Joachim N. Burghartz, John D. Cressler, et al.
IEEE Electron Device Letters
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
Joachim N. Burghartz, John D. Cressler, et al.
IEEE Electron Device Letters
John D. Cressler, Emmanuel F. Crabbé, et al.
IEEE Transactions on Electron Devices
Maurizio Arienzo, James H. Comfort, et al.
ESSDERC 1992
Wai Lcc, Jack Y.-C. Sun, et al.
VLSI Technology 1992