Composition dependence study of thermally evaporated nanocrystalline ZnTe thin films

Composition dependent structural and morphological study of nanocrystalline Zn_xTe_100−x (0, 5, 20, 30, 40, 50) thin films has been performed. The effect of annealing on these properties is also investigated. Nanocrystalline alloys and thin films of ZnTe were prepared using conventional melt quenching technique and thermal evaporation technique, respectively. The prepared thin films were characterized using Field emission scanning electron microscope (FE-SEM), Atomic force microscope (AFM) and Raman spectroscopy. FE-SEM images show that thin films consist of spherical, compact, densely packed and well-connected grains without any cracks, pitfalls, voids or pinholes. 2-D and 3-D AFM images show grain growth with increasing annealing temperature with improvement in crystallinity and average roughness. Raman Spectra show only Te peaks related to A₁ and E² mode, for x = 0. With addition of Zn, ZnTe peaks arises and the presence of 1LO, 2LO and 3LO ZnTe modes are observed. Only ZnTe peaks are observed at x = 50, with diminishing of Te peaks. Annealing effect on Raman spectra and dark conductivity is also reported.