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Analytical facilities

In thin  film deposition processes, a precise knowledge of plasma characteristics is critical. The physical plasma properties can be studied with a Langmuir probe which is a plasma diagnostics tool consisting in a small wire inserted in the plasma chamber.

During the process the current (I) as function of applied voltage (V) is measured. Analyzing the measured I/V curves the following plasma parameters can be estimated:

Acton Spectra Pro 2300i Monochromator/Spectrograph Princeton Instruments

With Optical Emission Spectrocsopy technique (OES) the main plasma parameters can be calculated.

From the emission spectra we can identify:

  • the emitted species
  • the concentration of atoms and molecules in the excited states
  • the density of charged particles and neutrals in plasma
  • the temperatures of excited atomic and molecular states.

 

Photoelectrons result from the interaction of electromagnetic radiation with matter. Useful energy ranges for the exciting radiation go from UV (Ultraviolet Photoelectron Spectroscopy, UPS, leading to valence electrons excitation) to soft X-Rays (X-Ray Photoelectron Spectroscopy, XPS, leading to core level electrons excitation and hence to elemental selectivity). Excited photoelectrons are analyzed according to their kinetic energy, which is, at least for core electrons, a fingerprint of the emitting element.

The Electron Spectroscopy Lab is equipped with two powerful analytical instruments:

  • PHI 4200 Thin Film Analyzer for AES depth profiles

  • PHI 545-590 Multiple Analytical System (XPS, UPS, AES)

 

Auger Electron Spectroscopy (AES)

Compared to other methods of analysis, X-ray diffraction technique (XRD) allows for rapid, non destructive characterization of crystalline materials without the need of extensively sample preparation. Identification is obtained by comparison of the diffraction pattern against a database maintained by the International Centre of Diffraction Data. It provides information on structures, phases, preferred crystal orientations and other structural parameters such as crystallite size, crystallinity, strain and crystal defects.