Preparation and characterization of indium and gallium doped transparent ZnO films for solar cell applications

Abstract

In this work, the effect of indium (In) and gallium (Ga) dopants on the structural, optical and electrical properties of ZnO thin films was studied. ZnO thin films were deposited on glass substrates at 400°C using the spray pyrolysis deposition technique. X-ray diffraction (XRD) results indicated that both undoped and doped ZnO films had (002) preferred orientation. The undoped ZnO films were found to exhibit high transmittance above 80%, while indium-doped (In:ZnO) and gallium-doped (Ga:ZnO) films had transmittance above 60% and 70% respectively. From the Hall Effect measurements, doping improved the conductivity of the ZnO thin films however, In:ZnO films showed higher electrical conductivity compared to Ga:ZnO films. Electron probe microanalysis (EPMA) results were used to confirm the presence of the respective dopants in the thin film samples.