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Title: Defect phase diagram for doping of Ga 2O 3

For the case of n-type doping of β-Ga 2O 3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO 2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO 2) conditions. Considering further the stability constraints due to sublimation of molecular Ga 2O, specific predictions of optimized pO 2 and Si dopant concentrations are given. To conclude, the incomplete passivation of dopant-defect complexes in β-Ga 2O 3 suggests a design rule for metastable doping above the solubility limit.
Authors:
ORCiD logo [1]
  1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-71414
Journal ID: ISSN 2166-532X
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
APL Materials
Additional Journal Information:
Journal Volume: 6; Journal Issue: 4; Journal ID: ISSN 2166-532X
Publisher:
American Institute of Physics (AIP)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Next Generation of Materials by Design: Incorporating Metastability (CNGMD)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; wide gap semiconductor; doping; defect equilibrium; first principles
OSTI Identifier:
1435905
Alternate Identifier(s):
OSTI ID: 1432739

Lany, Stephan. Defect phase diagram for doping of Ga2O3. United States: N. p., Web. doi:10.1063/1.5019938.
Lany, Stephan. Defect phase diagram for doping of Ga2O3. United States. doi:10.1063/1.5019938.
Lany, Stephan. 2018. "Defect phase diagram for doping of Ga2O3". United States. doi:10.1063/1.5019938. https://www.osti.gov/servlets/purl/1435905.
@article{osti_1435905,
title = {Defect phase diagram for doping of Ga2O3},
author = {Lany, Stephan},
abstractNote = {For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO2) conditions. Considering further the stability constraints due to sublimation of molecular Ga2O, specific predictions of optimized pO2 and Si dopant concentrations are given. To conclude, the incomplete passivation of dopant-defect complexes in β-Ga2O3 suggests a design rule for metastable doping above the solubility limit.},
doi = {10.1063/1.5019938},
journal = {APL Materials},
number = 4,
volume = 6,
place = {United States},
year = {2018},
month = {4}
}