First principles study of the structural, electronic and optical properties of epitaxial GaSb1-x-yNyBix, lattice matched to GaSb

The structural, electronic and optical properties of epitaxial GaSb1-x-yNyBix, lattice matched to GaSb substrates, are calculated under the density functional theory (DFT) formalism of Full Potential Linear Augmented Plane Wave (FP-LAPW) method, implemented in WIEN2K package. From the total energy calculations, the supercell lattice structure is optimized. The structural properties of this alloy are calculated from the equation of state, which indicates a high stability and compressive flexibility of the material. The contribution of the constituent elements to the partial and the total Density of States (DOS) of the quaternary alloy are calculated and the results suggest that the structure is sp-hybridized. Optical absorption coefficient, reflection and refraction coefficients, extinction coefficient and energy loss are calculated in the incident photon energy range 0-8 eV and compared with the corresponding parameters calculated for GaSb. Phenomenally high values are obtained for the static part of the complex refractive index as well as for the complex dielectric function of GaSb1-x-yNyBix. The optical conductivity assumes a significantly higher value at very low photon energies and inter-band optical absorption is found to be much less than that in GaSb. The reflectivity and the energy loss as functions of incident photon energy show characteristics inverse to each other. The overall results indicate that GaSb1-x-yNyBix could act as a competent material for infrared optoelectronic applications.