InGaAs/AlInAs strain-compensated Superlattices grown on metamorphic buffer layers for low-strain, 3.6 μm-emitting quantum-cascade-laser active regions

► We describe new designs for short-wavelength QCLs, employing a MBL on a GaAs substrate. ► Strain-compensated superlattice (SL) structures are representative of the QCL active region. ► SL structures are grown by MOVPE on an AlInGaAs compositionally step-graded MBL. ► Structural characterization of the SL underscores reducing the top-surface roughness of the MBL.