Electric Force Microscopy

Model ID: EFM-2017

Electrostatic Force Microscopy (EFM) is a type of dynamic noncontact atomic force Microscope where the electrostatic force is probed.

“Dynamic” here means that the cantilever is oscillating and does not make contact with the sample. This force arises due to the attraction or repulsion of separated charges. It is a long-ranged force and can be detected 100 nm from the sample. The EFM-2017 module is used for measuring EFM images in the TT-2, NP, LS, and SA-AFM products.

In EFM, a conductive cantilever tip is used a sample is prepared with surface potentials on it is needed. The tip and sample are separated a distance z usually by air or vacuum. A bias voltage between tip and sample is applied by an external voltage supply that form a capacitor, C, between tip and sample. The capacitance of the system depends on the geometry of the tip and sample. The total energy stored in that capacitor is U = 1/2C*ΔV^2. The work done by the voltage supply to maintain a constant voltage, ΔV, between the capacitor plates (tip and sample) is -2C*U. The z component of the force (the force along the axis connecting the tip and sample) is thus:

When the tip scans the surface of a sample at close distances (< 5 nm), not only long range electrostatic forces are sensed, but also van der Waals force and atomic interaction forces. In order to reduce topography artifacts in the EFM image, a second path of scan at lifted distance from the surface topography is implemented. The commercial implementation of this method is so-called “Lifting” method.

SECOND PASS
Above surface electrostatic forces

FIRST PASS
At surface hard forces

Include with EFM Option:

• Conductive Probes
• Power Supply
• Software
• Sample Holder
• Manual

Power Supply

Interface Unit

*Multily X Gain in nm/V to convert from volts to nanometers