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arXiv · 2005.13747

Kinetics of charge carrier recombination in beta-Ga2O3 crystals

T. T. Huynh·L. L. C. Lem·A. Kuramata·M. R. Phillips·C. Ton-That
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Abstract

Cathodoluminescence spectra were measured to determine the characteristics of luminescence bands and carrier dynamics in beta-Ga2O3 bulk single crystals. The CL emission was found to be dominated by a broad UV emission peaked at 3.40 eV, which exhibits strong quenching with increasing temperature; however, its spectral shape and energy position remain virtually unchanged. We observed a super-linear increase of CL intensity with excitation density; this kinetics of carrier recombination can be explained in terms of carrier trapping and charge transfer at Fe impurity centres. The temperature-dependent properties of this UV band are consistent with weakly bound electrons in self-trapped excitons with an activation energy of 48 +/- 10 meV. In addition to the self-trapped exciton emission, a blue luminescence (BL) band is shown to be related to a donor-like defect, which increases significantly in concentration after hydrogen plasma annealing. The point defect responsible for the BL, likely an oxygen vacancy, is strongly coupled to the lattice exhibiting a Huang-Rhys factor of ~ 7.3.

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T. T. Huynh, L. L. C. Lem, A. Kuramata, M. R. Phillips, C. Ton-That. 2020-05-28. Kinetics of charge carrier recombination in beta-Ga2O3 crystals. https://arxiv.org/abs/2005.13747

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