Synthesis of ZnO Ultra-Thin Film-Based Bottom-Gate Phototransistors for UV Detection

The present study illustrates the fabrication of ZnO ultra-thin film (25 nm)-based bottom gate phototransistors using RF sputtering and thermal evaporation on SiO2/Si substrate for UV detection. According to the literature, phototransistors have the ability to solve persistent photoconductivity (PPC). PPC increases the response time of metal oxide semiconductor-based conventional two-terminal photodetectors. Prior to transistor fabrication, the surface of the deposited ZnO thin film was treated with hydrogen peroxide (H2O2) in order to improve its crystal structure, surface morphology, energy bandgap, and electrical conductivity. The characteristics of ZnO thin film were investigated by atomic force microscope (AFM), field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), photoluminescence (PL), and x-ray photoelectron spectroscopy (XPS). The electrical and optical performance of phototransistors were investigated by measuring their output and transfer characteristics in dark and UV light. H2O2 treatment was found to be effective in producing efficient optical detection phototransistor. Optoelectronics properties (for UV detection) of the fabricated phototransistors were studied by using low-intensity and low power commercial LEDs of 365 nm wavelength.