A method to quantify the degree of uniformity of thickness of thin films

A method for determining the uniformity of as-deposited thin films is presented. Thin films were deposited by electrostatic spray deposition from a water-alcohol based solution. This coating method relies on the application of an electric field to generate an aerosol which subsequently undergoes electrostatic attraction to a high temperature substrate. Semi-transparent chalcopyrite films produced in this way were illuminated by a light box and images subsequently captured by a digital camera were employed in a simple test to quantify the uniformity of the samples. The effect of experimental parameters, such as voltage, precursor solution flow rate and needle-substrate distance were studied with this test. The effect of each parameter has been analysed in order to optimize the uniformity of the deposited films. The results show that this simple and rapid method is capable of quantifying the degree of uniformity using a simple image analysis process. (C) 2008 Elsevier B.V. All rights reserved.