Development of Integration Process of InGaAs/InP Heterojunction Bipolar Transistors with InP-Passivated InGaAs pin Photodiodes

We have successfully developed a fabrication process for OEICs in which each device structure and performance can be optimized. We integrated InGaAs/InP HBTs and InP-passivated InGaAs pin PDs on a semi-insulating InP substrate using multi-epi growth process. For the PDs with a 60 mum mesa diameter, the capacitance of 0.2 pF and the dark current of 0.1 nA at a reverse bias voltage of 5 V were obtained. For the HBTs with a 5.6-mum² emitter area, the current gain of 44, the turn-on voltage of 0.77 V, the cutoff frequency of 122 GHz, and the maximum oscillation frequency of 165 GHz at a collector current density of 1 mA/mum² were obtained. The HBTs show good uniformity and HBTs near the pin PDs show the same characteristics as those of remote HBTs. The result promises that this process can be used in fabrication of high-speed OEICs for practical applications.