Rutherford Backscattering Spectrometry (RBS) 2nd Summer School May 17, to June 6, 2010 University of JINR (DUBNA _ RUSSIA) Prepared by: Hani Negm Assistant Lecturer of Physics Assiut University Supervisor: Prof. A.P. Kobzev FLNP- JINR (Dubna, Russia)

RBS RBS is an ion scattering technique that is used for the surface layer analysis of solids. A target is bombarded with ions at an energy in the MeV-range (0.5 – 4 MeV) The energy of the backscattered projectiles is recorded with an energy sensitive detector, typically a solid state detector. RBS allows the quantitative determination of the composition of a material and depth profiling of individual elements.

RBS RBS is: quantitative without the need for reference samples, nondestructive, has a good depth resolution of the order of several nm, and a very good sensitivity for heavy elements of the order of parts-per-million (ppm).

RBS Chamber for RBS Method

RBS If a particle of mass M1 is scattered in electrical field of nuclear of mass M2 at angle θ, its energy is K-part of initial energy E0. Applying the principle of conservation of energy and momentum, one can obtain next equation for kinematic factor K:

RBS

RBS The yield of scattered particle is calculated using the differential scattering cross section which is given by Rutherford’s formula:

RBS If the ion is scattered at the depth X, it will losses energy as well along the inward path ΔEin as outward path ΔEout :

RBS Energy loss depends on the atomic number both of incident ion and target atoms, their atomic density N and on energy of the incident ion. For the calculations of RBS spectra, usually is used such named stopping cross section ε:

RBS the thickness of layers can calculate according to the energy width of the channel δE in the multichannel analyzer. The number of particles getting to the channel from Q incident particles is : H(E1) = Q σ(E,θ) ΔΩ δE/([S] cosΘ1) where ΔΩ – solid angle of the detector.

RBS

RBS Possibilities of RBS Method Element Ti Nb 30 10 1800 1500 264 Minimum Thickness, nm 30 10 Maximum Thickness, nm 1800 1500 Real Thickness, nm 264 169.5 Sensitivity, at/cm2 2x1016 1x1016

THANK YOU FOR YOUR ATTENTION 4/26/2017 negm_sci@aun.edu.eg