High field conduction studies in a-Se80-xTe20Sbx thin films in dark as well as in presence of light

Glassy alloys of Se80-xTe20Sbx (x=0; 5) were prepared by the quenching technique. Amorphous thin films of these alloys are prepared by the vacuum evaporation technique. Current-voltage (I-V) characteristics have been studied at various temperatures in dark as well as in presence of light. For this purpose, a dc voltage (0-300 V) is applied across the film. I-V characteristics show that, at low electric fields, an ohmic behaviour is observed. However, at high electric fields (Esimilar to10(4) V/cm), the current becomes super ohmic. Analysis of the data shows the absence of space charge limited currents in a-Se(80-x)Te2(0)Sb(x) thin films as In I/V vs V curves are not found to be straight lines with good correlation coefficient. Instead, In I vs V-1/2 curves are found to be straight lines having good correlation coefficient. The slope of these curves decreases with the increase in temperature. A more detailed analysis shows that the dominated mechanism of the conduction is of Poole-Frenkel type in dark as well as in presence of light.