AlGaInAs MultiQuantum Well Lasers on Silicon-on-Insulator Photonic Integrated Circuits based on InP-seed-bonding and Epitaxial Regrowth

The tremendous demand for low-cost, low-consumption and high-capacity optical transmitters in data centers challenges the current InP-photonics platform. The use of Si photonics platform to fabricate photonic integrated circuits (PICs) is a promising approach for low-cost large-scale fabrication considering the CMOS-technology maturity and scalability. However, silicon itself cannot provide an efficient emitting light source due to its indirect bandgap. Therefore, the integration of III-V semiconductors onto silicon wafers allows to benefit from the III-V emitting properties combined with benefits offered by the silicon photonics platform. Direct epitaxy of InP-based materials on 300 mm Si wafers is the most promising approach to reduce the costs. However, the differences between InP and Si in terms of lattice mismatch, thermal coefficients and polarity inducing the formation of antiphase domains are challenging issues to overcome. III-V/Si heterointegration platform by wafer-bonding is the most mature integration scheme. However, no additional epitaxial regrowth steps are implemented after the bonding step. Considering the much larger epitaxial toolkit available in the conventional monolithic InP platform, where several epitaxial steps are often implemented, this represents a significant limitation. In this paper, we review an advanced integration scheme of AlGaInAs-based laser sources onto Si wafers by bonding a thin InP layer on which further regrowth steps are implemented. A qualification of a 3 µm-thick AlGaInAs-based MQW laser structure grown onto on InP-SiO2/Si (InPoSi) wafer was done and compared to the same structure grown on InP wafer as a reference. The 400 ppm thermal strain on the structure grown on InPoSi, induced by the difference of thermal coefficient expansion between InP and Si, was assessed at growth temperature. We also shew that this structure demonstrates laser performance similar to the ones obtained for the same structure grown on InP. Therefore, no material degradation was observed in spite of the thermal strain. Then, we developed the Selective Area Growth (SAG) technique to grow multi-wavelength laser sources from a single growth step onto InPoSi. A 155 nm-wide spectral range from 1515 nm to 1670 nm was achieved. Futhermore, a AlGaInAs MQW-based laser source was successfully grown onto InP-SOI wafers and efficiently coupled to Si-photonic DBR cavities. Altogether, the regrowth onto InP-SOI wafers hold great promises to combine the best from the III-V monolithic platform combined with the possibilities offered by the Silicon photonics circuitry via efficient light-coupling.