The effect of annealing on structural and optical properties of ZnO thin films grown bypulsed filtered cathodic vacuum arc deposition

Abstract

Thin ZnO films were deposited at room temperature on glass substrates by a pulsed filteredcathodic vacuum arc deposition system. The crystallographic structure and the size of thecrystallites in the films were studied by means of x-ray diffraction. These measurementsshow that all the films are crystallized in the wurtzite form, present in a preferredorientation along the (002) direction, and the grain size is estimated to be 18.9–42 nm. Thecrystallite sizes were found to increase and the x-ray diffraction patterns were sharpened byannealing. Optical properties of the ZnO films were studied using a UV–visiblespectrometer and calculations made using the envelope method. The absorptioncoefficient and optical band gap of the films were increased while the refractive indexwas decreased by annealing. The best annealing temperature for pulsed cathodicvacuum arc deposition grown ZnO thin films on glass substrates was found to be600 °C from optical properties. This temperature is as high as can be measured for glass substratessamples because of the glass properties.