In Si/SiGe/Si heterojunction bipolar transistor structures, very shallow As implantation of the emitter can cause anomalous B diffusion to occur in the base. It was found that, by using PtSi contacts, the anomalous diffusion in the base was appreciably reduced.

D.X.Xu, C.J.Peters, J.P.Noël, S.J.Rolfe, N.G.Tarr: Applied Physics Letters, 1994, 64[24], 3270-2