Preparation and Characterization of CoevaporatedCd1−xZnxSAlloy Thin Films

Cd1-xZnxS thin films have been prepared by the vacuum coevaporation method. The structural, compositional, and optical properties of Cd1-xZnxS thin films have been investigated using X-ray diffraction, X-ray fluorescence, and optical transmittance spectra. As-deposited Cd1-xZnxS thin films are polycrystalline and show the cubic structure for x=1 and hexagonal one for x<1 with the highly preferential orientation. The composition of Cd1-xZnxS thin films determined from Vegard's law and quartz thickness monitors agrees with that determined from the X-ray fluorescence spectra. Optical absorption edge of optical transmittance for Cd1-xZnxS thin films shows a blue shift with the increase of the zinc content. The band gap for Cd1-xZnxS thin films can be tuned nonlinearly with x from about 2.38 eV for CdS to 3.74 eV for ZnS. A novel structure for CuInS2-based solar cells with a Cd0.4Zn0.6S layer is proposed in this paper