Effects of substrate orientation on opto-electronic properties in self-assembled InAs/GaAs quantum dots

摘要

Electronic structure and optical transition characteristics in (100), (110), and (111) oriented InAs/GaAs quantum dots (containing ～2 million atoms) were studied using a combination of valence force-field molecular mechanics and 20-band sp~3d~5s~* atomistic tight-binding framework. These quantum dots are promising candidates for non-traditional applications such as spintronics, quantum cryptography and quantum computation, but suffer from the deleterious effects of various internal fields. Here, the dependence of strain and polarization fields on the substrate orientation is reported and discussed. It is found that, compared to the (100) and (110) oriented counterparts, quantum dots grown on the (111) oriented substrate exhibit a smaller splitting (non-degeneracy) in the excited P states and enhanced isotropy in the interband optical emission characteristics.