Ordered InAs QDs using prepatterned substrates by monolithically integrated porous alumina

TL;DR

This paper presents a novel method for creating site-controlled InAs quantum dots on large-area GaAs surfaces using a monolithically integrated porous alumina mask, enabling precise nucleation site control.

Contribution

The study introduces a new approach combining nano-channel alumina masks and anodization to achieve site-controlled quantum dot growth on GaAs substrates.

Findings

Nanoholes serve as preferential nucleation sites for InAs QDs.

High filling factor of nearly 100% for QDs at patterned sites.

Suppressed QD formation on non-patterned surface regions.

Abstract

In this work, we explore a method for obtaining site-controlled InAs quantum dots (QDs) on large areas of GaAs (0 0 1) pre-patterned surface. The patterning of the substrate is obtained by using a monolithically integrated nano-channel alumina (NCA) mask and transferring its self-ordering to the underlying GaAs substrate by continuing the anodization process once the GaAs surface is reached. After patterning, the GaAs substrate follows a low temperature process for surface preparation before epitaxial growth for QD formation. As a final result, we observe that the nanoholes act as preferential nucleation sites for InAs QD formation, with a filling factor close to unity, while the QD formation on the surface region between the pattern holes is completely suppressed.