High-injection barrier effects in SiGe HBTs operating at cryogenic temperatures J.D. Cressler, D.M. Richey, R.C. Jaeger, E.F. Crabbé, J.H. Comfort and J.M.C. Stork J. Phys. IV France, 04 C6 (1994) C6-117-C6-122 DOI: 10.1051/jp4:1994618