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8 March 2019 Kinetics of charge carrier recombination in beta-Ga2O3 single crystals (Conference Presentation)
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Proceedings Volume 10919, Oxide-based Materials and Devices X; 109190V (2019)
Event: SPIE OPTO, 2019, San Francisco, California, United States
We used temperature-resolved cathodoluminescence to determine the characteristics of luminescence bands and carrier dynamics in edge-defined film-fed grown (EFG) beta-Ga2O3 single crystals synthesized by Tamura Corporation. The crystal is nominally undoped and has a (-201) surface orientation. The main impurities are Si, Ir, Al and Fe, with [Fe] ~ 10^17 cm-3 verified by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). 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 up to 500 K. Depth-resolved analysis reveals the luminescence spectrum is independent of sampling depth. 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 Fe3+/2+ centers. The temperature-dependent properties of this UV band were found to be 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 remote hydrogen plasma treatment. The point defect responsible for the BL, likely an oxygen vacancy or a complex, is strongly coupled to the lattice with a Huang-Rhys factor S = 7.3.
Conference Presentation
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Cuong Ton-That, Tung Huynh, Laurent Lee Cheong Lem, Akito Kuramata, and Matthew Phillips "Kinetics of charge carrier recombination in beta-Ga2O3 single crystals (Conference Presentation)", Proc. SPIE 10919, Oxide-based Materials and Devices X, 109190V (8 March 2019); doi: 10.1117/12.2518229;

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