@conference{
author = "Rašljić, Milena and Jakšić, Zoran and Smiljanić, Milče M. and Lazić, Žarko and Cvetanović, Katarina and Vasiljević-Radović, Dana",
year = "2017",
abstract = "Plasmonics deals with electromagnetic waves that are bound to an interface between
conductor with free electron plasma and dielectric, and are evanescent in the perpendicular
directions. This ensures extreme localizations of electromagnetic near fields in
subwavelength volumes [1,2].A number of systems where plasmonic activation is used for
photocatalysis has been reported until now [3-6]. A vast majority of these relies on localized
surface plasmon resonance on nanoparticles, which may have either monolithic [7] or core shell structure [8]. In our experiment we propose the use of disordered rough plasmonic
surface for the enhancement of photocatalytic microreactors. The basic idea was to fabricate a
microreactor structure with the microchannel bottom surface roughened by wet chemical
etching and subsequently covered by a thin gold layer (plasmonic material).
Experiments in wet chemical etching was performed on two single crystal, n-type silicon
wafers, double side polished, 3" in diameter. Thermal oxide was used as a masking layer on
Si wafers. A protective oxide had a thickness value about 0,6 µm for chemical etching in
KOH (potassiumhydroxide) and 1 µm for chemical etching in TMAH
(tetramethylammonium hydroxide). Thermal oxide was etched in BHF (buffered hydrofluoric
acid) from the top side of wafers, after that wafers were cut on 6 pieces, samples. One set of
samples was etched in 30 wt.% KOH water solution at 80 °C for 2 min, 4 min, 6 min, 8 min,
10 min, with etching rate of 1,1 µm/min. And the other set of samples was etched in 25 wt.%
TMAH water solution at 60 °C for 2 min, 3 min, 4 min, 5 min, 6 min, with etching rate of
0,16 µm/min.All samples were cut in half, and one half of each sample was gold sputtered.
As a coupler between propagating and surface modes for plasmonic enhancement of
photocatalytic optofluidicmicroreactors thin layer of gold, Au, was used with sublayer of
chrome, Cr. Sublayer must be present for purpose of good adhesion of gold on silicon
surface. The minimum of thickness value for gold and chrome as sublayer have to be around
20nm, 10 nm respectively. Thickness value of layer and sublayer, combined, must be smaller
then value of roughness of silicon surface. The roughness of the surface of the three dimensional images was determined with atomic force microscope TM Microscopes – Veeco
in contactless mode.
Different surface profiles were obtained by different profiling mechanisms.We obtained
better surface with samples which were etched in 30 wt. % KOH water solution. This opens a
path toward surface profile tailoring and optimization in the sense of maximizing the
coupling efficiency and tuning it to a desired spectral range. The approach can be used in
general optofluidics and for lab on chip devices.",
publisher = "University of Belgrade - Institute of Chemistry, Technology and Metallurgy",
journal = "Book of abstracts - COST MP1402 HERALD Scientific Workshop, "ALD and related ultra-thin film processes for advanced devices", 29-30 August 2017, Belgrade",
title = "Plasmonic enhancement of photocatalytic optofluidic microreactors with corrugated thin metal films",
pages = "16-17",
url = "https://hdl.handle.net/21.15107/rcub_cer_5797"
}
