The Structure and Composition of Semiconductor Quantum Materials

The size, shape, strain distribution, compositional profile, and spatial distribution are the critical factors determining the electronic levels and thus the physical properties of semiconductor nanostructures. For MBE-grown quantum dots, the interplay between lattice mismatch, surface segregation, interface diffusion and various kinetic effects makes their formation mechanism very complicated. In fact, the structure and the formation mechanism of these self-assembled quantum dots are still not well understood. In this work, we applied grazing incidence X-ray scattering methods including reciprocal space map and small angle X-ray scattering to study the strain field, shape and spatial distribution of InGaAs quantum dots. In particular, we focus on the application of grazing incidence resonant X-ray scattering technique to determine the compositional distribution within the quantum dots and its correlation with strain field. With the data obtained, we profiled the distribution of elastic energy within the dots.