Doppler-broadening of the 511keV positron annihilation line was used to identify defects. In the case of electrically compensated lightly n-type In-doped material, or lightly p-type or semi-insulating Cl-doped material, positron lifetime measurements indicated the presence of vacancy defects with characteristic lifetimes of 323 and 370ps, respectively. The shapes of the high-momentum parts of the measured electron-momentum distributions indicated that both defects contained a Cd vacancy. The defects were thus suggested to be the vacancy-donor complexes, VCd-In and VCd-Cl, respectively. A vacancy in molecular beam epitaxially grown I-doped layers, detected using a low-energy positron beam, was also suggested to be a Cd vacancy which was in a complex with I-donors.

H.Kauppinen, L.Baroux, K.Saarinen, C.Corbel, P.Hautojärvi: Journal of Physics - Condensed Matter, 1997, 9[25], 5495-505