0000000000165828
AUTHOR
M. Ahlskog
Strain sensing with sub-micron sized Al-AlOx-Al tunnel junctions
We demonstrate a local strain sensing method for nanostructures based on metallic Al tunnel junctions with AlOx barriers. The junctions were fabricated on top of a thin silicon nitride membrane, which was actuated with an AFM tip attached to a stiff cantilever. A large relative change in the tunneling resistance in response to the applied strain (gauge factor) was observed, up to a value 37. This facilitates local static strain variation measurements down to ~10^{-7}.
Environmental chamber for an atomic force microscope.
A commercial atomic force microscope (AFM), originally designed for operation in ambient conditions, was placed inside a compact aluminum chamber, which can be pumped down to high vacuum levels or filled with a desired gaseous atmosphere, including humidity, up to normal pressure. The design of this environmental AFM is such that minimal intrusion is made to the original setup, which can be restored easily. The performance inside the environmental chamber is similar to the original version.
Conduction properties of semiconductive multiwalled carbon nanotubes
AbstractWe have undertaken low-temperature conduction measurements on arc-discharge synthesized, semiconducting multiwalled carbon nanotubes (MWNT). The diameters of these are in the range 2.5–10 nm, corresponding to the sizes just above single-walled carbon nanotubes (SWNT), up to middle-sized MWNTs. The energy gap, inversely related to the diameter, varies strongly in this range, and consequently there is a strong dependence of the transport on tube diameter. Certain transport characteristics are much alike those found in SWNTs, such as the ON-state resistance and Coulomb blockade. However, the transport gap has a more complex behavior than the corresponding one in semiconducting SWNTs, a…
Lateral force microscopy of multiwalled carbon nanotubes
Carbon nanotubes are usually imaged with the atomic force microscope (AFM) in non-contact mode. However, in many applications, such as mechanical manipulation or elasticity measurements, contact mode is used. The forces affecting the nanotube are then considerable and not fully understood. In this work lateral forces were measured during contact mode imaging with an AFM across a carbon nanotube. We found that, qualitatively, both magnitude and sign of the lateral forces to the AFM tip were independent of scan direction and can be concluded to arise from the tip slipping on the round edges of the nanotube. The dependence on the normal force applied to the tip and on the ratio between nanotub…