Influence of oxygen in architecting large scale nonpolar GaN nanowires

TL;DR

This study demonstrates that reducing oxygen contamination during the growth of nonpolar GaN nanowires results in uniform size, improved surface morphology, and high optical quality, which are crucial for electronic and optoelectronic applications.

Contribution

It provides new insights into controlling surface architecture of GaN nanowires through oxygen management for large-scale, high-quality production.

Findings

Oxygen-rich conditions lead to inhomogeneous nanowire surfaces.

Oxygen-reduced conditions produce uniform, size-controlled nanowires.

High optical quality observed in nanowires grown with low oxygen levels.

Abstract

Manipulation of surface architecture of semiconducting nanowires with a control in surface polarity is one of the important objectives for nanowire based electronic and optoelectronic devices for commercialization. We report the growth of exceptionally high structural and optical quality nonpolar GaN nanowires with controlled and uniform surface morphology and size distribution, for large scale production. The role of O contamination (~1-10^5 ppm) in the surface architecture of these nanowires is investigated with the possible mechanism involved. Nonpolar GaN nanowires grown in O rich condition show the inhomogeneous surface morphologies and sizes (50 - 150 nm) while nanowires are having precise sizes of 40(5) nm and uniform surface morphology, for the samples grown in O reduced condition. Relative O contents are estimated using electron energy loss spectroscopy studies. Size-selective growth of uniform nanowires is also demonstrated, in the O reduced condition, using different catalyst sizes. Photoluminescence studies along with the observation of single-mode waveguide formation, as far field bright violet multiple emission spots, reveal the high optical quality of the nonpolar GaN nanowires grown in the O reduced condition.