Engineering GaN/AuNC core–shell nanowire heterojunctions by gold nanoclusters with excitation-dependent behavior for enhancing the responsivity and stability of self-driven photodetectors

Abstract

Self-driven broadband photodetectors (PDs) with low-power consumption have great potential applications in the wide range of next-generation optoelectronic devices. In this study, a self-driven broadband PD responding to an ultraviolet-visible range based on gallium nitride/gold nanocluster (GaN/AuNC) core–shell nanowire heterojunctions is fabricated for the first time. By introducing the AuNCs onto the GaN nanowire surfaces, the GaN/AuNC core–shell nanowire heterojunctions can be formed efficiently. It is crucial that AuNCs have the functions of light collectors and hole conductors in heterojunctions due to the suitable energy level alignment. Under the optimized conditions of AuNCs, it is found that GaN/AuNC core–shell nanowires can significantly increase the photocurrent and responsivity of PDs, mainly resulting from the light interreflection within the heterojunctions and the effective improvement of carrier transport. Owing to the excitation-dependent emission behavior of AuNCs, the responsivity of PD with GaN/AuNC core–shell nanowire heterojunctions can be enhanced by around 330% compared with that of PD without AuNCs under visible illumination. Furthermore, GaN/AuNC hybrid nanowires with excitation-dependent fluorescence behavior can modulate the enhanced amplitude performance of broadband PDs. Owing to the high stability of AuNCs, the photocurrent of the PD with AuNCs is still quite stable after continuous operation for more than 20 000 s. Therefore, this study provides an effective method for developing new broadband PDs with high performance and low energy consumption.