Design and characterization of strained InGaAs/GaAsSb type-II ‘W’ quantum wells on InP substrates for mid-IR emission

InGaAs/GaAsSb type-II 'W' quantum wells (QWs) grown on InP substrates by metalorganic vapour phase epitaxy were investigated for potential emission wavelengths in the mid-infrared spectral region. Design studies using an 8-band k · p Hamiltonian model indicate that emission wavelengths near 3 µm should be achievable without strain relaxation. Improved electron confinement can be achieved by adding higher-energy band gap alloys such as AlAsSb or GaInP around the type-II 'W' active region. Comparisons of the simulations with experiment indicate that photoluminescence (PL) spectra are consistent with a type-II band alignment. 4-period type-II 'W' In 0.8 Ga 0.2 As (∼4.0 nm)/GaAs 0.35 Sb 0.65 (∼1.5 nm) QWs separated by InP (5 nm) or AlAs 0.767 Sb 0.233 (1.5 nm) barrier layers, demonstrate room-temperature PL emission at ∼2.1 µm