Imec demonstrates wafer-scale GaAs lasers on silicon

Imec has managed to monolithically integrate GaAs laser diodes on 300-millimeter silicon-photonics wafers. This breakthrough opens the door to cost-effective, high-performance optical devices for applications in data communications, machine learning and artificial intelligence.

As silicon itself is incapable of efficiently generating light, direct epitaxial growth of high-quality III-V optical gain materials on silicon has been a longstanding dream in the world of integrated photonics. Although hybrid or heterogeneous flip-chip technology, micro-transfer printing or die-to-wafer bonding are viable alternatives, they may not always be an optimal solution.

Stacking silicon and III-V materials on top of each other is troublesome, however, because of their large mismatch in crystal lattice parameters and thermal expansion coefficients. The resulting formation of crystal defects is known to deteriorate laser performance and reliability. Imec has employed the so-called selective-area growth (SAG) technique combined with aspect-ratio trapping (ART) to significantly mitigate this phenomenon by confining misfit dislocations within narrow trenches etched in a dielectric mask.