Uniaxial Strain and Optical properties of GaP Nanowires

Abstract

The optical properties for wurtzite (WZ) Bulk GaP and GaP nanowires (GaP-NWs) in hexagonal(circular), triangular and square cross sectional are investigated by using full potential linear augmented plane waves and local orbitals (FP-LAPW-LO) method based on density functional theory (DFT). The wurtzite nanowires are investigated with diameters limited to ~27 ^oA. The optical functions  as a function of photon energy have been investigated for unstrained bulk WZ-GaP and WZ-GaP-NWs in the first part. Finally, the optical functions are investigated for WZ-GaP-NWs by applying uniaxial strain from -5% to +5%. The effect of cross sectional variation in the area and shape of the NWs on the optical functions is clear when compared with bulk GaP. GaP-NWs kept real dielectric constant  positive and refractive index  close to vacuum value for a wider range of energy on the contrary of bulk GaP. It is found that the dielectric constants  are slightly increased from the unstrained GaP-NWs values with strain increases. A shift in the threshold energy for  toward higher energy as the strain changes from tensile to compressive. The refractive index  shows a small change when passing from compressive toward tensile strain. It is found that GaP-NWs could play a role in solar cells structure and high speed electronic circuits.