High Performance InP/InGaAs HBTs for 40-Gb/s Optical Transmission ICs

Hiroshi MASUDA  Kiyoshi OUCHI  Akihisa TERANO  Hideyuki SUZUKI  Koichi WATANABE  Tohru OKA  Hirokazu MATSUBARA  Tomonori TANOUE  

IEICE TRANSACTIONS on Electronics   Vol.E82-C   No.3   pp.419-427
Publication Date: 1999/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Issue on Ultra-High-Speed IC and LSI Technology)
InP/InGaAs,  HBT,  T-shaped emitter electrode,  gas-source MBE,  Pt-based metal,  InP subcollector,  thermal runaway,  static 1/2 frequency divider,  

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We have developed a fabrication technique for high-performance high-thermal-stability InP/InGaAs heterojunction bipolar transistors (HBTs) for use in 40-Gb/s ICs. The HBT's T-shaped emitter electrode structure simplifies the fabrication process and enables high controllability of spacing between the emitter and the base electrodes. A highly-C-doped base, grown by gas-source MBE, and a new Pt-based metal system results in a low base resistance. An InP subcollector suppresses thermal runaway of HBTs at high collector current better than a conventional InGaAs subcollector does. Using these techniques, we fabricated a very-high-performance HBT with an extremely high cutoff frequency fT of 235 GHz. The RF measurements show that the collector current at the peak cutoff frequency is inversely proportional to collector thickness. We also fabricated a static 1/2 frequency divider, that can be used for 40-Gb/s optical transmission systems, operating up to 44 GHz. This divider confirmed that the developed HBT is applicable to 40-Gb/s optical transmission ICs.