Vertical scaling of type I InP HBT with FT > 500 GHZ

J. W. Lai, W. Hafez, M. Feng

Research output: Contribution to journalArticlepeer-review


We have fabricated the high-speed InP/InGaAs-based single heterojunction bipolar transistors (SHBTs) with current gain cutoff frequency, fT from 166GHz to over 500GHZ by the approach of vertical scaling. Collector thickness is reduced from 3000Å to 750Å and the peak current density is increased up to 1300kA/cm2. In this paper, device rf performance has been compared with respect to materials with different vertical dimensions. The scaling limitation is also studied by analytical approach. The extracted physical parameters suggest that the parasitic emitter resistance is the major limit on further enhancing ultra-scaled HBT intrinsic speed due to the associated RECBC delay. The cut-off frequency of a 500Å collector SHBT has been measured and the results indicate a dramatic drop on fT, supporting the conclusion projected by model analysis. It is also commented that for deeply downscaled HBTs, impact ionization could be another degrading mechanism limits device bandwidth.

Original languageEnglish (US)
Pages (from-to)625-631
Number of pages7
JournalInternational Journal of High Speed Electronics and Systems
Issue number3
StatePublished - Sep 2004

ASJC Scopus subject areas

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


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