Structural Metastability in Chalcogenide Semiconductors: The Role of Chemical Bonding

Abstract

This article reviews metastability in three different classes of chalcogenides-chalcogenide glasses, phase-change alloys, and transition-metal dichalcogenides-with the focus on the relationship between structural metastability and the nature of chemical bonding. While the presence of lone-pair electrons in chalcogenide glasses enables a variety of bond switching processes, the existence of resonant (metavalent) bonding in phase-change alloys is key to the transformation between the crystalline and amorphous states. Strong covalent bonds in 2D transition-metal dichalcogenides limit the transformation to slides and buckling of atomic planes without major bond rupture. It is proposed that combining different kinds of local bonding may be an efficient way to engineer amorphous chalcogenides with desired properties.