A Dual-Gate InGaZnO4-Based Thin-Film Transistor for High-Sensitivity UV Detection

Abstract

UV-sensing devices have received significant recent attention for applications in areas such as human health, fire detection, and optical communication. One key factor for product commercialization is determining the optimal materials that allow for integration of excellent UV-sensing properties with compatibility with industrial fabrication processes. However, current UV sensors often fail to achieve this due to either mismatched materials or a device that must be excessively large in order to produce enough photocurrent for UV detection. The UV-light-sensing properties of an amorphous InGaZnO4 (IGZO) thin-film transistor with a dual-gate structure and relatively small device size (width/length = 50 mu m/10 mu m) that achieves high sensitivity through a threshold-voltage-(V-th)-adjustment method is proposed. Comparing the drain currents under UV exposure to those under darkened conditions indicates that the ratio between the photoinduced and dark current reaches 10(6). Furthermore, the UV sensitivity of the dual-gate transistors can be adjusted by varying the bottom gate voltage, with each pixel of the sensor then being read out separately via scan line pulses. This allows the dual-gate a-IGZO transistor to be used for high-performance UV sensing while being effectively integrated in display applications.