Preparation of Al-doped ZnO (AZO) Thin Film by SILAR

Abstract

Aluminum doped zinc oxide (AZO) thin film was deposited on microscopic glass substrate following a chemical technique called successive ion layer adsorption and reaction (SILAR). The technique involves multiple dipping of the substrate in an aqueous solution of sodium zincate kept at room temperature and deionized water kept near boiling point. Al doping was found to increase the film growth rate. It was approximately 0.20 μm/mole/dipping for ZnO film and 0.22 μm/mole/dipping for AZO film. Structural characterization by X-ray diffraction (XRD) technique confirmed incorporation of aluminum in ZnO lattice. The c-axis orientation was significantly enhanced due to Al incorporation which was revealed from marked increase of (002) peak intensity compared to other peaks of hexagonal ZnO. The cross sectional view in SEM (Scanning electron micrograph) also reveals growth of large crystallites perpendicular to the substrate. The resistance of the film decreased about one order in magnitude due to Al doping. The activation barrier value of 0.31 eV for ZnO film was however found to be unaffected due to aluminum incorporation.