HREM structure characterization of interfaces in semiconducting multi-layers using molecular-dynamics-supported image interpretation

Multi-layer structures in binary systems, for example InAs/AlSb and AlSb/GaSb, as well as ternary InGaAs/AlGaAs quantum wells grown by molecular beam epitaxy (MBE) are investigated by high-resolution electron miscroscopy (HREM). Interpretation of the micrographs requires methods of image analysis and the computer simulation of the HREM contrast. The relaxed atomic structure of the interfaces is modelled by molecular dynamics (MD) and energy minimization. The importance of strain relaxations to the image interpretation will be demonstrated and compared with the image spread and shift caused by the microscope aberrations. The possibility of revealing the compositional variations and the elastic deformations at the interfaces by HREM imaging under special defocus and sample thickness conditions will be discussed.