Correlation between the density of defect states (DDS) and cross-linking of corner/edge sharing GeSe4 tetrahedral structural units

Abstract

We have estimated the DDS in the STSG [Se78-xTe20Sn2Gex (x = 0, 2, 4, 6)] system by using the Correlated Barrier Hopping (CBH) model by performing A.C. conduction measurements in the frequency range (1 kHz–10 kHz) and temperature underneath the glass transition temperature (303–333) K. The detailed analysis reveals that bi-polaron hopping is a leading conduction mechanism over single-polaron hopping. Further, there is a noticeable reduction in DDS with increasing concentration of Ge beyond the composition x = 2. A close inspection indicates that cross-linking of Se with Ge has an important role in controlling the DDS in terms of the corner/edge sharing configurations in the structural unit of GeSe4 tetrahedral.

Keywords

• Amorphous materials
• Defects
• Density of defect states
• Electrical properties
• A.C. conductivity