Studies on some structural and optical properties of ZnxCd1−xTe thin films

Abstract Five Zn x Cd 1− x Te solid solutions with x =0.1, 0.3, 0.5, 0.7 and 0.9 at.% were synthesized by fusing stoichiometric amounts of Zn, Cd and Te constituents in silica tubes. Each composition was used in the preparation of a group of thin films with different thicknesses. Structural investigation of prepared films indicates that they have polycrystalline structure of four predominant diffraction peaks corresponding to (1 1 1), (2 2 0), (3 1 1) and (3 3 1) reflecting planes. The refractive index, n , and the extinction coefficient, k , of Zn x Cd 1− x Te thin films of different compositions were determined in the spectral range, 500–2000 nm. It was found that at a certain wavelength these constants depend on the film’s structure, i.e. they are decreased with increasing the atomic percentage x . Also, plots of ( αhν ) 2 versus hν yield straight lines corresponding to direct allowed transitions. However, the band gap showed a non-linear variation with the value of x . The refractive index data were analyzed by using the Wemple–DiDomenico single oscillator fit. The effective masses of the carriers and the band gap bowing parameters of Zn x Cd 1− x Te thin films were estimated.