Pnictide and chalcogenide semiconductors

Amorphous pnictide and chalcogenide semiconductors (As, Se, As2Se3, Ge2Sb2Te5 etc., see the diagram and Library) exhibit significant photo- and current-induced changes whose nature is not well understood thus limiting the potential applications of the phenomenon (see for example phase-change memory).


It is generally believed that light-induced changes are intimately related to midgap electronic states localized on coordination defects and their pairs. In a series of papers we propose a novel approach for the description of the midgap states by taking into account the secondary bonding which is argued to be significant in pnictides and chalcogenides and results in the coordination defects linearly extended over several front and back bonds. Front-back bond switching makes the defects mobile which is the underlying mechanism of photo- and current-induced structural changes.