First Monolithic Integration of Group IV Waveguide Photodetectors and Modulators on 300 mm Si Substrates for 2-μm Wavelength Optoelectronic Integrated Circuit.

We report the first monolithic integration of group IV waveguide photodetectors (PDs) and modulators on 300 mm Si substrates for 2 μm wavelength applications. Our waveguide PDs and electro-absorption modulators (EAMs) employ Ge 0.92 Sn 0.08 /Ge multiple-quantum-well (MQW) as the active layer. We make use of the Ge buffer layer as the Ge-on-Si waveguide and grating coupler so that the light can be coupled to the EAM and PD for direct modulation and detection, respectively. The extended coupling path in our waveguide PD enhances the optical responsivity by 35 times over the surface illuminated mode with the same absorption layer, leading to the highest responsivity of 525 mA/W among all GeSn-based 2 μm PDs with a high 3-dB bandwidth of 6 GHz. In addition, for the first time, we demonstrate the feasibility of a 2 μm fully integrated transceiver with the successful operation of both PDs and EAMs on the same Si substrate.