Electronic band structure calculation of GaNAsBi alloys and effective mass study

Abstract

Electronic band structures of GaNxAs1−x−yBiy dilute nitrides–bismides have been determined theoretically within the framework of the band anticrossing (BAC) model and k⋅p method. We have developed computer codes based on our extended BAC model, denoted (16×16), in which the dimension of the used states basis was equal to 16. We have investigated the band gap and the spin orbit splitting as a function of Bi composition for alloys lattice matched to GaAs. We have found that the substitution of As element by N and Bi impurities leads to a significant reduction of band gap energy by roughly 198meV/%Bi. Meanwhile, spin orbit splitting increases by 56meV/%Bi regardless N content. There is an excellent agreement between the model predictions and experiment reported in the literature. In addition, alloys compositions and oscillator strengths of transition energies have been calculated for GaNAsBi alloys which represent active zone of temperature insensitive (1.55μm and 1.3μm) wavelength laser diodes intended for optical fiber communications. A crossover at about 0.6eV has occurred between Eg and Δso of GaN.039As.893Bi.068. When the quaternary is lattice mismatched to GaAs, resonance energy increases with Bi content if N content decreases. On the other hand, effective mass behavior of carriers at Γ point has been discussed with respect to alloy composition, k-directions and lattice mismatch.