What is the principle of AFM?

The underlying principle of AFM is that this nanoscale tip is attached to a small cantilever which forms a spring. As the tip contacts the surface, the cantilever bends, and the bending is detected using a laser diode and a split photodetector. This bending is indicative of the tip-sample interaction force.

How does a AFM work?

An AFM uses a cantilever with a very sharp tip to scan over a sample surface. As the tip approaches the surface, the close-range, attractive force between the surface and the tip cause the cantilever to deflect towards the surface. A laser beam is used to detect cantilever deflections towards or away from the surface.

What is the function of AFM?

The AFM can be used to image and manipulate atoms and structures on a variety of surfaces. The atom at the apex of the tip “senses” individual atoms on the underlying surface when it forms incipient chemical bonds with each atom.

What is tapping mode in AFM?

In tapping mode afm, the sharp probe tip is not scanned across the sample surface while in constant contact. Instead, the cantilever is vibrated near its resonance frequency causing the tip to oscillate up and down. This means the probe only comes into close contact with the surface intermittently; hence the title.

What is the resolution of AFM?

Normally, the probe is a sharp tip, which is a 3-6 um tall pyramid with 15-40nm end radius (Figure 1). Though the lateral resolution of AFM is low (~30nm) due to the convolution, the vertical resolution can be up to 0.1nm.

How does contact mode AFM work?

Contact mode is the basis for all AFM techniques in which the probe tip is in constant physical contact with the sample surface. While the tip scans along the surface, the sample topography induces a vertical deflection of the cantilever.

How does non contact AFM work?

Non-Contact AFM An NC-AFM vibrates the cantilever close to its intrinsic frequency of resonance (f0) with a piezoelectric bimorph. This frequency tends to lie between 100 – 400 kHz, with Park System’s True Non-Contact Mode AFM having a resonance frequency of 350 kHz, with an oscillation amplitude of 1-5 nm.

What types of samples can AFM analyze?

Atomic-force microscopy (AFM) is a powerful technique that can image almost any type of surface, including polymers, ceramics, composites, glass, and biological samples. AFM is used to measure and localize many forces, including adhesion strength, magnetic forces, and mechanical properties.

What is the limiting factor with respect to AFM resolution?

The main limiting factor of the imaging rate of AFM is the response speed of the moving components of the atomic force microscope, i.e., the probe and the scanner.

How does conductive atomic force microscopy ( AFM ) work?

The images show very good spatial correlation. Conductive atomic force microscopy (C-AFM) or current sensing atomic force microscopy (CS-AFM) is a mode in atomic force microscopy (AFM) that simultaneously measures the topography of a material and the electric current flow at the contact point of the tip with the surface of the sample.

How are conductive tips used in c-AFM?

The voltage is then ramped while the current is measured to generate local current versus voltage (I-V) curves. Several kinds of conductive tips can be used in C-AFM, but the most successful are the conductive diamond-coated silicon tips.

How does the c-AFM work in contact mode?

C-AFM scans the surface with a conductive cantilever, with a metal- or doped diamond coated or full-metal tip, while the feedback maintains a constant cantilever deflection and thereby a constant tip-sample force. Since C-AFM operates in contact mode this tip-sample force lies in the short-range repulsive interaction regime.

How is c-AFM used in the solar cell field?

C-AFM is applied in the nanoelectronics field, solar cell and semiconductor industries for a wide variety of high resolution measurements including semiconductor dopant profiling and quality control for dielectric films and oxide layers. In conductive AFM, a sharp conductive tip is in contact with the sample.