Experimental resolution of deuterium and hydrogen depth profiling with the nuclear reactions D(3He,p)α and p(15N,α,γ)12C

Abstract

In this paper well defined test samples are used to show how the analysis depth and the matrix material influence the depth resolution of nuclear reaction analysis. The reaction D(3He,p)α is used to detect deuterium. By covering 10nm thin deuterated amorphous carbon (a–C:D) films on silicon with tungsten (ZW=74) and titanium (ZTi=22) of various thicknesses between 500nm and 8μm the influence of the atomic number and the overlayer thickness on the depth resolution is studied. The most probable depth profiles are calculated from the experimental data with the program NRADC, which implements Bayesian statistics. The resulting apparent layer width of the deuterium containing layer broadens with increasing thickness of the coating and this broadening is more pronounced for coatings with higher Z. These apparent layer widths are a measure for the experimentally achievable depth resolution. Their absolute values are in the same range as the theoretical optimum calculated with RESOLNRA. To investigate the depth resolution of the p(15N,α,γ)12C reaction, a 12nm thin hydrogenated amorphous carbon (a–C:H) film on silicon and a pure tungsten sample are analysed. The width of the instrument function of this method is deduced from the surface hydrogen peak of the pure tungsten sample. The two methods are compared.