Stability, bonding, and electronic properties of silicon and germanium arsenides

First-principles calculations were carried out to study the stability, structural, and electronic properties of compounds of silicon arsenides (SiAs and SiAs2) and germanium arsenides (GeAs and GeAs2). The group IV atom (Si or Ge atom) is four-coordinated and the As atom is three-coordinated in both monoclinic and orthorhombic structures, which are energetically favored based on the calculated formation enthalpies for Si/Ge monoarsenides and diarsenides, respectively. The calculated Si-As bond lengths are slightly smaller than the Ge-As bond lengths. In agreement with the experimental results, our calculations show both silicon arsenides and germanium arsenides are semiconductors. The calculated bandgaps of germanium arsenides are slightly smaller than those of silicon arsenides, which may be related to the lower ionicity of the Ge-As bonds in germaniumarsenides. The calculated density of states (DOS) of As atoms in the four compounds are somewhat different from each other indicating the difference of their local atomic environments. The calculations show that Si/Ge arsenides with Si/Ge vacancies are metals, which may be due to the unsaturated As atoms near the vacancy sites. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim