InAs1−xSbx/In1−yGayAs multiple‐quantum‐well heterostructure design for improved 4–5 μm lasers

A new strained‐layer multiple‐quantum‐well (MQW) heterostructure comprising InAs1−xSbx wells and In1−yGayAs barrier layers is proposed for improved 4–5 μm lasers. Both well and barrier compositions are close to InAs and are potentially well suited for high‐quality crystal growth of MQWs on either InAs or GaSb substrates. Simple modeling shows favorable valence‐band alignment suitable for carrier confinement, free of the staggered band alignment problem generally found in the conventional designs. Perturbation calculation of the effect of the compressive strain in the wells also shows sufficient valence subband separation. This and the reduced hole mass are expected to considerably lower the threshold carrier density and Auger recombination.