Transfer Print Integration of Waveguide-Coupled Germanium Photodiodes Onto Passive Silicon Photonic ICs

We demonstrate the integration of waveguide-coupled germanium photodiodes onto passive silicon waveguide circuits by means of transfer printing. This involves the release of the photodiodes from the silicon-on-insulator source wafer by underetching the buried oxide layer while protecting the back-end stack. Tethers were formed to keep the released photodiode coupons in place. Coupons were then transfer printed to a silicon photonic target wafer with an alignment accuracy better than ±1 μm. 0.66 A/W waveguide-referred photodiode responsivity at 1550 nm was obtained. High-speed measurements yielded open eye diagrams at 40 Gb/s.