Electronic band structure and optical properties of GaAsSb/GaAs for optoelectronic device applications: A 14 band k.p study

Abstract

The band structure of GaAsSb/GaAs material is calculated along a crystallographic direction using a 14-band model approach. This model captures the reduction of bandgap by 13.5 meV/%Sb and provides a tool for device-level design under a range of wavelength ~ 0.9 μ m to 1.3 μ m for antimony composition limit 0.1%<Sb<35%, respectively. The analysis extends to calculating the outcome of the antimony composition on electron and hole effective mass. We have found that the electron effective mass (0.057 m o , 35% Sb) decreases by ~ 1.2 compared to GaAs (0.067 m o ). Which is responsible for improving the optical gain. So, from the obtained effective mass we determined intrinsic carrier concentration, which seems monotonic with antimony composition. Furthermore, due to uncertainty in VB and CB offset values a lateral variation of 160 nm between type I and type II QWs was observed in the optical gain spectrum. While for use in solar cells, the interband absorption coefficient was also examined as a function of photon energy with a fundamental absorption edge observed at 0.96 eV. The results obtained are well consistent with the literature result previously reported. • GaAs 1 − x Sb x band structures have been calculated by 14 band k.p hamiltonian. • Observed bandgap reduction of GaAs 1-x Sb x by 13.5 meV/%Sb. • Incorporation of Sb (35%) into the host GaAs leads to a decrease in electron effective mass by ~ 1.2 times. • Intrinsic carrier concentration analysis revealed that GaAsSb material pushes towards the p-type base. • Lateral variation by 160nm in optical gain spectrum between type-I and type-II QWs is observed.