High-Speed InP-InGaAs Heterojunction Phototransistors Employing a Nonalloyed Electrode Metal as a Reflector

H. Fukano, Y. Takanashi, M. Fujimoto

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


High-speed InP-InGaAs heterojunction phototransistors (HPT‘s) with a base terminal (three-terminal HPT's) have been fabricated. These HPT's have nonalloyed electrodes functioning as reflectors and a configuration in which light is incident through the substrate. These features lead to an increase in quantum efficiency in spite of the thin base and collector light-absorbing layers. Optical gain dependence on collector current is weak because of the low recombination current at the emitter-base interface. Maximum optical-gain cutoff frequencies of 22 and 14 GHz are obtained for a 3 x 3-μm2 emitter HPT illuminated by 1.3-and 1.55-μm light, respectively. This HPT has the capability of operating as a high-speed heterojunction bipolar transistor (HBT) as well. A current-gain cutoff frequency (fT) of 128 GHz is obtained for a 3 x 9-μm2 emitter HBT fabricated on the same wafer. Equivalent circuit analysis, in which all the components are determined by measuring both the electrical and optical characteristics of a three-terminal HPT, shows good agreement with experimental results.

Original languageEnglish
Pages (from-to)2889-2895
Number of pages7
JournalIEEE Journal of Quantum Electronics
Issue number12
Publication statusPublished - Dec 1994
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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