Low-current Scanning Tunneling Microscope for Nanoscale Imaging

  • R.K. Kale Defence Institute of Advanced Technology, Pune
Keywords: Nanoscale imaging, low-current STM, nanotechnology, scanning tunneling microscopy, scanning probe microscopy


Advances in the nanotechnology, which is still in its infancy, will depend on our ability to
design, build, replicate, and mass-produce usable nanoscale systems. At sub-nanometer length
scales, scanning tunneling microscopy (STM) and the related techniques, collectively called
scanning probe microscopies, replace the optical microscopy for real-space imaging and
manipulation of materials. STM operation is based on measurement of current due to tunneling
of electrons across a finite potential barrier between the probe and the sample. In conventional
STM, tunneling current of tens of nA and probe-sample distance of a few Å are maintained.
These conditions, while necessary for atomic-scale imaging under ultra high vacuum environment,
are not suited to handle nanostructures. Quantum structures deposited on a flat substrate usually
present a non-metallic sample, and the roughness levels involved are much too high for
conventional STM. STM operation with low tunneling current (few pA) and larger tunneling gap
(several nm) is preferred to overcome these difficulties. This paper presents experimental work
and theoretical considerations for developing an atmospheric low-current STM (LC-STM).
Researchers from diverse fields can build their own LC-STM for routine imaging and spectroscopy.
Several design details are included keeping this aspect in mind.
How to Cite
Kale, R. (2006). Low-current Scanning Tunneling Microscope for Nanoscale Imaging. Defence Science Journal, 56(4), 599-613. https://doi.org/10.14429/dsj.56.1926
Electronics & Communication Systems