Activity Report 2010 - CNRS

HIGHLIGHT : QUANTUM NANOELECTRONICS
CONTACTS
laurent.duraffourg@cea.fr
philippe.andreucci@cea.fr
roukes@caltech.edu
FURTHER READING
R. B. Karablin et al, Applied Physics Letters,
95, 103111, (2009)
E. Mile et al, Nanotechnology, 21, 165504
(2010)
1
NANO-
ELECTROMECHANICAL
RESONATORS
The Chair of Excellence of Michael
ROUKES aims to merge advances in
nanotechnology with very-large-scale
integration (VLSI) processes in order to
create complex nanomechanical systemsbased
tools for science and industry—
thus accelerating nanoscience out of the
laboratory and into the marketplace.
The emerging field of
nanoelectromechanical systems (NEMS)
is attracting considerable interest. These
miniaturized nanoscale devices,
particularly cantilever and beam flexuralmode
resonators, have enabled the
demonstrations of single molecule mass
sensors and single cell level-force
sensors. The small displacements of
these miniaturized devices induce very
low signals which are overwhelmed by
parasitic background. A lot of efforts
have been devoted to developing new
transduction and background reduction.
Piezoelectric and piezoresistive
transductions appear to be particularly
advantageous compared to the more
conventionally employed magnetomotive
and capacitive techniques.
Amongst the attributes of chosen
transduction, principles are intrinsic
integrability, high efficiency and electrical
tunability, low power consumption, and
low thermal budgets for materials
processing, permitting post-CMOS
integration.
Silicon nanowire
piezoresistive detection
A piezoresistive detection scheme offers
great potential compared to a capacitive
one especially for high resonant
frequency measurements. Recently, mass
resolution down to 7 zeptograms Hz 1/2 has
been demonstrated using a metallic
gauge layer deposited on the top of a
cantilever. Another approach consists in
using a doped silicon nanowire. However
to date bottom-up nanowires cannot be
fabricated using a VLSI process
compatible with a standard CMOS
technology.
We demonstrate a new kind of detection
scheme based on doped silicon nanowire
strain gauges that are fully compatible
with CMOS processes. This allows very
large scale integration of devices in a
straightforward manner. Measurements
obtained with this approach are showing
promising performances in terms of
frequency stability, dynamic range, and
achievable mass resolution (Fig.1).
Fig. 1: Nano cantilever beam resonator based
on silicon nanowire piezoresistive detection –
Very large signal to noise ratio
The devices tested in this work were
developed as prototypes and were not
optimized for mass detection at this
stage. Such NEMS have a great potential
for future performance improvements
and new applications opportunities.
Further device optimization for lower
mass and higher frequency, based on
advanced top-down nanowire fabrication
techniques (for instance 40nm-silicon
thickness), will lead to a resolution in the
range of a few zeptograms or less.
Piezoelectric
nanoelectromechanical
resonators
We also demonstrated piezoelectrically
actuated, electrically tunable NEMS based
on multilayers containing a 100-nm-thin
aluminum nitride (AlN) layer. Efficient
piezoelectric actuation of very high
frequency fundamental flexural modes up
to 80 MHz has been demonstrated at
room temperature (Fig.2).
Fig. 2: Very High Frequency AlN beam
resonators demonstrating nonlinearity (a) and
frequency tuning behaviour (b).
To conclude, 11 patents were deposited.
Moreover an Alliance for Nanosystems
VLSI between Caltech/KNI and Léti-
Minatec was created thanks to the
support of the Nanosciences Foundation.