Modification in the physical properties of nanocrystalline ZnO thin films by Sn/Ni co-doping for transparent conductive oxide applications

Abstract

In this paper, the modification in the physical properties of spin-coated ZnO thin films upon Sn/Ni co-doping has been presented. All the films possess the hexagonal wurtzite structure of ZnO with varying surface morphologies. Among all the films, the optical transmittance beyond 550 nm wavelength is maximum for the 1 at% Ni-doped ZnO (1NZO) and (1 at% Sn + 1 at% Ni) co-doped ZnO (1T1NZO) films. The optical band gap for the pristine ZnO film is 3.26 eV, which decreases upon doping and co-doping. The PL spectra of the films exhibit the UV emission corresponding to excitonic transitions and the blue and green emissions related to native defects in the ZnO structure. The room-temperature electrical conductivity is found maximum in the 1T1NZO film. The existence of 1T1NZO film with improved optical transmittance and high electrical conductivity supports its use in transparent conductive oxide applications.