Improved control over spontaneously formed GaN nanowires in molecular beam epitaxy using a two-step growth process

TL;DR

This study demonstrates that a two-step growth process with increased substrate temperature during nucleation improves control over GaN nanowire properties in molecular beam epitaxy, reducing growth time without affecting final nanowire quality.

Contribution

It introduces a two-step growth method that enhances control over nanowire characteristics and reduces overall growth time in plasma-assisted molecular beam epitaxy.

Findings

Two-step growth improves nanowire uniformity and coverage.

Growth conditions during incubation do not affect final nanowire properties.

Elevated temperatures during nucleation reduce total growth time.

Abstract

We investigate the influence of modified growth conditions during the spontaneous formation of GaN nanowires on Si(111) in plasma-assisted molecular beam epitaxy. We find that a two-step growth approach, where the substrate temperature is increased during the nucleation stage, is an efficient method to gain control over the area coverage, average diameter, and coalescence degree of GaN nanowire ensembles. Furthermore, we also demonstrate that the growth conditions employed during the incubation time that precedes nanowire nucleation do not influence the properties of the final nanowire ensemble. Therefore, when growing GaN nanowires at elevated temperatures or with low Ga/N ratios, the total growth time can be reduced significantly by using more favorable growth conditions for nanowire nucleation during the incubation time.