| AVS 59th Annual International Symposium and Exhibition | |
| Scanning Probe Microscopy Focus Topic | Tuesday Sessions |
| Session SP+AS+BI+ET+MI+NS-TuA |
| Session: | Advances in Scanning Probe Imaging |
| Presenter: | M. Ondracek, Institute of Physics of ASCR, Czech Republic |
| Authors: | M. Setvin, Institute of Physics of ASCR, Czech Republic M. Ondracek, Institute of Physics of ASCR, Czech Republic P. Mutombo, Institute of Physics of ASCR, Czech Republic Z. Majzik, Institute of Physics of ASCR, Czech Republic P. Jelinek, Institute of Physics of ASCR, Czech Republic |
| Correspondent: | Click to Email |
Scanning Probe techniques are widely used to image atomic and electronic structure of surfaces and nanostructures. However atomic and chemical resolution of complex nanostructures (e.g. molecules, nanoparticles or nanowires) is still the large challenge. Several methods (see e.g. [1-3]) have been already proposed to achieve the single-atom chemical resolution. In the work [3] it was showed that the single-atom chemical identification can be achieved via force-site spectroscopy measurements using Frequency Modulation Atomic Force Microscopy (FM-AFM). The validity of the method was demonstrated on semiconductor surface alloy composed of isovalent species (Si, Sn and Pb). In this particular case, the valence electrons of surface atoms possess very similar electronic structure close to sp3 hybridization with characteristic dangling bond state. Hence the maximum short-range force is mainly driven by the position of the dangling bond state with respect to the Fermi level.
In this work, we investigated atomic and chemical structure of heterogeneous 1-D chains made of III and IV group metals grown on Si(100) surface [4] by means of room-temperature (RT) FM-AFM measurements combined with DFT simulations. Here 1D chains consist of heterogeneous buckled-dimer structures with unknown chemical ordering. What more, the presence of buckled dimmers composed by chemical species of different valence makes this system very challenging for true atomic and chemical resolution by means of SPM.
In this contribution, we will show first that FM-AFM technique even at RT is able to achieve atomic resolution of individual atoms forming dimmer-rows, much superior to the contrast obtained by the traditional STM technique. Secondly, we will demonstrate that the single-atom chemical identification is still possible combining the force-site spectroscopy at RT with DFT simulations even in such complex systems as the heterogeneous 1D metallic chains.
[1] M. Schmid, H. Stadler, P. Varga Phys. Rev. Lett., 70, p. 1441 (1993)
[2] L. Gross et al, Science 325, 5944 (2009).
[3] A. Foster et al Phys. Rev. Lett. 102, 256103 (2009).
[4] Y. Sugimoto, P. Pou, M. Abe, P. Jelinek, R. Perez, S. Morita, O. Custance, Nature 446, 64 (2007)
[5] L. Magaud, A. Pasturel, and J.-Y. Veuillen, Phys. Rev. B 65, 245306 (2002).