page_title: Multi-tip scanning tunneling microscopy
section_title: Introduction
hierarchical_section_title: Multi-tip scanning tunneling microscopy / Introduction
caption_attribution_description: English: Four-tip STM
context_page_description: Multi-tip scanning tunneling microscopy extends scanning tunneling microscopy from imaging to dedicated electrical measurements at the nanoscale like a ″multimeter at the nanoscale″. In materials science, nanoscience, and nanotechnology, it is desirable to measure electrical properties at a particular position of the sample. For this purpose, multi-tip STMs in which several tips are operated independently have been developed. Apart from imaging the sample, the tips of a multi-tip STM are used to form contacts to the sample at desired locations and to perform local electrical measurements.
context_section_description: As microelectronics evolves into nanoelectronics, it is essential to perform electronic transport measurements at nanoscale. The standard approach is to use lithographic methods to contact nanostructures, as it is also used in the final nanoelectronic device. In research and development stages, however, other methods to contact nanoelectronic devices or generally nanostructures may be more suitable. An alternative approach for contacting nanostructures uses the tips of a multi-tip scanning tunneling microscope—in analogy to the test leads of a multimeter used at macroscale. The advantages of this approach are: (a) in situ contacting of ″as grown″ nanostructures still under vacuum helps keep delicate nanostructures free from contamination induced by lithography steps performed for contacting. (b) Flexible positioning of the contacting tips and different contact configurations are easy to realize, while lithographic contacts are fixed. (c) Probing with sharp tips can be non-invasive (high ohmic), while lithographic contacts are typically invasive (low ohmic). To use a scanning tunneling microscope (STM) for electrical transport measurements at nanostructures or at surfaces, more than one tip is required. This motivates the use of multi-tip scanning tunneling microscopes which give access to the above outlined advantages in nanoprobing. Several review articles about multi-tip STM can be found in the further reading section below.
caption: Four-tip STM with the four tips pointing up in the center. The diameter of the instrument is 50 mm.
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