Electrical Mode (AC)

HD-KFM™ III Kelvin Probe Force Microscopy

The Most Advanced Single-Pass KFM Mode

HD-KFM III™ represents the cutting edge of Kelvin Probe Force Microscopy (KFM) technology. This advanced module for the Nano-Observer II AFM offers unparalleled sensitivity and resolution in single-pass mode, revolutionizing surface potential measurements at the nanoscale.

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Single pass

Topography and surface potential, at the same time

One tip, one trajectory, one pass — both channels come out together.

  • Single pass — no lift, no second line
  • 2nd eigenmode harmonic detection
  • Tip stays 0.1–0.5 nm from the surface
  • Potential contrast at the resolution of the topography
  • Noise level below 1 mV
  • Sub-surface detection — structures buried under the surface (e.g. nanotubes in a polymer)

At a glance

HD-KFM™ III in numbers

1 passtopography + potential
<1 mVnoise level
0.1–0.5 nmtip–sample distance
2nd eigenmodeharmonic detection
MFM + KFMin the same scan
dC/dZdielectric mapping

Bimodal dual-frequency excitation: the first flexural mode follows the topography while the second, electrically excited mode measures the surface potential — amplified by the Q factor of that mode.

What sets HD-KFM™ apart

The second eigenmode: potential measured at its own resonance

AmplitudeFrequency →≈15 kHz≈70 kHz≈400 kHzVACf1 · Sideband KFMKFM frequencyf2 · Mechanicalresonance: topographyf3 · HD-KFM™second eigenmode
Example frequencies for one cantilever. The software finds and tunes the excitation frequency automatically.

HD-KFM™ is bimodal: one cantilever, two resonances. Instead of reading the potential in a second pass or as a low-frequency sideband, it drives the cantilever’s second eigenmode electrically — so topography and surface potential are recorded together, with the tip 0.1–0.5 nm from the surface.

  • f1 · Sideband KFM (≈15 kHz)The low frequency at which sideband KFM reads the electrical signal.
  • f2 · Mechanical resonance (≈70 kHz)The first flexural mode of the cantilever follows the topography.
  • f3 · HD-KFM™ second eigenmode (≈400 kHz)Excited electrically (VAC) to measure the surface potential — a signal amplified by the Q factor of that mode, far from the topography frequency, in the same single pass.

Key Features

HD-KFM III

HD-KFM III: Harmonic Detection – Kelvin Probe Force Microscopy

HD-KFM III is an advanced Kelvin Probe Force Microscopy solution that builds upon previous generations with several key improvements. Here are its notable features and capabilities:

  • Enhanced Measurement Accuracy: The system offers improved accuracy and significantly reduced background noise compared to previous versions, enabling more precise surface potential measurements at the nanoscale.
  • Simultaneous Multi-Parameter Imaging: One of the most impressive capabilities is the ability to perform simultaneous MFM (Magnetic Force Microscopy) and HD-KFM measurements, allowing researchers to correlate magnetic and electrical properties in a single scan.
  • Advanced Dielectric Capabilities: The system includes dC/dZ functionality, making it particularly valuable for dielectric measurements and characterization of insulating materials.
  • Electrical Field Compensation: Features an MFM with EFC (Electrical Field Compensation) option, which helps eliminate electrical interference during magnetic measurements.
dC/dZ and EFC

This technology represents a significant advancement in surface characterization capabilities, particularly valuable for research in materials science, semiconductor analysis, and advanced electronic materials development.

Advanced features

dC/dZ and EFC

dC/dZ Measurements: dC/dZ measures the change in capacitance with respect to the tip-sample distance, providing information about local dielectric properties.

Benefits: Enables mapping of dielectric constants and investigation of thin film properties at the nanoscale.

Topography (Metallic structure embedded on epoxy)
TopographyMetallic structure embedded on epoxy
dC/dZ (Metallic structure embedded on epoxy)
dC/dZMetallic structure embedded on epoxy

EFC (Electrical Field Compensation for MFM):

EFC nullifies the electrostatic interaction between the tip and sample during Magnetic Force Microscopy measurements.

Benefits: Allows for pure magnetic measurements without electrostatic interference, crucial for accurate characterization of magnetic nanostructures.

Sub-surface nanotubes in a polymer, seen by HD-KFM

HD-KFM detects carbon nanotubes buried in a polymer: topography shows only the surface particles, the HD-KFM surface potential shows the nanotubes under the surface

Gallery

Energy

Battery Sample (Soft ResiScope · 50 µm)
Battery SampleSoft ResiScope · 50 µmScan size: 50 microns · Modes: Soft ResiScope
P3HT (Organic PV cell)
P3HT (Organic PV cell)ResiScope III · 10×10 µmScan Mode: ResiScope III · Scan size: 10×10 microns
Back Surface Field (Silicon Solar cell)
Back Surface Field (Silicon Solar cell)3×3 µm90μA Conductive Stability · Sample: BSF – Silicon Solar cell · Scan size: 3×3 microns
P3HT (Organic PV cell)
P3HT (Organic PV cell)ResiScope · 3×3 μmScan Mode: Soft Intermittent Mode + ResiScope · Scan size: 3×3 μm
Perovskite Sample (ResiScope III · 2x2 µm)
Perovskite SampleResiScope III · 2×2 µmCurrent measurement · Scan Mode: ResiScope III · Scan size: 2×2 microns

Polymers

Block Copolymer (Oscillating Mode · 1x1µm)
Block CopolymerOscillating Mode · 1×1µmOscillating Mode · Scan size: 1x1um
PCL Polycaprolactone (Resonant Mode · 20x20 µm)
PCL PolycaprolactoneResonant Mode · 20×20 µmResonant Mode · Topography · Scan size: 20×20 microns
Polymer membrane (Resonant Mode · 0.5x0.5 µm)
Polymer membraneResonant Mode · 0.5×0.5 µmResonant Mode · Topography · Scan size 0.5×0.5 micron
Rubber (Phase Imaging · 10x10 µm)
RubberPhase Imaging · 10×10 µmPhase Imaging · Scan size: 10×10 microns
Grocery Bag (Resonant Mode · 1x1 µm)
Grocery BagResonant Mode · 1×1 µmResonant Mode · Phase signal · Scan size: 1×1 micron
Polymers blend (Resonant Mode · 2x2 µm)
Polymers blendResonant Mode · 2×2 µmResonant Mode · Phase signal · Scan size: 2×2 micron
Structured Polymer (Resonant Mode · 5x5 µm)
Structured PolymerResonant Mode · 5×5 µmResonant Mode · Topography · Scan size: 5×5 microns

Biological Samples

Cell (Oscillating mode · 80x80 µm)
CellOscillating mode · 80×80 µmOscillating mode · 80×80 micron
Proteins (Oscillating mode · 2x2µm)
ProteinsOscillating mode · 2×2µmOscillating mode · 2x2micron
Embryonic fibroblast cells
Embryonic fibroblast cellsOscillating mode · 80×80µmOscillating mode · 80×80µm
DNA (Oscillating mode · 800x800nm)
DNAOscillating mode · 800x800nmOscillating mode · 800x800nm
Collagens (Oscillating mode · 1.2x1.2 µm)
CollagensOscillating mode · 1.2×1.2 µmOscillating mode · 1.2×1.2 micron
Blood Cell (Oscillating mode)
Blood CellOscillating modeOscillating mode · 80micron
Blood Cell (Oscillating mode · 40x40µm)
Blood CellOscillating mode · 40×40µmOscillating mode · Scan size: 40×40µm
Collagens (Oscillating mode · 5x5 µm)
CollagensOscillating mode · 5×5 µmOscillating mode · Scan size 5×5 micron

2D Materials

Graphene Monolayers (HD-KFM)
Graphene MonolayersHD-KFMGraphene flakes on SiO2 substrate. HD-KFM shows graphene flakes of different thickness (1 ML, 2ML and 3 ML).
MoS2 flakes (HD-KFM · 30x30µm)
MoS2 flakesHD-KFM · 30×30µmHD-KFM Mode · Scan size: 30×30µm
MoS2 flakes (HD-KFM · 30x30µm)
MoS2 flakesHD-KFM · 30×30µmHD-KFM Mode · Scan size: 30×30µm
HBN (HD-KFM III)
HBNHD-KFM III2 microns size HD-KFM III and PFM measurement of a folded hBN device. Twhile surface potencial shows regions with characteristic moiré patterns. This patterns indicate the presence of domains with parallel alignment of the polarization vector. The visible contrast in the SP domains is compatible with AB and BA atomic arrangement (see inset). Alternatively PFM measurement also shows similar characteristic Moiré pattern.
HDKFM HBN (HD-KFM III)
HDKFM HBNHD-KFM III10 microns size HD-KFM III of a folded hBN device. Surface potential shows regions with characteristic moiré patterns. This patterns indicate the presence of domains with parallel alignment of the polarization vector. The visible contrast in the SP domains is compatible with AB and BA atomic arrangement (see inset). Alternatively PFM measurement also shows similar characteristic Moiré pattern.
HBN (HD-KFM III)
HBNHD-KFM III2 microns size HD-KFM III measurement of a folded hBN device. Twhile surface potencial shows regions with characteristic moiré patterns. The visible contrast in the SP domains indicates opposite polarization vectors.
Graphene
Graphene
hBn - HD-KFM & PFM
hBn – HD-KFM & PFM
hBn - HD-KFM
hBn – HD-KFM

Semiconductors

SIC Dopping Profiling (ResiScope)
SIC Dopping ProfilingResiScopeResiScope measurement on a cross-section of a silicon substrate of 500 nm with regions with increasing level of carrier concentration (staircase type). Topography (top) image of the sample; polishing vertical lines are visible. (middle and bottom) Resistance map and its cross-section profile respectively. The doped regions range from 100 ohms to 1 Mohm (from right to left). This shows the capability of ResiScope to track differences in realtime with several orders of magnitude in difference (fr
Vanadium Dioxide (ResiScope)
Vanadium DioxideResiScopeResiScope image on a Metal to Insulate VO2 sample (10 microns). By controlling the thickness of the film it is possible to generate a morphology with VO2 blocks with different resistance separated by insulating VO2 walls. Thanks to the realtime adjustment of the gains it is possible to measure the resistance differences with high sensitivity.
SRAM (HD-KFM)
SRAMHD-KFMHD-KFM image of an SRAM Memory device (50 micron size). Surface potential image shows clear distinction between p, n and n+ regions with high sensitivity without showing saturation.
Linear Electrodes (HD-KFM)
Linear ElectrodesHD-KFMHD-KFM image (10 microns size) of 3 biased linear electrodes on silicon surface (bias 1 volt). The surface potential shows homogeneous value on the surface of the electrodes (dark blue areas) but also lateral diffusion of the surface potential around the electrodes (cyan areas)
Trench (HD-KFM)
TrenchHD-KFMHD-KFM image (10 microns size) of trench
Silicon Doped Structure
Silicon Doped StructureHD-KFMHD-KFM image of a silicon doped structure (3 microns size) consisting on implanted n-dopped square structures (red color). The high sensitivity of the HD-KFM allows to clearly detect the lateral difusion of the implantation around the square (yellow shadow around the square structure).
BSF - ResiScope (ResiScope measurement on a silicon solar cell.)
BSF – ResiScopeResiScope measurement on a silicon solar cell.ResiScope measurement on a silicon solar cell. (Top) current image close to the edge of the solar cell. The multilayer structure is visible (red ,green, blue and dark blue areas). More importantly, the high speed response of the ResiScope allows to identify a thin layer ( bottom) in the blue region of 30 nm lateral size. This heavy doped layer is known as “Back Surface Field” and allows to prevent recombination at the back of the solar cell and increase the efficiency. This sample shows 3 mai
Doped dots (ResiScope)
Doped dotsResiScopeResiScope image of a semiconductor sample (50 micron size) with increasing doped dots. Resistance image shows clearly the position of the dopped dots with decreasing resistance from left to right due to increasing doping levels.
Electrode
Electrode

Materials Science

C36 Molecule (Example of high resolution image in X-y-z.)
C36 MoleculeExample of high resolution image in X-y-z.Example of high resolution image in · X-y-z. Atomic steps on HOPG are visible. · Also periodic arrange of self-assembled monolayers of C36 at different orientations. Periodic pitch visible in the image corresponds with the C36 chain length around 4.5 nm
Cobalt alloy coating (MFM · 30x30µm)
Cobalt alloy coatingMFM · 30×30µmMFM signals · Scan size 30×30µm
Gold deposition (ResiScope · 5x5 µm)
Gold depositionResiScope · 5×5 µmResiScope Mode · 45 Angtroms · Scan size: 5×5 µm
Polished PZT sample (PFM)
Polished PZT samplePFMPFM image (10 microns) of polished PZT sample. PFM signal phase shows alternate phases with polarization vector upwards (Orange domains) and downwards (grey domains)
Vanadium Dioxide - VO2
Vanadium Dioxide – VO2ResiScopeResiScope image on a Metal to Insulate VO2 sample (10 microns). By controlling the thickness of the film it is possible to generate a morphology with VO2 blocks with different resistance separated by insulating VO2 walls. Thanks to the realtime adjustment of the gains it is possible to measure the resistance differences with high sensitivity.
Nanotubes (Resonant Mode)
NanotubesResonant ModeTopography image of 500 nm obtained in Resonant Mode of a network of carbon nanotubes (5 nm width).

Principle of HD-KFM III

Bimodal Dual Frequency Excitation

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.
HD-KFM Schematics

Single-Pass Operation

Single-pass operation in HD-KFM III 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 III 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 III 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.

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.

Standard KFM vs HD-KFM

KFM versus HD-KFM
Graphene layers: lift-mode KFM (left) vs single-pass HD-KFM (right)

Specifications

HD-KFM III Technical Specifications
  • Operating Mode: Single-pass
  • Tip-Sample Distance: 0.1 – 0.5 nm (typical)
  • Excitation Modes: Dual-frequency (Bimodal)
  • Topography Measurement: First flexural mode frequency (mechanical excitation)
  • Surface Potential Measurement: Second flexural mode frequency (electrical excitation)
  • Signal Amplification: Q factor enhancement in the second eigenmode
  • VAC Bias: Optimized for second eigenmode, enabling lower voltage applications
  • Feedback System: Dual feedback control (topography and electrical signals)
  • AFM Compatibility: Nano-Observer II
  • Advanced Features: Dc/Dz Measurements, Electrical Field Compensation (EFC) for MFM, Lift Mode
  • Application Areas: Materials Science, Semiconductors, 2D Materials, Polymers, Life Sciences
  • Lateral Resolution: Superior to standard KFM (exact value not specified)
  • Sensitivity: Increased through minimized tip-sample distance and enhanced signal amplification
  • Electrostatic Field Strength: 100x to 10,000x stronger than standard KFM

Note: For specific numerical values on lateral resolution, sensitivity, or other detailed parameters, please contact CSInstruments for comprehensive technical data.

Application Fields

  • Materials Science (Surface potential mapping, work function measurements, defect detection, thin film analysis)
  • Semiconductors (Doping profiling, device characterization, failure analysis, nanoscale electronics)
  • 2D Materials (Layer identification, electronic property mapping, substrate interaction studies, defect analysis)
  • Polymers (Charge distribution mapping, blend differentiation, aging studies, nanoscale polymer electronics)
  • Life Sciences (Biomaterial characterization, cell membrane charge mapping, protein/DNA charge analysis, bioelectronics)

Where it is used

Application fields for HD-KFM™ III

Graphene Monolayers — HD-KFM™ III AFM scan

2D Materials

Layer counting, work function and moiré domains.

SIC Dopping Profiling — HD-KFM™ III AFM scan

Semiconductors

Doping contrast, junctions and device cross-sections.

Battery Sample — HD-KFM™ III AFM scan

Energy

Grain boundaries in solar cells and battery materials.

C36 Molecule — HD-KFM™ III AFM scan

Materials Science

Alloys, coatings and corrosion: potential and magnetic domains.

Combine and upgrade

Works with — and runs on

MFM with EFCElectrostatic interaction cancelled — pure magnetic contrast.EFMElectrostatic force imaging on the same instrument.ResiScope™ IIIAdd resistance and current over 10 decades.Soft Interaction ControlFor soft and fragile samples, without shear.
Nano-Observer IINano-Observer IIBuilt into the Nano-Observer II, with every other CSI mode available on the same head.Galaxy Dual ControllerGalaxy Dual ControllerAdd it to a Bruker MultiMode, Dimension, Agilent or Keysight AFM with the controller upgrade.

Product note

HD-KFM™ III product note

Principle, key specifications and application examples in one technical document. We send it to you by e-mail.

Request the product note

FAQ

Frequently Asked Questions

What is HD-KFM III?

HD-KFM III (High Definition Kelvin Force Microscopy III) is an advanced single-pass Kelvin Probe Force Microscopy module developed by CSInstruments for the Nano-Observer II AFM. It simultaneously measures surface topography and surface potential in a single scan pass using bimodal dual-frequency excitation, with a tip-sample distance of 0.1–0.5 nm — achieving electrostatic field sensitivity 100 to 10,000 times greater than standard KFM.

What is the difference between single-pass KFM and dual-pass KFM?

In dual-pass (lift mode) KFM, the AFM tip makes two separate scans: the first records topography, and the second is lifted 10–100 nm above the surface to measure surface potential. Single-pass KFM, as implemented in HD-KFM III, acquires both topography and surface potential simultaneously in one scan. This eliminates lift-height artifacts, operates at 0.1–0.5 nm tip-sample distance, and achieves significantly higher sensitivity and lateral resolution.

How does HD-KFM III achieve higher sensitivity than standard KPFM?

HD-KFM III uses bimodal excitation: the first flexural eigenmode of the cantilever is mechanically driven for topography, while the second flexural eigenmode is electrically excited for surface potential measurement. The VAC bias is automatically tuned to the second eigenmode resonance, amplifying the signal by the Q factor of that mode — often 100x or more. The close tip-sample proximity (0.1–0.5 nm vs. 10–100 nm for standard KFM) further increases electrostatic field strength by a factor of 100 to 10,000.

What materials can be characterized with HD-KFM III?

HD-KFM III is applicable to a broad range of materials: 2D materials (graphene, hBN, MoS2) for layer thickness identification and moiré pattern mapping; semiconductors for work function mapping, doping profiling, and SRAM device characterization; perovskite and organic photovoltaic materials for surface potential mapping; polymers for charge distribution; and biological samples for cell membrane charge analysis. It is also capable of simultaneous MFM and HD-KFM measurements on magnetic materials.

What AFM system is HD-KFM III compatible with?

HD-KFM III is exclusively designed for the Nano-Observer II AFM by CSInstruments. The Galaxy Dual Controller also enables HD-KFM capabilities on legacy AFM platforms including Bruker MultiMode, 5100, and 5500 systems.

Can HD-KFM III be used for perovskite solar cell research?

Yes. HD-KFM III is well-suited for perovskite solar cell characterization. It enables high-resolution surface potential mapping of perovskite thin films, grain boundary analysis, and work function measurements — all critical for understanding charge transport and photovoltaic efficiency. The single-pass mode avoids topography crosstalk that can affect standard lift-mode KFM measurements on these rough surfaces.

What is dC/dZ measurement in HD-KFM III?

dC/dZ measures the gradient of capacitance with respect to tip-sample distance. In HD-KFM III, this capability enables nanoscale mapping of local dielectric properties and thin film characterization. It is particularly useful for identifying dielectric constant variations in composite materials and insulating layers.

What is EFC (Electrical Field Compensation) in HD-KFM III?

EFC (Electrical Field Compensation) is a feature in HD-KFM III that nullifies the electrostatic interaction between the AFM tip and sample during simultaneous MFM (Magnetic Force Microscopy) measurements. This allows researchers to obtain pure magnetic contrast without electrostatic artifacts — essential for accurate characterization of magnetic nanostructures and spintronic materials.

Questions about HD-KFM™?

Ask the application scientists behind our AFMs and modes — about your samples, probes, set-up or which mode fits your measurement. We answer every message personally.