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Title: Real-time growth study of plasma assisted atomic layer epitaxy of InN films by synchrotron x-ray methods

Authors:
 [1];  [2];  [1];  [1];  [1];  [3];  [4];  [3];  [1]
  1. U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375
  2. American Society for Engineering Education, 1818 N Street NW, Washington, DC 20036
  3. Physics Department, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215
  4. Department of Physics, SUNY College at Brockport, 350 New Campus Dr, Brockport, New York 14420
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1420693
Grant/Contract Number:
AC02-98CH10886
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
Additional Journal Information:
Journal Volume: 35; Journal Issue: 3; Related Information: CHORUS Timestamp: 2018-02-14 18:57:46; Journal ID: ISSN 0734-2101
Publisher:
American Vacuum Society
Country of Publication:
United States
Language:
English

Citation Formats

Nepal, Neeraj, Anderson, Virginia R., Johnson, Scooter D., Downey, Brian P., Meyer, David J., DeMasi, Alexander, Robinson, Zachary R., Ludwig, Karl F., and Eddy, Jr., Charles R.. Real-time growth study of plasma assisted atomic layer epitaxy of InN films by synchrotron x-ray methods. United States: N. p., 2017. Web. doi:10.1116/1.4978026.
Nepal, Neeraj, Anderson, Virginia R., Johnson, Scooter D., Downey, Brian P., Meyer, David J., DeMasi, Alexander, Robinson, Zachary R., Ludwig, Karl F., & Eddy, Jr., Charles R.. Real-time growth study of plasma assisted atomic layer epitaxy of InN films by synchrotron x-ray methods. United States. doi:10.1116/1.4978026.
Nepal, Neeraj, Anderson, Virginia R., Johnson, Scooter D., Downey, Brian P., Meyer, David J., DeMasi, Alexander, Robinson, Zachary R., Ludwig, Karl F., and Eddy, Jr., Charles R.. Mon . "Real-time growth study of plasma assisted atomic layer epitaxy of InN films by synchrotron x-ray methods". United States. doi:10.1116/1.4978026.
@article{osti_1420693,
title = {Real-time growth study of plasma assisted atomic layer epitaxy of InN films by synchrotron x-ray methods},
author = {Nepal, Neeraj and Anderson, Virginia R. and Johnson, Scooter D. and Downey, Brian P. and Meyer, David J. and DeMasi, Alexander and Robinson, Zachary R. and Ludwig, Karl F. and Eddy, Jr., Charles R.},
abstractNote = {},
doi = {10.1116/1.4978026},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 3,
volume = 35,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1116/1.4978026

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  • The temporal evolution of high quality indium nitride (InN) growth by plasma-assisted atomic layer epitaxy (ALEp) on a-plane sapphire at 200 and 248 °C was probed by synchrotron x-ray methods. The growth was carried out in a thin film growth facility installed at beamline X21 of the National Synchrotron Light Source at Brookhaven National Laboratory and at beamline G3 of the Cornell High Energy Synchrotron Source, Cornell University. Measurements of grazing incidence small angle x-ray scattering (GISAXS) during the initial cycles of growth revealed a broadening and scattering near the diffuse specular rod and the development of scattering intensities duemore » to half unit cell thick nucleation islands in the Yoneda wing with correlation length scale of 7.1 and 8.2 nm, at growth temperatures (Tg) of 200 and 248 °C, respectively. At about 1.1 nm (two unit cells) of growth thickness nucleation islands coarsen, grow, and the intensity of correlated scattering peak increased at the correlation length scale of 8.0 and 8.7 nm for Tg = 200 and 248 °C, respectively. The correlated peaks at both growth temperatures can be fitted with a single peak Lorentzian function, which support single mode growth. Post-growth in situ x-ray reflectivity measurements indicate a growth rate of ~0.36 Å/cycle consistent with the growth rate previously reported for self-limited InN growth in a commercial ALEp reactor. Consistent with the in situ GISAXS study, ex situ atomic force microscopy power spectral density measurements also indicate single mode growth. Electrical characterization of the resulting film revealed an electron mobility of 50 cm2/V s for a 5.6 nm thick InN film on a-plane sapphire, which is higher than the previously reported mobility of much thicker InN films grown at higher temperature by molecular beam epitaxy directly on sapphire. These early results indicated that in situ synchrotron x-ray study of the epitaxial growth kinetics of InN films is a very powerful method to understand nucleation and growth mechanisms of ALEp to enable improvement in material quality and broaden its application.« less
  • Wide bandgap semiconducting nitrides have found wide-spread application as light emitting and laser diodes and are under investigation for further application in optoelectronics, photovoltaics, and efficient power switching technologies. Alloys of the binary semiconductors allow adjustments of the band gap, an important semiconductor material characteristic, which is 6.2 eV for aluminum nitride (AlN), 3.4 eV for gallium nitride, and 0.7 eV for (InN). Currently, the highest quality III-nitride films are deposited by metalorganic chemical vapor deposition and molecular beam epitaxy. Temperatures of 900 °C and higher are required to deposit high quality AlN. Research into depositing III-nitrides with atomic layermore » epitaxy (ALEp) is ongoing because it is a fabrication friendly technique allowing lower growth temperatures. Because it is a relatively new technique, there is insufficient understanding of the ALEp growth mechanism which will be essential to development of the process. Here, grazing incidence small angle x-ray scattering is employed to observe the evolving behavior of the surface morphology during growth of AlN by ALEp at temperatures from 360 to 480 °C. Increased temperatures of AlN resulted in lower impurities and relatively fewer features with short range correlations.« less
  • The surface bonding configuration and kinetics of hydrogen desorption from InN grown by plasma-assisted atomic layer epitaxy have been investigated. High resolution electron energy loss spectra exhibited loss peaks assigned to a Fuchs–Kliewer surface phonon, N-N and N-H surface species. The surface N-N vibrations are attributed to surface defects. The observation of N-H but no In-H surface species suggested N-terminated InN. Isothermal desorption data were best fit by the first-order desorption kinetics with an activation energy of (0.88 ± 0.06) eV and pre-exponential factor of (1.5 ± 0.5) × 10{sup 5 }s{sup −1}.
  • Real-time synchrotron x-ray scattering in the anti-Bragg configuration was used to monitor the dynamics of pentacene film growth on inert substrates. A distributed-growth model, according to which pentacene molecules adsorbed on the nth layer can either nucleate and contribute to the growth of the (n+1)th layer or transfer downward and contribute to the growth of the nth layer, gave a good description of the data. For molecules adsorbed on the first and second layers, the probability of downward transfer was found to be dependent on the substrate, and independent of temperature within the range from 25 to 60 deg. C.more » For films grown on SiO{sub 2}, an Ehrlich-Schwoebel barrier of the order of 70 meV dominated downward transfer of pentacene molecules in layers away from the substrate. For films grown on an alkylated self-assembled monolayer, significant desorption of pentacene molecules from the substrate at elevated temperatures forced the growth mode toward the three-dimensional limit.« less
  • Thin AlN layers were grown at 200–650 °C by plasma assisted atomic layer epitaxy (PA-ALE) simultaneously on Si(111), sapphire (1120), and GaN/sapphire substrates. The AlN growth on Si(111) is self-limited for trimethyaluminum (TMA) pulse of length > 0.04 s, using a 10 s purge. However, the AlN nucleation on GaN/sapphire is non-uniform and has a bimodal island size distribution for TMA pulse of ≤0.03 s. The growth rate (GR) remains almost constant for T{sub g} between 300 and 400 °C indicating ALE mode at those temperatures. The GR is increased by 20% at T{sub g} = 500 °C. Spectroscopic ellipsometrymore » (SE) measurement shows that the ALE AlN layers grown at T{sub g} ≤ 400 °C have no clear band edge related features, however, the theoretically estimated band gap of 6.2 eV was measured for AlN grown at T{sub g} ≥ 500 °C. X-ray diffraction measurements on 37 nm thick AlN films grown at optimized growth conditions (T{sub g} = 500 °C, 10 s purge, 0.06 s TMA pulse) reveal that the ALE AlN on GaN/sapphire is (0002) oriented with rocking curve full width at the half maximum (FWHM) of 670 arc sec. Epitaxial growth of crystalline AlN layers by PA-ALE at low temperatures broadens application of the material in the technologies that require large area conformal growth at low temperatures with thickness control at the atomic scale.« less