Persistent photoconductivity in ZnO thin films grown on Si substrate by spin coating method

Photoluminescence (PL) and photoconductivity (PC) have been studied in ZnO thin films grown on Si substrates by a spin-coating method. The PL spectra of ZnO films, studied under synchrotron radiation excitation in ZnO fundamental absorption range at 10 K, show the dominant UV emission band with two maxima at 3.28 and 3.235 eV corresponding to the luminescence of localized excitons around neutral and charged donors and acceptors, respectively. The PC measurements of ZnO films were performed in the air and in a vacuum. The UV irradiation of ZnO films results in the appearance of induced photocurrent. The dependence of photocurrent value in air/vacuum atmosphere on the intensity of UV radiation was investigated