Atomic Force Microscopy

Scanning probe microscopy (SPM) is the collective name for a family of microscopy techniques that use a scanning probe to scan the surface of a sample. The two main types of SPM are scanning tunneling microscopy (STM) and atomic force microscopy (AFM). The SPM technique provides information on topology (as well as mechanical, electrical and magnetic properties) on a scale from micrometres to fractions of nanometres.

The principle of the scanning tunneling microscope is based on the tunneling effect, i.e. the flow of tunnel current when the probe is close enough to the sample surface. As the probe moves across the sample surface, the topography of the sample changes and so does the tunnel current. The coupling loop, which provides a constant tunnel current, maintains a constant distance between the probe and the sample. STM can only be applied to conductive samples.

A technique much better suited to the study of dielectrics is atomic force microscopy, which uses a blade-like probe mounted on a flat lever to image surfaces with a resolution of a few nanometres. The AFM technique is based on the use of interatomic interactions. The three basic modes of AFM are

  • Contact mode
  • Non-contact mode
  • Intermittent contact mode

In addition to topological information, the technique can be extended to provide a wealth of interesting information about the surface properties of the biological and non-biological materials under investigation (solids and liquids), including

  • magnetic properties, then so-called Magnetic Force Microscopy
  • Characterisation of mechanical properties such as friction, adhesion, roughness, elasticity. For this purpose, e.g. Force Modulation Microscopy, Phase Detection Microscopy, Lateral Force Microscopy
  • electrostatic properties, so-called Electrostatic Force Microscopy
  • spatial variations in the electrical capacitance of the systems under investigation, so-called Scanning Capacitance Microscopy
  • electrical properties of nanostructures, so-called Conductive Atomic Force Microscopy (Conductive AFM)

Icon Bruker Atomic Force Microscope

XY-scanning range up to 90 µm2, Z-scanning range 11.6 µm, unique optoelectronic Closed-Loop system to stabilise scanner operation while maintaining low noise, temperature control from -10 ºC to +250 ºC, atomic resolution. Dedicated to the measurement of materials with a large surface area.

Available modes - ScanAsyst (in liquid and air), Tapping Mode (in liquid and air), Contact Mode (in liquid and air), Lateral Force Microscopy, PhaseImaging, Lift Mode, MFM, Force Spectroscopy, PeakForce Tuna, Force Volume, EFM, Surface Potential, Piezoresponse Microscopy, Force Spectroscopy, PeakForce QNM.

Nanoindenter

The Nanoindenter is a device for testing the mechanical properties of materials on the nanometre scale. Examples of the quantities measured include Young's modulus, hardness, damping coefficient and, consequently, scratch susceptibility, wear susceptibility due to friction and very low deflection under the influence of an applied force.

In addition, it also has an imaging capability (scanning on the SPM principle) whereby it is possible to obtain a topography image before indentation, select the indentation location with an accuracy of 10 nm, and then re-image the topography of the same area after indentation.

Key parameters:

  • range of motion XY at least 240 x 120 mm,
  • range of motion Z at least 40 mm,
  • resolution 700 nm,
  • maximum normal shift at least 5 um,
  • resolution of normal shift 0.02 nm,
  • true resolution (Noise Floor) 0.2 nm,
  • possibility to work in air as well as in liquid,
  • measurement of amplitude, phase, contact stiffness and damping ratio,
  • creation of viscoelastic response maps (damping, stiffness).
  • examination of Young's modulus distribution on the surface of the tested sample (mapping) using nanoDMA measurement module.