High-speed resonant cavity enhanced Ge photodetectors on reflecting Si substrates for 1550-nm operation

We have designed and fabricated high-speed resonant cavity enhanced germanium (Ge) Schottky photodetectors on a silicon-on-insulator substrate. These back-illuminated detectors have demonstrated 3-dB bandwidths of more than 12 GHz at 3-V reverse bias and a peak quantum efficiency of 59% (R = 0.73 A/W) at the resonant wavelength of similar to1540 nm. Time domain measurements of our Ge photodetectors with diameters of up to 48 mum show transit-time limited impulse responses corresponding to bandwidths of at least 6.7 GHz, making these detectors compatible with 10-Gb/s data communication systems.