EXAFS study of Sb-Te alloy films.

The local structures of three phases; stable compound Sb2Te3, metastable crystalline c-SbTe and amorphous a-SbTe films having the atomic ratio Sb/Te=3: in Sb-Te system have been studied by EXAFS. The c-SbTe has a partly similar local structure to crystalline Sb2Te3. The a-SbTe film has a local structure of NaCl-type, which is topologically analogous to the crystalline form. The amorphous phase has shorter bond distances 2.86A (around Sb-site) and 2.83A (around Te-site) than the corresponding distances 2.89A and 2.87A in the crystalline phase. This unbalanced bond distances between the Sb-site and Te-site implies that site-disordering occurs. Shortening of bond distances in the amorphous phase is due to the relaxation of locally distorted crystalline structure.