Positioning of InAs quantum dots on sub-250 nm facets using selective area epitaxy

Using oxide-patterned substrates, we have selectively grown GaAs mesas with (100) top facets ranging from several μm to less than 250 nm in width and InAs quantum dots (QDs) on top of these facets. For a given total InAs coverage, the dot density varies with the facet width. The QDs also tend to form at the facet edges. These observations suggest a strong surface diffusion effect of In-containing species adsorbed on the various GaAs facets of a mesa. By designing the oxide pattern in an appropriate manner, a two-dimensional array of QDs could be positioned in a pre-determined configuration at specific wafer locations