Terry I. Chappell, Stanley E. Schuster, et al.
IEEE Journal of Solid-State Circuits
Self-aligned heterojunction bipolar transistors with a high-low emitter profile consisting of a heavily doped polysilicon contact on top of a thin epitaxial emitter cap have been fabricated. The low doping in the single-crystal emitter cap allows a very high dopant concentration in the base with low emitter-base reverse leakage and low emitter-base capacitance. The thin emitter cap is contacted by heavily doped polysilicon to reduce the emitter resistance, the base current, and the emitter charge storage. A trapezoidal germanium profile in the base ensures a small base transit time and adequate current gain despite high base doping. The performance potential of this structure was simulated and demonstrated experimentally in transistors with near-ideal characteristics, very small reverse emitter-base leakage current, 52-GHz peak f, and in unloaded ECL and NTL ring oscillators with, respectively, 24- and 19-ps gate delays. © 1993 IEEE
Terry I. Chappell, Stanley E. Schuster, et al.
IEEE Journal of Solid-State Circuits
John D. Cressler, Emmanuel F. Crabbé, et al.
IEEE Transactions on Electron Devices
John D Cressler, Emmanuel F Crabe, et al.
IEDM 1991
John D. Cressler, Emmanuel F. Crabbé, et al.
IEEE Transactions on Electron Devices