Quantified HAADF for ultimate resolution in chemical mappings: Application to Quantum Cascasde Devices

Quantum cascade devices, used in an increasing number of applications in the mid and long infrared, rely on complex semiconductor alloy superlattices that often contain several hundred individual layers, some of with or only a few Angstrom thick. In a recent study, we used quantified HAADF-STEM to identify, model and remedy grading that occurs at the interfaces of InGaAs/InAlAs quantum cascade laser structures. Using the TEMPOS NANOTEM platform and a new quantification algorithm, we now are able to quantify compositional fluctuations within single atomic monolayers over large areas of the quantum cascade devices and model the influence of such fluctuations in end-device performances.