RBS or Rutherford Backscattering Spectrometry refers to a technique often used to know the composition and structure of materials. Typically, a beam of ions gets accelerated to high energy and then aimed at samples.
Researchers may know its composition by determining and analyzing the energy and distribution of ions, which are scattered from atoms in a sample. In order to accelerate ions to high energy, electrostatic accelerators are used.
How RBS Works
A measurement system is often introduced to quantify and observe adsorption at the liquid-sold interface as well as the formation of EDL (electrochemical double lawyer).
A Si3N4 as a membrane surface and BaCl2, a bicomponent electrolyte, are chosen as model systems to prove the ability of the whole setup.
The outcome of these Rutherford Backscattering measurements is usually combined with EIS (electrochemical impedance spectroscopy) so as to validate findings for liquid-solid interface under the assessment or study.
Strengths
- No reference samples or standards are needed for the analysis of the composition
- Micro-RBS is the only analytical method that can achieve analysis on density in a micron-scale region
- Best accuracy when it comes to elemental composition analysis
- An analysis is possible under vacuum or alternative atmosphere conditions
- RBS is capable of measuring concentrations of light elements, including Deuterium and Hydrogen
Limitations
- Samples must be compatible with the vacuum
- RBS can’t be able to determine the chemical structure of a sample
- Less sensitive to some light elements
Applications
RBS provides a combination of accuracy and sensitivity for thin film characterization. Applications often include analysis of contamination levels and composition. They may also involve determining thickness-density products of both adjacent films and silicide layers.
A large mass difference present in the refractory metal silicide films normally makes it suitable for Rutherford Backscattering Spectrometry analysis. Great sensitivity allows RBS analysis of refractory metals in other films. Apart from that, other RBS applications may include the following:
- Diffusion profiles
- Interface reaction and mixing
- Bulk and surface contamination
- Implantation profiles
- Determination of stoichiometric, thickness, and composition of ratio
- Composition of bulk material, multilayers, and films
- Determination of the sample crystallinity
- Quantification of film density
RBS and its Benefits in the Thin Films
RBS is one of the effective analytical-based techniques on an ion beam. This provides more accurate information on elemental composition near a material’s surface. It helps to obtain the composition profile of a material in the depth of some micrometers on the surface. Apart from thin films, the technique can also be used to analyze bulk samples.
The principle behind this technique involves putting a target in the monoenergetic 4He+ ion beam, which is generated from ion accelerators.
These particles usually interact with a target sample where only a few ions penetrate the target, whereas other ions are scattered elastically by surface atoms.
The Takeaway!
RBS is a non-destructive and quantitative technique used to analyze the depth profiles of atoms in a solid material. This method, developed by Marsden and Geiger, is often used to analyze ion-implanted materials and thin films.
In addition to that, the method can also be used to get information on the crystalline samples. This is called channeling and may probe the extent of damage in crystals and helps determine the amount of interstitial or substitutional species in the lattice.