Leveraging defect-induced internal gain for high-performance β-Ga ₂ O ₃ photodetectors on patterned sapphire substrates

We report a deep-ultraviolet (DUV) metal-semiconductor-metal (MSM) photodetector based on a β-Ga₂O₃ thin film deposited by chemical vapor deposition (CVD) on a patterned sapphire substrate (PSS), compared with a control device using a film grown on flat sapphire. To the best of our knowledge, this is the first demonstration of β-Ga₂O₃ films with a preferred (510) orientation. The film grown on PSS exhibited high defect densities, including structural disorders, oxygen vacancies, and dangling bonds, which enabled exceptional responsivity (106.5 A/W) and specific detectivity (1.36 × 10¹³ Jones) through strong internal gain and extrinsic transitions, despite a relatively large dark current. A UV/visible rejection ratio (R₂₅₅/R₄₀₀) above 10⁴ further confirmed the device's sensitivity. A comprehensive analysis was performed on the impact of defects on the increased dark current and slower response. These findings offer important insights into the growth mechanism of β-Ga₂O₃ on PSS and highlight its potential for scalable, cost-effective solar-blind photodetectors.