Effect of Mg concentration on morphological, structural and optical properties of Mg-K co-doped ZnO thin films prepared by sol-gel method

ZnO, K-doped ZnO (KZO) and (Mg, K) co-doped ZnO (MKZO) thin films have been prepared using sol-gel method and the morphological, structural and optical properties have been investigated by SEM, XRD, transmission spectra and PL spectra. All the films have a preferential c-axis orientation and an average transmittance of over 93% in the visible range. The optical band gap decreases by K doping, but gradually increases by Mg doping at a given K doping concentration. PL spectra show that the visible emission was enhanced, which indicates that the number of defects should be changed at Mg doping concentration of 8 mol%.