Structural properties and energetics of GaAs nanowires

• A systematic investigation of structure and electronic properties of GaAs NWs is presented.
• A revised cohesive energy is determined by the influence of dangling bonds' distribution.
• H passivation is very necessary to optimize the band property of GaAs ZB NWs.

Using the first-principles density functional theory, we have investigated the geometric structure and electronic properties of GaAs nanowires. Compared with bulk GaAs, wurtzite nanowires are found to be more stable over zinc-blende nanowires. A revised cohesive energy is provided based on the influence of different kinds of surface dangling bonds. Our calculation indicates that GaAs nanowires display bistability namely both zinc-blende and wurtzite nanowire will form around 90 Å diameters. Furthermore, most GaAs nanowires are found to be semiconducting except for the zinc-blende nanowires. In zinc-blende nanowires, it is mainly due to the twofold coordinated atoms associated with the surface state will decrease the band gap. Upon H passivation, these nanowires become semiconducting and the trend of the band gap decreases with the diameter increases.

The cohesive energy of different types of GaAs NWs converges into the bulk values with the increasing of the diameter and our revised cohesive energy is more close to the experimental value.Figure optionsDownload as PowerPoint slide