Local structure of amorphous and crystalline Ge2Sb2Te5 films

Abstract

An effective way to examine structural rearrangement in solids is Mössbauer spectroscopy. A key requirement to Mössbauer probes used for these purposes is the possibility of their localization in a certain site of the crystal lattice or in the structural network of the amorphous material. When absorption spectroscopy is used to examine the local structure of crystalline and amorphous Ge2Sb2Te5 films, this requirement is satisfied for 119Sn isotope. Tin atoms 119Sn isovalently substitute germanium atoms in the structure of both vitreous and crystalline germanium tellurides. The absorption Mössbauer spectroscopy on 119Sn impurity centers shows that germanium atoms in the structure of amorphous and polycrystalline Ge2Sb2Te5 films have different local symmetries (tetrahedral in the amorphous phase and octahedral in the crystalline).