The precise growth controls of strained AlInAs and GaInAs for strain-balanced quantum cascade lasers (QCLs) are optimized and developed. The precise measurements of constituent compositions and thicknesses of strained AlInAs and GaInAs are performed on the strain-balanced AlInAs/GaInAs superlattice (SL). The doping incorporation behaviour of strained AlInAs and GaInAs is studied. High-crystalline quality QCL structures with desired two-dimensional electron gas (2DEG) densities in the injector region are achieved through precise composition, thickness and doping controls. (C) 2008 Elsevier B.V. All rights reserved.