Advanced

Atomic-Scale Choreography of Vapor-Liquid-Solid Nanowire Growth

Ek, Martin LU and Filler, Michael A. (2018) In Accounts of Chemical Research 51(1). p.118-126
Abstract

ConspectusFunctional materials and devices require nanoscale control of morphology, crystal structure, and composition. Vapor-liquid-solid (VLS) crystal growth and its related growth modes enable the synthesis of 1D nanostructures, commonly called "nanowires", where the necessary nanoscale heterogeneity can be encoded axially. During the VLS process, a seed particle collects atoms and directs the nucleation of crystalline material. Modulating the delivery of growth species or conditions permits compositional and/or structural encoding. A range of materials and devices (e.g., for electronics, photonics, thermal transport, and bioprobes) have been produced by VLS growth, but plenty of challenges remain: many desirable structures cannot... (More)

ConspectusFunctional materials and devices require nanoscale control of morphology, crystal structure, and composition. Vapor-liquid-solid (VLS) crystal growth and its related growth modes enable the synthesis of 1D nanostructures, commonly called "nanowires", where the necessary nanoscale heterogeneity can be encoded axially. During the VLS process, a seed particle collects atoms and directs the nucleation of crystalline material. Modulating the delivery of growth species or conditions permits compositional and/or structural encoding. A range of materials and devices (e.g., for electronics, photonics, thermal transport, and bioprobes) have been produced by VLS growth, but plenty of challenges remain: many desirable structures cannot currently be made, and even for those structures that can be made, the parameter window - in terms of, e.g., temperatures and pressures - is often narrow. Moreover, we are quite far from ab initio determination of which growth conditions should be used or even if a desired structure is fundamentally achievable within the VLS framework.To fully understand the challenges and promises of VLS growth, the governing physicochemical processes must be explored and understood at the atomic scale. This final level of detail is being unraveled with the help of in situ characterization techniques. The picture that is emerging is of a highly dynamical process with several deeply interconnected and highly fundamental components that are difficult to detect with postgrowth ex situ interrogation. For example, recent in situ microscopy and spectroscopy studies have shown that the growth front can undergo cyclical reshaping involving dissolution as well as crystallization and that the state of the nanowire surface, which changes with growth conditions as a result of a competition between adsorption and desorption of passivating species, plays a crucial role in determining the transport to/from and the stability of the seed particle. The available in situ observations currently constitute a somewhat disparate list, but if they can be connected to each other and to the outstanding challenges, they promise meaningful advances in our understanding of VLS growth. In this Account, we review the state of the art regarding the atomic-scale thermodynamic and kinetic phenomena that control VLS growth. Rather than cataloging all of the outstanding contributions to the field, we give priority to in situ observations that have revealed unexpected effects as well as those that hint at incongruities in our current knowledge. As such, our discussion should be viewed as an opportunity to gain deeper understanding and control of the fundamental processes at play, which will be crucial in future scale-up efforts and expansion to completely new materials systems and application areas.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Accounts of Chemical Research
volume
51
issue
1
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85041182328
ISSN
0001-4842
DOI
10.1021/acs.accounts.7b00392
language
English
LU publication?
yes
id
296b5c8b-ee6f-4c04-9740-d88b5e2d05f6
date added to LUP
2018-02-12 11:41:02
date last changed
2018-02-13 03:00:12
@article{296b5c8b-ee6f-4c04-9740-d88b5e2d05f6,
  abstract     = {<p>ConspectusFunctional materials and devices require nanoscale control of morphology, crystal structure, and composition. Vapor-liquid-solid (VLS) crystal growth and its related growth modes enable the synthesis of 1D nanostructures, commonly called "nanowires", where the necessary nanoscale heterogeneity can be encoded axially. During the VLS process, a seed particle collects atoms and directs the nucleation of crystalline material. Modulating the delivery of growth species or conditions permits compositional and/or structural encoding. A range of materials and devices (e.g., for electronics, photonics, thermal transport, and bioprobes) have been produced by VLS growth, but plenty of challenges remain: many desirable structures cannot currently be made, and even for those structures that can be made, the parameter window - in terms of, e.g., temperatures and pressures - is often narrow. Moreover, we are quite far from ab initio determination of which growth conditions should be used or even if a desired structure is fundamentally achievable within the VLS framework.To fully understand the challenges and promises of VLS growth, the governing physicochemical processes must be explored and understood at the atomic scale. This final level of detail is being unraveled with the help of in situ characterization techniques. The picture that is emerging is of a highly dynamical process with several deeply interconnected and highly fundamental components that are difficult to detect with postgrowth ex situ interrogation. For example, recent in situ microscopy and spectroscopy studies have shown that the growth front can undergo cyclical reshaping involving dissolution as well as crystallization and that the state of the nanowire surface, which changes with growth conditions as a result of a competition between adsorption and desorption of passivating species, plays a crucial role in determining the transport to/from and the stability of the seed particle. The available in situ observations currently constitute a somewhat disparate list, but if they can be connected to each other and to the outstanding challenges, they promise meaningful advances in our understanding of VLS growth. In this Account, we review the state of the art regarding the atomic-scale thermodynamic and kinetic phenomena that control VLS growth. Rather than cataloging all of the outstanding contributions to the field, we give priority to in situ observations that have revealed unexpected effects as well as those that hint at incongruities in our current knowledge. As such, our discussion should be viewed as an opportunity to gain deeper understanding and control of the fundamental processes at play, which will be crucial in future scale-up efforts and expansion to completely new materials systems and application areas.</p>},
  author       = {Ek, Martin and Filler, Michael A.},
  issn         = {0001-4842},
  language     = {eng},
  month        = {01},
  number       = {1},
  pages        = {118--126},
  publisher    = {The American Chemical Society},
  series       = {Accounts of Chemical Research},
  title        = {Atomic-Scale Choreography of Vapor-Liquid-Solid Nanowire Growth},
  url          = {http://dx.doi.org/10.1021/acs.accounts.7b00392},
  volume       = {51},
  year         = {2018},
}