How kinetics drives the two- to three-dimensional transition in semiconductor strained heterostructures: the case of InAs/GaAs(001)

TL;DR

This study investigates how kinetic processes influence the transition from two- to three-dimensional growth in InAs/GaAs(001) heterostructures, revealing two distinct thresholds and mechanisms for quantum dot formation.

Contribution

It uncovers the kinetic mechanisms and thresholds governing quantum dot nucleation and growth in strained heterostructures, highlighting the role of aggregation and step edge erosion.

Findings

Identified two transition thresholds at 1.45 and 1.59 ML of InAs coverage.

Different aggregation mechanisms for small and large quantum dots.

Small dots produce monomers that promote explosive nucleation of large dots.

Abstract

The two- to three-dimensional growth transition in the InAs/GaAs(001) heterostructure has been investigated by atomic force microscopy. The kinetics of the density of three dimensional quantum dots evidences two transition thresholds at 1.45 and 1.59 ML of InAs coverage, corresponding to two separate families, small and large. Based on the scaling analysis, such families are characterized by different mechanisms of aggregation, involving the change of the critical nucleus size. Remarkably, the small ones give rise to a wealth of "monomers" through the erosion of the step edges, favoring the explosive nucleation of the large ones.