EXAFS investigation of the amorphous Ge$_{2}$Sb$_{2}$Te$_{5}$ optical memory material

Studies of amorphous (a-) semiconductors have been driven by technological advances as well as fundamental theories. Observation of electrical switching, for example, fueled early interest in a-chalcogenides. More recently a-chalcogenide switching has been applied successfully to programmable memory devices, as well as DVD technology where the quest for the discovery of better-suited materials continues. Thus, switching grants researchers today with an active arena of technological as well as fundamental study. Bond constraint theory and rigidity theory provide a powerful framework for understanding the structure and properties of a-materials. Application of these theories to switching in a-chalcogenides, combined with Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy yields the most detailed model to date of the a-Ge$_{2}$Sb$_{2}$Te$_{5}$ system.