| AVS 64th International Symposium & Exhibition | |
| Scanning Probe Microscopy Focus Topic | Monday Sessions |
| Session SP+AS+NS+SS-MoM |
| Session: | New Imaging and Spectroscopy Methodologies |
| Presenter: | Marek Kolmer, Jagiellonian University, Krakow, Poland |
| Correspondent: | Click to Email |
We present our recent results obtained on the new Scienta-Omicron low temperature ultra-high vacuum 4-probe STM (LT-Nanoprobe). This unique machine is equipped with 4 STM scanners able to operate on the same surface simultaneously with the stability of the state-of-art single tip low temperature STMs [1].
Firstly we show our methodology for fine relative positioning of two STM probes on a surface with unprecedented atomic precision and with a lateral exact probe to probe distance below 50 nm. Secondly we discuss our design of the 2-probe STM experiment, in which both tips are kept in tunnelling conditions above a grounded sample. Then, by applying a DC bias voltage between probes in the described configuration we can detect a probe to probe DC current signal. Moreover, we add a small AC component to a varied DC bias voltage and by demodulation of resulting current signals on each of the probes, we extract corresponding dI1/dV1 (vertical) and dI2/dV1 (planar) STS signals. Our method allows a direct testing of the electronic transport properties of atomic-scale structures in a fully planar geometry, what is shown on an example of a model system: bare Ge dimer wires on Ge(001) surface. In this case we determine ballistic charge transport regimes in the atomic wires by systematic 2-probe spectroscopic experiments on the probe to probe distances below 50 nm.
Finally, we discuss perspectives for application of the above methodology in characterization of molecular structures, i.e. molecular wires obtained by the on-surface synthesis approach on metal oxide surfaces [2-4].
Support by the European Commission under PAMS project (contract no. 610446) and by the Polish Ministry of Science and Higher Education (contract no. 0341/IP3/2016/74) are gratefully acknowledged.
[1] J. Yang et al., Eur. Phys. J. Appl. Phys., 73, 10702 (2016)
[2] M. Kolmer et. al., Angew. Chem. Int. Ed., 52, 10300 – 10303 (2013)
[3] M. Kolmer et. al., Chem. Comm., 51, 11276 – 11279 (2015)
[4] G. Vasseur et al., J. Am. Chem. Soc., 138, 5685−5692 (2016)