High structural and optical quality of III-V-on-Si 1.2 nm-thick oxide-bonded hybrid interface

In order to be compatible with CMOS processing, hybrid bonding of III-V materials on Silicon should be operated at 300°C, which requires an interface layer. The thinnest layer could be obtained when surfaces are prepared oxide-free and activated. We have investigated several activation processes of de-oxidized surfaces and measured their activation efficiency by X-ray Photoelectron Spectroscopy. We report here on the high structural and optical quality of a hybrid III-V on Silicon interface obtained by bonding under vacuum at 300°C de-oxidized surfaces activated by ozone. The resulting oxide interface layer is 1.2-nm thick the thinnest already reported. Structural characterization of this interface shows no defect in both crystalline lattices. Hybrid shallow ridge waveguides supporting an optical mode overlapping such an interface show 5cm−1 propagation losses comparable to the value measured for monolithic InP-based waveguides or SOI waveguides produced with the same technology, evidencing the high optical quality of the hybrid interface. Such a thin layer is favorable for an accurate control of the optical performances within hybrid devices and offers a large versatility for their design.