Effect of Sb impurity on the photoelectrical properties of a-Se

Composition dependence of steady state photoconductivity shows that photo conductivity as well as photosensitivity have a discontinuity at 2 and 8 at.% of Sb. A discontinuity in various photoelectrical parameters at 2 and 8 at.% of Sb, is related to the formation of mechanically stabilized structure at a particular average coordination number 2.02. Another argument suggests that the weaker homo-polar bonds break and energetically favored hetero-polar bonds are formed. This suggests the possibility of a local formation of Se3Sb2 molecular structure at low percentage of Sb.