Silicon Waveguide Integrated Germanium JFET Photodetector With Improved Speed Performance

This letter reports our recent results on the high-speed silicon-waveguided germanium junction-field-effect-transistor (JFET)-based photodetector. Although the Ge layer's footprint on wafer is as small as 2 mu m x 2 mu m, low standby current (0.5 mu A at 1 V), high responsivity (642 mA/W), and high speed (8 GHz) are achieved. The reported Ge JFET is a promising solution for photodetector's further scaling-down.