Heterogeneous CMOS Photonics Based on SiGe/Ge and III–V Semiconductors Integrated on Si Platform

The heterogeneous integration of SiGe, Ge, and III-V semiconductors on Si provides many opportunities to develop high-performance photonic integrated circuits through complementary metal oxide semiconductor (CMOS) processes. We found that strained SiGe possesses greater free-carrier effects than Si, contributing to the improved modulation efficiency of Si-based optical modulators. In addition to low-dark-current Ge photodetectors (PDs) with GeO 2 passivation, we investigated Ge CMOS photonics platform for midinfrared wavelengths. We demonstrated Ge passive waveguides and carrier-injection variable optical attenuators (VOAs) on a Ge-on-insulator wafer. We also investigated III-V CMOS photonics platform on a III-V-on-insulator (III-V-OI) wafer. The strong optical confinement in the III-V-OI structure enabled the realization of ultrasmall III-V passive waveguides similarly to those in Si photonics. Carrier-injection InGaAsP optical switches and VOAs as well as InGaAs waveguide PDs were also demonstrated on III-V-OI wafers. We discuss the opportunities and challenges of heterogeneous CMOS photonics technologies to develop high-performance electronic-photonic integrated circuits for near-infrared and midinfrared applications.