Ultrastable atomic force microscopy: atomic-scale stability and registration in ambient conditions

Area of Science:

• Atomic Force Microscopy
• Nanoscale Metrology
• Surface Science

Background:

• Instrumental drift in AFM limits tip-sample stability, registration, and signal-to-noise ratio.
• Current methods often require rapid scanning or extreme conditions (cryogenic/vacuum).
• Achieving atomic-scale precision in ambient environments remains a significant challenge.

Purpose of the Study:

• To develop and demonstrate a method for actively controlling AFM tip position.
• To overcome limitations imposed by instrumental drift in AFM imaging.
• To enable atomic-scale tip-sample stability and registration in perturbative environments.

Main Methods:

• Scattering a laser off the apex of a commercial AFM tip to measure and control its 3D position.
• Active feedback stabilization of tip position to sub-40 picometer precision.
• Imaging on transparent substrates to demonstrate long-term stability and registration.

Main Results:

• Achieved 3D tip position control to <40 pm (0.01-10 Hz) in air at room temperature.
• Demonstrated a 5-fold increase in image signal-to-noise ratio by overcoming rapid scanning requirements.
• Showcased atomic-scale (approx. 100 pm) tip-sample stability and registration over tens of minutes.

Conclusions:

• The laser-based stabilization technique significantly enhances AFM imaging performance.
• This method extends atomic-scale tip-sample control to ambient and perturbative operating environments.
• The technique requires low laser power, minimally perturbs the cantilever, and is independent of tip-sample interactions.