Metal Droplet Effects on the Composition of Ternary Nitrides

TL;DR

This study examines how metal droplets on the surface of InGaN epilayers grown by plasma-assisted molecular beam epitaxy influence indium incorporation, revealing a reduction in indium content correlated with droplet density and coverage.

Contribution

It introduces a general model explaining how metal droplets affect adatom incorporation during the growth of ternary compounds, applicable beyond InGaN.

Findings

In droplets reduce indium incorporation in InGaN layers.

Higher droplet density correlates with greater reduction in indium incorporation.

A proposed model explains the effects based on adatom mobility and vapor-liquid-solid growth mechanisms.

Abstract

We investigate effects of metal droplets on the In incorporation in InGaN epilayers grown at low temperature (450 C) by plasma assisted molecular beam epitaxy. We find a strong reduction of the In incorporation when the surface is covered by metal droplets. The such reduction increases with the droplet density and the droplet surface coverage. We explain this phenomenonology via a model that considers droplet effects on the incorporation of In and Ga adatoms into the crystal by taking into account the combined effects of the higher mobility of In, with respect to Ga, and to the vapor-liquid-solid growth that takes place under the droplet by direct impingement of nitrogen. The proposed model is general and can be extended to describe the incorporation of adatoms during the growth of the material class of ternary compounds when droplets are present on the surface.