Ordered InAs quantum dots on pre-patterned GaAs (0 0 1) by local oxidation nanolithography

TL;DR

This paper demonstrates a method to create ordered arrays of InAs quantum dots on GaAs substrates using AFM local oxidation nanolithography combined with MBE, controlling dot size and arrangement through nanohole patterning.

Contribution

It introduces a novel fabrication process that precisely controls quantum dot positioning and size by pre-patterning GaAs surfaces with nanoholes before InAs deposition.

Findings

Ordered quantum dot arrays can be achieved with controlled size and spacing.

Nanohole geometry influences quantum dot nucleation and density.

The process maintains pattern fidelity by low-temperature processing.

Abstract

Ordered InAs quantum dot (QD) arrays have been obtained on pre-patterned GaAs (0 0 1) substrates by atomic force microscopy (AFM) local oxidation nanolithography. Prior to InAs molecular beam epitaxy (MBE) deposition, an ordered square array of nanoholes is formed at the GaAs pre-patterned surface following in situ etching with atomic hydrogen. A low substrate temperature is maintained during the whole process in order to avoid pattern smoothing. Our results show that the density and dimensions of the nanoholes on the GaAs surface determine InAs QD size, nucleation site and InAs dose necessary for their formation. As a function of the geometrical parameters of the nanohole array, we can obtain either ordered 2D arrays of separated QD, closely packed QD or localized areas for QD formation.