First-principles study on structural stability and electronic properties of GaAs nanowire undergoing surface oxidization

Abstract

In this study, the structural stability and electronic properties for oxidized GaAs nanowire surfaces are systematically investigated through first-principles calculations based on density functional theory. Various oxidized nanowire surface models with two interaction types (adsorption and substitution) and different coverages of O atoms (one O, two O, three O and four O atoms) are built. The formation energy, atomic structure, Mulliken charge distribution, work function and dipole moment for each oxidized model are calculated and analyzed. The calculations indicate that the structural stability of oxidized nanowire surfaces is gradually enhanced with increasing O coverage, where O adsorption models are more energetically favorable than O substitution cases. In addition, O atoms interacting with GaAs nanowire surfaces have an obvious influence on the atomic structures near surface layer region, especially the thickness of the first bilayer. Moreover, the incorporation of O atoms leads to the redistribution of surface charge, which is further aggravated with higher coverage of O atoms. Overall, the dipole moment induced by O adsorption or substitution will increase surface work function and thus weaken the surface emission ability.