Frequency response of a resonant cavity encapsulated germanium-on-silicon Schottky photodiode

The high-frequency performance of a Ge-on-Si resonant cavity encapsulated Schottky photodetector (PD) has been investigated. The normalised photocurrent has been calculated and computed considering the trapping of carriers at the Si/Ge hetero-interfaces. Results show that at low bias, bandwidth of the PD is controlled by the carrier-trapping effect at the hetero-interfaces and at high bias it is controlled by resonant-cavity effect and trapping-free transit-time effect. The PD design can be optimised for bandwidth maxima depending on the applied bias.