Cross section for ERDA

Determination of the differential cross section of He-ERDA


Depth profiling of hydrogen isotopes in the near surface region of solid materials is very important for various cases in materials sciences, e.g., fusion technology, metals, semiconductors. A well known application is the dramatic influence of hydrogen on the electrical properties of hydrogenated amorphous silicon.

Although ERDA has been applied for depth profiling of hydrogen isotopes in several institutes, the existing experimental data for the differential cross section of the 1H(4He,4He)1H and 2H(4He,4He)2H reactions were rather unreliable.


Figure 1. Non-Rutherford differential cross section of 1H(4He,4He)1H reaction



In 1986 the non-Rutherford differential cross section values were determined in the 2.0-3.3 MeV at a recoil angle of 23o, while in 1989 the cross section values were determined in the 0.9-3.4 MeV energy and 16o to 41o recoil angle ranges. The results were fitted with a second order surface. This kind of fit is very useful for computer evaluations of measured spectra.

The cross section values of 2H(4He,4He)2H reaction were also determined in 1986 at the recoil angle of 30o in the energy range of 1.6-3.0 MeV.


Figure 2. Non-Rutherford differential cross section of 2H(4He,4He)2H reaction




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