Investigation of ecximer laser-induced photoconductivity effect and structural, optical and chemical variations in ZnO thin films

In this paper Al doped ZnO (AZO) thin films with 0, 3, 6 and 12% Al molar concentration were prepared by sol-gel process on glass substrates. The deposited films were annealed at different temperatures of 300-500 ˚C for 1 h in air. X-ray diffraction (XRD) showed wurtzite crystalline structure for the films annealed above 400 ˚C. Then the films were irradiated by beams of excimer (KrF, λ=248 nm) laser. The evolution of crystal structure and surface morphology were studied using XRD and filed emission scanning electron microscope (FE-SEM). The real-time measurement of electrical conductivity during laser irradiation showed a transient or persistent photoconductivity depending on sample type. The effect of laser energy on photoconductivity was also investigated. Using photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) spectra, the laser induced photoconductivity effect was discussed.