Structural and optical analysis of CdS thin films grown by magnetron sputtering technique

Structural and optical characterizations were performed on CdS polycrystalline thin films grown by magnetron sputtering method. The thicknesses of the films were estimated to be 200-550 nm by scanning electron microscopy (SEM) measurements. X-ray diffraction (XRD) data show that CdS films are in the stable hexagonal crystalline structure. Using Debye-Scherrer's formula, the average grain size for the samples was found to be 40 ∼ 45 nm. X-ray photoelectron spectroscopic (XPS) experiments indicate that the CdS samples are Cd rich in the surface region and S rich in the bulk region of the film. Photoluminescence (PL) bands, including green emission band, yellow emission band, orange emission band, and red emission band, were observed at room temperature and analyzed for the CdS films. The energy gap of the samples was also estimated and discussed from the room temperature optical transmittance spectra.