Mechanisms of GaN quantum dot formation during nitridation of Ga droplets

TL;DR

This paper investigates the formation mechanisms of GaN quantum dots during nitridation of Ga droplets, focusing on temperature, substrate effects, and diffusion processes to enable controlled QD size and polytype tailoring.

Contribution

It introduces new insights into GaN QD formation mechanisms, emphasizing the roles of Ga/N diffusivity and nucleation, aiding in precise QD size and polytype control.

Findings

GaN QD formation involves competing mechanisms mediated by Ga surface diffusion.

Temperature and substrate significantly influence QD size distribution.

Understanding nucleation and coarsening enables tailored QD properties.

Abstract

We have examined the formation mechanisms of GaN quantum dots (QDs) via annealing of Ga droplets in a nitrogen flux. We consider the temperature and substrate dependence of the size distributions of droplets and QDs, as well as the relative roles of Ga/N diffusivity and GaN nucleation rates on QD formation. We report on two competing mechanisms mediated by Ga surface diffusion, namely QD formation at or away from pre-existing Ga droplets. We discuss the relative roles of nucleation and coarsening dominant growth, as well as the polytype selection, on various substrates. The new insights provide an opportunity for tailoring QD size and polytype distributions for a wide range of III-N semiconductor QDs.