Growth and characterization of β-Ga2O3 thin films grown on off-angled Al2O3 substrates by metal-organic chemical vapor deposition

Abstract

Beta-gallium oxide (β-Ga2O3) thin films were deposited on c-plane (0001) sapphire substrates with different mis-cut angles along <> by metal-organic chemical vapor deposition (MOCVD). The structural properties and surface morphology of as-grown β-Ga2O3 thin films were investigated in detail. It was found that by using thin buffer layer and mis-cut substrate technology, the full width at half maximum (FWHM) of the () diffraction peak of the β-Ga2O3 film is decreased from 2° on c-plane (0001) Al2O3 substrate to 0.64° on an 8° off-angled c-plane (0001) Al2O3 substrate. The surface root-mean-square (RMS) roughness can also be improved greatly and the value is 1.27 nm for 8° off-angled c-plane (0001) Al2O3 substrate. Room temperature photoluminescence (PL) was observed, which was attributed to the self-trapped excitons formed by oxygen and gallium vacancies in the film. The ultraviolet–blue PL intensity related with oxygen and gallium vacancies is decreased with the increasing mis-cut angle, which is in agreement with the improved crystal quality measured by high resolution X-ray diffraction (HR-XRD). The present results provide a route for growing high quality β-Ga2O3 film on Al2O3 substrate.