Effect of design and stress relaxation on structural, electronic, and luminescence properties of metamorphic InAs(Sb)/In(Ga,Al)As/GaAs mid-IR emitters with a superlattice waveguide.

We report on structural and optical studies of metamorphic InAs(Sb)/In(Ga,Al)As quantum well (QW) heterostructures with different designs of the active region, grown by molecular beam epitaxy on GaAs substrates and emitting in the mid-IR spectral range (3.0–3.5 μm) at room temperature. The influence of the thickness of the InGaAs/InAlAs superlattice waveguide and design of the InSb/InAs/InGaAs QW on stress balance in such metamorphic structures, their luminescent properties, and density of extended defects in the active region is discussed. The peculiarities of electron and hole energy spectra of the active region vs stress and design are studied theoretically in the framework of the 8-band Kane model and verified experimentally by Fourier-transform infrared photoreflectance spectroscopy. Despite that optimized metamorphic heterostructures are characterized by the extended defect density in the active region of just about 107 cm−2, carrier confinement in the QW has a stronger impact on their mid-IR photoluminescence intensity at room temperature. [ABSTRACT FROM AUTHOR]