Influence of surface oxide layers on the performance of photoconductive detectors based on silicon wafers

Abstract Photoconductive detectors based on silicon wafers exhibit great potential in actual applications due to their simple structure and mature preparation process. In actual use, a surface protective coating and covering layer will always form on the surface of the device, which can affect the photodetection performance. In this paper, single CuO and Fe 2 O 3 layers were first prepared on the surface of a photoconductive detector based on a silicon wafer. The results demonstrate that the CuO and Fe 2 O 3 layers both improve the responsivity of the detector. The maximum responsivity can reach 286 mA W −1 at 515 nm for the device covered by the CuO layer. The heterojunction formed between the oxide layer and silicon wafer is the main reason for the improved performance. After inserting SiO 2 as a dielectric layer, the SiO 2 /CuO layer covered device exhibited weak photoresponse characteristics, while the SiO 2 /Fe 2 O 3 layer covered device still showed enhanced performance in the UV and visible light regions. The maximum responsivity of the SiO 2 /Fe 2 O 3 layer covered device was 61 mA W −1 at 515 nm, which is higher than that of the original detector based on silicon wafer (4.37 mA W −1 at 515 nm). The capacitor effect formed on both sides of the SiO 2 layer is the main reason for this phenomenon. These results provide a data foundation for the research and development of photodetectors based on silicon wafers and new insights for the design and construct of devices.