Correlation between the density of defect states (DDS) and cross-linking of corner/edge sharing GeSe4 tetrahedral
Shiv Kumar Pal1, A Dahshan2, Neeraj Mehta1
1Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
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.
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