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The latest instrument of SCSAM,
presently being constructed, is a
variable-temperature ultra-high vacuum
scanning probe microscope, made by RHK
Technologies. This instrument is part of a
complete UHV (ultra-high vacuum) system,
which includes a separately pumped specimen
preparation chamber and a load-lock chamber
in addition to the actual SPM (scanning
probe microscopy) chamber. The base
pressure of the system is specified to
2·
10–12 Pa.
In the preparation chamber, an electron
gun combined with a hemispherical electron
energy analyzer will be attached to enable
chemical analysis of the specimen surface
via Auger electron spectroscopy. A specimen
manipulator will be installed on the
vertical axis of the chamber for precise
positioning of the specimen in front of the
electron energy analyzer. The manipulator
can be connected to a cryostat via a
differentially-pumped rotary stage,
permitting us to cool the specimen down to
≈25 K. By resistive or
electron-beam heating, it will also be
possible to heat the specimen up to
temperatures of ≈1500 K.
To be able to clean the specimen
surface, the system will include an Ar
sputter gun. Evaporators installed at ports
in the lower half of the chamber will
enable the deposition of metals onto the
specimen surface. A gas dosing system will
facilitate gas adsorption experiments
without backfilling the entire chamber or
opening the main chamber to change gases. A
mass spectrometer will constantly detect
and analyze residual gas in the chamber.
Finally, the preparation chamber will
include a port large enough to install a
retractable reverse view LEED (low-energy
electron diffraction) system for studying
the surface structure of the specimen.
Using a magnetic transfer arm, the
specimen can be moved from the preparation
chamber into the actual SPM chamber. This
chamber houses a cantilever atomic force
microscope combined with a scanning
tunneling microscope, suitable to image the
surface structure of conducting as well as
non-conducting materials. Both instruments
will be capable of atomic-resolution
imaging. The scanning tunneling microscope
will also permit to probe the local work
function and the local density of states in
the specimen surface by STS (scanning
tunneling spectrometry). All modes of SPM
will work over a very broad range of
specimen temperatures: 25 to
≈750 K. The SPM chamber is
designed to accept thermal evaporators, a
sputter gun and a gas dosing system that
can perform their functions while the
sample is actively being studied by any of
the available scanning probe
techniques.
This material is based upon
work supported by the Department of Defense
(DoD) through the Army Research Office
(ARO) under contract no. CON047671.
Any opinions, findings, and conclusions or
recommendations expressed in this material
are those of the author(s) and do not
necessarily reflect the views of the
DoD/ARO.
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