Advanced InP/InGaAs HBTs Technology

for Low-Power Lightwave Communication Circuit Applications (Invited)
S. Yamahata, H. Nakajima, M. Ida, E. Sano, Y. Ishii
NTTPhotonics Laboratories
3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198, Japan

A reliable non-self-aligned process technology has been developed for InP/InGaAs HBTs with a carbon-doped base and applied to 40 Gbit/s lightwave communication ICs.  A hexagonal shaped emitter geometry aligned parallel to the Primary Flat of wafer is used to suppress the periphery base leakage current originating from the side-wall of the InP emitter-mesa.  This emitter orientation leads to stable emitter/base-junction I-V characteristics.  In addition, a dehydrogenation annealing method was devised to activate the carbon accepters of the InGaAs base layer, which is passivated by hydrogen during MOVPE growth.  A 6-mm2 hexigonal emitter HBT with a 1.2 mm width showed peak fT of 135.8 GHz and fmax of  183.7 GHz.  A 40-Gbit/s 1:4 demultiplexer IC, a 40-GBit/s decision IC, and a 40 GHz static 2:1 frequency divider IC were fabricated using non-self-aligned InP/InGaAs HBTs.  The power dissipations of the 1:4 demultiplexer and decision ICs were as low as 2.97 and 0.94 W, respectively.




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