Barrier-width effects on electronic and optical properties of type-II GaAsSb/GaAs/AlGaAs quantum-well lasers

The barrier-width effects on the electronic and the optical properties of type-II GaAsSb/GaAs/AlGaAs QW structure are investigated using a self-consistent method. The transition energy is shown to increase with increasing barrier width due to the band-bending effect. In the case of a low carrier density, the matrix element rapidly decreases with increasing barrier width. On the other hand, in the case of a relatively high carrier density, the decreasing rate of the matrix element is largely reduced with increasing barrier width because the conduction-band wave function is confined in the GaAsSb QW layer due to the band bending effect at a high carrier density. The gain peak rapidly decreases with increasing barrier width and begins to saturate when the barrier width exceeds 100 angstrom. These results show that consideration of the barrier-width effects in the design of GaAsSb-based QW structures is very important.