Composition and optical properties of (In,Ga)As nanowires grown by group-III-assisted molecular beam epitaxy

TL;DR

This study explores the growth, composition, and optical properties of (In,Ga)As nanowires grown by group-III-assisted molecular beam epitaxy on silicon, revealing how flux ratios influence their structure and luminescence for potential infrared applications.

Contribution

It demonstrates controlled incorporation of indium in (In,Ga)As nanowires and analyzes their optical emission, offering new insights for integrating infrared emitters on silicon.

Findings

Maximum In content of nearly 30% at high flux ratios.

Nanowire dimensions decrease with increasing In flux ratio.

Homogeneous luminescence observed in nanowire segments.

Abstract

(In,Ga) alloy droplets are used to catalyse the growth of (In,Ga)As nanowires by molecular beam epitaxy on Si(111) substrates. The composition, morphology and optical properties of these nanowires can be tuned by the employed elemental fluxes. To incorporate more than 10% of In, a high In/(In+Ga) flux ratio above 0.7 is required. We report a maximum In content of almost 30% in bulk (In,Ga)As nanowires for an In/(In+Ga) flux ratio of 0.8. However, with increasing In/(In+Ga) fl ux ratio, the nanowire length and diameter are notably reduced. Using photoluminescence and cathodoluminescence spectroscopy on nanowires covered by a passivating (In,Al)As shell, two luminescence bands are observed. A significant segment of the nanowires shows homogeneous emission, with a wavelength corresponding to the In content in this segment, while the consumption of the catalyst droplet leads to a spectrally-shifted emission band at the top of the nanowires. The (In,Ga)As nanowires studied in this work provide a new approach for the integration of infrared emitters on Si platforms.