Electronic Structures of Crystalline and Amorphous Silicon Dioxide and Related Materials

Abstract

In spite of considerable amount of research work done on the structures and properties of silicon dioxide, both experimentally and theoretically, in the last fifteen years [1–3], our understanding about this remarkable material in both crystalline and amorphous forms is still far from complete. Thus, there is still no consensus with regards to the structures of amorphous SiO₂ (a-SiO₂). Continuous random network (CRN) model [4], mixture of macrocrystalline model [5] and model of aggregation of large clusters [6] with internal surfaces, all have their respective supporters. Unlike semiconductors, the measured value of the band gap in SiO₂ has not yet been fully settled [1,7] and the interpretation of various spectroscopic data remains controversial [1,7]. One of the key elements in advancing further understanding about the structure and bonding of SiO₂ is the detailed knowledge of the electronic structures of various forms of SiO₂ and their dependence on the atomic scale structures. Early theoretical work on SiO₂ concentrated on studying molecular fragments [9–13]. Empirical methods have been used to study the electronic structure of bulk materials [14–17].