Vjachslav Ksenofontov PhD senior researcher [e-mail]

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Vjachslav Ksenofontov PhDsenior
researcher mikhailovskij_at_kipt.kharkov.ua

• National Scientific Centre Kharkov Institute of
  Physics and Technology,
• Kharkov, Ukraine

High-field technology for processing of
nano-sized objects
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• Developed technology for nano-scaled
  objects provides for surface modification into
  atomically smooth state.
• Applications
• - ultra-sharp atraumatic microsurgical
  instruments
• - ultra-fine microprobes for scanning
  tunneling microscopes
• - field emitters with localized
  emission.

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• The technology is based on the discovered
  phenomenon of field evaporation of metals in
  dielectric liquids and gas stimulated field
  evaporation.
• Previous method of field evaporation in high
  vacuum, faced problem caused by the destruction
  of objects under mechanical stress generated by
  super-high electric field.

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SMOOTHING METAL SURFACE BY LOW-TEMPERATURE FIELD
EVAPORATION

• UHV
  conditions, T21 K

Atomic smoothing during field evaporation
Surface of tungsten nanotip before treatment
Destruction at mechanical stress due to high
electric field F 60V/nm, s 20 GPa
(Theoretical Strength)
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SURFACE FORMING BY FIELD DESORPTION (Computer
modeling)
Nanotip 100 orientation

• Pulse field desorption

Evaporation rate 0.01 nm/s
Alternative field evaporation of nanotips KIPT
Kharkov, together with Oxford University, UK
(Prof. G.Smith) and Hahn-Meitner-Institute,Berlin
(Dr.N.Wanderka)
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PHENOMENON OF LOW-TEMPERATURE FIELD EVAPORATION
IN DIELECTRIC LIQUIDS
High-field forming without mechanical destruction
Electron microscopic image of W microtip after
high-field treatment in liquid nitrogen
a
b
FIM images W nanotips formed by
evaporation in liquid nitrogen at 0.4 kV (a) and
1.2 kV (b).
Joint patents with Dr. R. Forbes, University of
Surrey School of Electronic, UK Dr. N.
Wanderka, Hahn-Meitner-Institute, Berlin, Germany
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RATES OF FIELD EVAPORATION IN DIELECTRIC LIQUIDS
AND ACTIVE GASES
Gases hydrogen stimulated evaporation. Nb-Ti at
0.82 (1) and 0.25 (2) Pa
Evaporation in UHV (1) and liquid nitrogen (2) of
W Blunting of nanotips
Sharpening of nanotips
Joint patent with Dr. R. Forbes, University of
Surrey School of Electronic, UK
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FIELD EVAPORATION IN ACTIVE GASES Sharpening of
nanotips
15 s
10 s
5 s
R2 nm
0 s
W N2
Nanotip 100 orientation
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HIGH-FIELD FORMING OF STM MICROPROBES AND
MICROSURGICAL INSTRUMENTS
STM probe before (a) and after (b) high-field
sharpening
a
b
Graphite surface image obtained in the STM with
an atomically smooth microprobe
a
b Microknife (a) and Satoknife (b) Segment of
market related to medical instrumentation is
about 100000 per year
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PROBLEM OF FIELD-EMISSION NON-UNIFORMITY

• CNT (regular array)

• CNT-film (random)

CNT bundles (aligned)
SEM image of cross-section of film

Large-scale field emission J.Chen et
al,Ultramicroscopy 95 (2003) 153
Collapsed CNTs W.Yu et al, Nanotechnology
16 (2005) S291
Top-down view
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Next step proposed - HIGH-FIELD FORMING
OF CARBON, SILICON, AND OXIDE NANO-SIZED OBJECTS
- SELF-CONSISTENT HIGH-FIELD FORMING OF
NANORELIEF

• Field-ion emission of nanofibre carbon emitter

b
c
a
Nanorelief before (a), during (b) and after (c)
stimulated field evaporation
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OUR TEAM

• Mikhailovskij Igor, Dr. Sci., Prof., Leading
  researcher
• Mazilova Tatjana, Dr Sci, Senior researcher
  Ksenofontov Vjacheslav, PhD, Senior researcher
  Velikodnaya Olga, PhD, Researcher
• Sadanov Evgenij, PhD, Researcher
• Thank you for your attention!