Droplet Controlled Growth Dynamics in Plasma-Assisted Molecular Beam Epitaxy of In(Ga)N Materials

TL;DR

This study explores how metal droplet formation influences the growth dynamics of InGaN during plasma-assisted molecular beam epitaxy at low temperatures, revealing droplet effects on adatom incorporation and growth rate.

Contribution

It introduces a model explaining droplet impact on metal adatom incorporation and growth rate, highlighting the vapor-liquid-solid growth mode under droplets.

Findings

Droplet presence decreases growth rate as metal flux increases.

A model explains droplet effects on adatom incorporation.

Vapor-liquid-solid growth occurs under droplets.

Abstract

We investigate the effect of the formation of metal droplets on the growth dynamics of InGaN by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) at low temperatures (T = 450{\deg}C). We find that the presence of droplets on the growth surface strongly affects the adatom incorporation dynamics, making the growth rate a decreasing function of the overall metal flux impinging on the surface as soon as the metal dose exceeds the critical amount required for the nucleation of droplets. We explain this phenomenon via a model that takes into account droplet effects on the incorporation of metal adatoms into the crystal. A relevant role is played by the vapor-liquid-solid growth mode that takes place under the droplets due to nitrogen molecules directly impinging on the droplets.