Positron depth profiling in solid surface layers

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 dc-beams. 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.