[Zurück]

M.-H. Chien, M. Shawrav, H. D. Wanzenböck, S. Schmid:
"Nanomechanical membrane resonator as a novel platform for the detection and analysis of FEBID plasmonic nanostructures​";
Vortrag: Nanophotonics and Micro/Nano Optics International Conference 2017, Barcelona; 13.09.2017 - 15.09.2017; in: "Nanophotonics and Micro/Nano Optics International Conference 2017 Book of Abstracts", (2017), S. 238.

Localized surface plasmon resonance (LSPR) in nanostructures has been
extensively studied during the last decades due to its remarkable optical properties.
The understanding and analysis of LSPR in various nanostructures is important for
the optimizations of devices. Focused electron beam induced deposition (FEBID) is a
mask-free, resist-free direct write additive nanofabrication method where noble metal
plasmonic nanostructures can be deposited in-situ in a single process step with
minimum limitation on geometry and with high purity. In this work, as a proof of
principle, ellipse type gold nanostructures were deposited on a 50 nm-thick
rectangular silicon-rich silicon nitride membrane using 3 kV acceleration voltage and
1 nA beam current. A LEO 1530 VP SEM with home-built gas injection system was
used to inject precursors inside the system. By exploiting the thermoplasmonic effect
of nanostructures, we use a nanomechanical membrane resonator as a novel optical
detection scheme for the experimental analysis of LSPR, as shown in figure 1. The
FEBID nano-ellipsoids on membrane resonator are scanned with a 633 nm pumping
laser with linear polarization to investigate the effects of aspect ratio and orientation
on LSPR. During scanning, the excitation of LSPR in the nano-ellipsoids results in a
heat influx into the membrane. The heating-induced detuning of the membrane
resonance frequency was monitored with a laser Doppler vibrometer incorporated
with a phase-locked loop. The results in figure 2 demonstrate the corresponding
relative frequency detuning in the membrane resonator caused by the specific
absorption cross-section of nano-ellisoids with different aspect ratio and orientation.
Due to the shift of LSPR to longer wavelength with increasing aspect ratio of nanoellipsoids,
the enhanced absorption at 633 nm in high aspect ratio nano-ellisoids
results in larger relative frequency shift. The effect of nano-ellipsoid orientation
relative to polarization is also observable. With the current setup, we are able to
detect a dissipated power of 300 fW, which result in extremely high signal-to-noise
ratio in plasmonic nanostructure with LSPR around VIS-NIR regime even with small
pumping powers of only 300 μW. With this new plasmonic characterization technique,
in combination with FEBID, LSPR with various nanostructures can easily be
investigated with almost no limitation in geometry. This analysis technique benefit
future designs and optimizations of plasmonic nanostructures or analysis of defects
in nanofabrication.

Localized surface plasmon resonance (LSPR) in nanostructures has been
extensively studied during the last decades due to its remarkable optical properties.
The understanding and analysis of LSPR in various nanostructures is important for
the optimizations of devices. Focused electron beam induced deposition (FEBID) is a
mask-free, resist-free direct write additive nanofabrication method where noble metal
plasmonic nanostructures can be deposited in-situ in a single process step with
minimum limitation on geometry and with high purity. In this work, as a proof of
principle, ellipse type gold nanostructures were deposited on a 50 nm-thick
rectangular silicon-rich silicon nitride membrane using 3 kV acceleration voltage and
1 nA beam current. A LEO 1530 VP SEM with home-built gas injection system was
used to inject precursors inside the system. By exploiting the thermoplasmonic effect
of nanostructures, we use a nanomechanical membrane resonator as a novel optical
detection scheme for the experimental analysis of LSPR, as shown in figure 1. The
FEBID nano-ellipsoids on membrane resonator are scanned with a 633 nm pumping
laser with linear polarization to investigate the effects of aspect ratio and orientation
on LSPR. During scanning, the excitation of LSPR in the nano-ellipsoids results in a
heat influx into the membrane. The heating-induced detuning of the membrane
resonance frequency was monitored with a laser Doppler vibrometer incorporated
with a phase-locked loop. The results in figure 2 demonstrate the corresponding
relative frequency detuning in the membrane resonator caused by the specific
absorption cross-section of nano-ellisoids with different aspect ratio and orientation.
Due to the shift of LSPR to longer wavelength with increasing aspect ratio of nanoellipsoids,
the enhanced absorption at 633 nm in high aspect ratio nano-ellisoids
results in larger relative frequency shift. The effect of nano-ellipsoid orientation
relative to polarization is also observable. With the current setup, we are able to
detect a dissipated power of 300 fW, which result in extremely high signal-to-noise
ratio in plasmonic nanostructure with LSPR around VIS-NIR regime even with small
pumping powers of only 300 μW. With this new plasmonic characterization technique,
in combination with FEBID, LSPR with various nanostructures can easily be
investigated with almost no limitation in geometry. This analysis technique benefit
future designs and optimizations of plasmonic nanostructures or analysis of defects
in nanofabrication.