We report the fabrication of rhombohedral corundum-structured indium gallium oxide (alpha-( (InxGa1-x)(2)O-3) alloy thin films on sapphire substrates with alpha-Ga2O3 buffer layers. X-ray diffraction measurement showed the formation of the alloy thin films with In compositions of x=0, 0.05, 0.08, and 0.67. The optical band gaps and resistivity systematically changed depending on x, that is, from 5.3 to 4.0 eV and from 10(9) to 10(1) Omega cm, respectively, suggesting future applications to actual devices. Additionally, CL measurements for alpha-(In0.08Ga0.92)(2)O-3 alloy thin film suggest the emission from deep levels. (C) 2014 Elsevier B.V. All tights reserved.