Structural modification of Ge–Se amorphous films with the addition of Sb

Extended X-ray absorption fine-structure (EXAFS) measurements were undertaken to understand the structural modification of amorphous Ge–Se films that occurs with the addition of Sb. We found that Ge–Ge bonds exist along with Ge–Se bonds in Ge-rich Ge–Se films. These bonds disappear with increasing Se content, to the extent that Ge–Se bonds predominate in stoichiometric GeSe₂ films. When Ge is replaced by Sb, stable Sb–Se bonds are formed; concurrently, the proportion of Ge–Ge bonds is decreased at the expense of Ge–Se bonds. As a result, GeSbSe glasses have a more stable and stronger network structure.     

Estimation of density of charged defects in amorphous chalcogenides from a.c. conductivity: Random-walk approach for bipolarons based on correlated barrier hopping

Abstract

Although the pair approximation (PA) based on correlated bamer hopping (CBH) is now fairly well established to explain the a.c. conductivity of amorphous chalcogenides, the density of charged states deduced from PA is large compared with those estimated from other studies, namely light-induced electron spin resonance and drift mobility. We have used the continuous-time random-walk approximation based on CBH to estimate the density of charged defects and have applied it to experimental data for amorphous As₂Se₃, and a density of charged defects consistent with other measurements has been estimated.