Improvement of mid-wave infrared quantum cascade laser epitaxy by studying the effect of thermal annealing on GaInAs/AlInAs superlattice

GaInAs/AlInAs superlattice play an important role in the epitaxial structure of mid-wave infrared quantum cascade lasers. This paper find the optimal deoxidation temperature point for an InP/Ga0.31In0.69As/Al0.64In0.36As quantum cascade laser (QCL) epitaxial process combining MBE (for active cores) and MOCVD (for waveguide cladding) co-growth, and investigate the effect of thermal annealing on this superlattice. Comprehensive multi-technical analysis including atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) confirmed that slow annealing of the structure at a temperature of 480 °C can be properly optimized. The crystal quality and surface smoothness were confirmed, and the changes in element content of the ternary alloy under thermal reaction were analyzed. These results provide an extremely effective reference value for the QCL secondary epitaxial waveguide layer.