Metamorphic buffer layers (MBLs) were used as substrates with lattice constants selected for designing and fabricating intersubband transition sources involving strained superlattices (SLs) such as Quantum Cascade Lasers (QCLs). Chemical mechanical planarization (CMP) was used to prepare the InGaAs-based MBLs for epitaxial growth. Indium enrichment of the InGaAs layer on the MBL surfaces was observed when annealed at the regrowth temperatures. This post-anneal enhancement was eliminated by including a wet-etch treatment after CMP, which results in an epi-ready surface for regrowth. Ten stages of a QCL core region structure, designed for emission at a 3.4 m wavelength are regrown on a surface optimized MBL. Such structures exhibit well defined X-ray diffraction pendellosung fringes, and transmission electron microscopy confirms planar superlattice interfaces with layer thicknesses that are in good agreement with the design target. (C) 2016 Elsevier B.V. All rights reserved.