Control of Separation and Diameter of Ag Nanorods through Self-organized Seeds.

Paul R Elliott,Hanchen Huang,Stephen P Stagon

doi:10.1038/srep16826

Paul R Elliott, Hanchen Huang + Show 1 more

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https://doi.org/10.1038/srep16826

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Abstract

This paper proposes a mechanism of controlling the diameter and separation of metallic nanorods from physical vapor deposition through self-organized seeds and experimentally demonstrates the feasibility using Ag as the prototype metal, In as the seed, and Si the substrate. Being non-wetting on Si substrates, deposited In atoms self-organize into islands. Subsequently deposited Ag atoms attach to In islands, rather than to Si substrates, due to preferential bonding and geometrical shadowing. The experimental results show that self-organized In seeds of 5 nm nominal thickness give rise to the best separation and the smallest diameter of Ag nanorods.

Highlights

Small and well-separated metallic nanorods have unique properties that are advantageous for various applications, such as surface-enhanced Raman scattering (SERS)[1,2] and metallic glue[3]
We present the proposal by using silver (Ag) as the prototype nanorod metal, indium (In) as the self-organized seeds, and silicon (Si) with a native oxide layer as the substrate
To achieve small diameter Ag nanorods, it is desirable to deposit fewer In atoms so that the diameters of In islands are sufficiently small to facilitate the Mode II growth according to the theory[13]

Summary

Introduction

Small and well-separated metallic nanorods have unique properties that are advantageous for various applications, such as surface-enhanced Raman scattering (SERS)[1,2] and metallic glue[3]. It is desirable to decouple the variation of the diameter with that of the separation For this purpose, we propose a new mechanism to decouple the variations by introducing self-organized seeds before the growth of the nanorods. We present the proposal by using silver (Ag) as the prototype nanorod metal, indium (In) as the self-organized seeds, and silicon (Si) with a native oxide layer as the substrate. This choice of materials takes advantage of two pieces of knowledge: (1) In is non-wetting on Si substrates with native oxide[9], and (2) Ag bonds more strongly to In than to the native oxide layer on Si10,11. There is an optimal amount of In deposition

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Conclusion