Positron annihilation methods were used to investigate the DX(Si) and DX(Te) centers in n-type material. A vacancy defect was observed in the ground state of the DX centers. The vacancy signal disappeared in the shallow donor state which was reached at low temperatures upon illuminating the sample. The size of the vacancy was small as compared with isolated As and Ga vacancies. The results were in good agreement with the vacancy-interstitial model for the DX center.

T.Laine, J.Mäkinen, K.Saarinen, P.Hautojärvi, C.Corbel, P.Gibart: Materials Science Forum, 1995, 196-201, 1073-8