Theoretical performance and structure optimization of 3.5–4.5 μm InGaSb/InGaAlSb multiple-quantum-well lasers

We present a comprehensive theoretical investigation to optimize 3.5–4.5 μm InGaSb/InGaAlSb quantum-well (QW) lasers grown on ternary InGaSb substrates. We use an eight-band k⋅P Hamiltonian to calculate the Auger recombination and optical absorption coefficients in the active region, as well as the gain and threshold characteristics. The dominant Auger process involves hole excitation from the QW to unbound valence states. For structure optimization we varied the Ga content in the substrate and QW barrier layers. The optimized structure was obtained by maximizing the strain in the QWs, despite the Auger coefficient also increasing with strain. It is, therefore, demonstrated that the main aim for midinfrared laser optimization can be minimization of the threshold carrier density rather than reduction of the Auger coefficient.