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

Abstract—We critically assess recent progress in the integra-tion 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 fabri-cated using wafer-scale-compatible processes and lithographically aligned to the underlying SOI waveguides. The process is com-patible 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. Index Terms—Heterogeneous integration, photonic integrated circuit (IC), silicon-on-insulator (SOI), thin-film photodetectors. I