Low-Voltage Ultraviolet Detectors Using ZnO Thin-Film Transistor Isolated by B Ion Implantation

We report on the fabrication of a photo-detector and a photo-inverter adopting ZnO thin-film transistors (TFTs) that have been electrically isolated by implanting B ions onto peripheral ZnO area around active ZnO channel. Our isolated ZnO-TFT exhibited a fine mobility of 0.8 cm 2 /(V·s) and on/off current ratio of ∼10 4 . Since the device also showed quite a high threshold voltage of 21 V, it was effective to be a photo-detector under a zero gate bias. When our photo-devices were composed of a ZnO-TFT and a 100 MΩ resistor, a minimum response time of ∼5 ms under 364 nm ultraviolet light was achieved, thereby dynamically showing photo-inverting and detecting behaviors.