Problems in applying secondary reactions to the activation analysis of semiconductor surface layers

Abstract

Investigations have been made concerning the determination of special contaminants (e.g. oxygen, boron) in the surface layers or epitaxially grown layers of semi-conductor crystals. These contaminants are insensitive to the conventional (n, γ) analysis and for their activation charged particles (e.g. t, α) from nuclear reactions induced by the capture of reactor neutrons are used. The specific particle yield from such reactions, e.g.⁶Li(n,t)α, was studied. The optimum conditions for the producing of activating layers (containing Li) and their optimum contact with the sample under investigation are discussed. Considering the so-called activation depth, a method was developed for the appropriate removal of the activated layer and the elements to be determined are subsequently separated from the semiconductor matrix by a fast chemical procedure. The combined activation cross sections measured on standard samples are given for different compositions and species of activating layers.