Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 34: Poster Tuesday: Scanning Probe Techniques 2

O 34.3: Poster

Tuesday, September 6, 2022, 11:00–13:00, P3

Performance of an electrically driven q-plus sensor in a commercial Joule Thomson STM — •Hester Vennema, Laëtitia Farinacci, and Sander Otte — Delft University of Technology, Delft, The Netherlands

The q-plus sensor is a wide-spread tool for performing combined STM-AFM measurements in ultra-high vacuum at cryogenic temperatures. Here, we implement the use of q-plus sensors in a JT-STM. Contrary to other set-ups in which q-plus sensors are used, we do not drive our sensor mechanically, via an excitation of the Z-piezo, but electrically, with the excitation signal directly sent to the tuning fork.

In order to characterize the performance of our homemade q-plus sensors we develop a set-up to test their response to an electrical drive in ambient conditions. Following M. Lee et al. [1], we can disentangle the mechanical and electrical response of the sensors to the driving signal. After transfer into the JT-STM, we demonstrate the possibility to use electrically driven q-plus sensors for combined STM-AFM measurements: with a Q factor around 20000 we can control the amplitude of the oscillation to be as low as 70 pm. Our first principle measurements are performed on a CuCl2/Cu(100) surface [2]. We investigate with local contact potential difference measurements the local change of work function that leads to the confinement of field emission resonances above such vacancy patches.

[1] M. Lee et al., Appl. Phys. Lett. 91, 023117 (2007)

[2] R. Rejali et al., arXiv:2204.10559 (2022)