Investigation of high optical gain (MIR region) in AlSb/InAs/GaAsSb type-II quantum well heterostructure

A type-II (with broken bandgap) W-shaped nano-heterostructure having layers combination of AlSb, InAs and GaAsSb compound semiconductors has been proposed which can be utilized as high intensity lasing source in MIR (mid infrared region). For this heterostructure, a multiband band k.p Hamiltonian has been simplified to compute the required carrier's wavefunctions, their subband structures and matrix dipole elements accountable for the probabilistic transitions which results into the high optical gain. For 2-D charge carrier density of 1.5 × 1012 cm−2, the computed results confirm that only the light hole (LH) subbands take part in optical transition in order to produce the high optical gain of the order of ~8850 /cm which corresponds to ~5.2 µm. Keeping in view its high optical gain at ~5.2 µm, the proposed type-II AlSb/InAs/GaAsSb heterostructure can be useful in the environmental monitoring, particularly important for sensing the CO2, CO and NO toxic gases available in the polluted environment. Moreover, this type-II heterostructure can also play an important role in traditional applications such as industrial, medical, MIR spectroscopy, and telecommunications applications which require ~5200 nm wavelength.