skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Cd doping at PVD-CdS/CuInGaSe 2 heterojunctions

Abstract

In this paper, we report on direct evidence of Cd doping of the CuInGaSe 2 (CIGS) surface in physical vapor deposited (PVD) CdS/CIGS heterojunctions by scanning transmission electron microscopy (STEM) and related techniques. We find Cd doping of the CIGS near-surface region regardless of the presence or absence of Cu rich domains in the CdS for both zinc-blende (zb) and wurtzite (wz) CdS. However, we find that the Cd penetrates much farther into the CIGS when Cu-rich domains are present in the CdS. This suggests that Cu exchanges with Cd, increasing the concentration gradient for Cd in the CIGS and thus driving Cd into the CIGS surface. The Cd doping is clearly resolved at atomic resolution in aberration-corrected STEM-high angle annular dark field images. In zb-CdS/CIGS heterojunctions, Cd is shown to substitute for both Cu and Ga atoms, while in wz-CdS/CIGS heterojunctions Cd seems to predominantly occupy Cu sites. Finally, Cd doping in the CIGS surface layer suggests the formation of a p-n homojunction in the CIGS, which may account for the high device efficiencies, comparable to CBD-CdS/CIGS processed structures.

Authors:
 [1];  [2];  [3];  [4];  [5];  [5];  [5];  [5];  [5];  [5];  [2];  [4];  [1]
  1. Univ. of Illinois, Urbana, IL (United States). Materials Science and Engineering
  2. Univ. of Illinois, Chicago, IL (United States). Dept. of Physics
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Center for Electron Microscopy
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. MiaSole Hi-Tech, Santa Clara, CA (United States)
Publication Date:
Research Org.:
Univ. of Illinois at Urbana-Champaign, IL (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1366899
Alternate Identifier(s):
OSTI ID: 1398611; OSTI ID: 1435084
Report Number(s):
LLNL-JRNL-708969
Journal ID: ISSN 0927-0248
Grant/Contract Number:
AC52-07NA27344; AC02-05CH11231; EE0005956; DMR-0959470
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 164; Journal ID: ISSN 0927-0248
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; physical vapor deposition; Cu(In; Ga)Se2 photovoltaics; Cd doping; STEM-EDS mapping; atomic resolution; p-n homojunction

Citation Formats

He, Xiaoqing, Paulauskas, Tadas, Ercius, Peter, Varley, Joel, Bailey, Jeff, Zapalac, Geordie, Poplavskyy, Dmitry, Mackie, Neil, Bayman, Atiye, Spaulding, David, Klie, Robert, Lordi, Vincenzo, and Rockett, Angus. Cd doping at PVD-CdS/CuInGaSe2 heterojunctions. United States: N. p., 2017. Web. doi:10.1016/j.solmat.2017.01.043.
He, Xiaoqing, Paulauskas, Tadas, Ercius, Peter, Varley, Joel, Bailey, Jeff, Zapalac, Geordie, Poplavskyy, Dmitry, Mackie, Neil, Bayman, Atiye, Spaulding, David, Klie, Robert, Lordi, Vincenzo, & Rockett, Angus. Cd doping at PVD-CdS/CuInGaSe2 heterojunctions. United States. doi:10.1016/j.solmat.2017.01.043.
He, Xiaoqing, Paulauskas, Tadas, Ercius, Peter, Varley, Joel, Bailey, Jeff, Zapalac, Geordie, Poplavskyy, Dmitry, Mackie, Neil, Bayman, Atiye, Spaulding, David, Klie, Robert, Lordi, Vincenzo, and Rockett, Angus. Mon . "Cd doping at PVD-CdS/CuInGaSe2 heterojunctions". United States. doi:10.1016/j.solmat.2017.01.043. https://www.osti.gov/servlets/purl/1366899.
@article{osti_1366899,
title = {Cd doping at PVD-CdS/CuInGaSe2 heterojunctions},
author = {He, Xiaoqing and Paulauskas, Tadas and Ercius, Peter and Varley, Joel and Bailey, Jeff and Zapalac, Geordie and Poplavskyy, Dmitry and Mackie, Neil and Bayman, Atiye and Spaulding, David and Klie, Robert and Lordi, Vincenzo and Rockett, Angus},
abstractNote = {In this paper, we report on direct evidence of Cd doping of the CuInGaSe2 (CIGS) surface in physical vapor deposited (PVD) CdS/CIGS heterojunctions by scanning transmission electron microscopy (STEM) and related techniques. We find Cd doping of the CIGS near-surface region regardless of the presence or absence of Cu rich domains in the CdS for both zinc-blende (zb) and wurtzite (wz) CdS. However, we find that the Cd penetrates much farther into the CIGS when Cu-rich domains are present in the CdS. This suggests that Cu exchanges with Cd, increasing the concentration gradient for Cd in the CIGS and thus driving Cd into the CIGS surface. The Cd doping is clearly resolved at atomic resolution in aberration-corrected STEM-high angle annular dark field images. In zb-CdS/CIGS heterojunctions, Cd is shown to substitute for both Cu and Ga atoms, while in wz-CdS/CIGS heterojunctions Cd seems to predominantly occupy Cu sites. Finally, Cd doping in the CIGS surface layer suggests the formation of a p-n homojunction in the CIGS, which may account for the high device efficiencies, comparable to CBD-CdS/CIGS processed structures.},
doi = {10.1016/j.solmat.2017.01.043},
journal = {Solar Energy Materials and Solar Cells},
number = ,
volume = 164,
place = {United States},
year = {Mon Feb 20 00:00:00 EST 2017},
month = {Mon Feb 20 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

Save / Share:
  • We report on direct evidence of Cd doping of the CuInGaSe 2 (CIGS) surface in physical vapor deposited (PVD) CdS/CIGS heterojunctions by scanning transmission electron microscopy (STEM) and related techniques. We find Cd doping of the CIGS near-surface region regardless of the presence or absence of Cu rich domains in the CdS for both zinc-blende (zb) and wurtzite (wz) CdS. However, we find that the Cd penetrates much farther into the CIGS when Cu-rich domains are present in the CdS. This suggests that Cu exchanges with Cd, increasing the concentration gradient for Cd in the CIGS and thus driving Cdmore » into the CIGS surface. The Cd doping is clearly resolved at atomic resolution in aberration-corrected STEM-high angle annular dark field images. In zb-CdS/CIGS heterojunctions, Cd is shown to substitute for both Cu and Ga atoms, while in wz-CdS/CIGS heterojunctions Cd seems to predominantly occupy Cu sites. Cd doping in the CIGS surface layer suggests the formation of a p-n homojunction in the CIGS, which may account for the high device efficiencies, comparable to CBD-CdS/CIGS processed structures.« less
  • The photovoltaic Cd{sub 1-x}Zn{sub x}S thin films, fabricated by chemical bath deposition, were successfully used as n-type buffer layer in CuInGaSe{sub 2} (CIGS) solar cells. Comprehensive optical properties of the Cd{sub 1-x}Zn{sub x}S thin films were measured and modeled by spectroscopic ellipsometry (SE), which is proven to be an excellent and non-destructive technique to determine optical properties of thin films. The optical band gap of Cd{sub 1-x}Zn{sub x}S thin films can be tuned from 2.43 eV to 3.25 eV by controlling the Zn content (x) and deposition conditions. The wider-band-gap Cd{sub 1-x}Zn{sub x}S film was found to be favorable tomore » improve the quantum efficiency in the wavelength range of 450-550 nm, resulting in an increase of short-circuits current for solar cells. From the characterization of quantum efficiency (QE) and current-voltage curve (J-V) of CIGS cells, the Cd{sub 1-x}Zn{sub x}S films (x = 0.32, 0.45) were demonstrated to significantly enhance the photovoltaic performance of CIGS solar cell. The highest efficiency (10.5%) of CIGS solar cell was obtained using a dense and homogenous Cd{sub 0.68}Zn{sub 0.32}S thin film as the buffer layer.« less
  • To improve the utilization of visible light and reduce photogenerated electron/hole recombination, Ti 3+ self-doped TiO 2/oxygen-doped graphitic carbon nitride (Ti 3+-TiO 2/O-g-C 3N 4) heterojunctions were prepared via hydrothermal treatment of a mixture of g-C 3N 4 and titanium oxohydride sol obtained from the reaction of TiH 2 with H 2O 2. In this way, exfoliated O-g-C 3N 4 and Ti 3+-TiO 2 nanoparticles were obtained. Simultaneously, strong bonding was formed between Ti 3+-TiO 2 nanoparticles and exfoliated O-g-C 3N 4 during the hydrothermal process. Charge transfer and recombination processes were characterized by transient photocurrent responses, electrochemical impedance test,more » and photoluminescence spectroscopy. The photocatalytic performances were investigated through rhodamine B degradation test under an irradiation source based on 30 W cold visible-light-emitting diode. The highest visible-light photoelectrochemical and photocatalytic activities were observed from the heterojunction with 1:2 mass ratio of Ti 3+-TiO 2 to O-g-C 3N 4. The photodegradation reaction rate constant based on this heterojuction is 0.0356 min -1, which is 3.87 and 4.56 times higher than those of pristine Ti 3+-TiO 2 and pure g-C 3N 4, respectively. Here, the remarkably high photoelectrochemical and photocatalytic performances of the heterojunctions are mainly attributed to the synergetic effect of efficient photogenerated electron-hole separation, decreased electron transfer resistance from interfacial chemical hydroxy residue bonds, and oxidizing groups originating from Ti 3+-TiO 2 and O-g-C 3N 4.« less
  • It is shown experimentally to be possible to form rectifying photosensitive heterojunctions by using the method of reactive cathodic sputtering to deposit layers of Cd/sub 2/SnO/sub 4/ on the surface of n- and p-type CdGeP/sub 2/ single crystals. It is demonstrated that photosensitivity is seen in the range between widths of the forbidden bands of CdGeP/sub 2/ and Cd/sub 2/SnO/sub 4/; photosensitivity is 3-4 orders of magnitude greater for n-n junctions than for n-p junctions. The parameters of polarizational photosensitivity were established and analyzed, providing evidence that the investigated system, with an n-n contact, can be used to make polarimetricmore » photodetectors.« less