Spatial Point Analysis of Quantum Dot Nucleation Sites on InAs Wetting Layer

We perform spatial point analysis of InAs quantum dot nucleation sites and surface reconstruction domain pattern on an InAs wetting layer, giving insights for quantum dot nucleation mechanism. An InAs wetting layer grown to 1.5 monolayers in thickness on a GaAs(001) substrate has been observed at 300 degC by using in situ scanning tunneling microscopy. The surface exhibits (1x3)/(2x3) and (2x4) reconstruction domains. A nearest-neighbor analysis finds that point pattern of quantum dot precursors was more similar to that of (1x3)/(2x3) domains which are specific to Ga-rich region. This provides the evidence that InAs quantum dot nucleation is induced by Ga-rich fluctuation within an InAs wetting layer.