Fabrication of Fast-response Ultraviolet Light Sensors with LZO Thin Films using Sol-gel Spin-coating Method

The Li-doped ZnO (LZO) thin films with various Li concentrations (0, 1, 3, 5, 7, and 9 at.%) were deposited on quartz substrates by sol-gel spin-coating method. The effects of Li doping on the structural and optical properties of the thin films were investigated. Undoped ZnO thin film and LZO thin films had three different diffraction peaks at 31.5 °, 34.2 °, and 36.0 °corresponding to the ZnO (100), (002), and (101) planes, respectively. The c -axis orientation of the LZO thin films increased with increasing Li doping concentration, owing to the high diffusivity of the Li dopant. A broad red emission was observed by photoluminescence of the undoped ZnO thin film, whereas LZO thin films had broad green emissions. The transmittance and optical band gap blue-shifted with increasing Li doping concentration. In terms of photoresponse, all LZO thin films had greater rise and decay rates than the undoped ZnO thin film and the photosensitivity increased with increasing Li doping concentration.