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Title: Sub-band-gap absorption in Ga2O3

Abstract

β-Ga2O3 is a transparent conducting oxide that, due to its large bandgap of 4.8 eV, exhibits transparency into the UV. However, the free carriers that enable the conductivity can absorb light. We study the effect of free carriers on the properties of Ga2O3 using hybrid density functional theory. The presence of free carriers leads to sub-band-gap absorption and a Burstein-Moss shift in the onset of absorption. We find that for a concentration of 1020 carriers, the Fermi level is located 0.23 eV above the conduction-band minimum. This leads to an increase in the electron effective mass from 0.27–0.28 me to 0.35–0.37 me and a sub-band-gap absorption band with a peak value of 0.6 × 103 cm–1 at 3.37 eV for light polarized along the x or z direction. Both across-the-gap and free-carrier absorption depend strongly on the polarization of the incoming light. We also provide parametrizations of the conduction-band shape and the effective mass as a function of the Fermi level. β-Ga2O3 exhibits very good electronic conductivity in spite of its bandgap of 4.8 eV; this large gap makes it transparent into the UV. This combination allows for applications in devices such as deep-UV blind detectors and contacts for solarmore » cells. It also enables high-power devices, such as high-voltage metal-semiconductor field-effect transistors and Schottky barrier diodes.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]
  1. Univ. of California, Santa Barbara, CA (United States)
Publication Date:
Research Org.:
Univ. of California, Santa Barbara, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1505556
Alternate Identifier(s):
OSTI ID: 1408160
Grant/Contract Number:  
SC0010689
Resource Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 111; Journal Issue: 18; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Peelaers, Hartwin, and Van de Walle, Chris G. Sub-band-gap absorption in Ga2O3. United States: N. p., 2017. Web. doi:10.1063/1.5001323.
Peelaers, Hartwin, & Van de Walle, Chris G. Sub-band-gap absorption in Ga2O3. United States. doi:10.1063/1.5001323.
Peelaers, Hartwin, and Van de Walle, Chris G. Fri . "Sub-band-gap absorption in Ga2O3". United States. doi:10.1063/1.5001323. https://www.osti.gov/servlets/purl/1505556.
@article{osti_1505556,
title = {Sub-band-gap absorption in Ga2O3},
author = {Peelaers, Hartwin and Van de Walle, Chris G.},
abstractNote = {β-Ga2O3 is a transparent conducting oxide that, due to its large bandgap of 4.8 eV, exhibits transparency into the UV. However, the free carriers that enable the conductivity can absorb light. We study the effect of free carriers on the properties of Ga2O3 using hybrid density functional theory. The presence of free carriers leads to sub-band-gap absorption and a Burstein-Moss shift in the onset of absorption. We find that for a concentration of 1020 carriers, the Fermi level is located 0.23 eV above the conduction-band minimum. This leads to an increase in the electron effective mass from 0.27–0.28 me to 0.35–0.37 me and a sub-band-gap absorption band with a peak value of 0.6 × 103 cm–1 at 3.37 eV for light polarized along the x or z direction. Both across-the-gap and free-carrier absorption depend strongly on the polarization of the incoming light. We also provide parametrizations of the conduction-band shape and the effective mass as a function of the Fermi level. β-Ga2O3 exhibits very good electronic conductivity in spite of its bandgap of 4.8 eV; this large gap makes it transparent into the UV. This combination allows for applications in devices such as deep-UV blind detectors and contacts for solar cells. It also enables high-power devices, such as high-voltage metal-semiconductor field-effect transistors and Schottky barrier diodes.},
doi = {10.1063/1.5001323},
journal = {Applied Physics Letters},
number = 18,
volume = 111,
place = {United States},
year = {2017},
month = {11}
}

Journal Article:
Free Publicly Available Full Text
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Citation Metrics:
Cited by: 5 works
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Figures / Tables:

FIG. 1 FIG. 1: (a) The conventional unit cell of the monoclinic crystal structure of β-Ga2O3. Large spheres are Ga atoms, while small spheres are O atoms. (b) The band structure of Ga2O3 along two high-symmetry lines (X-Γ and C-Γ). The dashed red line is a hyperbolic fit of the lowest conductionmore » band using Eq. (2). The dotted line is a parabolic fit.« less

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