Preparation, characterisation and photocurrent study of sol-gel-derived Al, Mg-doped ZnO transparent thin films

In this work, sol-gel spin-coating was employed to prepare ZnO, Al-doped ZnO (AZO) and Mg-doped ZnO (MZO) thin films onto glass substrates. Structural properties and surface morphologies of as-prepared films were characterised by X-ray diffraction (XRD) and scanning electron microscope (SEM) while their optical properties were scrutinised from their transmission spectra measured by UV-VIS spectrophotometer. Their optical responses and sensitivity of the films were investigated by photocurrent spectroscopy. The XRD and SEM results show that the crystallinity and physical structure of as-prepared films are highly affected by Al and Mg doping. UV-VIS spectrophotometer results suggest that Mg and Al dopants could not only improve their optical transparency but also significantly cause the blue-shift in optical band gap of ZnO films. In addition, the enhancement in photosensitivity of ZnO films can be attained by specific Al and Mg doping content.