High Performance Self‐Powered p⁺‐GaN/n⁻‐ZnO/Au UV Heterojunction Phototransistor with 3D Interconnected ZnO Nanowire Network for Solar‐Blind Imaging and Optical Communication

Abstract Heterojunction phototransistor (HPT) is considered the most promising detector technology in weak ultraviolet (UV) signal detection due to its inherent internal gain through transistor action. However, achieving high‐performance self‐powered UV HPTs remains a significant challenge. In this study, a high‐performance self‐powered p⁺‐GaN/n⁻‐ZnO/Au UV HPT with ZnO serving as the floating base is cleverly designed. The device features a unique back‐to‐back configuration of the p⁺‐GaN/n⁻‐ZnO heterojunction and n⁻‐ZnO/Au Schottky junction, along with an ultrathin ZnO base layer of a 3D nanowire network structure. This design enables the fabricated p⁺‐GaN/n⁻‐ZnO/Au UV HPT to operate in a self‐powered mode with exceptional performance metrics. Under zero bias, the device exhibits outstanding characteristics including ultralow dark current of 1.7 × 10⁻¹³ A, remarkable I_photo/I_dark ratio of 10⁶, fast response speed (t_r = 150 µs / t_{f =} 250 µs), high responsivity of 9.74 A W⁻¹, and detectivity of 1.58 × 10¹⁴ Jones, representing the best result achieved for UV HPTs thus far at zero bias. Moreover, the fabricated UV HPT is successfully demonstrated in solar‐blind imaging and UV communication systems without the need for an external power supply. This work presents effective and practical design strategies for achieving high‐performance self‐powered UV HPTs.