Comparative study on electronic properties of GaN nanowires by external electric field

The electronic structure and optical properties of GaN nanowires under external electric fields with different directions and field intensities are studied via first-principles. The results show that the GaN nanowires under an electric field in the (001) direction is the most stable. The external electric field can adjust the band gap of GaN nanowires, and a further increase to the electric field intensity of 0.1 V/Å could suddenly reduce the band gap. Moreover, the GaN nanowires under the 0.2 V/Å field intensity exhibited the Stark effect. The application of an electric field could reduce the charge transfer between Ga atoms and N atoms in GaN nanowires. In addition, larger electric field intensity can reduce the absorption coefficient and reflectivity of GaN nanowires. These findings may provide valuable information for the development of field-assisted GaN nanowire photocathodes.