Structural investigation of uniform ensembles of self-catalyzed GaAs nanowires fabricated by a lithography-free technique

TL;DR

This study provides a detailed structural analysis of self-catalyzed GaAs nanowires grown via a lithography-free method, revealing high uniformity, defect-free segments, and insights into their growth kinetics and structural disorder.

Contribution

It introduces a comprehensive analysis of GaAs nanowire growth, highlighting their high uniformity, defect-free segments, and the first evidence of sub-Poissonian length distributions.

Findings

High uniformity due to nucleation site consistency

Presence of defect-free zincblende segments up to 2 μm

Detection of structural disorder through spectral analysis

Abstract

Structural analysis of self-catalyzed GaAs nanowires (NWs) grown on lithography-free oxide patterns is described with insight on their growth kinetics. Statistical analysis of templates and NWs in different phases of the growth reveals extremely high dimensional uniformity due to a combination of uniform nucleation sites, lack of secondary nucleation of NWs, and self-regulated growth under the effect of nucleation antibunching. Consequently, we observed the first evidence of sub-Poissonian GaAs NW length distributions. The high phase purity of the NWs is demonstrated using complementary transmission electron microscopy (TEM) and high-resolution x-ray diffractometry (HR-XRD). It is also shown that, while NWs are to large extent defect-free with up to 2 um long twin-free zincblende segments, low temperature micro-photoluminescence spectroscopy reveals that the proportion of structurally disordered sections can be detected from their spectral properties.