Direct Observation of Interface and Nanoscale Compositional Modulation in Ternary III-As Heterostructure Nanowires

TL;DR

This study uses high-resolution spectroscopy to directly observe nanoscale compositional variations and interface structures in ternary III-As heterostructure nanowires, revealing Ga enrichment and growth mechanisms.

Contribution

It provides the first direct nanoscale observation of compositional modulation and interface structure in ternary III-As nanowires, elucidating growth mechanisms.

Findings

Ga enrichment at interfaces and facet junctions

Structural change associated with GaInAs segments

Higher Ga concentration in early grown segments

Abstract

Straight, axial InAs nanowire with multiple segments of GaInAs were grown. High resolution X-ray energy-dispersive spectroscopy (EDS) mapping reveal the distribution of group III atoms at the axial interfaces and at the sidewalls. Significant Ga enrichment, accompanied by a structural change is observed at the GaInAs/InAs interfaces and a higher Ga concentration for the early grown GaInAs segments. The elemental map and EDS line profile infer Ga enrichment at the facet junctions between the sidewalls. The relative chemical potentials of ternary alloys and the thermodynamic driving force for liquid to solid transition explains the growth mechanisms behind the enrichment.