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

Abstract : In order to be compatiblewith 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 deoxidized 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 5 cm−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.