Density of Defect States in Se90Sb10-xAgx Glassy Alloys


The present paper reports the study of density of defect states in bulk glassy alloys of Se90Sb10-xAgx (where x = 0, 2, 4, 6 and 8). Space charge limited conduction technique is used for this purpose. I-V characteristics have been measured at various fixed temperatures in the range 300 K to 380 K. An ohmic behavior is observed at low electric fields upto 102 V/cm. However, superohmic behavior is observed at high electric fields (103 - 104 V/cm). High-field conduction theory of space charge limited conduction for uniform distribution of localized states in the mobility gap fits well with the experimental data. Using this theory, the density of defect states (DOS) near Fermi level is calculated for all the glassy alloys. A maxima is observed at 4 at. % of Ag, which is explained in terms of average co-ordination number.