Influence of Thermal Process on Physical Properties of ZnO Films Prepared by Spray Pyrolysis

ZnO films were deposited on glass substrates by ultrasonic spray pyrolysis technique at a substrate temperature of 300 +/- 5 degrees C. All of the films have been annealed at 500 degrees C temperature for different time (1, 2, and 3 h) to improve the optical, electrical and surface properties. The effect of annealing time on the films of physical properties has been investigated. UV-Vis spectrophotometer has been used for transmittance measurements. Also, band gap values of the films have been determined by optical method. Atomic force microscopy has been used to have information the surface morphology and roughness values of the films. Thicknesses, refractive index and extinction coefficient values of the films have been determined by spectroscopic ellipsometry technique. The electrical conduction mechanisms and resistivity of the films were investigated using two probe technique. After all the investigations it was concluded that annealing time has a dramatic effect especially on the surface, optical properties and electrical resistivity values of ZnO films. From the results of these investigations, the application potential of the films for solar cell devices as transparent electrode was searched.