Optimization of the depth resolution in ERDA of H using ¹²C ions

Depth resolution is one important parameter in the depth profiling of H by elastic recoil detection analysis (ERDA). We report on depth resolution measurements and compare them with those calculated by the DEPTH code [E. Szilágyi and F. Pászti, these Proceedings (IBA-11, Balatonfüred, Hungary, 1993) Nucl. Instr. and Meth. B 85 (1994) 616; E. Szilágyi, F. Pászti and G. Amsel, Nucl. Instr. and Meth. B, to be submitted]. Experimental conditions were determined as precisely as possible: the straggling in the absorber foil and the effect of its inhomogeneity were directly measured and an analytical approximation of the results was incorporated into the DEPTH code. ERDA depth resolutions were measured and calculated on a multilayered Ni-Ti:H sandwich target, with a ¹²C beam of 2.55 MeV in different geometrical conditions. Measurements and calculations agree fairly well. Optimization of depth resolution versus geometry has also been undertaken yielding a near-surface resolution of approximately 2 nm.