Abstract
Thin amorphous films of Cu-x(Ge3Se7)(100-x) (0 <= x <= 12 at. %) were prepared on glass substrates by the thermal evaporation method. The dc electrical resistivity (rho(dc)) and current-voltage (I-V) characteristics were measured within the temperature range from 190 to 420 K for the prepared films. For x < 6 at. %, the electrical conductivity (sigma(dc)) shows three temperature regimes arise from three different conduction mechanisms, while for x = 9 and 12 at. %, only two distinct regimes were observed. The Fermi energy (E-f) and the charged carriers' mobility (mu(o)) of the studied thin films were estimated. The variation of current density (J) as a function of electric field (E) indicating Ohmic behavior for low applied electric field (E < 2.4 x 10(5) V/cm). Above such electric field (at higher voltage V > 12 V), a space charge limited conduction (SCLC) occurs. By fitting the experimental data according to the SCLC, the density of localized states (DOS) close to Fermi level was estimated. The increasing of the DOS with an increase of the Cu content can be ascribed to increasing the defect states.