It was demonstrated that the incorporation of C, into the base of an npn Si/SiGe/Si heterojunction bipolar transistor, markedly reduced the out-diffusion of B from the base under post-growth implantation and annealing conditions. The reduction in B diffusivity, when compared with C-free samples, was reflected by secondary ion mass spectroscopic data and by improved electrical characteristics.

L.D.Lanzerotti, C.Sturm, E.Stach, R.Hull, T.Buyuklimanli, C.Magee: Applied Physics Letters, 1997, 70[23], 3125-7