Thin-Film III–V Photodetectors Integrated on Silicon-on-Insulator Photonic ICs

We critically assess recent progress in the integration of near-infrared photodetectors onto nanophotonic silicon-on-insulator (SOI) waveguide circuits. Integration of thin-film InGaAs photodetectors is studied in detail. This method consists of bonding unprocessed III–V dies onto the SOI substrate using an intermediate adhesive layer. Both benzocyclobutene and spin-on glass are studied and compared as bonding agents. After the removal of the III–V substrate, the thin-film detectors are fabricated using wafer-scale-compatible processes and lithographically aligned to the underlying SOI waveguides. The process is compatible with the fabrication of InP/InGaAsP laser diodes on SOI. A new design of an evanescently coupled metal–semiconductor–metal detector is proposed, proving the ability to obtain compact and highly efficient integrated InGaAs photodetectors.