Growth of CaS thin films by solid source metalorganic chemical vapor deposition

Abstract

Using the solid source metalorganic chemical vapor deposition (MOCVD) technique, we were able to grow high quality CaS films on glass substrates with Ca(tmhd)2 and butanethiol as precursors at a reactor pressure of 76 Torr. The layers were colorless and at lower growth rates clear and specular reflective. At higher growth rates, the polycristalline nature of the layers became more obvious and the surface roughness increased. By means of X-ray photoelectron spectroscopy (XPS), no incorporation of carbon or oxygen could be detected. The temperature dependence of the growth rate showed a kinetically limited growth region up to about 500°C, followed by a temperature independent region indicating mass transport limitation. In both regions, the growth rate was dependent on the partial pressures of the Ca- and the S-precursor as well.