Abstract
A compact self-powered solar-blind UV-C photodiode was demonstrated using an ultra-wide bandgap (UWBG) α-Ga2O3 thin film as a wavelength-selective absorber layer. The UWBG-based Schottky junction architecture renders the use of low-performance and bulky solar-blind UV bandpass filters unnecessary. High-quality α-Ga2O3 thin films with a thickness of 1.25 µm were 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/α-Ga2O3 Schottky junction exhibited excellent responsivity (1.17 × 10−4 A/W), photo-to-dark current ratio (1.12 × 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 ∼ P0.69, indicating the high-quality of the halide vapor-phase epitaxy-grown α-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 α-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.
Highlights
Solar radiation of wavelengths shorter than 280 nm is strongly absorbed in the stratosphere, causing ultraviolet (UV)-C light to be undetectable on Earth’s surface.1–3 A solar-blind UV-C photodetector is an optoelectronic device that selectively detects light with wavelengths in the UV-C and shorter regions of the spectrum
The absence of persistent photoconductivity (PPC), which is common in WBGsemiconductor-based photodetectors, implies that the halide vapor-phase epitaxy (HVPE)-grown α-Ga2O3 thin film is of high quality and does not require additional surface treatment or passivation processes
Our findings prove that an energy-independent solarblind UV-C photodetector can be fabricated using an α-Ga2O3 thin film based on a Schottky barrier photodiode without a UV bandpass filter
Summary
Solar radiation of wavelengths shorter than 280 nm is strongly absorbed in the stratosphere, causing ultraviolet (UV)-C light to be undetectable on Earth’s surface (this is known as the “black background”).1–3 A solar-blind UV-C photodetector is an optoelectronic device that selectively detects light with wavelengths in the UV-C and shorter regions of the spectrum. A compact self-powered solar-blind UV-C photodiode was demonstrated using an ultra-wide bandgap (UWBG) α-Ga2O3 thin film as a wavelength-selective absorber layer.
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