High Responsivity Si/Ge Phototransistor on Silicon Photonics Platform for Small Signal Application

We report a new type of Si/Ge waveguide phototransistor with high responsivity under low bias voltages for small signal and low noise applications. The phototransistor is fabricated using a standard silicon photonics foundry and shows a responsivity higher than 500 A/W at 0.5 V bias, where the dark current is on the order of a few micron amperes.