DC and AC performances in selectively grown SiGe-base HBTs

Katsuya Oda, Eiji Ohue, Masamichi Tanabe, Hiromi Shimamoto, Katsuyoshi Washio

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


A selectively grown Si,Gex base heterojunction bipolar transistor (HBT) was fabricated, and effects of Ge and B profiles on the device performance were investigated. Since no obvious leakage current was observed, it is shown that good crystallinity of Si, jGe-4 was achieved by using a UHV/CVD system with high-pressure H2 pre-cleaning of the substrate. Very high current gain of 29,000 was obtained in an HBT with a uniform Ge profile by both increasing electron injection from the emitter to the base and reducing band gap energy in the base. Since the Early voltage is affected by the grading of Ge content in the base, the HBT with the graded Ge profile provides very high Early voltage. However, the breakdown voltage is degraded by increasing Ge content because of reducing bandgap energy and changing dopant profile. To increase the cutoff frequency, dopant diffusion must be suppressed, and carrier acceleration by the internal drift field with the graded Ge profile has an additional effect. By doing them, an extremely high cutoff frequency of 130 GHz was obtained in HBT with graded Ge profiles.

Original languageEnglish
Pages (from-to)2013-2019
Number of pages7
JournalIEICE Transactions on Electronics
Issue number11
Publication statusPublished - 1999 Jan 1
Externally publishedYes


  • Ge profile
  • SiGe HBT
  • current gain
  • cutoff frequency
  • selective epitaxial growth

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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