Triple V-shaped type-II quantum wells for long wavelength interband cascade lasers

We investigate triple V-shaped type-II quantum wells designed to emit at 6-9 μm wavelength range, consisting of three InAs(Sb) electron quantum wells and two G a 0.6 I n 0.4 Sb hole quantum wells. The wells’ composition and thicknesses are optimized in terms of wavefunction overlap and valence intersubband absorption (VISA) by using k·p calculation. The triple V-shaped type-II quantum well designed for emission at 6.2 μm, 7.5 μm, and 9.0 μm, shows 18.8 %, 18.9 % and 19.2 % higher wavefunction overlap, respectively, compared to the corresponding W-shaped designs of InAs/ G a 0.6 I n 0.4 Sb /InAs wells commonly employed in active regions of interband cascade lasers. In addition, the calculated VISA in V-shaped quantum wells for the designed wavelength is significantly smaller than in W-shaped wells. These enhancements might extend the wavelength limit of room temperature emission of GaSb-based interband cascade lasers.