Positron beam and He desorption techniques were applied to various materials, especially semiconductors, in order to detect the presence of defects. The positron technique yielded values of the positron diffusion length and values of the Doppler broadening parameter. The results showed that cavities could be easily detected. It was also shown that gas which accumulated in the cavities reduced the observed differences between the defective and defect-free material. It was found that layers which were deposited under bombardment with low-energy ions did not exhibit signs of micro-cavities.

A.Van Veen, R.A.Hakvoort, H.Schut, P.E.Mijnarends: Journal de Physique III, 1995, 5[C1], 37-47