Review of Hybrid Integration Techniques for Integrating III-V Onto Silicon

Silicon photonics promises higher on-chip communication speeds through optical interconnects, high performance LIDAR sensors, advances in biological sensors, and high performance, high-bandwidth 5G transceivers. It has the unique advantage that it is compatible with current CMOS technology. While silicon photonic devices can integrate nearly any desired photonic structure, silicon itself is an indirect bandgap semiconductor so the light source for any photonic circuit must be sourced elsewhere. Coupling a light source from off-chip remains one of the most difficult packaging, performance, and integration challenges for silicon photonics. To address these issues, myriad research efforts over the last several years have focused on heterogeneously integrating direct-bandgap materials like indium phosphide (InP) directly onto silicon photonic devices. Hybrid integration is a promising integration technique because it allows the CMOS or III-V laser diode fabrication processes to be optimized independently. This paper provides a review of state-of-the-art hybrid integration technologies, including bonding and alignment techniques, and how to integrate those with CMOS technologies. The focus will be on telecom wavelength edge coupled laser diodes since these are well established and have low coupling losses.