Structure and stability of semiconductor tip apexes for atomic force microscopy

Pou, P. and Ghasemi, S. A. and Jelinek, P. and Lenosky, T. and Goedecker, S. and Perez, R.. (2009) Structure and stability of semiconductor tip apexes for atomic force microscopy. Nanotechnology, Vol. 20, H. 26 , 264015, 10 S..

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Official URL: http://edoc.unibas.ch/dok/A5251774

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The short range force between the tip and the surface atoms, that is responsible for atomic-scale contrast in atomic force microscopy (AFM), is mainly controlled by the tip apex. Thus, the ability to image, manipulate and chemically identify single atoms in semiconductor surfaces is ultimately determined by the apex structure and its composition. Here we present a detailed and systematic study of the most common structures that can be expected at the apex of the Si tips used in experiments. We tackle the determination of the structure and stability of Si tips with three different approaches: (i) first principles simulations of small tip apexes; (ii) simulated annealing of a Si cluster; and (iii) a minima hopping study of large Si tips. We have probed the tip apexes by making atomic contacts between the tips and then compared force-distance curves with the experimental short range forces obtained with dynamic force spectroscopy. The main conclusion is that although there are multiple stable solutions for the atomically sharp tip apexes, they can be grouped into a few types with characteristic atomic structures and properties. We also show that the structure of the last atomic layers in a tip apex can be both crystalline and amorphous. We corroborate that the atomically sharp tips are thermodynamically stable and that the tip-surface interaction helps to produce the atomic protrusion needed to get atomic resolution.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Physik (Goedecker)
UniBasel Contributors:Goedecker, Stefan
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:IOP Publ.
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:17 Apr 2020 03:10
Deposited On:22 Mar 2012 13:57

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