Effect of Sb incorporation on the dark conductivity and photoconductivity of Se75In25 glassy alloy thin films

In the present paper current-voltage (I-V) characteristics have been studied at various temperatures in vacuum evaporated thin films of Se75In25−xSbx (where x=0, 5, 10 and 15) glassy alloys. Ohmic behavior is observed at low electric fields, while at high electric fields (E∼104 V/cm) current becomes superohmic. An analysis of the experimental data confirms that due to large currents dielectric breakdown occurs at high voltages which may prohibit the SCLC mechanism in Se75In25 sample. Such type of behavior is not observed when the third element Sb as an impurity is incorporated in the Se75In25 binary glassy alloy. In case of samples with 5-15 at% of Sb, the experimental data are found to fit well with the theory of space charge limited conduction (SCLC). Density of defect states (DOS) near Fermi-level is determined for these samples by applying the theory of an SCLC. Temperature and intensity dependence of the photoconductivity in the aforesaid glassy systems has been also examined. The variation in DOS could be correlated with the photoconductivity results obtained. The observed discontinuity at 10 at% of an Sb could be correlated with the coordination number and chemically ordered network model (CONM).