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Temperature-dependent cathodoluminescence spectra of (2¯01) Si-doped β-Ga2O3 single crystals and (010) N-doped epitaxial films were comprehensively shown to investigate their electronic structure and defect states. The decrease in the self-trapped exciton (STE) emission at low temperatures in heavily Si-doped crystals implied the Debye-Hückel screening of STEs with the critical charge density larger than 2 × 1018 cm−3. The analysis based on the rate equation model suggested a significant influence of the donor-acceptor-pair recombination involving a SiGa donor on the UV luminescence band in the Si-doped crystals. The blue luminescence band was suppressed for the heavily N-doped epitaxial films with a N concentration of 1 × 1018 cm−3, implying the decrease in the oxygen vacancy (VO) concentration by N doping. The increase in the NO acceptor concentration as well as the decrease in the VO concentration were found to contribute to the compensation of residual Si donors resulting in high resistivity of N-doped epitaxial films.
Onuma et al. (Mon,) studied this question.