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Mater Sci Nanotechnol 2017 | Volume 1 Issue 2
allied
academies
Nanomaterials and Nanochemistry
November 29-30, 2017 | Atlanta, USA
International Conference on
I
t is commonly accepted that the presence of so-called hot-
spots is necessary for obtaining high enhancement factor
(EF) of Raman signal from individual molecules attached to
the plasmonic metal particles. The hot-spots contribute most
significantly to the overall SERS intensity. Two approaches are
usually used in order to deliver SERS platforms, namely planar
and nano-structured substrates, both with plasmonic metal
particles on the top surface. The aim of this presentation
is to review the new technology of nano-structuring of
hetero-epitaxial GaN layers. The nano-structures are formed
using galvanic, electroless and orthodox etching methods.
The principles of etching methods, commonly used for
revealing and analysis of crystallographic and electrically
active defects, will be discussed. As a result of studying
defects in hetero-epitaxial GaN, the nano-structured
hetero-epitaxial GaN surfaces appeared to be suitable for
SERS measurements. It will be shown that the dislocation-
related nano-pillars and pits (formed during electroless
and orthodox etching, respectively) are responsible for
formation of hot-spots and the increased EF. Tailoring of
plasmonic metal layers sputtered on etched GaN surfaces
for increased SERS efficiency using dealloying and annealing
will be also addressed. The novel SERS platforms based
on etched GaN show very good mechanical and chemical
stability and high EF up to 10
6
for the examined molecules
of para-mercaptobenzoic acid (pMBA) and pyridine. This
feature enables also time-lapse measurements of various
biological systems such as Hepatitis B virus antigen and
different bacteria (BC, BT, BS).
e:
weyher@unipress.waw.plTechnology of nanofabrication of GaN-based substrates for surface enhanced Raman spectroscopy
measurements: Chase for hot-spots
J L Weyher
Polish Academy of Sciences, Poland