Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip...

Area of Science:

• Surface science
• Nanotechnology
• Microscopy techniques

Background:

• Conventional scanning tunneling microscopy (STM) and atomic force microscopy (AFM) often face limitations in simultaneous electrical and topographical measurements.
• Independent control of tip potential is crucial for advanced applications like multi-tip systems and precise electrical property mapping.

Purpose of the Study:

• To present a novel method for independent scanning tunneling microscopy (STM) tip biasing during frequency modulated atomic force microscopy (AFM) operation.
• To enable simultaneous acquisition of topography and conductivity data using a single instrument.
• To facilitate the development of multi-tip STM/AFM systems.

Main Methods:

• An electronic circuit combining frequency shift and tunneling current signals via inductive coupling was developed.
• An extensional quartz sensor (needle sensor) with a conductive tip was employed for simultaneous data recording.
• A new amplitude calibration method based solely on the frequency shift signal was established.

Main Results:

• The method allows for tip potential control independent of the sample potential, overcoming previous limitations.
• Simultaneous recording of sample topography and conductivity was achieved with high efficiency.
• A resonance frequency of 1 MHz for the needle sensor enabled rapid surface scanning.
• A contact-free amplitude calibration recipe was successfully demonstrated.

Conclusions:

• The presented method offers a significant advancement for combined STM/AFM techniques, particularly for multi-tip configurations.
• Independent tip biasing enhances the versatility and precision of nanoscale electrical and topographical characterization.
• The developed system provides a robust platform for high-resolution, high-speed surface analysis.