Accurate prediction of optical transitions in epitaxial InGaAs/InAlAs asymmetric coupled quantum well structures

Atomically-resolved Z-contrast and strain mappings are used to extract a model of the composition of an InGaAs/InAlAs asymmetric coupled quantum-well structure grown on InP using metal-organic vapor phase epitaxy. The model accounts for grading across the multiple alloy interfaces. The model is used to compute intersubband absorption in the structure. The simulation accurately predicts the experimental absorption spectrum of the structure within only a few meV, an almost ten-fold improvement over simulations using a square-band profile with nominal alloy compositions, and a significant step forward in accurate and predictive simulations of the optical properties epitaxial heterostructures for emission, modulation and detection in mid-infrared.