Self-powered solar-blind alpha-Ga2O3 thin-film UV-C photodiode grown by halide vapor-phase epitaxy

Abstract

A compact self-powered solar-blind UV-C photodiode was demonstrated using an ultra-wide bandgap (UWBG) alpha-Ga2O3 thin film as a wavelength-selective absorber layer. The UWBG-based Schottky junction architecture renders the use of low-performance and bulky solarblind UV bandpass filters unnecessary. High-quality alpha-Ga2O3 thin films with a thickness of 1.25 mu mwere grown on a (0001) sapphire substrate via the halide vapor-phase epitaxy technique. The self-powered solar-blind UV-C photodetector based on the Ni/alpha-Ga2O3 Schottky junction exhibited excellent responsivity (1.17 x 10(-4) A/W), photo-to-dark current ratio (1.12 x 105), and reproducibility, as well as fast rise/decay characteristics without persistent photoconductivity upon exposure to UV-C radiation (254 nm wavelength). The relationship between light intensity (I) and photocurrent (P) was modeled by I x P-0.69, indicating the high-quality of the halide vapor-phase epitaxy-grown alpha-Ga2O3 thin film. Upon exposure to natural sunlight, the fabricated solar-blind photodetector showed excellent solar blindness with sensitivity to UV-C radiation and did not require an external power source. Therefore, this UWBG alpha-Ga2O3 thin-film Schottky barrier photodiode is expected to facilitate the development of a compact and energy-independent next-generation UV-C photodetector with solar blindness. (C) 2021 Author(s).