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Proceedings Paper

Kinetics of charge carrier recombination in beta-Ga2O3 single crystals (Conference Presentation)
Author(s): Cuong Ton-That; Tung Huynh; Laurent Lee Cheong Lem; Akito Kuramata; Matthew Phillips

Paper Abstract

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.

Paper Details

Date Published: 8 March 2019
Proc. SPIE 10919, Oxide-based Materials and Devices X, 109190V (8 March 2019); doi: 10.1117/12.2518229
Show Author Affiliations
Cuong Ton-That, Univ. of Technology, Sydney (Australia)
Tung Huynh, Univ. of Technology, Sydney (Australia)
Laurent Lee Cheong Lem, Univ. of Technology, Sydney (Australia)
Akito Kuramata, Novel Crystal Technology, Inc. (Japan)
Matthew Phillips, Univ. of Technology, Sydney (Australia)

Published in SPIE Proceedings Vol. 10919:
Oxide-based Materials and Devices X
David J. Rogers; David C. Look; Ferechteh H. Teherani, Editor(s)

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