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.

Suppression of Boron Transient Enhanced Diffusion in SiGe Heterojunction Bipolar Transistors by Carbon Incorporation. L.D.Lanzerotti, C.Sturm, E.Stach, R.Hull, T.Buyuklimanli, C.Magee: Applied Physics Letters, 1997, 70[23], 3125-7