Point defect induced degradation of electrical properties of Ga2O3 by 10 MeV proton damage

Abstract

Deep electron and hole traps in 10 MeV proton irradiated high-quality β-Ga₂O₃ films grown by Hydride Vapor Phase Epitaxy (HVPE) on bulk β-Ga₂O₃ substrates were measured by deep level transient spectroscopy with electrical and optical injection, capacitance-voltage profiling in the dark and under monochromatic irradiation, and also electron beam induced current. Proton irradiation caused the diffusion length of charge carriers to decrease from 350–380 μm in unirradiated samples to 190 μm for a fluence of 10¹⁴ cm⁻², and this was correlated with an increase in density of hole traps with optical ionization threshold energy near 2.3 eV. These defects most likely determine the recombination lifetime in HVPE β-Ga₂O₃ epilayers. Electron traps at E_c-0.75 eV and E_c-1.2 eV present in as-grown samples increase in the concentration after irradiation and suggest that these centers involve native point defects.