Self-Powered ZTO/ZnO Nanowire-Based Photodetectors with Ultrahigh Photosensitivity for Advanced UV Sensing

High-performance photodetectors are crucial to developing cutting-edge technologies in many disciplines, such as medicine, optical communication, display and imaging, military, environmental monitoring, security checks, scientific research, and industrial process control. Field-effect phototransistors (FETs) using an amorphous oxide semiconductor, zinc–tin oxide (ZTO), show great potential as next-generation photodetectors. Regrettably, typical ZTO-based FETs have drawbacks preventing their widespread adoption in commercial applications, including reduced photosensitivity, slow reaction time, and insufficient mechanical flexibility. Here, ZnO nanowire (NW) growth on ZTO-based FETs for a superior photosensitive self-powered photodetector was studied for the first time. Initially, the ZTO-based photodetector was illuminated under 550 μW/cm2 ultraviolet (UV) intensities, which exhibit sensitivity (responsivity) of 7.33 (0.21 AW–1) and 1.34 (0.66 AW–1) under atmosphere and vacuum environments, respectively. The excess oxygen ions in the atmosphere significantly boost photosensitivity compared to that in a vacuum environment. Furthermore, ZTO/ZnO NWs-based FETs were illuminated under 106 μW/cm2 UV intensities, thus exhibiting excellent sensitivity (responsivity) of 8.67 × 104 (160.79 AW–1) under an atmosphere environment. Moreover, our device is a promising candidate for UV detection under weak UV illumination. Additionally, the superior charge carrier transport and mobility of ZnO NWs lower the recombination rate of photogenerated charge carriers and extend the lifespan of free charge carriers in photodetectors. Highly sensitive photodetectors based on ZTO/ZnO NW transistors are expected to have critical applications in various forefront domain fields, including bio-, flexible, wearable, transparent electronics and neuromorphic synaptic applications.