Investigation of DC conductivity and switching phenomenon of Se80Te20−xGex amorphous system

Se80Te20−xGex (x = 5, 7 and 10 at%) chalcogenide glass system was prepared by the conventional melt-quenching technique. Thin films of different thicknesses (283-823 nm) were prepared by thermal evaporation technique. The DC conductivity and switching properties were investigated in the temperature range 303-373 K below the corresponding glass transition temperature. The obtained results of DC conductivity showed that it decreases with decreasing Te content in the considered system, while it increases with temperature as well as with film thickness through the studied range. The conduction activation energy has two values Eσ1 and Eσ2 indicating the presence of two different conduction mechanisms through the studied range of temperature. The obtained results of the temperature dependence of DC conductivity are explained in accordance with Mott and Davis model. The switching effect in amorphous films was also investigated. The switching phenomenon for these compositions was of the memory type. The mean value of the threshold voltage V¯th increases linearly with increasing film thickness in the range 283-823 mm, while it decreases exponentially with increasing temperature in the investigated range. Values of the threshold voltage and power activation energies were obtained for the investigated compositions. The obtained results agree with the electrothermal model for the switching process.