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Title: Observation and mitigation of RF-plasma-induced damage to III-nitrides grown by molecular beam epitaxy

Abstract

In this work, radio-frequency (RF) plasma-induced damage to III-nitride surfaces and bulk defects is observed and mitigated. It is shown that for InN films, the surface is more sensitive to plasma-induced damage than GaN films, as observed via atomic force microscopy and reflection high energy electron diffraction. In order to isolate any possible plasma-induced damage, a growth window for InN is established, and temperature ranges are determined for other damaging effects which include roughening due to low adatom mobility, InN decomposition, and indium desorption. In situ plasma monitoring and optimization are accomplished with a combination of optical emission spectroscopy as well as a remote Langmuir probe. It is shown that by increasing the plasma nitrogen flow, the positive ion content increases; however, the ion acceleration potential reduces. Additionally, a reduced RF plasma power results in a reduction of atomic nitrogen species. These plasma species and energetic variations result in variations in the bulk unintentional background electron concentrations observed by room temperature Hall effect measurements of ~1 um thick InN films. By increasing the nitrogen flow from 2.5 to 7.5 sccm for a constant RF power of 350 W, the background electron concentration decreases by 74% from 1.36 x 1019 cm-3more » to 3.54 x 1018 cm-3, while maintaining a smooth surface morphology. Additionally, photoluminescence spectra indicate optical emission energies shift from ~0.81 to 0.71 eV (closer to the fundamental bandgap of InN) by limiting the damaging plasma species. Finally, conditions are presented to further minimize plasma-induced damage in III-nitride devices.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2];  [1]
  1. Georgia Inst. of Technology, Atlanta, GA (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1545263
Alternate Identifier(s):
OSTI ID: 1530634
Report Number(s):
[NREL/JA-5K00-74387]
[Journal ID: ISSN 0021-8979]
Grant/Contract Number:  
[AC36-08GO28308; DEAR0000470]
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
[ Journal Volume: 126; Journal Issue: 1]; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; epitaxy; nitrides; optical emission spectroscopy; surface and interface chemistry; plasma diagnostics; photoluminescence spectroscopy

Citation Formats

Clinton, Evan A., Vadiee, Ehsan, Tellekamp, M. Brooks, and Doolittle, W. Alan. Observation and mitigation of RF-plasma-induced damage to III-nitrides grown by molecular beam epitaxy. United States: N. p., 2019. Web. doi:10.1063/1.5097557.
Clinton, Evan A., Vadiee, Ehsan, Tellekamp, M. Brooks, & Doolittle, W. Alan. Observation and mitigation of RF-plasma-induced damage to III-nitrides grown by molecular beam epitaxy. United States. doi:10.1063/1.5097557.
Clinton, Evan A., Vadiee, Ehsan, Tellekamp, M. Brooks, and Doolittle, W. Alan. Tue . "Observation and mitigation of RF-plasma-induced damage to III-nitrides grown by molecular beam epitaxy". United States. doi:10.1063/1.5097557.
@article{osti_1545263,
title = {Observation and mitigation of RF-plasma-induced damage to III-nitrides grown by molecular beam epitaxy},
author = {Clinton, Evan A. and Vadiee, Ehsan and Tellekamp, M. Brooks and Doolittle, W. Alan},
abstractNote = {In this work, radio-frequency (RF) plasma-induced damage to III-nitride surfaces and bulk defects is observed and mitigated. It is shown that for InN films, the surface is more sensitive to plasma-induced damage than GaN films, as observed via atomic force microscopy and reflection high energy electron diffraction. In order to isolate any possible plasma-induced damage, a growth window for InN is established, and temperature ranges are determined for other damaging effects which include roughening due to low adatom mobility, InN decomposition, and indium desorption. In situ plasma monitoring and optimization are accomplished with a combination of optical emission spectroscopy as well as a remote Langmuir probe. It is shown that by increasing the plasma nitrogen flow, the positive ion content increases; however, the ion acceleration potential reduces. Additionally, a reduced RF plasma power results in a reduction of atomic nitrogen species. These plasma species and energetic variations result in variations in the bulk unintentional background electron concentrations observed by room temperature Hall effect measurements of ~1 um thick InN films. By increasing the nitrogen flow from 2.5 to 7.5 sccm for a constant RF power of 350 W, the background electron concentration decreases by 74% from 1.36 x 1019 cm-3 to 3.54 x 1018 cm-3, while maintaining a smooth surface morphology. Additionally, photoluminescence spectra indicate optical emission energies shift from ~0.81 to 0.71 eV (closer to the fundamental bandgap of InN) by limiting the damaging plasma species. Finally, conditions are presented to further minimize plasma-induced damage in III-nitride devices.},
doi = {10.1063/1.5097557},
journal = {Journal of Applied Physics},
number = [1],
volume = [126],
place = {United States},
year = {2019},
month = {7}
}

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