Formation of InAs Self-Assembled Quantum Rings on InP

TL;DR

This study investigates the shape transformation of InAs quantum dots into quantum rings on InP substrates, revealing rapid anisotropic material redistribution without compositional change, challenging previous models of ring formation.

Contribution

It provides new insights into the shape transformation mechanism of InAs quantum dots into rings on InP, emphasizing anisotropic redistribution over compositional changes.

Findings

Rapid anisotropic redistribution of InAs material occurs within minutes.

Quantum dots transform from lens-like to ring-like shapes without compositional change.

The observed formation mechanism contradicts previous models based on surface diffusion differences.

Abstract

Shape transformations of partially capped self-assembled InAs quantum dots grown on InP are studied. Atomic force microscopy images show large anisotropic redistribution of the island material after coverage by a 1 nm thick InP layer. The anisotropic material redistribution occurs within a few minutes and leads to a change from lens-like to elongated ring-like islands. The shape transformation is not accompanied by dot material compositional change. The formation of InAs/InP quantum rings disagrees with a previous model of InAs/GaAs ring formation that assumes that the driving force for the dot to ring transformation is the difference in surface diffusion velocity of indium and gallium atoms.