Structural, Morphological, and Optical Studies on Li-doped ZnO Thin Films Deposited by Using PLD

We report the structural and the optical properties of Zn(1-x)Li(x)O (x = 0.0, 0.02, 0.08, 0.12, 0.18) nanocrystalline thin films deposited on alpha-Al(2)O(3) substrates by using pulsed laser deposition. X-ray diffraction (XRD) analysis revealed that all the films were single phase and had a hexagonal wurtzite structure. The lattice constant increased gradually with increasing Li content. Atomic force microscopy (AFM) showed that the grain size of the films was approximately 20 - 30 nm. Optical absorption studies in the wavelength range 200 - 900 nm revealed an increase in the band gap of the Li-doped ZnO films from 3.19 to 3.41 eV. Photoluminescence (PL) spectroscopy of these films was carried out. The luminescence observed was attributed to defects in the nanocrystalline Li-doped ZnO films, and the PL intensity decreased with increasing Li content.