The influence of Ge content and annealing temperature on the d.c and a.c conductivity of $Ge_xSe_{1-x}$ thin films

Özet

Various samples of $Ge_xSe_{1 - x}$ system have been prepared for x = 0.05, 0.15& 0.25 in an evacuated quartz tube. Thin films of $Ge_xSe_{1 - x}$ film have been prepared via a thermal evaporation method with 350 $\pm$ 5 nm thickness and rate deposition 6 nm/s. The alloy structure and thin films have been examined by X-ray diffraction (XRD). Atomic absorption spectroscopy (AAS) was used to examine the concentration of the composite elements (Ge and Se). The d.c and a.c conductivity of $Ge_xSe_{1 - x}$ thin film have been studied as a function of Ge content x and annealing temperature within the range 303--448 K. Our results showed that the dc conductivity $\sigma$ of thin $Ge_xSe_{1-x}$ films increases with increasing Ge content and decreases with increasing annealing temperature $T_a$. Electrical activation energy $E_a$ decreases with increasing x values and increases with increasing annealing temperature. The a.c conductivity increases with increasing x values. The exponent s in the relation $\sigma$a.c $\prompto$ $\omega^s$, and which determines the transfer mechanism, decreases with increasing x and Ta. While the electrical a.c activation energy $E_w$ increases with increasing x and $T_a$ and at frequencies f = $10^2$, $10^3$ and $10^5$ Hz. The relaxation time $\tau$ and polarizibility a have been measured from the cole-cole plot for x = 0.05 at $T_a$ = 303, 398 and 448 K, with the finding that the relaxation time and polarizibility decreased with increasing $T_a$.