Nanoscale tip positioning with a multi-tip scanning tunneling microscope using topography images.

Area of Science:

• Nanoscience
• Surface Science
• Condensed Matter Physics

Background:

• Multi-tip scanning tunneling microscopy (STM) enables nanoscale charge transport measurements.
• Four-point resistance measurements require precise positioning of multiple STM tips.
• Current methods often rely on scanning electron microscopy for tip localization.

Purpose of the Study:

• To present an alternative to scanning electron microscopy for determining multi-tip positions in STM.
• To achieve accurate nanoscale inter-tip distance measurements.
• To facilitate precise four-point probe measurements in dedicated geometric configurations.

Main Methods:

• Utilizing STM scanning itself for tip position determination, complementing optical microscopy for coarse positioning.
• Employing a large STM overview scan as a reference map.
• Matching topographic features between the reference map and individual tip scans for precise localization.

Main Results:

• Tip positions can be identified with an accuracy of approximately 20 nm for typical tip spacings of ~1 μm.
• This method provides an alternative to scanning electron microscopy for tip localization.
• Accurate tip positioning is crucial for reliable nanoscale charge transport measurements.

Conclusions:

• STM scanning can be effectively used to determine inter-tip distances, offering an alternative to SEM imaging.
• Precise tip positioning is achievable with careful calibration to account for piezoelectric element non-linearities.
• This technique enhances the capability of multi-tip STM for nanoscale four-point resistance measurements.