1
Nanorobotic Strategies for Handling and Characterization of
Metal Assisted Etched Silicon Nanowires
Christian Stolle1, Malte Bartenwerfer1, Caroline Celle2, Jean-Pierre Simonato2 and Sergej Fatikow1, Fellow, IEEE
1
Division Microrobotics and Control Engineering, University of Oldenburg, Germany
2
CEA-Grenoble, LITEN/DTNM/LCRE, France
This paper gives insight into nanorobotic handling and electrical characterization of silicon nanowires inside a scanning electron
microscope. The synthesis of metal assisted etched, both end doped silicon nanowires is presented. Several nanorobotic pick and place
strategies for handling individual nanowires are discussed. Key approaches such as force-based and adhesive bonding (focus ion and
electron beam induced deposition) have been realized experimentally and evaluated towards their suitability for automation.
Preliminary results on electrical characterization are presented.
Index Terms—Nanorobotics, silicon-nanowires, handling strategies, material characterization, electrical characterization
I. INTRODUCTION
N
in general objects with dimensions in the
nanometer regime have grown more and more in
importance over the last years. Especially carbon nanotubes,
different types of metallic, metal-alloy, semi-conducting, and
insulating nanowires offer outstanding and partly unique
physical properties caused by their atomic configuration and
their tiny size, which primarily affects of all the surface-tovolume-ratio.
Nanotubes and nanowires are predetermined to improve
sensors and even actuators in several ways. This is not related
to size, sensitivity, and performance only [1], but also to
energy consumption and the prospects of new material
properties on the nanometer scale caused by quantum
mechanics, such as ballistic electron transport [2]. For these
reasons, nanotubes and nanowires are discussed to be crucial
parts in novel sensors, actuators, and ICs based on these
structures. All application fields of sensors are addressed:
temperature, flow, chemistry, biosensors, pressure, strains,
resonators, and antennas [3, 4, 5, 6, 7, 8].
Among nanowires, one of the most discussed kinds are
silicon nanowires (SiNW). Due to the fact that this material is
very well know in the entire microelectronics- and MEMSindustry, several processing and modeling techniques are
known and available, mostly for bulk- and surfacemicrofabrication. For most semiconductor products, silicon
technology is the basis and therefore, the application of
SiNWs add low contamination risk by similar material
properties such as thermal expansion. Overall, the interest of
SiNWs is reported in several publications over the past few
years [9, 10, 11, 12, 13]. Especially, SiNWs are discussed to
work as light traps for solar cells [14], tunneling field effects
transistors [1], transducers for biological/chemical sensors and
first of all transducers for all kinds of nano-electromechanical
systems [15, 16].
Despite the growing interest, the high understanding of
silicon, and all positive attributes of nanowires, they are hardly
ANOMATERIALS
Manuscript received April 8th, 2011. Corresponding author: C. Stolle (email: christian.stolle@uni-oldenburg.de).
Digital Object Identifier inserted by IEEE
used as individual objects, even though all proposed
applications would benefit especially from the utilization of
single nanowires. Some of the main challenges for a
successful and directed application in industrial products still
remain. For instance, the techniques for positioning of the
aforementioned individual nanowires between two metallic
electrodes for electrical characterization in a reproducible way
are still in their infancy.
In general there are two different approaches to tackle this
challenge. The bottom up approach often referred to as selfassembly and the top-down approach that tries to scale down
techniques and strategies from the macro world to the
nanoworld. Self-assembly strategies that have been applied to
this specific challenge are dielectrophoresis [17] and sliding or
fluidic motion [18, 19]. Robotic handling of nanowires has
been reported in [20, 21].
The rest of this article is organized as follows: Section II
describes the microrobotic setup which has been used
throughout the handling experiments. The synthesis process of
the SiNWs is described in detail in Section III. Different
handling strategies are identified and their applicability is
discussed based on the experimental results in Section IV. In
Section V the main results of the electrical characterization are
presented, and finally the article is concluded in Section VI.
Fig. 1: Microrobotic set-up for handling and characterization of SiNWs.
2
Fig. 2: In lens Detector image of the doped nanowires. The differently
doped regions are visible due to different electron absorption levels.
II. EXPERIMENTAL SETUP
A nanorobotic system consisting of a coarse and a fine
positioning stage (Fig. 1) has been set-up. The coarse
positioning stage has three degrees of freedom (DoF). It
consists of linear axes, which are arranged as a Cartesian robot
system. The z-axis is carrying an endeffector mounting. All
three axes are slip-stick-driven with build in optical position
sensors. The linear axes offer strokes of 35 mm in the x- and
y-direction and 27 mm in the z-direction with a resolution of
several nanometers.
In contrast to the high velocity and range of the coarse
positioning system, the fine positioning system (3 DoF) is
based on piezo stacks, and offers a resolution of 1.6 nm. The
three orthogonally aligned axes have a maximum stroke of
50x50x50 μm and build in capacitive sensors.
Combining a coarse and a fine positioning robot system
enables large work space, while keeping high resolutions.
These advantages are required for switching between several
substrates and still having a high enough resolution for
aligning nano-objects. During the experiments the coarse
positioning unit was carrying manipulation tools such as
grippers and tungsten tips. The different SiNW-substrates and
electrical characterization structures were mounted next to
each other and on top of the fine positioning stage tilted
towards the handling tool (see Fig. 1).
The entire system has been modular designed and can be
mounted onto the stage of a scanning electron microscope
(SEM) chamber. This way, most of the workspace of the SEM
stage can be used, including tilting and rotating, to position the
robotic setup optimally inside the view of the SEM and
towards the SEM’s secondary electron detector.
For the force closure handling experiments a LEO 1450
SEM is used. The adhesive bond handling experiments took
place in an FEI Quanta 600 SEM. Finally, the ion-beam-based
handling experiments took place in a Tescan Lyra 3 fieldemitter SEM with focused ion beam (FIB).
layers were deposited in a 200 mm CVD Centura reactor
(Applied Materials) via epitaxial growth at 600 °C, using
silane (SiH4) and phosphine (PH3) diluted in hydrogen [24]. A
stack of three silicon layers is build. The first layer has a
thickness of 3µm, is highly phosphorous n-doped (2.1019
at/cm3). The second layer is 5 µm thick and is nonintentionally doped (4.1017at/cm3). The third layer has a
thickness of 3µm, and is highly phosphorous n-doped
(2.1019at/cm3).
The chemicals AgNO3 (99.9%), HF (>40% and 1%), HNO3
(65–68%), H2O2 (30%) and H2SO4 (> 98%) were used, as
received from Aldrich without further purification. The
aqueous solution HF (10%)/AgNO3 (0.02M) were used for the
synthesis of SiNWs.
Silicon wafers were cut into 1 cm2 chips and were immersed in
a piranha solution (1:3 vol. of H2O2:H2SO4) for 15 min, rinsed
with deionised water, and were finally blown dry with argon.
Before etching, the chips were cleaned by a 30s dipping in HF
1% at room temperature, followed by rinsing with DI water
and drying under argon flow. First, the cleaned silicon chips
were immersed into aqueous HF and AgNO3 reactants. The
process was carried out at 50°C. After etching, samples were
rinsed with diluted HNO3 to entirely remove silver and
thoroughly washed with DI water.
The morphologies of the samples were observed by SEM
(LEO 1530) and the highly doped wire-ends are easily
observable in Fig. 2. The density of nanowires was ca. 200
SiNWs.µm-² and the mean diameter ca. 50 nm.
IV. HANDLING STRATEGY
Robotic handling of nanowires introduces several
challenges which are distinct from those in macro robotic
handling. For example, the influence of adhesive forces
compared to gravity increases, such that gravity is the smallest
force starting in the low micrometer scale [25]. Therefore,
III. SYNTHESIS OF BOTH END DOPED SINWS
Silver assisted electroless etching ) [22, 23] was chosen for the
synthesis of Si nanowires (SiNWs), because it is an easy,
rapid and straightforward route to make monocrystalline
SiNWs in high yield. Four-inch single-polished (100) silicon
wafers with doping profiles were used as substrates for the
SiNW-fabrication in order to obtain SiNWs bearing two
highly doped ends for electrical contact improvement. Silicon
Fig. 3: An outline of the SiNW handling task. It consists of four phases. The
pick and the place phase depend on the handling strategy.
3
contact areas of materials and tools strongly influence the
outcome of pick and place operations. In addition, materials
act differently in thin layers. While silicon will brittle break as
bulk material during bending, it becomes very flexible in the
shape of a nanowire. These challenges need to be addressed
for successful manual handling operation and especially
automation. Therefore, experiments on several handling
strategies have been performed and investigated with different
SiNWs and the results are presented in this section.
Pick and place operations can be subdivided into four
different phases (see Fig. 3): Selection, pick, transport and
place phase. During the selection phase a nanowire needs to be
identified which fulfills the following requirements:
 the dimension of the nanowire needs to meet the
target’s requirements (e.g. length to fill the gap
between two electrodes), and
 the spacing between the nanowire and the surrounding
needs to be large enough to move the handling tool into
contact.
This task can be time consuming depending on the layout of
the nanowire substrate. The nanowires for the handling
experiments (Fig. 2) are rather dense. For an automation of the
pick and place process a preprocessing of the substrate or a
substrate with defined spaces between single nanowires as
described [21] would be required. The alignment of tool and
nanowire in a way that their relative distance is below 10 µm
finalized this step in our experiments. The pick phase itself is
tool dependent and described in the following subsections.
The transport phase is used to move the tool towards the
target structure with the nanowire. In the scope of our
experiments the SiNW substrate has been lowered and the
target substrate with the four point probe has been moved
below the tool. A course z-alignment has been performed such
that the distance between the nanowire and the target substrate
surface was below 1 µm. The place phase is, similar to the
pick phase, tool dependant and is described in the following
subsections.
The most time consuming steps of the pick and place phase
are the fine alignment phases. The uncertainty about the actual
z-position leads to lowering the tool towards the substrate or
the nanowire stepwise.
A. Force Closure Handling Approach
The force closure handling experiments have been
performed with an electrostatic gripper (FT-G30, FemtoTools) with a maximum opening gap of up to 30 µm and a
gripper area of 20µm x 50µm. Fig. 3 (blue area) illustrates the
different tasks of the pick and place phases during force
closure handling.
The pick phase is subdivided into two steps. During the
pick step the nanowire is clamped between the gripper jaws.
Then in the pull out step the nanowire is separated from the
substrate. The most obvious approach is a pull-out movement
perpendicular to the substrate surface. However, this method
mostly fails because the clamping forces that can be applied
by the gripper jaws are smaller than the forces that need to be
applied to break the nanowires. The second approach,
Fig. 4: Electrostatic microgripper grips a SiNW from the substrate.
separation of nanowire and gripper by a shearing-off
movement, is theoretically investigated and supposed to apply
much higher forces at the nanowires base [20]. In the
experimental performance, this approach achieved much better
results than the pull-out movement. However, the experiments
indicate, that this method cannot be applied to thinner
nanowires, since the higher flexibility of thinner wires
prevents them from breaking at the bottom. This particular
experiment is illustrated in Fig. 4 and shows the aligned
gripper and the nanowire before the first task (left) and the
gripped nanowire after the second task (right).
The outcome of the place phase is less predictable then the
grip phase. First, the gripper is opened. Then the nanowire is
brought into contact with the target structure. Due to the high
adhesive forces and the low gravity influence the SiNWs stick
to the gripper surface. Therefore, the nanowire needs to be
stripped off the substrate by increasing the adhesive forces
between the substrate and the nanowire, until they outweigh
the forces between the gripper and the nanowire. However,
this process is not predictable and failed during the
experiments. A functionalized target structure might overcome
this problem.
B. Adhesive Bond Handling Approach
During the following experiments a tungsten tip was used as
manipulation tool. The tips are prepared from a tungsten wire
(0.2 µm diameter) and cut into 10 mm long parts which are
soldered to a socket. The edges are thinned by etching in
NaOH leach. The average tip diameter was about 30 nm.
As an additional infrastructure adhesive bond handling
requires an SEM equipped with a gas injection system (GIS).
This allows injecting different precursor gases through micro
capillary tubes. Activated by the energy of the electron beam,
this technique facilitates beam-induced etching and beaminduced deposition [26].
The green squares in Fig. 3 indicate the different strategies
during adhesive bond handling in the pick and place phases.
The pick phase starts with the coarse aligned tip and nanowire.
First, the GIS is moved into its working position. The distance
of the GIS nozzle and the bond side needs to be such that the
4
Fig. 5: Schematic description of the adhesive bonding handling approach.
precursor gas concentration is high enough for a successful
deposition, but still far enough that the handling scene can be
monitored via the SEM image. In our experiments this
distance was at about 400-500 µm. The second step of the pick
phase is the actual beam-induced deposition and the
subsequent separation of the wire and the substrate. This step
is described in more detail in the following sections.
The adhesive bond place phase is illustrated in Fig. 5 where
a) indicates the pick phase. The tip and the target substrate are
aligned and brought into contact. The contact has been
detected by visually monitoring the deflection of the wire
during surface contact. The nanowire and the target substrate
are mechanically and electrically connected by several beaminduced deposition steps (Fig. 5b), one at each contact pad. As
precursor gas hexacarbonyltungsten has been employed. The
separation step (Fig. 5c) is technology dependant and will be
described in the following sections. The final result (Fig. 5d)
is a mechanically and electrically connected nanowire, which
can be characterized in absence of any disturbing influences
(e.g. the STM-tip or the electron beam). A successfully
established connection can be detected by measurements of
finger-to-finger resistances.
C. Fully EBiD-based Handling Experiments
During the fully electron beam induced deposition (EBiD)
based handling experiments all deposition steps are performed
by electron beam and hexacarbonyltungsten as precursor gas.
As separation strategy during the pick phase we tried two
different approaches. The nanowire and the STM tip are
detached by a) electron beam induced etching (EBiE) by
fluorine gas or b) by pulling the SiNW out of the substrate.
Neither strategy was very reliable. The EBiE strategy suffered
from hard to control precursor concentrations at the etching
side. The reliability increased when etching at the bottom of
the SiNW close to the surface and decreased on freestanding
nanowires. The second strategy was hard to control as well,
because the break position of the nanowire is hard to predict.
While the deposition itself is very stable the wire often broke
close to the deposition side because this was the position of
the highest stress due to bending forces.
During the place phase the welding process allows well
directed placing of wire and the electrical connection is
Fig. 7: SiNW positioned between the center electrodes of a four point probe.
The silicon substrates shows signs of under etching.
necessarily established during the tungsten deposition.
However, the direction of the etching process is hardly
controllable. While the silicon oxide surface layer requires the
electron beam for etching. The florin gas itself etches the pure
silicon substrate isotropically. The results can be seen in Fig.
7. The dark spots close to the electrodes indicate underetched
areas which influences the electrical measurement due to the
change in the conductivity of the substrate surface.
The most time consuming part of the fully EBiD-based
handling is the amount of time required for the deposition or
etching process itself. In our experiments we required five to
ten minutes for bonding and about three minutes for etching.
Another source of delay is the GIS itself which requires
outgassing and preheating of precursor reservoirs between
switching precursors.
D. Ion-Beam-based Handling Experiments
During the pick and place phases (Fig. 6) all deposition
steps are performed by FIB (Ga+) and tungsten as depositing
material. The nanowire and STM tip as well as the nanowire
and surface are detached by ion beam cutting (physical
Fig. 6: Handling sequence starting from SiNW-substrate (upper left), to the
electrical connected nanowire (lower right). Intermediate steps are tungsten
tip with SiNW (upper center), target substrate with tungsten tip (upper right),
target substrate with tungsten deposition electrical connecting the outer
electrodes (lower left) and SiNW connected by a tungsten deposition on one
side and connected to the tungsten tip on the other side (lower center).
5
Fig. 8: Final result of the ion beam-based handling experiments. A SiNW is
mounted between the inner electrodes of a four point probe.
etching).
The pick phase and the deposition step in the place phase
are similar to the fully EBiD-based approach. Therefore, this
handling strategy includes most of the advantages and
disadvantages of full EBID-based handling. However, the ion
beam-based deposition is very fast and avoids drift problems.
Ion cutting is regional without any collateral damage. In
addition, it avoids the switching of precursor gases since no
fluorine precursor is required and very fast (seconds) due to
the physical etching process. However, the instrumental effort
is the highest of all methods outlined in this article. The
outcome of the FIB-based experiments can be seen in Fig. 8.
The SiNW is interconnecting the inner electrodes of the
four point probe. The gap between the electrodes is about
5 µm long. The nanowire is electrically connected by squarelike tungsten depositions to the gold electrodes. The outer
electrodes are each connected by a wire-like tungsten
deposition to the corresponding inner electrode. Some
remaining nanowire and bond parts of previous experiments
can also be seen. However, they are not electrically connecting
the electrodes, so the influence on the electrical measurement
can be neglected and all electrical measurement analysis take
the state before nanowire placing in account. Small substrate
cuts can be seen to the left of the left SiNW-contact
deposition, which are due to the FIB etching process.
E. Handling Strategy Analysis
The main results of the handling experiments are illustrated
in Table 1. The risk of contamination of force closure handling
is negligible compared to adhesive force handling. For
adhesive force handling the deposition itself is a source of
controllable contamination. The contamination area can be
controlled by setting the area of the beam accordingly.
The pick reliability was high for the adhesive bond handling
process, and medium for the force closure bonding process.
The reason for this estimation is the issue of finding a suitable
1
If possible at all, SiNWs that meet the requirements for gripping are hard
to find
SiNW which meets the geometric constraints introduced by
the gripper. The EBiD- and gripper-based separation step both
had similar issues controlling the pull out of the SiNW. The
experiments indicate that the strategy is less successful for
smaller diameter nanowires than for larger ones. EBIE as
described in the previous section suffered from damaging the
substrate by under etching. The highest reliability could be
achieved by focused ion beam induced etching (FBiE). Both
EBiE as well as FBiE have the advantage that no force needs
to be applied during separation.
The reliability during the place phase was rather undefined
during the force closure handling approach. We did not
succeed in striking off the nanowire on the contact pads.
However, by structuring the contact area such that the gripper
does not touch the surface and functionalizing the contact
areas of the electrodes by increasing the adhesive forces, it
might be feasible to reproducibly place nanowires with a
gripper. Due to the under etching and the problem of
concentrating the precursor at the surface of the SiNW during
EBiE the adhesive bond handling had medium reliability
during the separation step. This problem is solved by the
focused ion beam induced deposition (FBiD) due to the very
defined impact of the ion beam.
The time effort for gripper based handling was medium.
The extra time was required for finding a suitable SiNW and
for separation. The effort for placing the nanowire to the
substrate is not taken into account. The EBiD/EBiE-based
adhesive bond handling has the most overhead due to the low
growth rate of the tungsten depositions and the preheating and
cooling of the precursor reservoirs. The FBiD/FBiE-based
approach overcame these problems due to the higher growth
rate and the very short separation overhead.
The electrical contact could not be guaranteed by the force
closure handling approach. Due to possible thin oxide layers
on the SiNWs as well as a weak mechanical contact the
electrical contact is rather undefined. The tungsten depositions
in the adhesive bond handling experiments however are
conductive and lead to a well defined mechanical and
electrical contact between the electrodes and the nanowire.
One major drawback of FBiD/FBiE handling is the high
instrumental effort. A GIS as well as a FIB is required. The
EBiD/EBiE approach is less expensive, however, it still
requires the GIS. The gripper handling experiments can take
place in a standard SEM and therefore this method is the least
Table 1
Main results of the adhesive bond and force closure handling experiments.
Contamination risk
Pick reliability
Place reliability
Time effort
Electrical contact
Instrumental effort
Automation of
handling
Gripper
based
handling
EBiD/EBiE
FBiD/FBiE
low
low1
undefined
medium1
undefined
low
low
high
medium
medium
long
yes
medium
medium
medium
high
high
small
yes
high
medium
Adhesive bond handling
6
1,E-06
1.10-6
1,E-07
1.10-7
5.10-4
5,E-04
1,E-09
1.10-9
4.10-4
4,E-04
-10
1,E-10
1.10
1/2)
√IDS (A(A^1/2)
Id^1/2
abs(Id) (A)
|IDS| (A)
1.10-8
1,E-08
3.10-4
3,E-04
2,E-04
2.10-4
1.10-4
1,E-04
-11
1,E-11
1.10
0
0,E+00
-30 -20 -10
-30
-10 00
Fig. 9: Comparison of the current-voltage characteristics. The curve shows
strong diode characteristics before the placement of the nanowire (blue) and
more ohmic characteristics after the placing (red).
expensive one. However, if we consider that the target
structure needs to be designed for gripper based handling, this
estimation might change.
The automation of the whole handling task strongly
depends on the reliability of the different steps. Low or
undefined reliability of the gripper based handling makes
gripper-based automation rather complicated. The best results
can be expected with FIB-based adhesive bond handling.
If we consider the scalability of these three approaches
gripper based handling has a rather limited scalability. While
down-sizing of the gripper is possible, the applicable force
also decays [27]. In contrast, the FIB has a medium scalability.
While etching is still possible at smaller structures the
deposition areas might not be much smaller due to the
reversing effects of material abrasion and deposition at smaller
deposition areas. The solution could be a mixed method of
EBiD and FBiE, because EBiD can deposit smaller structures
and is only limited by the diameter of the electron beam
impact area [28].
V. ELECTRICAL CHARACTERIZATIONS
An electrical characterization of the four-finger-sample is
performed before and after the placement of the nanowires.
Thus, the already semiconducting-behavior of the underlying
substrate can be subtracted in order to determine the
nanowire’s resistivity.
Fig. 9 shows the current-voltage characteristics of the fourfinger sample with and without placed nanowires. The fourfinger alone has a distinct diode-behavior caused by silicon of
the four-finger-smple carrier. After the placement of the
SiNW, the diode-characteristic almost vanishes and an ohmiccurve is measured. The resistivity of the nanowires can be
estimated by the difference of these measurements and
amounts to about 4 kΩ.
The ohmic characteristic of the nanowires measurement
confirms that the connected part of the wire consists of
intrinsic silicon only.
Another device was fabricated in order to investigate the
SiNW as a standard field effect transistor in a bottom gate–top
contact geometry. They were made up of SiNWs,
30
10 20 30
VVg
GS (V)
-12
1,E-12
1.10
-30
-30
-20
-20
-10
-10
00
10
10
20
20
30
30
Vg (V)
VGS (V)
Fig. 10: Transfer characteristic of localized SiNW field effect transistor in the
linear regime (VDS = -10 V).
mechanically handled onto highly As-doped silicon substrates,
and also used as gate electrodes, coated with 200 nm of
thermal SiO2 as a dielectric. Ti/Au (10/50nm) source and
drain pads were used. Fig. 10 exhibits the electrical
characterization of the undoped part of one nanowire bridging
the channel. Due to the nanowire release procedure, Tungstenbased FIB top contacts pads are used.
It clearly shows a field effect transistor behavior. This
device has exhibited effective mobility of 6 cm².V-1.s-1,
Ion/Ioff ratio of 2.105, Off current of 1.10-12A and
subtreshold slope of 1V/dec. Same performances have been
reported in the litterature on non flexible substrate [29]. These
first preliminary promising results demonstrate that it is
possible to fabricate SiNW-based FET with the mechanical
handling procedure. Further experiments are ongoing to
improve this issue.
VI. CONCLUSION AND FUTURE WORK
Throughout this paper we addressed several key challenges
related to robotic handling of single SiNWs. The synthesis of
both end doped SiNWs has been presented. A robotic handling
station for SiNWs has been setup inside the vacuum chamber
of an SEM/FIB. Several pick and place strategies have been
discussed in detail and their results are presented in Section
IV.
The experience gathered in the different handling sequences
and techniques reveals that deposition-based techniques are a
very promising approach, due to the controllability of the tiny
particles and the reliable electrical and mechanical junction.
An automation of the handling sequences could be possible
and would be a tremendous improvement of the experiment‘s
most time consuming elements such as alignment of
endeffector and SiNW as well as selection of a suitable SiNW.
Due to its reliability, FBiD/FBiE-based adhesive bond
handling has been identified as the most promising handling
technique for automation.
7
First preliminary yet promising electrical measurements on
mechanically handling nanowire were performed. As main
result, the resistivity of the intrinsic part of the nanowires is
determined by a high sensitive measurement engaging sensor
lead, while almost no diode characteristic could be discovered.
However, in order to improve the electrical characterization
results, the length of the nanowire has to be much longer than
the width of the four-finger-probe. This would enable a real
four-terminal sensing measurement. Therefore, specific
SiNWs etching has to be developed to allow easy handling
and picking of isolated and well organized nanowires [30].
Moreover surface functionalization should be considered for
gripping and releasing the nano-objects [31].
Further improvement with automated localization systems
can allow us to develop new electronic SiNW-based devices
such as sensors [13].
[14]
[15]
[16]
[17]
[18]
ACKNOWLEDGMENT
This research was supported in part by the European
integrated project Hydromel NMP2-CT-2006-026622.
[19]
[20]
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
M. T. Björk, J. Knoch, H. Schmid, H. Riel, and W. Riess, “Silicon
nanowire tunneling field-effect transistors,” Applied Physics Letters,
vol. 92, no. 19, p. 193504, 2008. [Online]. Available: http://link.aip.org/link/?APL/92/193504/1
A. Krüger, Neue Kohlenstoffmaterialien - Eine Einführung, ser.
Studienbücher Chemie. Teubner, 2007, vol. XIII.
N. Sinha, J. Ma, and J. T. W. Yeow, “Carbon Nanotube-Based
Sensors,” Journal of Nanoscience and Nanotechnology, vol. 6, p.
573–590, 2006. [Online]. Available: http://biomems.uwaterloo.ca/papers/JNN.pdf
U. Yogeswaran and S.-M. Chen, “A Review on the Electrochemical
Sensors and Biosensors Composed of Nanowires as Sensing Material,”
Sensors, vol. 8, pp. 290–313, 2008.
K. L. Ekinci, “Electromechanical transducers at the nanoscale:
Actuation and sensing of motion in nanoelectromechanical systems
(nems),” small, vol. 1, pp. 786–797, July 2005, review.
A. K. Hüttel, G. A. Steele, B. Witkamp, M. Poot, L. P. Kouwenhoven,
and H. S. J. van der Zant, “Carbon Nanotubes as Ultrahigh Quality
Factor Mechanical Resonators,” Nano Letters, vol. 9, no. 7, pp. 2547–
2552, 2009.
C. Rutherglen and P. Burke, “Nanoelectromagnetics: Circuit and
electromagnetic properties of carbon nanotubes,” Small, vol. 5, no. 8,
pp. 884–906, 2009. [Online]. Available: http://dx.doi.org/10.1002/smll.200800527
I. Popov, S. Gemming, S. Okano, N. Ranjan, and G. Seifert,
“Electromechanical switch based on mo6s6 nanowires,” Nano Letters,
vol. 8, no. 12, pp. 4093–4097, 2008. [Online]. Available: http://pubs.acs.org/doi/abs/10.1021/nl801456f
Y. Cui and C. M. Leiber, “Functional nanoscale electronic devices
assembled using silicon nanowire building blocks,” Science, vol. 291,
pp. 851–853, 2001. [Online]. Available: 10.1126/science.291.5505.851
W. Lu and C. M. Lieber, “Nanoelectronics from the bottom up,” Nature
Materials, vol. 6, no. 11, pp. 841–850, November 2007. [Online].
Available: http://dx.doi.org/10.1038/nmat2028
B. K. Teo and X. H. Sun, “Silicon-based low-dimensional
nanomaterials and nanodevices,” Chemical Reviews, vol. 107, no. 5, pp.
1454–1532, 2007. [Online]. Available: http://pubs.acs.org/doi/abs/10.1021/cr030187n
L. J. Chen, “Silicon nanowires: the key building block for future
electronic devices,” J. Mater. Chem., vol. 17 (44), pp. 4639–4643,
2007. [Online]. Available: http://dx.doi.org/10.1039/B709983E
S. Clavaguera, A. Carella, L. Caillier, C. Celle, J. Pecaut, S. Lenfant,
D. Vuillaume, and J. Simonato, “Sub-ppm detection of nerve agents
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
using chemically functionalized silicon nanoribbon field-effect
transistors.” Angewandte Chemie Int. Ed., vol. 49, pp. 1–5, 2010.
E. Garnett and P. Yang, “Light trapping in silicon nanowire solar
cells,” Nano Letters, vol. 10, no. 3, pp. 1082–1087, 2010, pMID:
20108969. [Online]. Available: http://pubs.acs.org/doi/abs/10.1021/nl100161z
G. Zheng, X. P. A. Gao, and C. M. Lieber, “Frequency domain
detection of biomolecules using silicon nanowire biosensors,” Nano
Letters, vol. 10, no. 8, pp. 3179–3183, 2010. [Online]. Available:
http://pubs.acs.org/doi/abs/10.1021/nl1020975
R. He, X. L. Feng, M. L. Roukes, and P. Yang, “Self-transducing
silicon nanowire electromechanical systems at room temperature,”
Nano Letters, vol. 8, no. 6, pp. 1756–1761, 2008, pMID: 18481896.
[Online]. Available: http://pubs.acs.org/doi/abs/10.1021/nl801071w
M. Lu, M.-W. Jang, G. Haugstad, S. A. Campbell, and T. Cui, “Wellaligned and suspended single-walled carbon nanotube film: Directed
self-assembly, patterning, and characterization,” Applied Physics
Letters, vol. 94, no. 26, p. 261903, 2009. [Online]. Available: http://link.aip.org/link/?APL/94/261903/1
X. Duan, C. Niu, V. Sahi, J. Chen, J. W. Parce, S. Empedocles, and
J. L. Goldman, “High-performance thin-film transistors using
semiconductor nanowires and nanoribbons,” Nature, vol. 425, pp. 274–
278, Sep. 2003. [Online]. Available: http://www.sciencedirect.com/science/article/B6WVB-49KTGDS-1FR/2/bb298bab2434024333844f44914c9f3a
G. Yu, A. Cao, and C. Lieber, “Large-area blown bubble films of
aligned nanowires and carbon nanotubes.” Nature Nanotechnology,
vol. 2, no. 6, p. 372, 2007.
K. N. Andersen, D. H. Petersen, K. Carlson, K. Molhave, O. Sardan,
A. Horsewell, V. Eichhorn, S. Fatikow, and P. Bøggild, “Multimodal
electrothermal silicon microgrippers for nanotube manipulation,” IEEE
Transactions on Nanotechnology, vol. 8, no. 1, pp. 76–85, January
2009.
T. Wich, C. Stolle, O. Frick, and S. Fatikow, “Automated NanoAssembly in the SEM I: Challenges in setting up a warehouse,” in
Proceedings of the 17th International Federation of Automatic Control
world congress, Seoul, pp. 12751–12756.
N. Megouda, R. Douani, T. Hadjersi, and R. Boukherroub, “Formation
of aligned silicon nanowire on silicon by electroless etching in hf
solution,” Journal of Luminescence, vol. 129, no. 12, pp. 1750 – 1753,
2009, special Issue based on The 15th International Conference on
Luminescence and Optical Spectroscopy of Condensed Matter
(ICL’08). [Online]. Available: http://www.sciencedirect.com/science/article/B6TJH-4WB3NJB-1/2/0016d2235d4b9754e306ca3fcff17083
K. Peng, H. Fang, J. Hu, Y. Wu, J. Zhu, Y. Yan, and S. Lee, “Metalparticle-induced, highly localized site-specific etching of si and
formation of single-crystalline si nanowires in aqueous fluoride
solution,” Chemistry – A European Journal, vol. 12, no. 30, pp.
7942–7947, 2006. [Online]. Available: http://dx.doi.org/10.1002/chem.200600032
S. Bozzo, J.-L. Lazzari, C. Coudreau, A. Ronda, F. A. d’Avitaya,
J. Derrien, S. Mesters, B. Hollaender, P. Gergaud, and O. Thomas,
“Chemical vapor deposition of silicon-germanium heterostructures,”
Journal of Crystal Growth, vol. 216, pp. 171–184(14), 15 June 2000.
[Online]. Available: http://www.ingentaconnect.com/content/els/00220248/2000/00000216/00000001/art00429
R. S. Fearing, “Survey of Sticking Effects for Micro Parts Handling,”
in Proc. of IEEE/RSJ Intl. Conference on Intelligent Robots and
Systems, Pittsburgh, PA, USA, 1995, pp. 212–217.
T. Wich, T. Luttermann, and I. Mircea, “Hardness determination of
EBiD-layers containing tungsten and cobalt,” in 3rd Int. Conference On
Computational
Methods
And
Experiments
In
Materials
Characterisation III, Bologna, Italy, June 2007, pp. 73–82.
T. Wich, Werkzeuge und Methoden zur Automatisierung der seriellen
Nanomontage im Rasterelektronenmikroskop. Logos Berlin, Oktober
2008, vol. 1.
I. Utke, P. Hoffmann, and J. Melngailis, “Gas-assisted focused electron
beam and ion beam processing and fabrication,” Journal of Vacuum
Science & Technology B: Microelectronics and Nanometer Structures,
vol. 26, no. 4, pp. 1197–1276, 2008. [Online]. Available: http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JVTBD900002600000400119700000
1&idtype=cvips&gifs=yes
C. Celle, A. Carella, D. Mariolle, N. Chevalier, E. Rouviere, and J.-P.
Simonato, “Highly end-doped silicon nanowires for field-effect
8
transistors on flexible substrates,” Nanoscale, vol. 2, pp. 677–680,
2010. [Online]. Available: http://dx.doi.org/10.1039/B9NR00314B
[30] S.-W. Chang, V. P. Chuang, S. T. Boles, C. A. Ross, and C. V.
Thompson, “Densely packed arrays of ultra-high-aspect-ratio silicon
nanowires fabricated using block-copolymer lithography and metalassisted etching,” Advanced functional materials, vol. 19, pp. 2495–
2500, 2009.
[31] C. Suspene, R. Barattin, C. Celle, A. Carella, and J.-P. Simonato,
“Chemical functionalization of silicon nanowires by an electroactive
group: A direct spectroscopic characterization of the hybrid
nanomaterial,” The Journal of Physical Chemistry C, vol. 114, no. 9,
pp. 3924–3931, 2010. [Online]. Available: http://pubs.acs.org/doi/abs/10.1021/jp912118m