Hybrid Silicon Photonic Integrated Circuits

A number of important breakthroughs in the past decade have focused attention on Si as a photonic platform. We review here recent progress in this field, focusing on efforts to make lasers on or in silicon and on silicon photonic integrated circuits. The impact active silicon photonic integrated circuits could have on telecommunications and on silicon electronics is reviewed. Rapid advances in silicon photonics are being driven by a combination of a need for more complex, higher functionality and lower cost photonics integrated circuits. It is also driven by the needs of silicon electronics to limit the pin count and power limits of electronic chips, as summarized in the International Technology Roadmap for Semiconductors (ITRS). In direct bandgap materials, such as GaAs and InP, radiative recombination occurs rapidly and efficiently and this is the biggest reason why GaAs-, InP- and GaN-based materials have been the dominant material systems for semiconductor diode lasers. Silicon, like germanium, is an indirect bandgap material, and has a light emission efficiency on the order of 10-6. Hence, we have focused on Hybrid Silicon Lasers[1], which use bonding to combine III-V materials with SOI substrates. The SOI substrates used in silicon photonics are usually made by wafer bonding two oxidized silicon wafers together. We can use the same process to wafer bond a compound semiconductor wafer to a SOI substrate. This combines the superior gain characteristics of compound semiconductors with the superior passiv