Structural and Surface Studies of Vacuum Evaporated Cadmium Telluride Thin Films

Abstract

Cadmium Telluride (CdTe) is one of the most well established II–VI compounds largely due to its use as a photonic material. Existing applications, as well as those under consideration, are increasingly demanding stringent control of the material properties. The deposition of high quality thin films is of the utmost importance to such applications. This tendency has also manifested itself in the structural and surface morphology with higher structural perfection yielding smoother surfaces. The present investigations are about the structural and surface characterization of CdTe thin films. Thin films of CdTe with thickness around 4000A have been deposited by the thermal evaporation method at room temperature. The structural characterization of this film was carried out using XRD (X-ray diffraction technique) and TEM (Transmission electron microscopy). The structure of CdTe film was found to be hexagonal. Also, the lattice parameters, grain size (D), dislocation density (ρ) and micro strain (e), were taken from the XRD data. From TEM of CdTe thin films, the polycrystalline nature was confirmed. A surface morphology study was done by SEM (Scanning electron microscopy) technique. Atomic Force Microscopy (AFM) provides numerical data of surface height at digitized locations, which are usable for various surface characterizations. In this paper, the results have been analyzed to draw some conclusions which are also presented here.