First-principles study of electronic properties of GaN nanowires: Effect of surface orientation, passivation, and Mn doping

The present work is a comprehensive analysis of the electronic and magnetic properties of pristine and Mn-doped GaN nanowires (NWs) using first-principles calculations. The investigations were performed by considering the effects of size, shape, and passivation on GaN NWs oriented in three different crystallographic growth directions, namely [0001], [110], and [100]. Binding energy calculations predict that the stability increases with the size of NWs with and without passivation. Formation energy shows that surface (core) position is energetically suitable for substitutional Mn doping in unpassivated (passivated) NWs. We found that [0001]-orientated GaN NW is most energetically favorable and [100]-orientated GaN NW is most suitable for substitutional doping. Mn doping causes the localization of energy states in the vicinity of the Fermi level and enhances the metallicity in the NWs. It is revealed that NWs retain their electronic nature even after doping, except for square-shaped [110]-oriented NW. The spin-polarized electronic properties were also calculated for Mn-doped NW. The result shows a unique half-metallicity in square-shaped NW oriented along the [1] direction. The energetic stability of [0001]-oriented GaN NW and the electronic behavior of unpassivated-oriented GaN NW can be useful as an interconnection between nanoelectronic devices and spin-based applications.