SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 87: Focus Session: Scanning Probe Microscopy with Quartz Sensors III

O 87.6: Vortrag

Donnerstag, 30. März 2023, 16:45–17:00, TRE Ma

On the origin and elimination of cross coupling between excitation and tunneling current in scanning probe experiments that utilize the qPlus sensor — •Michael Schelchshorn — Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstraße 31, 93053 Regensburg

The qPlus sensor is a stiff quartz cantilever that facilitates high-resolution combined STM/AFM [1]. Both a tunneling current and the deflection signal resulting from the forces at the tip are measured simultaneously; however, unwanted cross coupling between the tunneling current signal and the excitation of the sensor oscillation can occur. At one bias polarity, this cross coupling acts as an excitation of the oscillation, in the opposite bias it appears as a damping.

This unwanted effect has been observed since the early years of combined STM/AFM experiments using qPlus sensors, but was difficult to explain. Here, we present a new theory that explains this phenomenon, supported by experiments and supplemented by verified measures on how to prevent or at least minimize cross talk. [2]

[1] F.J. Giessibl, The qPlus sensor: a powerful core for the atomic force microscope, Rev. Sci. Instrum. 90, 011101 (2019).

[2] M. Schelchshorn, On the origin of cross coupling between excitation and tunneling current in combined STM/AFM qPlus experiments, University of Regensburg, B.Sc. thesis (2022)