Room temperature spectroscopic characterization of mid-infrared GaInSb quantum-well laser structures

Three GaInSb/AlGaInSb type I multi-quantum-well (QW) laser structures grown on GaAs, with increasingly strained QWs, aimed at emitting at ∼4 µm, are analysed using our Fourier transform infrared surface photo-voltage spectroscopy technique. The measurements clearly yield a full set of transitions including not only the barrier bandgap, but also the QW ground state transition, from which the device operating wavelengths can be inferred, and up to five excited state QW transitions. The full set of measured transition energies are then compared closely with those predicted by an 8-band k . p model which gives a generally good agreement for the QW transitions, but an indication that the current literature values for the AlGaInSb bandgap seem to be in considerable error for the present alloy compositions