Influence of Oxygen Adsorption on Local N-Doped TiO2/p-Si (100) Heterojunction UV-Visible Photodetector

TiO2-based devices are known for their responsive behavior to environmental conditions. In this study, we report the fabrication of a locally N-doped TiO2/p-Si (100) heterojunction UV-vis photodetector, achieved through a series of processes including magnetron sputtering, high-temperature annealing, hydrothermal synthesis, and thermal evaporation. Due to surface oxygen adsorption and partial nitrogen doping in TiO2, the photocurrent of the device was found to be higher in vacuum than in air at low voltage, and lower in vacuum than in air at higher voltage. Moreover, the photocurrent was more likely to reach saturation under vacuum at low voltage. Under UV light illumination (380 nm), the voltage applied to the device to reach the saturation currents in vacuum and air were approximately −1 V and −1.5 V, respectively, and these values increased slightly when illuminated by visible light (480 nm). The study of the impact of oxygen adsorption and partial N doping in TiO2 on the hindrance and multiplier effects of carrier movement in photodetectors can be beneficial for the development and application of wearable, biosensing, and vacuum sensing devices.