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Updated: Jun 17, 2025
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All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
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High dynamic range scanning tunneling microscopy
Ajla Karić1, Carolina A Marques1, Berk Zengin1
1Department of Physics, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland.
Methodsx
|August 6, 2024
Summary
We enhance scanning tunneling microscope (STM) dynamic range by actively removing current harmonics. This method prevents preamplifier saturation, enabling high-fidelity spectroscopy and imaging without hardware modification.
Area of Science:
- Physics
- Materials Science
- Nanotechnology
Background:
- Scanning tunneling microscopy (STM) is crucial for nanoscale imaging and spectroscopy.
- Nonlinearities in current-voltage characteristics generate current harmonics.
- These harmonics can saturate preamplifiers, limiting the dynamic range of STM measurements, especially at low impedances or high gains.
Purpose of the Study:
- To increase the dynamical range of a scanning tunneling microscope (STM).
- To overcome preamplifier saturation issues caused by current harmonics.
- To enable high dynamic range spectroscopy and imaging in STM.
Main Methods:
- Actively subtracting dominant current-harmonics generated by nonlinearities.
- Utilizing the phase relationship between excitation voltage and current-harmonics for cancellation.
- Employing a compensating capacitor at the preamplifier input to cancel harmonics via displacement current.
- Using two phase-synchronized voltage sources and a multi-frequency lock-in amplifier.
Main Results:
- Successful cancellation of dominant current-harmonics.
- Prevention of current preamplifier saturation.
- Demonstration that DC current removal has no effect and first harmonic removal causes a reversible shift in differential conductance.
- Achieved high dynamic range spectroscopy and imaging.
Conclusions:
- The developed method effectively expands the dynamic range of STM.
- Active harmonic subtraction is a viable technique for improving STM performance.
- The approach requires minimal hardware changes, relying on synchronized voltage sources and lock-in amplification.
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