High-bandwidth OEIC receivers using heterojunction bipolar transistors: Design and demonstration

The design, fabrication, and performance of the highest speed optoelectronic integrated circuit (OEIC) receivers reported to date are presented. These consist of PIN detectors and AlGaAs/GaAs HBT transistors fabricated on the same GaAs substrate. The p-i-n detectors were made from the same base and collector epitaxial layers as used for the HBT transistors and were completely compatible with the authors´ usual transistor fabrication process; no process alteration was required. The authors report 20-mm detectors with 35.6% quantum efficiency, 40-nA dark current at -3-V bias, and bandwidth in excess of 17 GHz. These detectors were used to produce two OEIC receivers, one with a bandwidth of 6.7 GHz and an equivalent input noise current of 4.3 pA/Hz^1/2 and another with a bandwidth of 13 GHz and an equivalent input noise current of 10 pA/Hz^1/2. The performances of a variety of circuit topologies are compared, and the effect of different epitaxial layer structures on OEIC performance is investigated