Enhanced performance of a-GaOx thin-film transistor photodetectors via in situ hydrogen incorporation using water vapor†

Amorphous gallium oxide photodetectors have garnered increasing attention in solar-blind ultraviolet detection applications. However, the inherent high-density defects in the material pose a significant challenge, as improving the photo-response often leads to deteriorated recovery time, making it difficult to achieve a balance between high responsivity and a relatively fast response time. In this study, water vapor is introduced as part of the deposition atmosphere during the magnetron sputtering process to facilitate in situ hydrogen incorporation, aiming to enhance the performance of a-GaO_x thin films. It is observed that water vapor incorporation induces numerous hydrogen-related unstable defects in the as-deposited films. Nevertheless, after vacuum annealing, these hydrogen-related defects and oxygen vacancies are significantly reduced, improving the film packing density and microstructural ordering. The optimized a-GaO_x photodetectors exhibit significant performance enhancement compared to non-hydrogenated devices, with responsivity increasing by approximately one order of magnitude (from 44.05 A W⁻¹ to 832.6 A W⁻¹), accompanied by an effective reduction in response time. This approach presents a promising solution to address the longstanding trade-off between responsivity and response time in amorphous oxide photodetectors.