Atomistic mechanisms and diameter selection during nanorod growth

TL;DR

This paper investigates the atomic mechanisms behind nanorod growth, identifying a characteristic radius that influences diameter selection and growth morphology, with theoretical predictions aligning well with experimental data.

Contribution

It introduces a theoretical framework linking atomic-scale processes to nanorod diameter selection, highlighting the role of a characteristic radius in growth mode determination.

Findings

A characteristic radius proportional to the fifth root of adatom hopping rate to deposition rate ratio.

Growth mode transition depends on initial island size relative to the characteristic radius.

Theoretical predictions match experimental observations of ZnO nanorod growth.

Abstract

We study in this paper the atomic mechanisms of nanorod growth and propose the way of diameter selection of nanorod. A characteristic radius is demonstrated to be crucial in nanorod growth, which increases proportional to one fifth power of the ratio of the interlayer hopping rate of adatoms across the monolayer steps to the deposition rate. When the radius of the initial island is larger than this characteristic radius, the growth morphology evolves from a taper-like structure to a nanorod with radius equal to the characteristic radius after some transient layers. Otherwise the nanorod morphology can be maintained during the growth, with stable radius being limited by both the radius of the initial island and the three-dimensional Ehrlich-Schwoebel barrier. Therefore different growth modes and diameter of nanorod can be selected by tuning the characteristic radius. The theoretical predictions are in good agreement with experimental observations of ZnO growth.