Annealing-induced tunable bandgap and photoluminescence of (InGa)2O3 films deposited by magnetron sputtering

Abstract

(InGa)2O3 films are grown on quartz substrates by radio frequency magnetron sputtering using In/Ga2O3 target. The crystal structure, morphology, chemical states and optical properties of (InGa)2O3 films after annealing are investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy, optical transmission spectroscopy and photoluminescence spectroscopy. The crystallinity of (InGa)2O3 film improves and phase segregation occurs as the annealing temperature is raised to 800 °C. A mass of cavities are formed on the surface of annealed (InGa)2O3 films. The nanocrystal particles are found in the (InGa)2O3 film annealed at 800 °C. The optical bandgap values of (InGa)2O3 films change from 4.68 to 4.89 eV with increasing annealing temperature from room temperature to 800 °C, which is associated with the decrease of oxygen vacancies and loss of In component of (InGa)2O3 films. The variation of emission band in (InGa)2O3 films is influenced by the tunable bandgap, increasing grain boundary and phase segregation. This work investigates the effect of annealing on the optical properties of (InGa)2O3 films and promotes the application of (InGa)2O3 films in the optical field.