Application of ZnO Nanorods for a UV Photodetector

C.Y. Kung, S.L. Young, C.C. Lin, H.H. Lin, J.H. Lin, H.Z. Chen, M.C. Kao, Y.T. Shih
National Chung Hsing University, TW

Keywords: ZnO, doped, UV photodetector

Summary:

A simple solution process for the fabrication of p-type Li-doped ZnO nanorods by hydrothermal on n-type silicon was reported, and their applications in UV photodetectors were investigated. The influences of Li-doping on the microstructure, photoluminescence, and Raman scattering of ZnO nanorods were systematically investigated. From the XRD patterns, all nanowire samples exhibited a single (002) diffraction peak at about 2θ=34.5o, indicating well c-axis orientation with the same wurtzite hexagonal structure of space group P63/mc as pure ZnO film. Compared with the pure ZnO nanorods, the E2(LO) mode Raman peak intensity of ZnO:Li decreases significantly which indicates higher concentration of oxygen vacancy than that of ZnO nanorods. The PL spectra show the green-yellow emission in of Li-doped ZnO nanorods indicate higher concentration of oxygen defects than that of pure ZnO nanorods. Finally, the p-type ZnO nanorod arrays were obtained by Li doping. The characteristics of the UV photodetector with p-ZnO:Li nanorods/n-Si were also measured. The device revealed the distinct rectifying current–voltage characteristics with a turn-on voltage of 2.0 V. We obtained the photocurrent to dark current contrast ratio, 147.1 %, which illustrated the possibility for the application of photodetector.