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 at the same time 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 micrometer. 0.66 A/W waveguide-referred photodiode responsivity at 1550 nm was obtained. High speed measurements yielded open eye diagrams at 40 Gbit/s.
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