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Growth mechanism of photoreduced silver nanostructures on periodically proton exchanged lithium niobate: Time and concentration dependence
Date Issued
2013-05-08
Date Available
2013-06-10T12:12:26Z
Abstract
Photodeposition of metallic nanostructures
onto ferroelectric surfaces, which have been chemically patterned using a
proton exchange process, has recently been demonstrated. By varying the
molar concentration of the AgNO3
solution and the illumination time, one can determine the initial
nucleation sites, control the rate of nucleation and the height of
silver nanostructures formed, and study the mechanisms by which these
processes occurs. The nanoparticles are found to deposit preferentially
in the boundary between ferroelectric and proton exchanged regions, in
an area proton exchanged via lateral diffusion under the masking layer
used for chemical patterning, consistent with our previous results.
Using a short illumination time (3 min), we are able to determine that
the initial nucleation of the silver nanostructure, having a width of
0.17±0.02µm and a height of
1.61±0.98nm, occurs near the edge of the reactive ion etched area
within this lateral diffusion region. Over longer illumination times (15
min), we find that the silver deposition has spread to a width of
1.29±0.06µm, extending across the entire lateral diffusion region. We report that at a high molar concentration of AgNO3 (10¯² M), the amount of silver deposition for 5 min UV illumination is greater (2.88±0.58nm) compared to that at low (10¯4M)
concentrations (0.78±0.35nm), however, this is not the case for
longer time periods. With increasing illumination time (15 min),
experiments at 10¯4 M had greater overall deposition, 6.90±1.52nm, compared to 4.50±0.76nm at 10 ¯² M. For longer exposure times (30min) at 10 ¯² M the nanostructure height is 4.72±0.59nm, suggesting a saturation
in the nanostructure height. The results are discussed in terms of the
electric double layer that forms at the crystal surface. There is an
order of magnitude difference between the Debye lengths for 10¯² and 10¯4 M solutions, i.e., 3.04 vs. 30.40nm, which suggests the Debye length plays a role in the availability of Ag+ ions at the surface.
Sponsorship
Science Foundation Ireland
Other Sponsorship
This publication has emanated from research conducted with the financial support of the DGPP and NANOREMEDIES, which are funded under the Programme for Research in Third Level Institutions (PRTLI) Cycle 5 and co-funded by the European Regional Development Fund. This work was also supported by Science Foundation Ireland (SFI10/RFP/MTR2855), the Swedish Scientific Research Council (VR 622-2010-526 and 621-2011-4040), and the ADOPT Linné Center for Advanced Optics and Photonics. The authors are grateful to COST actions MP0702 and MP0904. The AFM used for this work was funded by Science Foundation Ireland (SFI07/IN1/B931).
Type of Material
Journal Article
Publisher
AIP
Journal
Journal of Applied Physics
Volume
113
Issue
18
Start Page
187212
Copyright (Published Version)
2013 AIP Publishing LLC
Web versions
Language
English
Status of Item
Peer reviewed
This item is made available under a Creative Commons License
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