Tunability of physical properties of (Cd:Zn)S thin filmby Close Space Sublimation Process (CSSP)

The present paper reports on a systematic study of the influence of Zn alloying on thestructural and optical properties of Cd1 xZnxS thin films. X-ray diffraction study for structuralanalysis reveals that the two binary compounds have been completely transformed into ternarycompound with hexagonal (wurtzite) structure with preferred orientation along c-direction with(002) planes. The optical properties such as optical constants and band gap energy of the films wereexamined by using spectroscopic ellipsometer and Photospectrometery. It was found that theoptical constants (n and k) decrease with the addition of Zn content in the alloy. It was alsoconfirmed that the band gap increases with increasing Zn amount in the alloy and is attributed toquantum size effect in the grain size. Raman spectroscopy analysis shows one dominant phononband at 326 cm 1, the so-called longitudinal optical (LO) mode for all the alloy composition (x).The appearance of a single phonon band in the Raman spectra established the formation of singlephase hexagonal structured Cd1 xZnxS thin film. The LO band is asymmetrically broaden and highfrequency shifted due to potential fluctuation caused by the dopant material. The AFM resultsshowed that the surface roughness was decreased with increasing Zn content.