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

Authors: MAYSOON FAISAL ALIAS, M. N. MAKADSI, Z. M. AL-AJELI

Abstract: Various samples of Ge_{x}Se_{1 - x} system have been prepared for x = 0.05, 0.15& 0.25 in an evacuated quartz tube. Thin films of Ge_{x}Se_{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_{x}Se_{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_{x}Se_{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} \propto \omega^{s}, and which determines the transfer mechanism, decreases with increasing x and T_{a}. While the electrical a.c activation energy E_{\omega} 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 \alpha 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}.

Keywords: a.c conductivity, d.c conductivity, thin Ge_{x}Se_{1 - x} film, dielectric constant

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