Quantum confinement induced strain in quantum dots

We investigate quantum confinement induced strain in quantum dots. While the impact of mechanical strain on the electronic structure of quantum dots is well studied, the “reverse” effect remains relatively unexplored. Even in the complete absence of external stress, for very small sizes (1–3 nm range), the electronic structure change due to quantum confinement may induce a strain in the quantum dot, which in turn will further alter the electronic structure. Despite the limitations of an envelope function approach for small sizes, a multiband analytical model is developed to make explicit the qualitative features of this phenomenon with physical interpretation in terms of acoustic polarons. We quantitatively predict the induced strain due to quantum confinement and the polaron binding energy for the example cases of Si and GaAs. The Si polaron binding energy calculated from the developed model compares favorably with both our density-functional and semiempirical atomistic calculations.