Effect of Cu ratios dopant on ZnSe thin films structural and optical properties

This study focused to prepare poly-crystalline (ZnSe)(1-x) Cu-x thin films, where x values vary from 0 to 0.1 %. the effect of Cu ratios dopant on structural, phases and optical properties has been investigated. As prepared thin films were deposited onto a cleaning glass substrate under high vacuum conditions (10(-7) mbr) at room temperature using the "evaporation technique". The analysis results according to data of the X-ray diffraction technique of all films refer to the growth polycrystalline with hexagonal wurtzite structure of Zn-Se with no presence of any further phases. The changes in numerous parameters such as volume of the unit cell, atomic packing factor, dislocation density, lattice constant and bond length with the Cu ratio were estimated and described. As well, the crystallite sizes,D, the lattice micro-strain,epsilon and dislocation density,delta have been calculated the results evidence that the micro-structural parameters enhancement with increment Cu atoms. On the other hand, the optical parameters of the as-synthesized films (ZnSe)(1-x)Cu-x (0 <= x <= 0.1) were performed utilizing "UV-V is spectro-photometer" with a wavelength range of 300 to 2400 nm. The results show that as the Cu ratio increases, the absorption edge shifts to a higher wavelength and the optical band gap, E-g(opt) decreases from 2.63 eV to 2.52 eV. Finally, the behaviour of the optical constant parameters as real,epsilon(r)/ imaginary, epsilon(i) parts, dissipation factor,tan delta, volume/surface energy loss functions and dispersion parameters were shown to depend on the variation of the Cu ratio and wavelengths.