Microstructure, surface morphology and optical properties of N-incorporated Ga2O3 thin films on sapphire substrates

• N2 gas flux affects the microstructure, surface morphology and optical properties.
• The films have better crystallization quality after incorporating properly.
• The photoluminescence spectra include ultraviolet and green emission parts.
• The optical band gap decreases with increasing the N2 gas flux.

N-incorporated Ga2O3 films were successfully prepared on sapphire substrates in Ar–N2 gas mixtures by radio frequency magnetron sputtering. The influence of N2 gas flux on microstructure, surface morphology and optical properties of N-incorporated Ga2O3 films was analyzed in detail. The films have better crystalline quality after nitrogen incorporating properly, while keeping their original β-Ga2O3 crystalline structure. The surface morphology of the N-incorporated Ga2O3 films was investigated by atomic force microscopy (AFM). The photoluminescence spectra consisted of ultraviolet emission peak and green emission band were also observed and discussed. The optical transmittance of the as-deposited N-incorporated Ga2O3 films exceeds 80% in the visible range. The optical band gap decreases with increasing the N2 gas flux, resulting from the formation of Ga–N bonds.