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

TL;DR

This study uses spatial point analysis to investigate the nucleation sites of InAs quantum dots on a wetting layer, revealing that Ga-rich fluctuations induce quantum dot formation.

Contribution

It provides new evidence linking Ga-rich surface fluctuations to quantum dot nucleation on InAs wetting layers, using in situ microscopy and point pattern analysis.

Findings

Quantum dot precursors are associated with (1x3)/(2x3) domains.

Ga-rich fluctuations induce quantum dot nucleation.

Surface reconstruction domains influence nucleation sites.

Abstract

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.