Third Day Poster Session, 17 June 2010 - NanoTR-VI

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Poster Session, Thursday, June 17
Theme F686 - N1123
Construction of a Combined Non-Contact Atomic Force Microscope & Scanning Tunnelling
Microscope (nc-AFM/STM)
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UDerya GemiciUP P*, Hüsnü AslanP P, Özhan ÜnverdiP Ahmet OralP
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PFaculty of Engineering & Natural Sciences, Sabancı University, Istanbul, 34956, Turkey
Abstract-A combined non-contact Atomic Force Microscope (nc-AFM) & Scanning Tunnelling Microscope (STM) operating in Ultra
High Vacuum(UHV) has been designed and constructed. The nc-AFM uses a fiber interferometer and Digiatl Phase Locked Loop for high
resolution detection of cantilever displacements.
In the early 1980's two IBM scientists, Binnig & Rohrer,
developed a new technique for studying surface structure
at atomic scale - Scanning Tunnelling Microscopy(STM).
This invention was quickly followed by the development
of a whole family of related techniques called Scanning
Probe Microscopy (SPM). The most important SPM
method is the Atomic Force Microscopy (AFM) where the
tip-sample forces are measured to obtain topography of the
sample even at the atomic scale. The inventions of STM
and AFM revolutionised the surface science, helping
scientist to resolve the atomic structure of surfaces in real
space.
In this work, we have designed and constructed a
combined non-contact Atomic Force Microscope (nc-
AFM) & Scanning Tunnelling Microscope (STM) based
on fiber interferometer for the imaging surfaces ranging
from non-conducting to conducting and from hard to soft
and delicate samples in Ultra High Vacuum(UHV). The
design is based on our previous work [3,4] with substantial
improvement in vibration isolation and ease of assembly.
UHV by imaging Gold evaporated on glass. STM images
of this specimen is given in Figure 3.
Figure 2. Optical Microscope images of home-made tungsten tips
have been used for the experiment
Figure 3. The STM image of of gold surface at UHV,
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p < 3×10P IRT R= 0.3 nA & VRBiasR = 1 V
This work is supported by TÜBTAK , Project Number
108T001, Ministry of Industry & Commerce, Project
Number 409.STZ.2009-1 and NanoMagnetics Instruments
Ltd.
*Corresponding author: deryagemici@sabanciuniv.edu
Figure 1. Photograph of the home made combined nc-
AFM/STM.
We have designed the combined microscope using
Solidworks CAD program, the parts are machined at the
workhops around Ankara. The final assembled nc-
AFM/STM is shown in Figure 1 is mounted on a special
8’’ CF flange. The base of the microscope is suspended
using springs mounted on adjustable collars attached to
four posts. In order to damp the external vibrations eddycurrent
damping is used. Twenty eight SmCo magnets
attached separately to the posts on a magnet holder as
shown in Figure 1 are surrounded by copper plates fixed to
the microscope base, the height of the magnet ring can be
adjusted to set the desired damping coefficient. Tungsten
tips are etched in KOH solution as shown in Figure 2. The
microscope is going to be mounted in a separate UHV
system, but the initial tests are performed in our existing
UHV system. Nc-AFM/STM is tested for STM only in
[1] G. Binning, H. Rohrer ‘Scanning Tunnelling Microscopy’,
Helvetica Physica Acta, 55,726 (1982)
[2 ] S.Morita,R.Wiesendanger, E.Meyer ‘Noncontact Atomic
Force Microscopy’ pg 11-76 principle of NC AFM and
semiconductor surfaces
[3] M. Atabak, PhD Thesis, 2007, Bilkent University
[4] M. Atabak, Ö. Ünverdi, H.Ö. Özer & A. Oral, J. Vac. Sci.
Technol. B 27, 1001 (2009)
6th Nanoscience and Nanotechnology Conference, zmir, 2010 667