Positron interactions on solid surfaces and at bilayered structures

A monoenergetic positron beam, operated under ultrahigh vacuum, was utilized to examine the interaction mechanisms of a positron at the vacuum-solid and the solid-solid interfaces. The positron surface processes and the underlying mechanisms are studied by monitoring their temperature and energy dependencies. Different fundamental aspects influencing positron motion at an interface of two materials are discussed. Positron energy loss mechanisms at the final stages of thermalization and thermal positron motion in the solids are studied. The positron diffusion is applied to extract defect profiles in heteroepitaxial structures.