Clarifying the atomic origin of electron killers in β-Ga2O3 from the first-principles study of electron capture rates

Abstract The emerging wide bandgap semiconductor -Ga 2 O 3 has attracted great interest due to its promising applications for high-power electronic devices and solar-blind ultraviolet photodetectors. Deep-level defects in -Ga 2 O 3 have been intensively studied towards improving device performance. Deep-level signatures E 1 , E 2 , and E 3 with energy positions of 0.55–0.63, 0.74–0.81, and 1.01–1.10 eV below the conduction band minimum have frequently been observed and extensively investigated, but their atomic origins are still under debate. In this work, we attempt to clarify these deep-level signatures from the comparison of theoretically predicted electron capture cross-sections of suggested candidates, Ti and Fe substituting Ga on a tetrahedral site (Ti GaI and Fe GaI ) and an octahedral site (Ti GaII and Fe GaII ), to experimentally measured results. The first-principles approach predicted electron capture cross-sections of Ti GaI and Ti GaII defects are 8.56 × 10 –14 and 2.97 × 10 –13 cm 2 , in good agreement with the experimental values of E 1 and E 3 centers, respectively. We, therefore, confirmed that E 1 and E 3 centers are indeed associated with Ti GaI and Ti GaII defects, respectively. Whereas the predicted electron capture cross-sections of Fe Ga defect are two orders of magnitude larger than the experimental value of the E 2 , indicating E 2 may have other origins like C Ga and Ga i , rather than common believed Fe Ga .