Enhancing β-Ga2O3-film ultraviolet detectors via RF magnetron sputtering with seed layer insertion on c-plane sapphire substrate

Abstract

Gallium oxide (Ga2O3) possesses a band gap of approximately 4.9 eV, aligning its detection wavelength within the solar-blind region, making it an ideal semiconductor material for solar-blind photodetectors. This study aims to enhance the performance of Ga2O3 ultraviolet (UV) detectors by pre-depositing a Ga2O3 seed layer on a c-plane sapphire substrate. The x-ray diffraction and x-ray photoelectron spectroscopy analyses validated that the deposited films, following high-temperature annealing, comprised β-Ga2O3. Comparing samples with and without a 20 nm seed layer, it was found that the former exhibited fewer oxygen defects and substantially improved crystal quality. The incorporation of the seed layer led to the realization of detectors with remarkably low dark current (≤15.3 fA). Moreover, the photo-to-dark current ratio was enhanced by 30% (surpassing 1.3 × 104) and the response/recovery time reduced to 0.9 s/0.01 s, indicating faster performance. Furthermore, these detectors demonstrated higher responsivity (4.8 mA W−1), improved detectivity (2.49 × 1016 Jones), and excellent solar-blind characteristics. This study serves as a foundational stepping toward achieving high-quality β-Ga2O3 thin film and UV detector arrays.