Waveguide-integrated telecom-wavelength photodiode in deposited silicon

We demonstrate photodiodes in deposited polycrystalline silicon at 1550 nm wavelength with 0.15 A/W responsivity, 40 nA dark current, and gigahertz time response. Subband absorption is mediated by defects that are naturally present in the polycrystalline material structure. The material exhibits a moderate absorption coefficient of 6 dB/cm, which allows the same microring resonator device to act as both a demultiplexing filter and a photodetector. We discuss the use of deposited silicon-based complementary metal-oxide semiconductor materials for nanophotonic interconnects.