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

We have fabricated high-speed resonant cavity enhanced Ge-on-SOI photodetectors, demonstrating 3 dB bandwidths of more than 12 GHz at 3 V reverse bias and a peak quantum efficiency of 59% at the resonant wavelength of 1540 nm.

The monolithic integration of photodetectors designed for operation around the long-haul communication wavelengths (1300, 1550 nm) with silicon-based IC technologies has been a long-standing goal within the optical communications industry. One attractive solution involves direct monolithic integration, given the relative ease of fabrication and potential cost advantage associated with this approach. Si-based photo detectors would be ideal for monolithic integration with Si-based electronics; however, such detectors would not be viable for operation around the long-haul communication wavelengths, given the lack of sensitivity Si exhibits at wavelengths beyond 1100 nm.