Abstract

Heterojunction bipolar transistors (HBTs) based on III-V compound semiconductors offer significant performance advantages in ultrahigh speed digital and analog circuits, and, as a result, they are attractive candidates for use in multigigabit lightwave systems. HBTs incorporate an emitter with bandgap wider than that of the base, and are able to use higher base doping and lower emitter doping than their homojunction counterparts. This yields low base resistance and low emitter base capacitance. Electron velocity in III-Vs is higher than in Si, yielding shorter transit times. Use of semi-insulating substrates reduces parasitic capacitances, including collector substrate and pad contributions. Fabrication based on III-Vs allows integration of optical and electronic devices.

© 1990 Optical Society of America