Role of Noise in Nanostructure Formation: A Theoretical Investigation of Quantum Dots and Quantum Dot Molecules

We theoretically model the formation of quantum dots(QDs) and quantum dot molecules(QDMs) in silicon germanium heteroepitaxy by explicitly incorporating the role of noise in a continuum theory for surface evolution in molecular beam epitaxy. Using the connection between flux and noise, we explain how changing flux can lead to a transition from QD to QDM formation, as seen in experiments. In these systems we show a dual role of noise in nanostructure growth; one where it promotes formation of QDMs via pit nucleation, and another where it curtails QDM formation due to stochastic effects.