Rutherford Backscattering Spectrometry (RBS)

 

An alpha particle, typically 2-3 MeV, impinges on a sample and is backscattered into a nearby solid state detector as illustrated in the figure above. In this example we have a thin layer of GaAs on a Si substrate. The energy of a backscattered particle determines the mass of the target atom as seen in the spectra below. Particles scattered from below the surface lose energy at a measurable rate; hence the energy scale yields the depth of the scattering of the particle. That is to say that the peak width of the Ga or As signal is proportional to the areal density or thickness of the GaAs film.

 

Ion Channeling

Ion Channeling steers energetic ions by a series of gentle, small angle collisions through rows or planes of atoms in a single crystal. An aligned single crystal will experience a dramatic reduction of surface scattering events and display a reduction of spectral yield as seen in the figure above.This will provide the following information:

(1) Amount and depth distribution of lattice disorder.

(2) Location of impurity atoms in lattice site.

(3) Thickness of amorphous or defective epitaxial surface layers.

 

The Advantages of RBS:

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