Local strain-mediated chemical potential control of quantum dot self-organization in heteroepitaxy.

From observations of self-assembly of Ge quantum dots directed by substrate morphology, we propose the concept of control of ordering in heteroepitaxy by a local strain-mediated surface chemical potential. Using quite simple lithography, we demonstrate directed quantum dot ordering. The strain part of the chemical potential is caused by the spatially nonuniform relaxation of the strained layer, which in our study is the Ge wetting layer, but, more generally, can be a deposited strained buffer layer. This model provides a consistent picture of prior literature.