Microstructural characterization and optical properties of ZnSe thin films

Zinc Selenide (ZnSe) thin films ( d = 0.09–1.25 μm) on glass substrates were prepared by physical vapour deposition under vacuum, using the quasi-closed volume technique. X-ray diffraction (XRD) analysis indicated that the samples are polycrystalline , have a cubic (zinc blende) structure and that the crystallites are preferentially oriented with the (1 1 1) planes parallel to the substrates. The microstructure of ZnSe films examined by transmission electron microscopy (TEM), including electron diffraction (ED) and high-resolution electron microscopy (HRTEM), confirms the preferential orientation of crystallites . The HRTEM micrographs show that preferred orientation of crystallites , along (1 1 1) planes, increases if, after deposition, the samples are subjected to a heat treatment. The spectral dependences of the transmission and absorption coefficients were studied in the range 300–1400 nm. The values of the bandgap energy, E g , calculated from the absorption spectra , ranged between 2.50 eV and 2.80 eV.