Mechanical and electronic properties of stoichiometric silicene and germanene oxides from first-principles

Using first-principles calculations, we investigate the fully oxidized silicene and germanene with stoichiometric ratio Si:O/Ge:O = 1:1. For both compounds, the zigzag ether-like conformation (z-sSiO/z-sGeO) is found to be the most energetically favorable structure. These z-sSiO and z-sGeO nanosheets have prominent elastic characteristics, which even exhibit an unconventional auxetic behavior with negative Poisson ratios. After oxidation, the semi-metallic nanosheets are transformed into semiconductors with narrow direct band gaps. Due to the anisotropic mechanical and electronic properties, the z-sSiO and z-sGeO possess an axially high intrinsic charge mobility up to the order of 104 cm2/Vs, which is comparable to that of graphene nanoribbons. Our studies demonstrate that the silicene and germanene oxides have peculiar mechanical and electronic properties, which endow these nanostructures for potential applications in nanoelectronics and devices. ((c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)