Profile scaling constraints for ion-implanted and epitaxial bipolar technology designed for 77 K operation

John D. Cressler, Emmanuel F. Crabe, James H. Comfort, James Warnock, Keith A. Jenkins, Johannes M.C. Stork, Jack Y.C. Sun

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Scopus citations


The scaling constraints on vertical profile design which are unique to liquid nitrogen temperature operation (LNT equivalent to 77 K) of ion-implanted and epitaxial Si and SiGe bipolar technologies are investigated experimentally. While conventional on-implantation techniques can yield transistors with cutoff frequencies as high as 36 GHz at LNT, these devices have limited extendibility for circuit applications due to excessive base freeze-out. A more advanced epitaxial SiGe technology can be used to simultaneously achieve an fT for 59 GHz and superior base freeze-out properties at low temperatures, yielding a very aggressive ECL (emitter coupled logic) gate delay of 28 ps at LNT. For SiGe devices, however, the optimum collector profile design is constrained by a barrier induced at the SiGe-Si heterojunction under high injection which limits the device transconductance and fT at LNT.

Original languageEnglish
Title of host publicationInternational Electron Devices Meeting 1991, IEDM 1991
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages4
ISBN (Electronic)0780302435
StatePublished - 1991
EventInternational Electron Devices Meeting, IEDM 1991 - Washington, United States
Duration: 8 Dec 199111 Dec 1991

Publication series

NameTechnical Digest - International Electron Devices Meeting, IEDM
ISSN (Print)0163-1918


ConferenceInternational Electron Devices Meeting, IEDM 1991
Country/TerritoryUnited States


  • Coupling circuits
  • Cutoff frequency
  • Delay
  • Germanium silicon alloys
  • Logic devices
  • Logic gates
  • Nitrogen
  • Silicon germanium
  • Temperature
  • Transistors


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