Thermal fabrication of gold nanocages
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Date
2011-04-11
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Vanderbilt University. Department of Physics and Astronomy
Abstract
The purpose of this research project was to test and characterize a new method
for gold nanoparticle production. The main idea was based on the preliminary
observations made in earlier work, which had suggested that small amounts of
gold deposited onto a silicon substrate will spontaneously reshape into gold
nanoparticles when treated to controlled high-temperature heating for a
sufficient period of time. This idea for a fabrication process was extended
to incorporate Electron Beam Lithography (EBL) gold patterning. The full
fabrication method consisted of the following steps: (1) Preparation of
clean silicon substrates, (2) Addition of a Poly(methyl methacrylate) (PMMA)
Coat via spin coating, (3) Design of gold patterns for the EBL, (4) Gold
patterning via EBL, (5) Gold deposition via electron beam evaporation,
(6) PMMA mask removal via acetone wash, and (7) High-Temperature furnace
heating, as well as plans for a final step (8) Isolation of the gold
nanocages via HF etching. The project research required the use of the
photolithographic facilities of the Vanderbilt Institute of Nanoscale
Science and Engineering (VINSE), as well as the use of the high-temperature
furnace and other basic needs supplied by the research group of Professor
Dickerson. Some of the VINSE equipment required relatively extensive
operational training.
The research project has demonstrated that the described thermal fabrication
method can uniformly and repeatedly produce Au nanoparticles of about 400 nm
in diameter from Au deposits of 1 um2 area and 20 nm thickness. Larger areas
displayed structural fragmentation into multiple nanoparticles, and this
fragmentation effect increased proportionally with increasing area size. Due
to time constraints, the many available parameters prevented a complete
characterization of this fabrication method; however, useful insights were
obtained for several of the parameters of the fabrication process. In
particular, it can be expected that smaller nanoparticles may be fabricated
in a straightforward manner by reducing the patterned area sizes of the gold
deposits. Results suggested an intrinsic limitation to the method: for the
requirement of product uniformity, each Au-area deposit had to produce only
a single nanoparticle.
Description
Keywords
hollow gold particle, thermal annealing, e-beam lithographical patterning, focused ion beam, photoemission electron microscopy, surface plasmon resonance, gold nanocage synthesis, gold patterned film, nanoscale patterned thin film