Apr 23, 2010
Etched carbon fibre tip suits dual STM/AFM systems
Researchers at the University Autonoma of Madrid, Spain, have implemented a combined scanning tunnelling microscope (STM) and atomic force microscope (AFM) with carbon-based tips. The tips are made from a single carbon fibre that is seven microns in diameter and can be handled easily with regular tweezers. An electrochemical etching procedure is used to form a sharp tip apex.
The remarkable electrical and mechanical properties of carbon fibre make these tips more suitable for combined and/or simultaneous STM and AFM than conventional metallic tips. For instance, the high resistance to oxidation means that the carbon fibre tips can be used over several days in air without a significant degradation in their STM operation. Moreover, the extraordinary mechanical properties of carbon fibre allow the tips to be lightweight, rigid and much more robust against accidental tip crashes than metallic tips.
Opening up new possibilities
The development of tips based on novel materials has extended the capabilities of local probe techniques. The ability to chemically modify the tip surface may open up new possibilities to study molecular electronic devices or biofunctionalized surfaces.
Carbon-based tips may also allow the local properties of surfaces to be studied with scanning probe techniques under extremely oxidative environments, measuring electric transport through carbon-based nanostructures and probing mechanical and electrical properties of molecules on surfaces.
The researchers presented their results in the journal Nanotechnology.
About the author
The study was conducted by researchers from the Condensed Matter Physics Department, University Autonoma of Madrid, Spain. Andres Castellanos-Gomez is a PhD student in the Low Temperature Laboratory (LBT). He is currently studying the electronic properties of graphene using the combined STM/AFM developed in this work. This study has been carried out under the supervision of Prof. Nicolas Agraït from the LBT and the Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia) and Prof. Gabino Rubio-Bollinger from the LBT. They are working on single-molecule electronics and electron transport, mechanics and superconductivity at the atomic scale. This work was supported by MICINN (Spain) (MAT2008-01735 and CONSOLIDER en Nanociencia molecular CSD-2007-00010) and Comunidad de Madrid (Spain) through the program Citecnomik (S_0505/ESP/0337) and a graduate fellowship.