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Title: Impact of proton irradiation on conductivity and deep level defects in β-Ga 2O 3

Abstract

Single crystalline bulk and epitaxially grown gallium oxide (β–Ga 2O 3) was irradiated by 0.6 and 1.9 MeV protons to doses ranging from 5 × 10 9 to 6 × 10 14 cm -2 in order to study the impact on charge carrier concentration and electrically active defects. Samples irradiated to doses at or above 2 × 10 13 cm -2 showed a complete removal of free charge carriers in their as-irradiated state, whereas little or no influence was observed below doses of 6 × 10 12 cm -2. From measurements at elevated temperatures, a thermally activated recovery process is seen for the charge carriers, where the activation energy for recovery follow a second-order kinetics with an activation energy of ~1.2 eV. Combining the experimental results with hybrid functional calculations, we propose that the charge carrier removal can be explained by Fermi-level pinning far from the conduction band minimum (CBM) due to gallium interstitials (Ga i), vacancies (V Ga), and antisites (Ga O), while migration and subsequent passivation of V Ga via hydrogen-derived or V O defects may be responsible for the recovery. Following the recovery, deep level transient spectroscopy (DLTS) reveals generation of two deep levels, with energy positionsmore » around 0.75 and 1.4 eV below the CBM. Of these two levels, the latter is observed to disappear after the initial DLTS measurements, while the concentration of the former increases. Here, we discuss candidate possibilities and suggest that the origins of these levels are more likely due to a defect complex than an isolated point defect.« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [2];  [2];  [3];  [1];  [4]
  1. Univ. of Oslo (Norway). Dept. of Physics, Centre for Materials Science and Nanotechnology
  2. ABB Corporate Research, Baden-Dättwil (Switzerland)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Lawrence Livermore National Laboratory, Livermore, California 94550, USA
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1497944
Report Number(s):
LLNL-JRNL-758422
Journal ID: ISSN 2166-532X; 946177
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
APL Materials
Additional Journal Information:
Journal Volume: 7; Journal Issue: 2; Journal ID: ISSN 2166-532X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Ingebrigtsen, M. E., Kuznetsov, A. Yu., Svensson, B. G., Alfieri, G., Mihaila, A., Badstübner, U., Perron, A., Vines, L., and Varley, J. B. Impact of proton irradiation on conductivity and deep level defects in β-Ga2O3. United States: N. p., 2018. Web. doi:10.1063/1.5054826.
Ingebrigtsen, M. E., Kuznetsov, A. Yu., Svensson, B. G., Alfieri, G., Mihaila, A., Badstübner, U., Perron, A., Vines, L., & Varley, J. B. Impact of proton irradiation on conductivity and deep level defects in β-Ga2O3. United States. doi:10.1063/1.5054826.
Ingebrigtsen, M. E., Kuznetsov, A. Yu., Svensson, B. G., Alfieri, G., Mihaila, A., Badstübner, U., Perron, A., Vines, L., and Varley, J. B. Fri . "Impact of proton irradiation on conductivity and deep level defects in β-Ga2O3". United States. doi:10.1063/1.5054826. https://www.osti.gov/servlets/purl/1497944.
@article{osti_1497944,
title = {Impact of proton irradiation on conductivity and deep level defects in β-Ga2O3},
author = {Ingebrigtsen, M. E. and Kuznetsov, A. Yu. and Svensson, B. G. and Alfieri, G. and Mihaila, A. and Badstübner, U. and Perron, A. and Vines, L. and Varley, J. B.},
abstractNote = {Single crystalline bulk and epitaxially grown gallium oxide (β–Ga2O3) was irradiated by 0.6 and 1.9 MeV protons to doses ranging from 5 × 109 to 6 × 1014 cm-2 in order to study the impact on charge carrier concentration and electrically active defects. Samples irradiated to doses at or above 2 × 1013 cm-2 showed a complete removal of free charge carriers in their as-irradiated state, whereas little or no influence was observed below doses of 6 × 1012 cm-2. From measurements at elevated temperatures, a thermally activated recovery process is seen for the charge carriers, where the activation energy for recovery follow a second-order kinetics with an activation energy of ~1.2 eV. Combining the experimental results with hybrid functional calculations, we propose that the charge carrier removal can be explained by Fermi-level pinning far from the conduction band minimum (CBM) due to gallium interstitials (Gai), vacancies (VGa), and antisites (GaO), while migration and subsequent passivation of VGa via hydrogen-derived or VO defects may be responsible for the recovery. Following the recovery, deep level transient spectroscopy (DLTS) reveals generation of two deep levels, with energy positions around 0.75 and 1.4 eV below the CBM. Of these two levels, the latter is observed to disappear after the initial DLTS measurements, while the concentration of the former increases. Here, we discuss candidate possibilities and suggest that the origins of these levels are more likely due to a defect complex than an isolated point defect.},
doi = {10.1063/1.5054826},
journal = {APL Materials},
number = 2,
volume = 7,
place = {United States},
year = {2018},
month = {12}
}

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Works referenced in this record:

A climbing image nudged elastic band method for finding saddle points and minimum energy paths
journal, December 2000

  • Henkelman, Graeme; Uberuaga, Blas P.; Jónsson, Hannes
  • The Journal of Chemical Physics, Vol. 113, Issue 22, p. 9901-9904
  • DOI: 10.1063/1.1329672