High Performance UV-B Photodetector Based on Highly (200)-Oriented SnO₂ Film With a Hydrophobic PTFE Passivation Layer

The detection and characterization of ultraviolet-B (UV-B) light are critical for industrial applications and human activities. We report on an UV-B photodetector composed of a SnO
₂
film and a polytetrafluoroethylene (PTFE) cap layer, fabricated by radio frequency (RF) magnetron sputtering method. Benefiting from the small lattice mismatch, highly (200)-oriented SnO
₂
thin film was prepared on a (0001) c-plane sapphire substrate. UV-B photodetector with metal-semiconductor-metal structure was fabricated based on the SnO
₂
film. A highly transparent hydrophobic PTFE cap layer was sputtered on the device as a passivation layer to minimize the influence of atmosphere. Compared to the device without the PTFE cap layer, the device exhibits improved photosensitivity, speed, and environmental stability. At an applied voltage of 5 V, the typical SnO
₂
UV-B photodetector exhibits a peak response at 290 nm, an on/off ratio of around 100 and a response time of less than 1 s. The highly transparent hydrophobic PTFE has ideal passivation property, which can act as the self-clean coating for various electronic devices, such as LEDs, transistors, solar cells.