Critical role of two-dimensional island-mediated growth on the formation of semiconductor heterointerfaces

TL;DR

This paper reveals that two-dimensional island-mediated growth universally causes sigmoidal composition profiles across various semiconductor heterointerfaces, with experimental and modeling evidence showing island growth dominates interface development.

Contribution

It introduces a simple cooperative growth model explaining sigmoidal profiles and demonstrates its applicability across multiple material systems.

Findings

Sigmoidal composition profiles are common in diverse semiconductor systems.

Island growth dominates over nucleation in interface formation.

The model predicts a minimum interfacial width depending on material chemistry.

Abstract

We experimentally demonstrate a sigmoidal variation of the composition profile across semiconductor heterointerfaces. The wide range of material systems (III-arsenides, III-antimonides, III-V quaternary compounds, III-nitrides) exhibiting such a profile suggests a universal behavior. We show that sigmoidal profiles emerge from a simple model of cooperative growth mediated by two-dimensional island formation, wherein cooperative effects are described by a specific functional dependence of the sticking coefficient on the surface coverage. Experimental results confirm that, except in the very early stages, island growth prevails over nucleation as the mechanism governing the interface development and ultimately determines the sigmoidal shape of the chemical profile in these two-dimensional grown layers. In agreement with our experimental findings, the model also predicts a minimum value of the interfacial width, with the minimum attainable value depending on the chemical identity of the species.