Indium Doping Effect on Structural, Optical and Electrical Properties of Sprayed ZnO Thin Films

Abstract

In the current work, indium doped zinc oxide thin films were deposited by spray pyrolysis technique on glass substrate at 350 °C. The effect of the preparation conditions on the structural, morphological, optical and electrical properties of the films has been studied. The molar ratio of indium in the spray solution was varied from 0 to 5 at %. All the deposited films are polycrystalline with a (002) preferential orientation at low indium concentration. X-ray diffraction technique shows that the quality of the films was deteriorated when increasing indium concentration. Scanning Electron Microscopy and Atomic Force microscopy were performed to examine the surface morphology of the films. The deposited films showed an average optical transmittance around 85 % in the visible region; meanwhile the band gap value was varied between 3.13 and 3.25 eV. Hall Effect measurements revealed that the indium doping induces an increase in the electron concentrations, making the films heavily n type. A lowest resistivity (0.3 W cm), compared to that of the undoped ZnO (66 W cm), is obtained for the film doped with 3 % of indium.

Keywords

• ZnO
• TCO
• Spray Pyrolysis
• Thin films
• Characterization.