Improvement of universal pin photodetectors in 0.35μm SiGe BiCMOS technology

Universal pin photodiodes combine low capacitance with high bandwidth and high responsivity. A speed improvement is achieved for a pin finger photodiode in a high-speed 0.35 mum SiGe heterojunction bipolar transistor (HBT) BiCMOS technology. The cathode finger structure results in a high responsivity of 0.2 A/W (quantum efficiency 61 ) for 410 nm light and a bandwidth of 1253 MHz at a reverse bias voltage of 3 V. Owing to the thick low doped intrinsic epitaxial layer, high bandwidths and high dynamic quantum efficiencies result for a wide spectrum of optical wavelengths from ultraviolet and blue to red and near-infrared.