Characterization and photocurrent study of Al, Mg-doped ZnO transparent thin films prepared by sol-gel route

In this work, ZnO, Al-doped ZnO (AZO) and Mg-doped ZnO (MZO) thin films were deposited onto glass substrates by sol-gel spin-coating method. The doping composition was varied from 0-10 at.%. Structural properties and surface morphologies of as-prepared films were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical properties of the films were interpreted from their transmission spectra using UV-VIS spectrophotometer. The photocurrent spectroscopy was employed to study their optical response and sensitivity of the films. The XRD and SEM results disclosed that the crystallinity and grain size of as-prepared films were strongly influenced by Al and Mg doping. UV-VIS spectrophotometer results indicated that Mg and Al additives could not only efficiently improve the optical transparency but also obviously induce the blue-shift in optical band gap of ZnO films. The photocurrents of as-prepared films disclosed that the enhancement in photosensitivity of ZnO films can be achieved by specific content of either Al or Mg additives.