Structural and optical characterization of thermally evaporated cadmium sulfide thin films

Abstract

The article reports the structural and optical properties of vacuum-evaporated cadmium sulfide (CdS) films with different thicknesses at room temperature. The structural investigations performed by means of X-ray diffraction (XRD) technique have showed that all the films have the zinc-blende structure, a face-centered cubic form with lattice constants a=b=c=5.82 Å and point group F43m. Crystallite sizes calculated from Scherrer relation are in the range of 173-345 Å. So far, because the optical parameters of the metastable cubic CdS have not been so well known, we apply spectroscopic ellipsometry to determine the thickness, optical constants and energy band gap of CdS thin film deposited by thermal evaporation onto opaque gold substrate, a perfect reflectivity and inert metal. As shown the measured spectral behavior of the optical constants and the band gap value of CdS thin film are in agreement with those obtained by the reflectance and transmittance methods. The energy band gap of CdS thin film determined from the spectral behavior of the absorption coefficient is about 2.46 eV.

Growth of CdS thin films and nanowires for flexible photoelectrochemical cells

“…It is also well known that CdS thin films have two crystalline modifications: the hexagonal (wurtzite) phase and the cubic (zincblende) phase. Both phases have peaks around 26 • (2Â) (Derin and Kantarlı, 2009;Natalia et al, 2009). Therefore, it is very difficult to differentiate the CdS peak from the XRD pattern of CdS thin films deposited onto ITO coated PET.…”

Annealing effect on structural, morphological, and optical behaviors of CBD-CdS nanostructured films for solar cells

“…The last mentioned position in 2θ corresponds to the (002) crystallographic plane of the hexagonal phase of CdS. It has been reported [4,19] that CdS can display a preferential orientation in that crystallographic plane when it is deposited by chemical bath and annealed. Additionally, it is clearly observed that the full-width at half-maximum (FWHM) of the main peak increase as a function of temperature, and is associated with the increase of the crystal size in CdS films.…”

“…CdS is an n-type semiconductor with a typical direct band gap of 2.42 eV and appropriated optical absorption in the visible region. CdS thin films can be obtained by different techniques, such as: sputtering [2], thermal evaporation [3,4], the SILAR method [5], spray pyrolysis [6,7], and chemical bath deposition [8,9]. Chemical bath deposition (CBD) is widely used for thin film deposition, because, it is a simple, economic, large scale, and viable technique.…”

Laser Crystallization of Nanostructure CdS Thin Film

“…Theabsorptioncoefficient is found to increase afterl aser irradiationo ft he thin film.T hisi sp ossiblydue to thei ncreasei ng rain size andt he decreasei nt he numbero fd efects 11 .I ti sc learly seen from theo ptical spectra that the absorption edge is reds hifted fori rradiated filmst hiss hift indicates ad ecreaseo ft he optical band gap' E g ' Optical band gapwas calculated usingthe following relation 1,12 : )withwavelength(").…”