (100) and (111) oriented thin films were epitaxially grown by pulsed-laser deposition on (100) and (111) BaF2 crystalline substrates respectively. The onset superconducting transition temperatures are about 3.8 K for (100) and 3.6 K for (111) orientations, slightly lower than that of the bulk. Magneto-resistive measurements indicate that these thin films may have upper critical fields higher than that of the bulk.more » With large surface-to-bulk ratio, superconducting indium doped SnTe thin films provide a rich platform for the study of topological superconductivity and potential device applications based on topological superconductors.« less

  11. Pair correlations in neutrinoless double {beta} decay candidate {sup 130}Te.

    SciTech Connect (OSTI)

    Bloxham, T.; Kay, B. P.; Schiffer, J. P.; Clark, J. A.; Deibel, C. M.; Freeman, S. J.; Freedman, S. J.; Howard, A. M.; McAllister, S. A.; Parker, P. D.; Sharp, D. K.; Thomas, J. S. (Physics); ( PSC-USR); (LBNL); (Michigan State Univ.); (Univ. of Manchester); (Yale Univ.)

    2010-08-16

    Pair correlations in the ground state of {sup 130}Te have been investigated using pair-transfer experiments to explore the validity of approximations in calculating the matrix element for neutrinoless double-{beta} decay. This nucleus is a candidate for the observation of such decay, and a good understanding of its structure is crucial for eventual calculations of the neutrino mass, should such a decay indeed be observed. For proton-pair adding, strong transitions to excited 0{sup +} states had been observed in the Te isotopes by Alford et al. [Nucl. Phys. A 323, 339 (1979)], indicating a breaking of the BCS approximation for protons in the ground state. We measured the neutron-pair removing (p,t) reaction on {sup 130}Te and found no indication of a corresponding splitting of the BCS nature of the ground state for neutrons.

  12. Pair correlations in the neutrinoless double-{beta} decay candidate {sup 130}Te

    SciTech Connect (OSTI)

    Bloxham, T.; Freedman, S. J. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kay, B. P.; Schiffer, J. P.; Clark, J. A. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Deibel, C. M. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48825 (United States); Freeman, S. J.; Howard, A. M.; McAllister, S. A.; Sharp, D. K.; Thomas, J. S. [Schuster Laboratory, University of Manchester, Manchester, M13 9PL (United Kingdom); Parker, P. D. [A. W. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States)

    2010-08-15

    Pair correlations in the ground state of {sup 130}Te have been investigated using pair-transfer experiments to explore the validity of approximations in calculating the matrix element for neutrinoless double-{beta} decay. This nucleus is a candidate for the observation of such decay, and a good understanding of its structure is crucial for eventual calculations of the neutrino mass, should such a decay indeed be observed. For proton-pair adding, strong transitions to excited 0{sup +} states had been observed in the Te isotopes by Alford et al. [Nucl. Phys. A 323, 339 (1979)], indicating a breaking of the BCS approximation for protons in the ground state. We measured the neutron-pair removing (p,t) reaction on {sup 130}Te and found no indication of a corresponding splitting of the BCS nature of the ground state for neutrons.

  13. Synthesis, crystal and electronic structure, and physical properties of the new lanthanum copper telluride La{sub 3}Cu{sub 5}Te{sub 7}

    SciTech Connect (OSTI)

    Zelinska, Mariya; Assoud, Abdeljalil [Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1 (Canada); Kleinke, Holger, E-mail: kleinke@uwaterloo.c [Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1 (Canada)

    2011-03-15

    The new lanthanum copper telluride La{sub 3}Cu{sub 5-x}Te{sub 7} has been obtained by annealing the elements at 1073 K. Single-crystal X-ray diffraction studies revealed that the title compound crystallizes in a new structure type, space group Pnma (no. 62) with lattice dimensions of a=8.2326(3) A, b=25.9466(9) A, c=7.3402(3) A, V=1567.9(1) A{sup 3}, Z=4 for La{sub 3}Cu{sub 4.86(4)}Te{sub 7}. The structure of La{sub 3}Cu{sub 5-x}Te{sub 7} is remarkably complex. The Cu and Te atoms build up a three-dimensional covalent network. The coordination polyhedra include trigonal LaTe{sub 6} prisms, capped trigonal LaTe{sub 7} prisms, CuTe{sub 4} tetrahedra, and CuTe{sub 3} pyramids. All Cu sites exhibit deficiencies of various extents. Electrical property measurements on a sintered pellet of La{sub 3}Cu{sub 4.86}Te{sub 7} indicate that it is a p-type semiconductor in accordance with the electronic structure calculations. -- Graphical abstract: Oligomeric unit comprising interconnected CuTe{sub 3} pyramids and CuTe{sub 4} tetrahedra. Display Omitted Research highlights: {yields} La{sub 3}Cu{sub 5-x}Te{sub 7} adopts a new structure type. {yields} All Cu sites exhibit deficiencies of various extents. {yields} The coordination polyhedra include trigonal LaTe{sub 6} prisms, capped trigonal LaTe{sub 7} prisms, CuTe{sub 4} tetrahedra and CuTe{sub 3} pyramids. {yields} La{sub 3}Cu{sub 5-x}Te{sub 7} is a p-type semiconductor.

  14. Thermoelectric study of crossroads material MnTe via sulfur doping

    SciTech Connect (OSTI)

    Xie, Wenjie Populoh, Sascha; Sagarna, Leyre; Trottmann, Matthias; Ga??zka, Krzysztof; Xiao, Xingxing; Liu, Yufei; He, Jian; Weidenkaff, Anke

    2014-03-14

    Here, we report thermoelectric study of crossroads material MnTe via iso-electronic doping S on the Te-site. MnTe{sub 1-x}S{sub x} samples with nominal S content of x?=?0.00, 0.05, and 0.10 were prepared using a melt-quench method followed by pulverization and spark plasma sintering. The X-ray powder diffraction, scanning electron microscopy, and ZAF-corrected compositional analysis confirmed that S uniformly substitutes Te up to slightly over 2%. A higher content of S in the starting materials led to the formation of secondary phases. The thermoelectric properties of MnTe{sub 1-x}S{sub x} samples were characterized by means of Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 300?K to 773?K. Furthermore, Hall coefficient measurements and a single parabolic band model were used to help gain insights on the effects of S-doping on the scattering mechanism and the carrier effective mass. As expected, S doping not only introduced hole charge carriers but also created short-range defects that effectively scatter heat-carrying phonons at elevated temperatures. On the other hand, we found that S doping degraded the effective mass. As a result, the ZT of MnTe{sub 0.9}S{sub 0.1} was substantially enhanced over the pristine sample near 400?K, while the improvement of ZT became marginal at elevated temperatures. A ZT???0.65 at 773?K was obtained in all three samples.

  15. Multiband Te p Based Superconductivity of Ta4Pd3Te16

    SciTech Connect (OSTI)

    Singh, David J.

    2014-10-06

    We recently discovered that Ta4Pd3Te16 is a superconductor that has been suggested to be an unconventional superconductor near magnetism. Here, we report electronic structure calculations showing that despite the layered crystal structure the material is an anisotropic three-dimensional (3D) metal. The Fermi surface contains prominent one-dimensional (1D) and two-dimensional (2D) features, including nested 1D sheets, a 2D cylindrical section, and a 3D sheet. Moreover, the electronic states that make up the Fermi surface are mostly derived from Te p states with small Ta d and Pd d contributions. This places the compound far from magnetic instabilities. The results are discussed in terms of multiband superconductivity.

  16. .sup.123m Te-Labeled biochemicals and method of preparation

    DOE Patents [OSTI]

    Knapp, Jr., Furn F.

    1980-01-01

    A novel class of .sup.123m Te-labeled steroids and amino acids is provided by the method of reacting a .sup.123m Te symmetric diorgano ditelluride with a hydride reducing agent and a source of alkali metal ions to form an alkali metal organo telluride. The alkali metal organo telluride is reacted with a primary halogenated steroidal side chain, amino acid, or amino acid precursor such as hydantoin. The novel compounds are useful as biological tracers and as organal imaging agents.

  17. Graphene/CdTe heterostructure solar cell and its enhancement with photo-induced doping

    SciTech Connect (OSTI)

    Lin, Shisheng Chen, Hongsheng; Li, Xiaoqiang; Zhang, Shengjiao; Wang, Peng; Xu, Zhijuan; Zhong, Huikai; Wu, Zhiqian

    2015-11-09

    We report a type of solar cell based on graphene/CdTe Schottky heterostructure, which can be improved by surface engineering as graphene is atomic thin. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the power conversion efficiency is increased from 2.08% to 3.10%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by field effect transport, Raman, photoluminescence, and quantum efficiency measurements. This work demonstrates a feasible way of improving the performance of graphene/semiconductor heterostructure solar cells by combining one dimensional with two dimensional materials.

  18. Renaissance of the ~1 TeV Fixed-Target Program

    SciTech Connect (OSTI)

    Adams, T.; Appel, Jeffrey A.; Arms, Kregg Elliott; Balantekin, A.B.; Conrad, Janet Marie; Cooper, Peter S.; Djurcic, Zelimir; Dunwoodie, William M.; Engelfried, Jurgen; Fisher, Peter H.; Gottschalk, E.; /Fermilab /Northwestern U.

    2009-05-01

    This document describes the physics potential of a new fixed-target program based on a {approx} TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.

  19. Renaissance of the ~ 1-TeV Fixed-Target Program

    SciTech Connect (OSTI)

    Adams, T.; Appel, J.A.; Arms, K.E.; Balantekin, A.B.; Conrad, J.M.; Cooper, P.S.; Djurcic, Z.; Dunwoodie, W.; Engelfried, J.; Fisher, P.H.; Gottschalk, Erik Edward; de Gouvea, A.; Heller, K.; Ignarra, C.M.; Karagiorgi, G.; Kwan, S.; Loinaz, W.A.; Meadows, B.; Moore, R.; Morfin, J.G.; Naples, D.; /Pittsburgh U. /St. Mary's Coll., Minnesota /New Mexico State U. /Michigan U. /Wayne State U. /South Carolina U. /Florida U. /Carnegie Mellon U. /Cincinnati U. /Columbia U. /Columbia U. /Northwestern U. /Yale U. /Fermilab /Argonne /Northwestern U. /APC, Paris

    2011-12-02

    This document describes the physics potential of a new fixed-target program based on a {approx}1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.

  20. Preliminary design for a 20 TeV Collider in a deep tunnel at Fermilab

    SciTech Connect (OSTI)

    Not Available

    1985-01-12

    The Reference Design Study for a 20 TeV Collider demonstrated the technical and cost feasibility of a 20 TeV superconducting collider facility. Based on magnets of 3T, 5T, and 6.5T the Main Ring of the Collider would have a circumference of 164 km, 113 km, or 90 km. There would be six collision regions, of which four would be developed intially. The 5T and 6.5T rings would have twelve major refrigeration stations, while the 3T design would have 24 major refrigeration stations.

  1. Aqueous Synthesis of Zinc Blende CdTe/CdS Magic-Core/Thick-Shell

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Tetrahedral Shaped Nanocrystals with Emission Tunable to Near-Infrared Aqueous Synthesis of Zinc Blende CdTe/CdS Magic-Core/Thick-Shell Tetrahedral Shaped Nanocrystals with Emission Tunable to Near-Infrared Authors: Deng, Z., Schulz, O., Lin, S., Ding, B., Liu, X., Wei, X., Ros, R., Liu, Y., Yan, H., and Francis, M. Title: Aqueous Synthesis of Zinc Blende CdTe/CdS Magic-Core/Thick-Shell Tetrahedral Shaped Nanocrystals with Emission Tunable to Near-Infrared Source: Journal of the American

  2. Optical Observations of Gamma-Ray Bursts: Connections to GeV/TeV Jets

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Conference: Optical Observations of Gamma-Ray Bursts: Connections to GeV/TeV Jets Citation Details In-Document Search Title: Optical Observations of Gamma-Ray Bursts: Connections to GeV/TeV Jets Authors: Vestrand, W. Thomas [1] + Show Author Affiliations Los Alamos National Laboratory Publication Date: 2013-08-21 OSTI Identifier: 1091318 Report Number(s): LA-UR-13-26624 DOE Contract Number: AC52-06NA25396 Resource Type: Conference Resource Relation: Conference:

  3. Passivation of an isoelectronic impurity by atomic hydrogen: The case of ZnTe:O

    SciTech Connect (OSTI)

    Felici, Marco; Polimeni, Antonio; Capizzi, Mario; Nabetani, Y.; Okuno, T.; Aoki, K.; Kato, T.; Matsumoto, T.; Hirai, T.

    2006-03-06

    We investigated the optical properties of ZnTe:O/GaAs before and after atomic hydrogen irradiation. Oxygen incorporation gives rise to energy levels associated with single O atoms, O-O pairs, and O clusters, and to a blueshift of the energy gap of the material with respect to that of pure ZnTe/GaAs. All of these effects disappear progressively after irradiation with H, which also leads to an increase in the tensile strain of the epilayer. These observations provide experimental evidence of H-induced passivation of an isoelectronic impurity in II-VI alloys.

  4. High efficiency thin film CdTe and a-Si based solar cells

    SciTech Connect (OSTI)

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10

  5. Charge transport properties of p-CdTe/n-CdTe/n{sup +}-Si diode-type nuclear radiation detectors based on metalorganic vapor-phase epitaxy-grown epilayers

    SciTech Connect (OSTI)

    Niraula, M.; Yasuda, K.; Wajima, Y.; Yamashita, H.; Tsukamoto, Y.; Suzuki, Y.; Matsumoto, M.; Takai, N.; Tsukamoto, Y.; Agata, Y.

    2013-10-28

    Charge transport properties of p-CdTe/n-CdTe/n{sup +}-Si diode-type nuclear radiation detectors, fabricated by growing p-and n-type CdTe epilayers on (211) n{sup +}-Si substrates using metalorganic vapor-phase epitaxy (MOVPE), were studied by analyzing current-voltage characteristics measured at various temperatures. The diode fabricated shows good rectification properties, however, both forward and reverse biased currents deviate from their ideal behavior. The forward current exhibits typical feature of multi-step tunneling at lower biases; however, becomes space charge limited type when the bias is increased. On the other hand, the reverse current exhibits thermally activated tunneling-type current. It was found that trapping centers at the p-CdTe/n-CdTe junction, which were formed due to the growth induced defects, determine the currents of this diode, and hence limit the performance of the nuclear radiation detectors developed.

  6. Local-moment magnetism in superconducting FeTe0.35Se0.65 as seen...

    Office of Scientific and Technical Information (OSTI)

    Local-moment magnetism in superconducting FeTe0.35Se0.65 as seen via inelastic neutron scattering Prev Next Title: Local-moment magnetism in superconducting FeTe0.35Se0.65 as ...

  7. Sonochemical and hydrothermal synthesis of PbTe nanostructures with the aid of a novel capping agent

    SciTech Connect (OSTI)

    Fard-Fini, Shahla Ahmadian; Salavati-Niasari, Masoud; Mohandes, Fatemeh

    2013-10-15

    Graphical abstract: - Highlights: • PbTe nanostructures were prepared with the aid of Schiff-base compound. • Sonochemical and hydrothermal methods were employed to fabricate PbTe nanostrucrues. • The effect of preparation parameters on the morphology of PbTe was investigated. - Abstract: In this work, a new Schiff-base compound derived from 1,8-diamino-3,6-dioxaoctane and 2-hydroxy-1-naphthaldehyde marked as (2-HyNa)-(DaDo) was synthesized, characterized, and then used as capping agent for the preparation of PbTe nanostructures. To fabricate PbTe nanostructures, two different synthesis methods; hydrothermal and sonochemical routes, were applied. To further investigate, the effect of preparation parameters like reaction time and temperature in hydrothermal synthesis and sonication time in the presence of ultrasound irradiation on the morphology and purity of the final products was tested. The products were analyzed with the aid of SEM, TEM, XRD, FT-IR, and EDS. Based on the obtained results, it was found that pure cubic phased PbTe nanostructures have been obtained by hydrothermal and sonochemical approaches. Besides, SEM images showed that cubic-like and rod-like PbTe nanostructures have been formed by hydrothermal and sonochemical methods, respectively. Sonochemical synthesis of PbTe nanostructures was favorable, because the synthesis time of sonochemical method was shorter than that of hydrothermal method.

  8. Study of W boson production in pPb collisions at sNN=5.02 TeV...

    Office of Scientific and Technical Information (OSTI)

    Study of W boson production in pPb collisions at sNN5.02 TeV Citation Details In-Document Search Title: Study of W boson production in pPb collisions at sNN5.02 TeV Publication...

  9. Cadmium sulfate and CdTe-quantum dots alter DNA repair in zebrafish (Danio rerio) liver cells

    SciTech Connect (OSTI)

    Tang, Song; Cai, Qingsong; Chibli, Hicham; Allagadda, Vinay; Nadeau, Jay L.; Mayer, Gregory D.

    2013-10-15

    Increasing use of quantum dots (QDs) makes it necessary to evaluate their toxicological impacts on aquatic organisms, since their contamination of surface water is inevitable. This study compares the genotoxic effects of ionic Cd versus CdTe nanocrystals in zebrafish hepatocytes. After 24 h of CdSO{sub 4} or CdTe QD exposure, zebrafish liver (ZFL) cells showed a decreased number of viable cells, an accumulation of Cd, an increased formation of reactive oxygen species (ROS), and an induction of DNA strand breaks. Measured levels of stress defense and DNA repair genes were elevated in both cases. However, removal of bulky DNA adducts by nucleotide excision repair (NER) was inhibited with CdSO{sub 4} but not with CdTe QDs. The adverse effects caused by acute exposure of CdTe QDs might be mediated through differing mechanisms than those resulting from ionic cadmium toxicity, and studying the effects of metallic components may be not enough to explain QD toxicities in aquatic organisms. - Highlights: Both CdSO{sub 4} and CdTe QDs lead to cell death and Cd accumulation. Both CdSO{sub 4} and CdTe QDs induce cellular ROS generation and DNA strand breaks. Both CdSO{sub 4} and CdTe QDs induce the expressions of stress defense and DNA repair genes. NER repair capacity was inhibited with CdSO{sub 4} but not with CdTe QDs.

  10. Modification of electron states in CdTe absorber due to a buffer layer in CdTe/CdS solar cells

    SciTech Connect (OSTI)

    Fedorenko, Y. G. Major, J. D.; Pressman, A.; Phillips, L. J.; Durose, K.

    2015-10-28

    By application of the ac admittance spectroscopy method, the defect state energy distributions were determined in CdTe incorporated in thin film solar cell structures concluded on ZnO, ZnSe, and ZnS buffer layers. Together with the Mott-Schottky analysis, the results revealed a strong modification of the defect density of states and the concentration of the uncompensated acceptors as influenced by the choice of the buffer layer. In the solar cells formed on ZnSe and ZnS, the Fermi level and the energy position of the dominant deep trap levels were observed to shift closer to the midgap of CdTe, suggesting the mid-gap states may act as recombination centers and impact the open-circuit voltage and the fill factor of the solar cells. For the deeper states, the broadening parameter was observed to increase, indicating fluctuations of the charge on a microscopic scale. Such changes can be attributed to the grain-boundary strain and the modification of the charge trapped at the grain-boundary interface states in polycrystalline CdTe.

  11. Effect of hydrostatic pressure and uniaxial strain on the electronic structure of Pb1-xSnxTe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Geilhufe, Matthias; Nayak, Sanjeev K.; Thomas, Stefan; Dane, Markus; Tripathi, Gouri S.; Entel, Peter; Hergert, Wolfram; Ernst, Arthur

    2015-12-09

    The electronic structure of Pb1–xSnxTe is studied by using the relativistic Korringa-Kohn-Rostoker Green function method in the framework of density functional theory. For all concentrations x, Pb1–xSnxTe is a direct semiconductor with a narrow band gap. In contrast to pure lead telluride, tin telluride shows an inverted band characteristic close to the Fermi energy. It will be shown that this particular property can be tuned, first, by alloying PbTe and SnTe and, second, by applying hydrostatic pressure or uniaxial strain. Furthermore, the magnitude of strain needed to switch between the regular and inverted band gap can be tuned by themore » alloy composition. In conclusion, there is a range of potential usage of Pb1–xSnxTe for spintronic applications.« less

  12. Low-temperature photoluminescence analysis of CdTeSe crystals for radiation-detector applications

    SciTech Connect (OSTI)

    YANG G.; Roy, U. N.; Bolotnikov, A. E.; Cui, Y.; Camarda, G.S.; Hossain, A.; and James, R. B.

    2015-10-05

    Goal: Understanding the changes of material defects in CdTeSe following annealing. Experimental results and discussions: Infrared (IR) transmission microscopy; current-voltage measurements (Highlight: Improvement of resistivity of un-doped crystals after annealing); low-temperature photoluminescence (PL) spectrum of as-grown and annealed samples.

  13. Te-Moak Tribe of Western Shoshone: Battle Mountain Colony- 2012 Project

    Broader source: Energy.gov [DOE]

    The Feasibility Study for the Battle Mountain Renewable Energy Park project ("Feasibility Study") will assess the feasibility, benefits, and impacts of a 5-megawatt (MW) solar photovoltaic (PV) generating system (the "Solar Project" or "Energy Park") on the Te-Moak Tribe of Western Shoshone Indians of Nevada Battle Mountain Colony in Battle Mountain, Nevada.

  14. Investigation of deep level defects in CdTe thin films

    SciTech Connect (OSTI)

    Shankar, H.; Castaldini, A.; Dauksta, E.; Medvid, A.; Cavallini, A.

    2014-02-21

    In the past few years, a large body of work has been dedicated to CdTe thin film semiconductors, as the electronic and optical properties of CdTe nanostructures make them desirable for photovoltaic applications. The performance of semiconductor devices is greatly influenced by the deep levels. Knowledge of parameters of deep levels present in as-grown materials and the identification of their origin is the key factor in the development of photovoltaic device performance. Photo Induced Current Transient Spectroscopy technique (PICTS) has proven to be a very powerful method for the study of deep levels enabling us to identify the type of traps, their activation energy and apparent capture cross section. In the present work, we report the effect of growth parameters and LASER irradiation intensity on the photo-electric and transport properties of CdTe thin films prepared by Close-Space Sublimation method using SiC electrical heating element. CdTe thin films were grown at three different source temperatures (630, 650 and 700 C). The grown films were irradiated with Nd:YAG LASER and characterized by Photo-Induced Current Transient Spectroscopy, Photocurrent measurementand Current Voltage measurements. The defect levels are found to be significantly influenced by the growth temperature.

  15. Relic neutralino surface at a 100 TeV collider

    SciTech Connect (OSTI)

    Bramante, Joseph; Fox, Patrick J.; Martin, Adam; Ostdiek, Bryan; Plehn, Tilman; Schell, Torben; Takeuchi, Michihisa

    2015-03-11

    We map the parameter space for minimal supersymmetric Standard Model neutralino dark matter which freezes out to the observed relic abundance, in the limit that all superpartners except the neutralinos and charginos are decoupled. In this space of relic neutralinos, we show the dominant dark matter annihilation modes, the mass splittings among the electroweakinos, direct detection rates, and collider cross sections. The mass difference between the dark matter and the next-to-lightest neutral and charged states is typically much less than electroweak gauge boson masses. With these small mass differences, the relic neutralino surface is accessible to a future 100 TeV hadron collider, which can discover interneutralino mass splittings down to 1 GeV and thermal relic dark matter neutralino masses up to 1.5 TeV with a few inverse attobarns of luminosity. This coverage is a direct consequence of the increased collider energy: in the Standard Model events with missing transverse momentum in the TeV range have mostly hard electroweak radiation, distinct from the soft radiation shed in compressed electroweakino decays. As a result, we exploit this kinematic feature in final states including photons and leptons, tailored to the 100 TeV collider environment.

  16. Nanowire CdS-CdTe solar cells with molybdenum oxide as contact

    SciTech Connect (OSTI)

    Dang, Hongmei; Singh, Vijay P.

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. As a result, this work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.

  17. Computational discovery of ferromagnetic semiconducting single-layer CrSnTe3

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhuang, Houlong L.; Xie, Yu; Kent, P. R. C.; Ganesh, P.

    2015-07-06

    Despite many single-layer materials being reported in the past decade, few of them exhibit magnetism. Here we perform first-principles calculations using accurate hybrid density functional methods (HSE06) to predict that single-layer CrSnTe3 (CST) is a ferromagnetic semiconductor, with band gaps of 0.9 and 1.2 eV for the majority and minority spin channels, respectively. We determine the Curie temperature as 170 K, significantly higher than that of single-layer CrSiTe3 (90K) and CrGeTe3 (130 K). This is due to the enhanced ionicity of the Sn-Te bond, which in turn increases the superexchange coupling between the magnetic Cr atoms. We further explore themore » mechanical and dynamical stability and strain response of this single-layer material for possible epitaxial growth. Lastly, our study provides an intuitive approach to understand and design novel single-layer magnetic semiconductors for a wide range of spintronics and energy applications.« less

  18. In-situ crystallization of GeTe\\GaSb phase change memory stacked films

    SciTech Connect (OSTI)

    Velea, A.; Borca, C. N.; Grolimund, D.; Socol, G.; Galca, A. C.; Popescu, M.; Bokhoven, J. A. van

    2014-12-21

    Single and double layer phase change memory structures based on GeTe and GaSb thin films were deposited by pulsed laser deposition (PLD). Their crystallization behavior was studied using in-situ synchrotron techniques. Electrical resistance vs. temperature investigations, using the four points probe method, showed transition temperatures of 138 °C and 198 °C for GeTe and GaSb single films, respectively. It was found that after GeTe crystallization in the stacked films, Ga atoms from the GaSb layer diffused in the vacancies of the GeTe crystalline structure. Therefore, the crystallization temperature of the Sb-rich GaSb layer is decreased by more than 30 °C. Furthermore, at 210 °C, the antimony excess from GaSb films crystallizes as a secondary phase. At higher annealing temperatures, the crystalline Sb phase increased on the expense of GaSb crystalline phase which was reduced. Extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges revealed changes in their local atomic environments as a function of the annealing temperature. Simulations unveil a tetrahedral configuration in the amorphous state and octahedral configuration in the crystalline state for Ge atoms, while Ga is four-fold coordinated in both as-deposited and annealed samples.

  19. Resonance photoelectron spectroscopy of TiX{sub 2} (X = S, Se, Te) titanium dichalcogenides

    SciTech Connect (OSTI)

    Shkvarin, A. S. Yarmoshenko, Yu. M.; Skorikov, N. A.; Yablonskikh, M. V.; Merentsov, A. I.; Shkvarina, E. G.; Titov, A. N.

    2012-11-15

    The photoelectron valence band spectra of TiS{sub 2}, TiSe{sub 2}, and TiTe{sub 2} dichalcogenides are investigated in the Ti 2p-3d resonance regime. Resonance bands in the vicinity of the Fermi energy are found for TiS{sub 2} and TiTe{sub 2}. The nature of these bands is analyzed based on model calculations of the density of electronic states in TiS{sub 2}, TiSe{sub 2}, and TiTe{sub 2} compounds intercalated by titanium atoms. Analysis of experimental data and their comparison with model calculations showed that these bands have different origins. It is found that the resonance enhancement of an additional band observed in TiS{sub 2} is explained by self-intercalation by titanium during the synthesis of this compound. The resonance enhancement in TiTe{sub 2} is caused by occupation of the 3d band in Ti.

  20. Comparison of Minority Carrier Lifetime Measurements in Superstrate and Substrate CdTe PV Devices: Preprint

    SciTech Connect (OSTI)

    Gessert, T. A.; Dhere, R. G.; Duenow, J. N.; Kuciauskas, D.; Kanevce, A.; Bergeson, J. D.

    2011-07-01

    We discuss typical and alternative procedures to analyze time-resolved photoluminescence (TRPL) measurements of minority carrier lifetime (MCL) with the hope of enhancing our understanding of how this technique may be used to better analyze CdTe photovoltaic (PV) device functionality. Historically, TRPL measurements of the fast recombination rate (t1) have provided insightful correlation with broad device functionality. However, we have more recently found that t1 does not correlate as well with smaller changes in device performance, nor does it correlate well with performance differences observed between superstrate and substrate CdTe PV devices. This study presents TRPL data for both superstrate and substrate CdTe devices where both t1 and the slower TRPL decay (t2) are analyzed. The study shows that changes in performance expected from small changes in device processing may correlate better with t2. Numerical modeling further suggests that, for devices that are expected to have similar drift field in the depletion region, effects of changes in bulk MCL and interface recombination should be more pronounced in t2. Although this technique may provide future guidance to improving CdS/CdTe device performance, it is often difficult to extract statistically precise values for t2, and therefore t2 data may demonstrate significant scatter when correlated with performance parameters.

  1. Rashba effect in single-layer antimony telluroiodide SbTeI

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhuang, Houlong L.; Cooper, Valentino R.; Xu, Haixuan; Ganesh, P.; Hennig, Richard G.; Kent, P. R. C.

    2015-09-04

    Exploring spin-orbit coupling (SOC) in single-layer materials is important for potential spintronics applications. In this paper, using first-principles calculations, we show that single-layer antimony telluroiodide SbTeI behaves as a two-dimensional semiconductor exhibiting a G0W0 band gap of 1.82 eV. More importantly, we observe the Rashba spin splitting in the SOC band structure of single-layer SbTeI with a sizable Rashba coupling parameter of 1.39 eV Å, which is significantly larger than that of a number of two-dimensional systems including surfaces and interfaces. The low formation energy and real phonon modes of single-layer SbTeI imply that it is stable. Finally, our studymore » suggests that single-layer SbTeI is a candidate single-layer material for applications in spintronics devices.« less

  2. Nanowire CdS-CdTe solar cells with molybdenum oxide as contact

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dang, Hongmei; Singh, Vijay P.

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potentialmore » way for a transparent back contact to nanowire CdS-CdTe solar cells. As a result, this work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.« less

  3. Shape-controlled narrow-gap SnTe nanostructures: From nanocubes to nanorods and nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Guo, Shaojun; Andrew F. Fidler; He, Kai; Su, Dong; Chen, Gen; Lin, Qianglu; Pietryga, Jeffrey M.; Klimov, Victor I.

    2015-11-06

    In this study, the rational design and synthesis of narrow-gap colloidal semiconductor nanocrystals (NCs) is an important step toward the next generation of solution-processable photovoltaics, photodetectors, and thermoelectric devices. SnTe NCs are particularly attractive as a Pb-free alternative to NCs of narrow-gap lead chalcogenides. Previous synthetic efforts on SnTe NCs have focused on spherical nanoparticles. Here we report new strategies for synthesis of SnTe NCs with shapes tunable from highly monodisperse nanocubes, to nanorods (NRs) with variable aspect ratios, and finally to long, straight nanowires (NWs). Reaction at high temperature quickly forms thermodynamically favored nanocubes, but low temperatures lead tomore » elongated particles. Transmission electron microscopy studies of reaction products at various stages of the synthesis reveal that the growth and shape-focusing of monodisperse SnTe nanocubes likely involves interparticle ripening, while directional growth of NRs and NWs may be initiated by particle dimerization via oriented attachment.« less

  4. Relic neutralino surface at a 100 TeV collider

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bramante, Joseph; Fox, Patrick J.; Martin, Adam; Ostdiek, Bryan; Plehn, Tilman; Schell, Torben; Takeuchi, Michihisa

    2015-03-11

    We map the parameter space for minimal supersymmetric Standard Model neutralino dark matter which freezes out to the observed relic abundance, in the limit that all superpartners except the neutralinos and charginos are decoupled. In this space of relic neutralinos, we show the dominant dark matter annihilation modes, the mass splittings among the electroweakinos, direct detection rates, and collider cross sections. The mass difference between the dark matter and the next-to-lightest neutral and charged states is typically much less than electroweak gauge boson masses. With these small mass differences, the relic neutralino surface is accessible to a future 100 TeVmore » hadron collider, which can discover interneutralino mass splittings down to 1 GeV and thermal relic dark matter neutralino masses up to 1.5 TeV with a few inverse attobarns of luminosity. This coverage is a direct consequence of the increased collider energy: in the Standard Model events with missing transverse momentum in the TeV range have mostly hard electroweak radiation, distinct from the soft radiation shed in compressed electroweakino decays. As a result, we exploit this kinematic feature in final states including photons and leptons, tailored to the 100 TeV collider environment.« less

  5. Higgs Coupling Measurements at a 1 TeV Linear Collider

    SciTech Connect (OSTI)

    Barklow, T

    2003-12-18

    Methods for extracting Higgs boson signals at a 1 TeV center-of-mass energy e{sup +}e{sup -} linear collider are described. In addition, estimates are given for the accuracy with which branching fractions can be measured for Higgs boson decays to b{bar b} WW, gg, and {gamma}{gamma}.

  6. Nuclear structure relevant to neutrinoless double beta decay candidate {sup 130}Te and other recent results

    SciTech Connect (OSTI)

    Kay, B. P. [Physics Division, Argonne National Laboratory, Illinois 60439 (United States)

    2013-12-30

    We have undertaken a series of single-nucleon and pair transfer reaction measurements to help constrain calculations of the nuclear matrix elements for neutrinoless double beta decay. In this talk, a short overview of measurements relevant to the {sup 130}Te?{sup 130}Xe system is given. Brief mention is made of other recent and forthcoming results.

  7. Project Reports for Te-Moak Tribe of Western Shoshone: Battle Mountain Colony- 2012 Project

    Broader source: Energy.gov [DOE]

    The Feasibility Study for the Battle Mountain Renewable Energy Park project ("Feasibility Study") will assess the feasibility, benefits, and impacts of a 5-megawatt (MW) solar photovoltaic (PV) generating system (the "Solar Project" or "Energy Park") on the Te-Moak Tribe of Western Shoshone Indians of Nevada Battle Mountain Colony in Battle Mountain, Nevada.

  8. Signals of a 2 TeV $W'$ boson and a heavier $Z'$ boson

    SciTech Connect (OSTI)

    Dobrescu, Bogdan A.; Fox, Patrick J.

    2015-11-05

    We construct an SU(2)L x SU(2)R x U(1)B-L model with a Higgs sector that consists of a bidoublet and a doublet, and with a right-handed neutrino sector that includes one Dirac fermion and one Majorana fermion. This model explains the CMS and ATLAS excess events in the e+e-jj, jj, Wh0 and WZ channels in terms of a W' boson of mass near 1.9 TeV and of coupling gR in the 0.4-0.5 range (with the lower half preferred by the limits on tb- resonances). We found that the production cross section of this W' boson at the 13 TeV LHC is in the 720-1100 fb range, allowing sensitivity in more than 17 final states. Furthermore, we determine that the Z' boson has a mass in the 2.9-4.5 TeV range and several decay channels that can be probed in Run 2 of the LHC, including cascade decays via heavy Higgs bosons. Interpreting the CMS e+e-event at 2.9 TeV as coming from the Z', the mass ratio of the Z' and W' bosons requires gR ≈0.48, which implies a pp →Z' → ℓ+-cross section of 2 fb at √s = 13 TeV.

  9. Impact of annealing on the chemical structure and morphology of the thin-film CdTe/ZnO interface

    SciTech Connect (OSTI)

    Horsley, K. Hanks, D. A.; Weir, M. G.; Beal, R. J.; Wilks, R. G.; Blum, M.; Häming, M.; Hofmann, T.; Weinhardt, L.; and others

    2014-07-14

    To enable an understanding and optimization of the optoelectronic behavior of CdTe-ZnO nanocomposites, the morphological and chemical properties of annealed CdTe/ZnO interface structures were studied. For that purpose, CdTe layers of varying thickness (4–24 nm) were sputter-deposited on 100 nm-thick ZnO films on surface-oxidized Si(100) substrates. The morphological and chemical effects of annealing at 525 °C were investigated using X-ray Photoelectron Spectroscopy (XPS), X-ray-excited Auger electron spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and atomic force microscopy. We find a decrease of the Cd and Te surface concentration after annealing, parallel to an increase in Zn and O signals. While the as-deposited film surfaces show small grains (100 nm diameter) of CdTe on the ZnO surface, annealing induces a significant growth of these grains and separation into islands (with diameters as large as 1 μm). The compositional change at the surface is more pronounced for Cd than for Te, as evidenced using component peak fitting of the Cd and Te 3d XPS peaks. The modified Auger parameters of Cd and Te are also calculated to further elucidate the local chemical environment before and after annealing. Together, these results suggest the formation of tellurium and cadmium oxide species at the CdTe/ZnO interface upon annealing, which can create a barrier for charge carrier transport, and might allow for a deliberate modification of interface properties with suitably chosen thermal treatment parameters.

  10. Search for contact interactions in dimuon events from pp collisions at ?s=7 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; et al

    2011-07-01

    A search for contact interactions has been performed using dimuon events recorded with the ATLAS detector in proton-proton collisions at ?s=7 TeV. The data sample corresponds to an integrated luminosity of 42 pb?. No significant deviation from the standard model is observed in the dimuon mass spectrum, allowing the following 95% C.L. limits to be set on the energy scale of contact interactions: ?>4.9 TeV (4.5 TeV) for constructive (destructive) interference in the left-left isoscalar compositeness model. These limits are the most stringent to date for ??qq contact interactions.

  11. Role of chalcogen vapor annealing in inducing bulk superconductivity in Fe1+yTe1-xSex [How does annealing in chalcogen vapor induce superconductivity in Fe1+yTe-xSex?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lin, Wenzhi; Ganesh, P.; Gianfrancesco, Anthony; Wang, Jun; Berlijn, Tom; Maier, Thomas A.; Kalinin, Sergei V.; Sales, Brian C.; Pan, Minghu

    2015-02-01

    Recent investigations have shown that Fe1+yTe1-xSex can be made superconducting by annealing it in Se and O vapors. The current lore is that these chalcogen vapors induce superconductivity by removing the magnetic excess Fe atoms. To investigate this phenomenon we performed a combination of magnetic susceptibility, specific heat and transport measurements together with scanning tunneling microscopy and spectroscopy and density functional theory calculations on Fe1+yTe1-xSex treated with Te vapor. We conclude that the main role of the Te vapor is to quench the magnetic moments of the excess Fe atoms by forming FeTem (m ≥ 1) complexes. We show thatmore » the remaining FeTem complexes are still damaging to the superconductivity and therefore that their removal potentially could further improve superconductive properties in these compounds.« less

  12. Electronic tuning of the transport properties of off-stoichiometric Pb{sub x}Sn{sub 1−x}Te thermoelectric alloys by Bi{sub 2}Te{sub 3} doping

    SciTech Connect (OSTI)

    Guttmann, Gilad M.; Dadon, David; Gelbstein, Yaniv

    2015-08-14

    The recent energy demands affected by the dilution of conventional energy resources and the growing awareness of environmental considerations had motivated many researchers to seek for novel renewable energy conversion methods. Thermoelectric direct conversion of thermal into electrical energies is such a method, in which common compositions include IV-VI semiconducting compounds (e.g., PbTe and SnTe) and their alloys. For approaching practical thermoelectric devices, the current research is focused on electronic optimization of off-stoichiometric p-type Pb{sub x}Sn{sub 1−x}Te alloys by tuning of Bi{sub 2}Te{sub 3} doping and/or SnTe alloying levels, while avoiding the less mechanically favorable Na dopant. It was shown that upon such doping/alloying, higher ZTs, compared to those of previously reported undoped Pb{sub 0.5}Sn{sub 0.5}Te alloy, were obtained at temperatures lower than 210–340 °C, depending of the exact doping/alloying level. It was demonstrated that upon optimal grading of the carrier concentration, a maximal thermoelectric efficiency enhancement of ∼38%, compared to that of an undoped material, is expected.

  13. Rare-earth-rich tellurides: Gd{sub 4}NiTe{sub 2} and Er{sub 5}M{sub 2}Te{sub 2} (M=Co, Ni)

    SciTech Connect (OSTI)

    Magliocchi, Carmela; Meng, Fanqin; Hughbanks, Timothy . E-mail: trh@mail.chem.tamu.edu

    2004-11-01

    Three new rare earth metal-rich compounds, Gd{sub 4}NiTe{sub 2}, and Er{sub 5}M{sub 2}Te{sub 2} (M=Ni, Co), were synthesized in direct reactions using R, R{sub 3}M, and R{sub 2}Te{sub 3} (R=Gd, Er; M=Co, Ni) and single-crystal structures were determined. Gd{sub 4}NiTe{sub 2} is orthorhombic and crystallizes in space group Pnma with four formula units per cell. Lattice parameters at 110(2)K are a=15.548(9), b=4.113(2), c=11.7521(15)A. Er{sub 5}Ni{sub 2}Te{sub 2} and Er{sub 5}Co{sub 2}Te{sub 2} are isostructural and crystallize in the orthorhombic space group Cmcm with two formula units per cell. Lattice parameters at 110(2)K are a=3.934(1), b=14.811(4), c=14.709(4)A, and a=3.898(1), b=14.920(3), c=14.889(3)A, respectively. Metal-metal bonding correlations were analyzed using the empirical Pauling bond order concept.

  14. Cooling effect of nanoscale Bi2Te3/Sb2Te3 multilayered thermoelectric thin films

    SciTech Connect (OSTI)

    Hines, Mardecial; Lenhardt, Joshua; Lu, Ming; Jiang, Li; Xiao, Zhigang

    2012-01-01

    Managing high heat flux is one of the greatest technical challenges the integrated circuit (IC) industry is facing because the rising temperature limits device minimization and decreases its lifetime. In this paper, we report the characterization of the cooling effect of nanoscale Bi2Te3/Sb2Te3 multilayered thin films. The multilayerthin film was prepared with e-beam evaporation, and had 21 layers (5-nm-thick each layer and 105-nm-thick total). A thermoelectric device of the multilayerfilm, which is sandwiched between a diode temperature sensor and a platinum temperature sensor, was fabricated to measure the cooling effect. A maximum cooling temperature difference of about 3K was obtained from the film at an applied dc electrical current of 5 mA. The nanoscale multilayerfilm could be integrated in the IC devices for the application of high-efficiency thermoelectric solid-state cooling.

  15. CdSe/CdTe type-II superlattices grown on GaSb (001) substrates by molecular beam epitaxy

    SciTech Connect (OSTI)

    Li Jingjing; Liu Shi; Wang Shumin; Ding Ding; Johnson, Shane R.; Zhang Yonghang; Liu Xinyu; Furdyna, Jacek K.; Smith, David J.

    2012-03-19

    CdSe/CdTe superlattices are grown on GaSb substrates using molecular beam epitaxy. X-ray diffraction measurements and cross-sectional transmission electron microscopy images indicate high crystalline quality. Photoluminescence (PL) measurements show the effective bandgap varies with the superlattice layer thicknesses and confirm the CdSe/CdTe heterostructure has a type-II band edge alignment. The valence band offset between unstrained CdTe and CdSe is determined as 0.63 {+-} 0.06 eV by fitting the measured PL peak positions using the envelope function approximation and the Kronig-Penney model. These results suggest that CdSe/CdTe superlattices are promising candidates for multi-junction solar cells and other optoelectronic devices based on GaSb substrates.

  16. One-Dimensional Reaction-Diffusion Simulation of Cu Migration in Polycrystalline CdTe Solar Cells

    SciTech Connect (OSTI)

    Guo, Da; Akis, Richard; Brinkman, Daniel; Sankin, Igor; Fang, Tian; Vasileska, Dragica; Ringhofer, Christain

    2014-06-13

    In this work, we report on developing 1D reaction-diffusion solver to understand the kinetics of p-type doping formation in CdTe absorbers and to shine some light on underlying causes of metastabilities observed in CdTe PV devices. Evolution of intrinsic and Cu-related defects in CdTe solar cell has been studied in time-space domain self-consistently with free carrier transport and Poisson equation. Resulting device performance was simulated as a function of Cu diffusion anneal time showing pronounced effect the evolution of associated acceptor and donor states can cause on device characteristics. Although 1D simulation has intrinsic limitations when applied to poly-crystalline films, the results suggest strong potential of the approach in better understanding of the performance and metastabilities of CdTe photovoltaic device.

  17. Search for quark compositeness in dijet angular distributions from pp collisions at sqrt(s) = 7 TeV

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; et al.

    2012-05-01

    A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.

  18. Thin Metal Oxide Films to Modify a Window Layer in CdTe-Based Solar Cells for Improved Performance

    SciTech Connect (OSTI)

    Lemmon, John P.; Polikarpov, Evgueni; Bennett, Wendy D.; Kovarik, Libor

    2012-05-25

    We report on CdS/CdTe photovoltaic devices that contain a thin Ta₂O₅ film deposited onto the CdS window layer by sputtering. We show that for thicknesses below 5 nm, Ta₂O₅ films between CdS and CdTe positively affect the solar cell performance, improving JSC, VOC, and the cell power conversion efficiency despite the insulating nature of the interlayer material. Using the Ta₂O₅ interlayer, a VOC gain of over 100 mV was demonstrated compared to a CdTe/CdS baseline. Application of a 1nm Ta₂O₅ interlayer enabled the fabrication of CdTe solar cells with extremely thin (less than 30 nm) CdS window layers. The efficiency of these cells exceeded that of a base line cell with 95 nm of CdS.

  19. Modeling Cu Migration in CdTe Solar Cells Under Device-Processing and Long-Term Stability Conditions: Preprint

    SciTech Connect (OSTI)

    Teeter, G.; Asher, S.

    2008-05-01

    An impurity migration model for systems with material interfaces is applied to Cu migration in CdTe solar cells. In the model, diffusion fluxes are calculated from the Cu chemical potential gradient. Inputs to the model include Cu diffusivities, solubilities, and segregation enthalpies in CdTe, CdS and contact materials. The model yields transient and equilibrium Cu distributions in CdTe devices during device processing and under field-deployed conditions. Preliminary results for Cu migration in CdTe photovoltaic devices using available diffusivity and solubility data from the literature show that Cu segregates in the CdS, a phenomenon that is commonly observed in devices after back-contact processing and/or stress conditions.

  20. Polarization of Bi{sub 2}Te{sub 3} thin film in a floating-gate capacitor structure

    SciTech Connect (OSTI)

    Yuan, Hui E-mail: qli6@gmu.edu; Li, Haitao; Zhu, Hao; Zhang, Kai; Baumgart, Helmut; Bonevich, John E.; Richter, Curt A.; Li, Qiliang E-mail: qli6@gmu.edu

    2014-12-08

    Metal-Oxide-Semiconductor (MOS) capacitors with Bi{sub 2}Te{sub 3} thin film sandwiched and embedded inside the oxide layer have been fabricated and studied. The capacitors exhibit ferroelectric-like hysteresis which is a result of the robust, reversible polarization of the Bi{sub 2}Te{sub 3} thin film while the gate voltage sweeps. The temperature-dependent capacitance measurement indicates that the activation energy is about 0.33?eV for separating the electron and hole pairs in the bulk of Bi{sub 2}Te{sub 3}, and driving them to either the top or bottom surface of the thin film. Because of the fast polarization speed, potentially excellent endurance, and the complementary metaloxidesemiconductor compatibility, the Bi{sub 2}Te{sub 3} embedded MOS structures are very interesting for memory application.

  1. The effects of deep level traps on the electrical properties of semi-insulating CdZnTe

    SciTech Connect (OSTI)

    Zha, Gangqiang; Yang, Jian; Xu, Lingyan; Feng, Tao; Wang, Ning; Jie, Wanqi

    2014-01-28

    Deep level traps have considerable effects on the electrical properties and radiation detection performance of high resistivity CdZnTe. A deep-trap model for high resistivity CdZnTe was proposed in this paper. The high resistivity mechanism and the electrical properties were analyzed based on this model. High resistivity CdZnTe with high trap ionization energy E{sub t} can withstand high bias voltages. The leakage current is dependent on both the deep traps and the shallow impurities. The performance of a CdZnTe radiation detector will deteriorate at low temperatures, and the way in which sub-bandgap light excitation could improve the low temperature performance can be explained using the deep trap model.

  2. Characterization of silver photodiffusion in Ge{sub 8}Sb{sub 2}Te{sub 11} thin films

    SciTech Connect (OSTI)

    Kumar, Sandeep; Singh, D.; Sandhu, S.; Thangaraj, R.

    2015-06-24

    Silver-doped amorphous Ge{sub 8}Sb{sub 2}Te{sub 11} thin films have been prepared by photodiffusion at room-temperature; the Ge{sub 8}Sb{sub 2}Te{sub 11}/Ag bilayer was deposited by vacuum thermal evaporation. Photodiffusion of Ag into the amorphous Ge{sub 8}Sb{sub 2}Te{sub 11} thin films has been carried out by illuminating the prepared Ge{sub 8}Sb{sub 2}Te{sub 11}/Ag bilayer with halogen lamp. The photodiffused silver depth profile was traced by means of time of flight secondary ion mass spectroscopy. The film remains amorphous after Ag photodiffusion. The crystallization temperature of the films was evaluated by temperature dependent sheet resistance measurement. The amorphous nature and crystalline phases of the films have been identified by using X-ray diffraction.

  3. Photoluminescence studies of type-II CdSe/CdTe superlattices

    SciTech Connect (OSTI)

    Li Jingjing; Johnson, Shane R.; Wang Shumin; Ding Ding; Ning Cunzheng; Zhang Yonghang; Yin Leijun; Skromme, B. J.; Liu Xinyu; Furdyna, Jacek K.

    2012-08-06

    CdSe/CdTe type-II superlattices grown on GaSb substrates by molecular beam epitaxy are studied using time-resolved and steady-state photoluminescence (PL) spectroscopy at 10 K. The relatively long carrier lifetime of 188 ns observed in time-resolved PL measurements shows good material quality. The steady-state PL peak position exhibits a blue shift with increasing excess carrier concentration. Self-consistent solutions of the Schroedinger and Poisson equations show that this effect can be explained by band bending as a result of the spatial separation of electrons and holes, which is critical confirmation of a strong type-II band edge alignment between CdSe and CdTe.

  4. Diffusion-Reaction Modeling of Cu Migration in CdTe Solar Devices

    SciTech Connect (OSTI)

    Guo, Da; Brinkman, Daniel; Fang, Tian; Akis, Richard; Sankin, Igor; Vasileska, Dragica; Ringhofer, Christian

    2015-09-04

    In this work, we report on development of one-dimensional (1D) finite-difference and two-dimensional (2D) finite-element diffusion-reaction simulators to investigate mechanisms behind Cu-related metastabilities observed in CdTe solar cells [1]. The evolution of CdTe solar cells performance has been studied as a function of stress time in response to the evolution of associated acceptor and donor states. To achieve such capability, the simu-lators solve reaction-diffusion equations for the defect states in time-space domain self-consistently with the free carrier transport. Re-sults of 1-D and 2-D simulations have been compared to verify the accuracy of solutions.

  5. Broadening of optical transitions in polycrystalline CdS and CdTe thin films

    SciTech Connect (OSTI)

    Li Jian; Chen Jie; Collins, R. W.

    2010-11-01

    The dielectric functions {epsilon} of polycrystalline CdS and CdTe thin films sputter deposited onto Si wafers were measured from 0.75 to 6.5 eV by in situ spectroscopic ellipsometry. Differences in {epsilon} due to processing variations are well understood using an excited carrier scattering model. For each sample, a carrier mean free path {lambda} is defined that is found to be inversely proportional to the broadening of each of the band structure critical points (CPs) deduced from {epsilon}. The rate at which broadening occurs with {lambda}{sup -1} is different for each CP, enabling a carrier group speed {upsilon}{sub g} to be identified for the CP. With the database for {upsilon}{sub g}, {epsilon} can be analyzed to evaluate the quality of materials used in CdS/CdTe photovoltaic heterojunctions.

  6. Right-Handed Neutrinos and the 2 TeV $W'$ Boson

    SciTech Connect (OSTI)

    Coloma, Pilar; Dobrescu, Bogdan A.; Lopez-Pavon, Jacobo

    2015-12-30

    The CMS e+e-jj events of invariant mass near 2 TeV are consistent with a W' boson decaying into an electron and a right-handed neutrino whose TeV-scale mass is of the Dirac type. We show that the Dirac partner of the right-handed electron-neutrino can be the right-handed tau-neutrino. Furthermore, a prediction of this model is that the sum of the τ+e+jj and τ-e-jj signal cross sections equals twice that for e+e-jj. The Standard Model neutrinos acquire Majorana masses and mixings compatible with neutrino oscillation data.

  7. Search for Dijet Resonances in 7 TeV pp Collisions at CMS

    SciTech Connect (OSTI)

    Khachatryan, V.; et al.

    2010-11-01

    A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9 inverse pb collected by the CMS experiment at the LHC. Upper limits at the 95% confidence level (CL) are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% CL: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E_6 diquarks, in specific mass intervals. This extends previously published limits on these models.

  8. The High-Resolution Lightweight Telescope for the EUV (HiLiTE)

    SciTech Connect (OSTI)

    Martinez-Galarce, D S; Boerner, P; Soufli, R; De Pontieu, B; Katz, N; Title, A; Gullikson, E M; Robinson, J C; Baker, S L

    2008-06-02

    The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that will be made entirely of Silicon Carbide (SiC), optical substrates and metering structure alike. Using multilayer coatings, this instrument will be tuned to operate at the 465 {angstrom} Ne VII emission line, formed in solar transition region plasma at {approx}500,000 K. HiLiTE will have an aperture of 30 cm, angular resolution of {approx}0.2 arc seconds and operate at a cadence of {approx}5 seconds or less, having a mass that is about 1/4 that of one of the 20 cm aperture telescopes on the Atmospheric Imaging Assembly (AIA) instrument aboard NASA's Solar Dynamics Observatory (SDO). This new instrument technology thus serves as a path finder to a post-AIA, Explorer-class missions.

  9. Influence of deep level defects on carrier lifetime in CdZnTe:In

    SciTech Connect (OSTI)

    Guo, Rongrong; Jie, Wanqi Wang, Ning; Zha, Gangqiang; Xu, Yadong; Wang, Tao; Fu, Xu

    2015-03-07

    The defect levels and carrier lifetime in CdZnTe:In crystal were characterized with photoluminescence, thermally stimulated current measurements, as well as contactless microwave photoconductivity decay (MWPCD) technique. An evaluation equation to extract the recombination lifetime and the reemission time from MWPCD signal is developed based on Hornbeck-Haynes trapping model. An excellent agreement between defect level distribution and carrier reemission time in MWPCD signal reveals the tail of the photoconductivity decay is controlled by the defect level reemission effect. Combining {sup 241}Am gamma ray radiation response measurement and laser beam induced transient current measurement, it predicted that defect level with the reemission time shorter than the collection time could lead to better charge collection efficiency of CdZnTe detector.

  10. Photoluminescence Imaging of Large-Grain CdTe for Grain Boundary Characterization

    SciTech Connect (OSTI)

    Johnston, Steve; Allende Motz, Alyssa; Reese, Matthew O.; Burst, James M.; Metzger, Wyatt K.

    2015-06-14

    In this work, we use photoluminescence (PL) imaging to characterize CdTe grain boundary recombination. We use a silicon megapixel camera and green (532 nm) laser diodes for excitation. A microscope objective lens system is used for high spatial resolution and a field of view down to 190 um x 190 um. PL images of large-grain (5 to 50 um) CdTe samples show grain boundary and grain interior features that vary with processing conditions. PL images of samples in the as-deposited state show distinct dark grain boundaries that suggest high excess carrier recombination. A CdCl2 treatment leads to PL images with very little distinction at the grain boundaries, which illustrates the grain boundary passivation properties. Other process conditions are also shown, along with comparisons of PL images to high spatial resolution time-resolved PL carrier lifetime maps.