Classification of hydrides according to features of band structure

Abstract

Band structure of hydrides has been studied by density functional calculations. From analysis of band structures, it is found that, similar to semiconductors, some hydrides possess open fundamental band gap, and can be classified according to the following three characteristic features. The first is based on the value of the fundamental band gap and, therefore, the hydrides have been classified as narrow or wide band gap materials. The second feature is based on a comparison of the relative location in k space of the bottommost conduction band and topmost valence band (VB). Thus, hydrides can be classified as either direct or indirect band gap materials. The third feature is based on the origin of the topmost valence band and depends on the dominant contribution of s-, p-, and d-electrons to the topmost VB. According to this criterion, hydrides can be classified as type s, p, d or hybridised materials. This classification will be useful in the application of hydrides for the construction and processing of electronic devices within the framework of the recent innovations in ‘hydride electronics’.