Preparation And Optimization Of Photosensitive Gate Gan-Based High Electron Mobility Transistor Devices

Based on the gate controlled characteristics of GaN High Electron Mobility Transistors (HEMTs) and on the photovoltaic effect in lead zirconate-titanate(PZT) ferroelectric thin films, a new type of photosensitive layer/HEMT detector structure is proposed. For this purpose, a PZT ferroelectric thin film is deposited on the gate of a HEMT device to prepare films with optimized photovoltaic performance, the surface morphology and ferroelectric properties of PZT films prepared by different sputtering powers and annealing temperatures are analyzed. It is found that the best conditions for the grain growth on the surface of the film are at 200 W sputtering power and 700 degrees C annealing temperature, and the residual polarization intensity is 38.0 mu C.cm(2). The output characteristics of the fabricated photosensitive gate PZT/GaN-based HEMT devices are compared to those of pristine HEMTs under both dark condition and 365 nm ultraviolet light. The results show that the source drain saturation voltage of the HEMT with the ferroelectric thin film decreases by 3.55 V and the saturation current increases by 5.84 mA, compared with those without light, clearly indicating a significant UV photodetection capability. To achieve the purpose of optimizing the structure of the new type of detector, detectors with different grid lengths such as 1 mu m, 2 mu m, and 3 mu m are tested. The results show that under ultraviolet light, the drain saturation currents of the three detectors are 23 mA, 20 mA, and 17 mA, respectively. Therefore, the longer the gate length, the smaller the saturation current of the device, and the worse the detection performance.