Unit cell structure of the wurtzite phase of GaP nanowires: X-ray diffraction studies and density functional theory calculations

Abstract

We present structural characterization of the wurtzite crystal structure of GaP nanowires, which were recently shown to have a direct electronic band gap. The structural parameters of the wurtzite phase do consist of two lattice parameters and one internal degree of freedom, determining the Ga-P bond length along the c direction. Using density functional theory calculations, we study the influence of the internal degree of freedom on the band structure. By synchrotron x-ray diffraction studies near the Ga-K edge we determine the lattice parameters a = 3.8419Å and c = 6.3353Å as well as the internal degree of freedom u = 0.37385 with high accuracy. We find that different Ga-P bond lengths are not equal, in contrast to the case in the zinc blende bulk phase. As a result, a spontaneous polarization is predicted for wurtzite GaP.

Polytypism in ZnS, ZnSe, and ZnTe: First-principles study

“…The influence of the optimized u on c/a and V , in general, is very small. However, its small deviation can significantly modify the local electronic properties and internal electric fields due to the spontaneous polarization in hexagonal polytypes [29][30][31][32][33]. This especially holds for heterocrystalline junctions and superlattices [34,35], or the presence of interfaces between two polytypes of one-and-thesame compound in the [0001] direction.…”

GaP–ZnS Pseudobinary Alloy Nanowires

“…36-1450; a = 3.820 Å and c = 6.257 Å) and GaP (a = 3.8419 Å and c = 6.3353 Å). 39 As shown in the following TEM images and EDX data, the NW consisted of a GaP-rich core and ZnS-rich shell. In the ZnS-rich shell, the ZB and WZ phases coexist.…”

Band structures and spatial carrier confinement in GaAs/GaP core-shell nanowires: Core/shell composition and size effects

“…Owing to the underestimation of DFT/GGA method for the band gap of semiconductor materials, the band gap of GaP bulk is calculated by the HSE method [36]. The calculated band gaps of GaP in ZB and WZ phases are 2.28 eV and 2.21 eV respectively, which are in good agreement with the experimental values (2.33 eV in ZB phase [37] and 2.10 eV in WZ phase [38]). Using the Eq.…”