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Title: Ni-Silicide Growth Kinetics in Si and Si/SiO2 Core/Shell Nanowires

Abstract

A systematic study of the kinetics of axial Ni silicidation of as-grown and oxidized Si nanowires (SiNWs) with different crystallographic orientations and core diameters ranging from {approx} 10 to 100 nm is presented. For temperatures between 300 and 440 C the length of the total axial silicide intrusion varies with the square root of time, which provides clear evidence that the rate limiting step is diffusion of Ni through the growing silicide phase(s). A retardation of Ni-silicide formation for oxidized SiNWs is found, indicative of a stress induced lowering of the diffusion coefficients. Extrapolated growth constants indicate that the Ni flux through the silicided NW is dominated by surface diffusion, which is consistent with an inverse square root dependence of the silicide length on the NW diameter as observed for <111> orientated SiNWs. In situ TEM silicidation experiments show that NiSi{sub 2} is the first forming phase for as-grown and oxidized SiNWs. The silicide-SiNW interface is thereby atomically abrupt and typically planar. Ni-rich silicide phases subsequently nucleate close to the Ni reservoir, which for as-grown SiNWs can lead to a complete channel break-off for prolonged silicidation due to significant volume expansion and morphological changes.

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) Center for Functional Nanomaterials
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1026789
Report Number(s):
BNL-96104-2011-JA
KC020401H; TRN: US201121%%98
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Nanotechnology
Additional Journal Information:
Journal Volume: 22; Journal Issue: 36
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; DIFFUSION; KINETICS; MORPHOLOGICAL CHANGES; SILICIDES; functional nanomaterials

Citation Formats

Hofmann, S., Sutter, E., Ogata, K., and Zhu, X. Ni-Silicide Growth Kinetics in Si and Si/SiO2 Core/Shell Nanowires. United States: N. p., 2011. Web.
Hofmann, S., Sutter, E., Ogata, K., & Zhu, X. Ni-Silicide Growth Kinetics in Si and Si/SiO2 Core/Shell Nanowires. United States.
Hofmann, S., Sutter, E., Ogata, K., and Zhu, X. Wed . "Ni-Silicide Growth Kinetics in Si and Si/SiO2 Core/Shell Nanowires". United States.
@article{osti_1026789,
title = {Ni-Silicide Growth Kinetics in Si and Si/SiO2 Core/Shell Nanowires},
author = {Hofmann, S. and Sutter, E. and Ogata, K. and Zhu, X.},
abstractNote = {A systematic study of the kinetics of axial Ni silicidation of as-grown and oxidized Si nanowires (SiNWs) with different crystallographic orientations and core diameters ranging from {approx} 10 to 100 nm is presented. For temperatures between 300 and 440 C the length of the total axial silicide intrusion varies with the square root of time, which provides clear evidence that the rate limiting step is diffusion of Ni through the growing silicide phase(s). A retardation of Ni-silicide formation for oxidized SiNWs is found, indicative of a stress induced lowering of the diffusion coefficients. Extrapolated growth constants indicate that the Ni flux through the silicided NW is dominated by surface diffusion, which is consistent with an inverse square root dependence of the silicide length on the NW diameter as observed for <111> orientated SiNWs. In situ TEM silicidation experiments show that NiSi{sub 2} is the first forming phase for as-grown and oxidized SiNWs. The silicide-SiNW interface is thereby atomically abrupt and typically planar. Ni-rich silicide phases subsequently nucleate close to the Ni reservoir, which for as-grown SiNWs can lead to a complete channel break-off for prolonged silicidation due to significant volume expansion and morphological changes.},
doi = {},
journal = {Nanotechnology},
number = 36,
volume = 22,
place = {United States},
year = {2011},
month = {9}
}