First Principle Electronic Structure Calculations of Ternary Alloys. BNxP1-x, GaxB1-x N and BxIn1-x N inZinc Blende Structure

In this work full-potential linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT) and within generalized gradient approximation (GGA) are used to investigate, electronic band structure, structural properties and thermodynamic properties of III (In, B, Ga) - V (N, P ) compounds and their ternary alloys of BNxP1-x, GaxB1-xN, BxIn1-xN in zinc blende structure. The present DFT-GGA calculations have shown direct band gap energy in zinc-blende phase for InN, GaN, and indirect band gap energy for BN and BP. Here, the conduction band minima of both InN and GaN are located at Γ point, while that of BN is at a position lying along Γ–X direction and BP at Γ–∆min . In our work we have found that the band gap engineering of BNxP1-x, GaxB1-xN, BxIn1-xN alloys have been studied for range of constituents (x= 0.25, 0.50, 0.75). The downward band gap bowing seems the largest in GaxB1-xN alloy comparable with the other alloys considered in this work. Even for a small amount of contents (x), adecrease of the electronic effective mass around Γ point appears for BNxP1-x, GaxB1-xN, BxIn1-xN alloys manifesting itself by an increase of the band curvature . The calculated cross over from indirect to direct band gap of ternary alloys has been found to be consistent with the experimental measurements. At last, the determinations of the band gaps of alloys as a function of contents, the concentration range of constituents leading to metallic character of the alloys, the change of the electronic effective mass around (Γ) as a function of the cross over from indirect to direct band gap of the alloys which are direct on one end, indirect on the other end are main achievements in this work. We have found also that the optimize volume and the thermo- dynamic properties were different with different concentrations of the component of their ternary alloys above and we have also analyzed the relative stability, the bulk modulus, and the minimized energy of these ternary compounds.