Positron depth profiling in solid surface layers

Abstract

-We briefly review the principles of the Doppler Broadening of the positron annihilation radiation line, the most common technique used in defect depth profiling of solids relevant to dcbeams. We focus on some specific examples of Slow Positron Implantation Spectroscopy (SPIS) investigations related to technological issues such as, for instance, i) phase transitions in metal coatings possibly induced by internal stresses, ii) substrate pre-treatment or annealing dependence of defect profiles at metal/polymer interfaces or in the deposited layers, and. iii) near-surface structural modification by ion implantation in ceramics and multilayers. In each case we elaborate on the possibility of using SPIS results and possible depth profile features as criteria for on-or off-line quality control in industrial processes. We finally conclude with an overall picture of the operating characteristics of positron annihilation techniques.Résumé -Profils d'implantation des positons dans des couches de surface des solides. Nous passons brièvement en revue les principes de la méthode de l'élargissement Doppler de la raie d'annihilation des positons, technique la plus fréquemment utilisée en analyse de surface des solides par faisceau à courant continu. Nous considérons quelques d'applications technologiques de la caractérisation par spectroscopie d'implantation des positrons lents (SPIS), telles que, par exemple, i) les transitions de phases éventuellement induites par contraintes internes dans les dépôts métalliques, ii) l'influence de prétraitements du substrat ou de recuits sur le profil des défauts aux interfaces métal/polymère ou dans des couches déposées, et iii) la modification structurale par implantation ionique en proche surface de céramiques et de multicouches. Dans tous les cas nous envisageons l'éventualité d'utiliser la technique SPIS et les particularités des profils de défauts comme critères dans des contrôles de qualité en ligne ou en post-production industrielle. Enfin, nous concluons par un panorama des caractéristiques de mise en oeuvre des techniques de spectroscopie d'annihilation des positrons.

Investigations of HAVAR^® Alloy Using Positrons

“…1 presents a diagram that compares our knowledge of the sensitivity of positron annihilation techniques in defect studies to some other common measuring methods. Similar diagrams regarding methods and sensitivity limits have already been published before [9][10][11]. This diagram shows that positron techniques are most sensitive to very small defects, cover a large range of defect concentrations, and span the wider distribution of penetration depths, from the surface and deep into the bulk.…”

Structural characterization of H plasma‐doped ZnO single crystals by positron annihilation spectroscopies

“…This source was always covered with two identically treated ZnO crystals thus forming a sandwich. The depth profile of the positrons in each sample exhibits a distribution which reaches a maximum at ∼43 µm and has a low intensity tail that extends as deep as ∼173 µm into ZnO 25. It has been estimated 3 that ∼90% of the positrons are annihilated within 100 µm of the surface, i.e., about 1/5 of the sample thickness.…”

Positron Annihilation Spectroscopy: A Prelude to Modern Aspects

“…It is very encouraging to note that the slow positron tool increasingly finds its importance in studying subtle structural imperfections that could lead to crucial surface functional properties. It has also resulted in non-destructive depth profiling of defects in surfaces and interfaces [66] (depth selective from ~0.01 to 20 m).…”