LD02 – Microscopic modeling of interface roughness scattering and application to the simulation of quantum cascade lasers

The theory of interface roughness (IFR) scattering in semiconductor heterostructures is well established in the case of idealized abrupt interfaces. However, in reality, interfaces have a finite width, i.e. interfaces are graded. In such case, the effect of interface roughness, i.e. the breaking of in-plane invariance, a general framework has been lacking to describe the induced scattering processes. We have developed a more general model of IFR scattering applicable in presence of grading of the interfaces. We have applied it to the simulation of quantum cascade lasers (QCLs). An important consequence is that the grading tends to reduce the effect of interface roughness and can be exploited as a resource to improve the QCL performances.