LSPR-driven synergistic photoelectric enhancement for broadband and self-powered photodetection in Au/InSb nanohybrids

Among heavy-metal-free III-V colloidal nanocrystals, Indium antimony (InSb) stands out as a promising candidate for constructing solution-processed broadband photodetectors (PDs) owing to its ultranarrow bandgap and exceptionally high carrier mobility. However, the high affinity of Sb element for oxygen makes InSb susceptible to native surface oxidation, a process that creates barriers to carrier transport and reduces light absorption efficiency, thereby significantly degrading the performance of InSb-based PDs. In this study, we propose a solution-based route for fabricating InSb nanowires (NWs) decorated with Au nanoparticles (NPs) to fabricate a broadband, self-driven PD. The incorporation of Au NPs significantly reduces the surface trap states introduced by surface native oxide layer and enhances the performance of the PD across the visible to near-infrared (NIR) region. Compared with bare InSb NWs PDs, the Au/InSb nanohybrid device achieves a dramatic improvement in the switching ratio, reaching approximately 300 under visible-to-NIR illumination at an intensity of 36 mW/cm 2 . The maximum responsivity and detectivity values of the Au/InSb nanohybrid PD were 100 times higher than those of bare InSb NWs. Finite-difference time-domain (FDTD) simulations were employed to analyze the spatial distribution of the electromagnetic field across Au/InSb nanohybrids. The localized surface plasmon resonance (LSPR) of Au NPs and the transfer of hot electrons were identified as key factors contributing to the observed performance enhancement. This study serves as a foundational exploration of the potential for high-performance PDs utilizing Au NPs and other narrow-band III-V materials exhibiting LSPR effects.