Planar microcrystalline ZnO/Si heterojunction photodetector with Al electrodes

The fabrication of planar Al/ZnO/Si heterojunction photodetectors has received considerable attention. The crystalline quality of ZnO plays an important role in the properties of the fabricated device. In this study, ZnO micro-rods were grown on Si (100) without any catalysts using atmospheric pressure chemical vapor deposition, and were characterized to determine their potential for application in highly photosensitive ZnO/Si photodetectors. The ZnO rods were grown with various diameters and had a wurtzite structure oriented in the (002) plane. The effect of the substrate temperature on the crystalline structure was studied in the range of 450–750 °C. The planar structure of the Al/ZnO heterojunction photodetector indicated that the device is highly sensitive to ultraviolet and visible light. The photoresponse of the fabricated Al/ZnO device had a peak at 360 nm. The responsivity of the device reached 0.03 at a bias voltage of 1 V and reached 0.085 at a bias voltage of 5 V. The responsivity increased to 0.121 as the bias voltage increased to 10 V. The quantum efficiency of the device was 11, 32, and 42 % at bias voltages of 1, 5, and 10 V, respectively.