Structural and optical investigation of electrosynthesized ZnxCd1-xSe thin films

Thin films of ZnxCd1-xSe were electrodeposited from an acidic aqueous solution of selenite (SeO2) and Cd-/Zn-sulphates. The film composition was determined by x-ray diffraction (XRD) and energy dispersive x-ray (SEM/EDX) spectroscopy. In addition, the structural and optical film properties were studied by micro-Raman spectroscopy at room temperature. The Raman spectra were fitted with the modified random element isodisplacement model including interactions to first and second neighbour atoms. It is shown that the dependence of the Raman phonon modes on the molar fraction x can be described in terms of an intermediate-mode behaviour. The results of both the XRD and Raman techniques are in good agreement for most of the prepared films. Deviations were observed for small fractions x due to the presence of an excessive CdSe phase. The dependence of the band-gap energy of the ternary system on the molar fraction is discussed in the light of photoelectrochemical measurements as well as considerations within the virtual crystal approximation.