Effect of Zn addition on some physical properties of Se-Te chalcogenide system

Abstract

In the present thesis, the structural, thermal kinetics, both of dc and ac electrical properties, the switching phenomenon and optical properties for Se88Te12 and Se88Te8Zn4 films have been studied and discussed. X-ray diffraction patterns (XRD) and Energy dispersive X-ray analysis (EDX) analysis have been used to check the structural nature and chemical composition of our samples. The thermal kinetics has been performed using differential thermal analysis (DTA) under non-isothermal condition at different heating rate dependence on the characteristic transition temperature has been used to determine the glass transition and crystallization activation energy. Most widely and more recently glass stability criteria are used to evaluate the effect of Zn addition of the thermal stability. The dc electric conductivity has been studied as a function temperature, film thickness and Zn addition. The ac electric conductivity and dielectric measurements include the temperature and frequency dependence for these studied films deposited into glass substrates. The electrical switching phenomenon has been studied by measuring the I-V characteristic curves for Se88Te12 and Se88Te8Zn4 films which deposited on the pyrographite substrates. Switching (voltage, resistance, power and electric field) are measured as a function of temperature, film thickness and Zn addition. the switching activation energy and the switching mechanism are also reported.

The spectral distributions of the transmittance and reflectance have been measured to calculate the optical constant for Se88Te12 and Se88Te8zn4 films at room temperature. The optical energy gap is determined and the type of electronic transitions.