Low-power UV photodetection characteristics of ZnO tetrapods grown on catalyst-free glass substrate

We report the catalyst-free growth of various morphologies of three-dimensional ZnO tetrapods on glass substrate by thermal evaporation of Zn powder in the presence of O2 gas. In this study, controllable synthesis of tetrapods was achieved through two independent temperature regions: 650-425 °C and 750-475 °C. The effects of the growth temperature on the structural, morphological, and optical properties of tetrapods were systematically studied using field emission scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy, and photoluminescence spectroscopy. In the presence of junctions (needle-wire junctions), the optimal sample of ZnO tetrapods-based metal-semiconductor-metal UV detector was fabricated. Upon exposure to 365 nm light (0.22 mW/cm2) at five-bias voltage, the device exhibited a high sensitivity of 15.22 × 103 with a low dark current. In addition, the internal photoconductive gain was 153.2, and the photoresponse peak was 917 mA/W. Furthermore, the response and recovery times were 1.1 and 0.59 s, respectively. This new approach provides a cost effective substrate and simple method to control the synthesis of tetrapods and demonstrates the possibility of constructing nanoscale photodetectors for nano-optics applications.