InP based HBT integrated circuits

Shows InP based bipolar transistors integrated into high performance circuits and their application to an optoelectronic integrated circuit. The motivation for InP based heterojunction bipolar transistors is chiefly for integration with optoelectronic devices operating at the fibre windows of 1.3 and 1.55 μm; in addition InP HBTs offer many of the performance advantages of GaAs HBT circuits but with reduced power consumption (due to the lower bandgap in GaInAsP). The high transconductance, good drive capability, vertical structure and small area requirement of the HBT makes it a natural choice for opto-electronic integration. Further advantages are a short transit time and semi-insulating substrate-which greatly reduces parasitic capacitance and also eases device isolation. The starting point for the process, as with other GaInAsP devices, is the growth of the epitaxial structure by MOCVD. The substrates are 2" diameter semi-insulating InP to allow for device isolation