ZnO Nanowires Photosensitive Grid Photodetector Based on AlGaN/GaN HEMT Structure

In the conventional AlGaN/GaN high electron mobility transistor (AlGaN/GaN HEMT) photodetector with ZnO films, there are many limitations such as low light absorption efficiency, low photoelectric conversion efficiency and small photocurrent. To improve the above problems, a ZnO nanowire photosensitive gate photodetector based on AlGaN/GaN HEMT structure was proposed and successfully fabricated in this experiment.First, ZnO nanowires were successfully prepared on Si substrates and AlGaN/GaN high electron mobility transistor(HEMT) substrate materials by hydrothermal method. A series of tests were carried out by using X-ray diffractometer, scanning electron microscope (SEM), photo luminescence (PL) Spectrum and other instruments. It is found that the ZnO nanowires grown on the AlGaN/GaN HEMT substrate material has lower defect density, better crystallinity and better optoelectronic properties. Then, the ZnO nanowires were successfully integrated into the gate of the AlGaN/GaN HEMT device, and an AlGaN/GaN HEMT ultraviolet photodetector with a ZnO nanowire photosensitive gate was fabricated. Comparing the AlGaN/GaN HEMT device with ZnO nanowire photosensitive gate prepared in the experiment with the conventional AlGaN/GaN HEMT device, it is found that the device with ZnO nanowire can reach a peak value of 1.15×10⁴ A/W in the ultraviolet band. The responsivity is about 2.85 times higher than that of the conventional AlGaN/GaN HEMT. The response time and recovery time of the prepared ZnO nanowire device are shortened to τ_r=10 ms and τ_f=250 ms, which significantly improves the performance of the detector.