β-Ga₂O₃-Based Solar-Blind Photodetector With Ultrahigh Responsivity via Optimizing Interdigital Electrode Parameters

Abstract

High-quality $\beta $ -Ga ₂ O ₃ films were prepared via the metal organic chemical vapor deposition method and construction of metal–semiconductor–metal–structured photodetectors (PDs) with varying parameters, including length, width, and distance of the Ti/Au interdigital electrodes. Under a 10 V bias and UV light illumination ( $50~\mu $ W/cm ² ), the peak response of PDs is present in the solar-blind region (254 nm), and the responsivity is as high as $1.87\times10$ ⁵ A/W. The cut-off wavelength is ~266 nm, with a deep UV/visible light responsivity rejection ratio (R ₂₅₄ nm/R ₄₀₀ nm) of ~10 ² . The light–dark current ratio reaches 10 ⁵ , the detectivity is about $3.37\times10$ ¹⁴ Jones, and the rise and decay response time is < 1 s. These high performances are attributed to defect center trapping carriers, yielding inconsistent electron and hole collection efficiency. Additionally, the nonlinear effect between light intensity and photocurrent that is induced by avalanche ionization under a high electric field (50 V) is demonstrated. This study might be of great value for the design and fabrication of high-performance solar-blind UV PDs.