Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 84: Scanning Probe Techniques: Method Developments

O 84.6: Talk

Thursday, March 10, 2016, 16:30–16:45, S054

high frequency transmission to a junction of a scanning tunneling microscope — •marie hervé, moritz peter, and wulf wulfhekel — Physikalisches Institut, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

We report on an easy method to calibrate the transmission of radio-frequency (rf) voltages to the tunneling junction of a scanning tunneling microscope. The transmission strongly depends on frequency, as the cabling shows frequency dependent damping and the impedance mismatch between the cable and the tunneling junction induces reflections. To first order, the current-voltage characteristic of the junction induces a rf tunneling current of the same frequency as the rf voltage. Omnipresent non-linearities of the current-voltage characteristic of the junction to second order, however, generates an additional rectified DC current. A direct comparison between this current and the second derivative of the current-voltage curve allows to determine the rf transmission to the tunneling junction. The transmission data up to 2 GHz were used to compensate the rf damping such that at every frequency a constant amplitude at the tunneling junction could be realized expanding the bandwidth of the experiment from less than 100 MHz to 2 GHz [1].

[1] M. Hervé, M. Peter, and W. Wulfhekel, Appl. Phys. Lett. 107, 093101 (2015)