Ultra-sensitive detector for Silicon Photonics; a photodiode incorporating integrated bipolar gain

Phototransistors built this way offer a low-capacitance, high-speed integrated solution for receivers, with decoupled absorption and amplification regions. Having the first stage of gain directly integrated with the absorption region of the transistor means that the sensitivity of the device can be greatly increased, thanks to it's low capacitance and high gain. Furthermore the fabrication of such a device requires little change to the process required to make electrical bipolar transistors, and much of the knowledge can be reused for phototransistors. If fabricated in Germanium, one could easily imagine using these devices for high speed data communications applications at 1550 or 1310 nm, either as standalone detectors or integrated within a Silicon Photonics process.