Slide 53 of 64
This is an intriguing plot from a paper by Jim Sturm here at Princeton. I guess he was unable to be here during the HTMT meeting. This is from a 1995 paper he wrote on another alloy that includes not only Si and Ge but also a tiny amount (less than a percent by atomic weight) of carbon. Although only partially seen in the above figure one can spot the onset of breakdown in the left transistor that has no C in its base, but not in the SiGeC base transistor. Evidently it went up in voltage. This might be evidence that even thinner base and faster transistors might be possible, but the beta is low in the right transistor.