Ge photodetector monolithically integrated with amorphous Si waveguide on wafer-bonded Ge-on-insulator substrate

We present a proof-of-concept demonstration of a Ge/a-Si hybrid photonic integrated circuit platform utilizing a high-quality Ge-on-insulator (GeOI) wafer fabricated by wafer bonding technology. Amorphous Si (a-Si) formed by PECVD is found to be a promising alternative to conventional Si passive waveguides on a SiO2 BOX. Taking advantage of the high crystal quality of the Ge active layer and the easy fabrication of an a-Si waveguide, a low-dark-current Ge waveguide PIN photodetector monolithically integrated with an a-Si passive waveguide is successfully demonstrated on a GeOI wafer.