The band structure and optical gain have been calculated for GaInNAs/GaAs quantum wells (QWs) with various nitrogen concentrations within the 10-band and 8-band kp models. Two approaches to calculate optical properties of GaInNAs/GaAs QWs have been compared and discussed in the context of available material parameters for dilute nitrides and the conduction band nonparabolicity due to the band anti-crossing (BAC) interaction between the N-related resonant level and the conduction band of a host material. It has been clearly shown that this nonparabolicity can be neglected in optical gain calculations since the dispersion of conduction band up to the Femi level is very close to parabolic for carrier concentrations typical for laser operation, i.e., 5 × 1018 cm−3. This means that the 8-band kp model when used to calculate the optical gain is very realistic and much easier to apply in QWs containing new dilute nitrides for which the BAC parameters are unknown. In such an approach, the energy gap and electron effective mass for N-containing materials are needed, instead of BAC parameters. These parameters are available experimentally much easier than BAC parameters.

We performed an extensive numerical study of the linewidth enhancement factor ͑␣-parameter͒ in single and multiple-quantum-well structures built from In 0.38 Ga 0.62 As 1−y N y / GaAs material systems. A ten-band kp Hamiltonian matrix was used in the calculations and solved self-consistently with Poisson's equation. The linewidth enhancement factor was evaluated as a function of wavelength, nitrogen composition, well width, and carrier density and shows significant dependence on those parameters. The simulated results are in good agreement with published experimental data for a single quantum well. We demonstrate that engineering the desired linewidth enhancement factor is possible by varying the aforementioned parameters.

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