Activated hybrid g-C3N4/porous GaN heterojunction for tunable self-powered and broadband photodetection

Top-down contamination-free uniform etching techniques for preparing porous micro-structure of GaN to enhance its optical absorption has long been explored to arrive at a convenient and efficient strategy. Besides, appropriate heterointerfacing to enhance the photoexcited charge transport with minimal recombination and quenching for consistent and efficient photodetection has been a challenging issue. Herein, we demonstrate one-step solvothermal etching for preparing macroporous GaN (m-GaN), followed by its activation with 2D g-C3N4 to fabricate type II heterojunction for broadband and self-powered (360-635 nm) photodetector (PD). Additionally, tunability in photoresponse and self-powered operation is achieved by impregnating g-C3N4 in thermally reduced graphene oxide (rGO) and chemically modified graphene oxide (CMGO) in separate experiments. With the optimized thickness and composition of CMGO:g-C3N4 on m-GaN, the developed PD displays remarkable photoresponse with broadened photosensitivity and estimated responsivity, detectivity, and external quantum efficiency of 3 A/W, similar to 10(14) Jones, and 10(3)%, respectively. CMGO treated devices exhibit better self-powered characteristics compared to rGO due to improved carrier transport from g-C3N4 and higher built-in potential developed with m-GaN. Under laboratory testing environment, the devices' stability has been recorded for 40 days without noticing any decay in dark current and photoresponse. This work suggests the application of hybrid g-C3N4/m-GaN heterojunction for stable, high-performance, and self-powered photodetection. Further, the modification in band-structure and optical properties of g-C3N4 with graphene oxides of different reduction levels can be leveraged in functional optoelectronics.