HD-KFM™ I Kelvin Probe Force Microscopy

HD-KFM I represents the next generation of Kelvin Probe Force Microscopy (KFM) technology. This advanced module for the Nano-Observer AFM delivers exceptional sensitivity and resolution in single-pass mode, transforming surface potential measurements at the nanoscale.

Key Features:

• Single-pass operation for faster acquisition and reduced tip wear
• Enhanced sensitivity and resolution compared to standard double-pass methods
• Bimodal dual-frequency design for optimal performance
• High frequency KFM resonance for improved accuracy
• One-click automated measurement system

Comparison:
Standard KFM & HD-KFM

Single-pass operation in HD-KFM represents a significant advancement over traditional Kelvin Probe Force Microscopy techniques:

Elimination of Lift Scans:

• Traditional KFM requires two passes: one for topography and another lifted pass for potential measurement.
• HD-KFM combines both measurements in a single pass, saving time and reducing potential errors.

Proximity to Surface:

• The tip operates at a typical minimum distance of 0.1-0.5 nm from the sample surface.
• This close proximity allows for much stronger interaction with the sample’s electrostatic field.
• Compared to standard KFM (10-100 nm lift height), HD-KFM probes an electrostatic field 100-10,000 times stronger.

Enhanced Resolution and Sensitivity:

• Closer proximity leads to significant improvements in lateral resolution.
• Sensitivity is greatly enhanced, allowing for detection of subtle variations in surface potential.
• Enables clear differentiation between features like single and multiple layers of 2D materials.

Topography Frequency:

• The first flexural mode of the cantilever is excited mechanically.
• This frequency is used to measure and control the sample topography.
• Allows for precise tracking of surface features without interference

Surface Potential Frequency:

• The second flexural mode of the cantilever is excited electrically.
• This separate frequency is dedicated to measuring surface potential.
• Enables simultaneous, independent measurement of topography and surface

Signal Amplification:

• The use of the second eigenmode for electrical excitation inherently amplifies the signal.
• This amplification occurs even with very small applied AC voltages.
• Results in improved signal-to-noise ratio and higher sensitivity to small potential differences.

Enhanced Signal Amplification:

• The VAC bias is fine-tuned to the second eigenmode of the cantilever.
• This tuning amplifies the signal by the Q factor of the second mode.
• The Q factor amplification can be significant, often 100 times or more, greatly enhancing sensitivity.

Improved Stability:

• The second eigenmode has a stiffer effective spring constant compared to the fundamental mode.
• This increased stiffness provides more stable oscillation during surface scanning.
• Stability translates to more reliable and consistent measurements, especially on challenging samples.

Automated Frequency Optimization:

• The Vac bias is fine-tuned to the Second eigenmode automatically by the software without user intervention.
• Patented algorithm selects the best frequency position around the resonance peak.
• Achieves better resolution and sensitivity through optimized frequency selection.