Introduction to NanoEducator

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Introduction to NanoEducator
NanoEducator is a device designed for training in
basic SPM techniques STM, SFM, nanolithography
1- base , 2-sample holder , 3-probe , 4- probe
fixing screw, 5- approach screw, 6- x,y
table, 7-camera
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NanoEducator structure
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NanoEducator scanner
The NanoEducator scanner is a tripode structure,
obtained with 3 bimorph piezo disks attached to 3
stems that support the sample holder
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NanoEducator vibrating probe
The probe is a piezo tube with 3 electrodes
the inner electrode is grounded, the two outer
electrodes provide excitation and detection of
the tube flexural vibrations
The frequency is swept in a wide range to select
the resonance peak
5
The resonance curve and the amplitude-distance
curve
The oscillation amplitude changes with frequency
(left) and with probe-sample distance (right)
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Vibration amplitude change
When approaching the probe to the sample, the
oscillation amplitude decreases because the
resonant peak shifts to a lower value
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The tip sharpening tool
The piezo probe with a bent tungsten wire
inserted.
Tip etching by electrochemical corrosion in KOH
solution.
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Calibration grating
TGX1 calibration grating
TGT calibration grating
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Calibration grating 2
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Cracks in InGaAs/InP films
Top view
3D view (note the
different scale for x,y and z axes)
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Nanostructures
Indium Arsenide epitaxially grown on GaAs. The
image shows both the substrate atomic planes and
the InAs nanostructures
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Submonolayer film
1.7 Monolayers of InP on GaAs. The film, grown
layer-by-layer does not complete the first atomic
layer before starting the next
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SPM-Lithography types
Depending on the operating mode, lithography can
be done in different ways by applying voltage
pulses between the probe and the sample when
working in STM mode or with conductive
cantilevers in AFM mode or by "scratching" , or
engraving the surface with the probe when
working in SFM mode or by using the probe (and
applied voltage) to displace atoms on a smooth
sample surface.
- STM lithography - AFM anodic-oxidation
lithography - SFM force lithography
An example of STM nanomanipulation. IBM company
name is composed of Xenon atoms precipitated on
the nickel surface.
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Anodic oxidation lithography
This method is used in air, when tip and sample
are covered by a thin water layer. When the tip
approaches the sample a water bridge is formed
due to the capillary effect. An applied voltage
triggers an electrochemical reaction. If the
sample is charged positively, an oxide layer is
formed under the tip apex.
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Force lithography
(a) Schematic diagram of static force lithography
(b) image of Al surface (1,6?1,6 ?m2) with a
scratch
Examples of vector dynamic force lithography
(nanoembossing) the surface is modified due to
indentations formed by oscillating tip in
semicontact mode
(a) regular array of pits (220?220 nm2) (b)
raster lithography (2,5?2,6 ?m2 )
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Lithography with NanoEducator
Spectroscopy procedure to evaluate the clearance
between the tip and the sample using the
amplitude vs. distance curve
Load the pattern image (.bmp graphics format) to
be lithographed. Press Projection button to
project the pattern image to the field of
scanning and to form the matrix of pits.