The electrical deactivation of As in highly-doped material was studied by using the positron-beam technique. Direct experimental evidence was reported which linked the formation of As-vacancy complexes to the deactivation process. The average number of As atoms per complex was determined by comparing observed complex concentrations with the concentrations of deactivated As that were deduced from Hall-effect measurements. Positron annihilation measurements confirmed the generation of Asn Si4-n-v complexes. The deactivation process was correlated with a reduction in the positron diffusion length (vacancy formation) and the appearance of As nearest-neighbors (so-called decoration of vacancies) at annihilation sites. Experimental uncertainty prevented distinctions from being made between clusters that involved n-values of 2, 3 and 4. The average number of As atoms per vacancy was greater than 2. It was concluded that further work would be required in order to decide whether n was a function of the As concentration.

D.W.Lawther, U.Myler, P.J.Simpson, P.M.Rousseau, P.B.Griffin, J.D.Plummer: Applied Physics Letters, 1995, 67[24], 3575-7