Photoresponse characteristics of bulk gallium nitride schottky barrier metal-semiconductor-metal ultraviolet photodetectors

In this work, bulk gallium nitride (GaN) Schottky barrier metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors (PDs) were fabricated, and their key performance metrics such as photoresponse, photosensitivity, gain, external quantum efficiency, detectivity, noise equivalent power, rise time, and fall time were thoroughly evaluated. The Schottky barrier was formed using platinum (Pt) metal with two different sizes of interdigitated electrode on the bulk GaN samples.The effects of mask size on the photoresponse characteristics were investigated. The Pt/bulk GaN MSM UV PDs exhibited outstanding performance under 365 nm UV light. At a bias voltage of 5 V, the PDs with smaller active areas (0.238 cm²) achieved a responsivity of 13.6 mA/W and a fast rise time of 174 ms, while those with larger active areas (0.412 cm²) demonstrated a responsivity of 2.62 mA/W and a rise time of 286 ms. Even at 0 V bias, these devices showed responsivities of 1.34 µA/W and 3.40 µA/W for the small and large masks, respectively, indicating that they possess self-powered device capabilities. [Display omitted] •Bulk GaN Schottky barrier MSM UV photodetectors were fabricated and tested.•The impact of mask size on photoresponse using Pt Schottky barriers with two electrode sizes was evaluated.•Smaller active area GaN MSM UV PDs showed 13.6 mA/W responsivity and 174 ms rise time.•Bulk GaN Schottky barrier MSM UV PDs demonstrated self-powered operation with 11600 % photosensitivity.