A variable-energy positron beam was used to study the formation of defects beneath the surface of epitaxially grown material at room temperature. Samples which had just been etched were compared with samples which had lain in air for some 4000h after etching. The formation of a defect layer was observed which was suggested to involve vacancies that resulted from the diffusion of Hg out of the material.

A.Towner, P.C.Rice-Evans, N.Shaw: Applied Surface Science, 1995, 85, 315-9