Thermoreflectance characterization of β-Ga2O3 thin-film nanostrips

Nanostructure of beta-Ga2O3 is wide-band-gap material with white-light-emission function because of its abundance in gap states. In this study, the gap states and near-band-edge transitions in beta-Ga2O3 nanostrips have been characterized using temperature-dependent thermoreflectance (TR) measurements in the temperature range between 30 and 320 K. Photoluminescence (PL) measurements were carried to identify the gap-state transitions in the beta-Ga2O3 nanostrips. Experimental analysis of the TR spectra revealed that the direct gap (E-0) of beta-Ga2O3 is 4.656 eV at 300 K. There are a lot of gap-state and near-band-edge (GSNBE) transitions denoted as E-D3, E-W1, E-W2, E-W3, E-D2, E-DB(ex), E-DB, E-D1, E-0, and E-0' can be detected in the TR and PL spectra at 30 K. Transition origins for the GSNBE features in the beta-Ga2O3 nanostrips are respectively evaluated. Temperature dependences of transition energies of the GSNBE transitions in the beta-Ga2O3 nanostrips are analyzed. The probable band scheme for the GSNBE transitions in the beta-Ga2O3 nanostrips is constructed. (C) 2010 Optical Society of America