Self-assembling of Ge quantum dots in an alumina matrix

TL;DR

This paper demonstrates the self-assembly of a highly ordered three-dimensional Ge quantum dot lattice within an alumina matrix during magnetron sputtering, with tunable parameters and detailed modeling of the formation process.

Contribution

It reports a novel method for self-assembling Ge quantum dots into a well-ordered lattice during sputtering, with insights into the formation mechanism.

Findings

Quantum dots are smaller than 4 nm with narrow size distribution.

The quantum dot lattice is well-ordered and tunable by deposition parameters.

A kinetic Monte Carlo model explains the self-assembly process.

Abstract

In this work we report on a self-assembled growth of a Ge quantum dot lattice in a single 600-nm-thick Ge+Al2O3 layer during magnetron sputtering deposition of a Ge+Al2O3 mixture at an elevated substrate temperature. The self-assembly results in the formation of a well-ordered threedimensional body-centered tetragonal quantum dot lattice within the whole deposited volume. The quantum dots formed are very small in size less than 4.0 nm, have a narrow size distribution and a large packing density. The parameters of the quantum dot lattice can be tuned by changing the deposition parameters. The self-ordering of the quantum dots is explained by diffusionmediated nucleation and surface-morphology effects and simulated by a kinetic Monte Carlo model.