Bi-catalyzed vapor-liquid-solid approach for epitaxial growth of InAs : Bi nanowires on Si substrate.

This work reports a novel low-temperature approach for the direct heteroepitaxial integration of narrow-bandgap III-V materials on silicon. We demonstrate the self-catalyzed vapor-liquid-solid molecular beam epitaxy growth of InAs : Bi nanowires via Bi catalytic droplets directly on Si (111) substrates. Compared to Au-catalyzed growth, bismuth-induced vapor-liquid-solid synthesis improves the compatibility of the proposed low-thermal-budget fabrication technique with the silicon platform. The nanowire geometry enables the direct synthesis of dislocation-free zinc blende InAs : Bi nanowires on silicon with a Bi content of 0.05%. The bismuth concentration in NWs growing from Bi droplets is consistent with the Bi solubility limit in bulk InAs, suggesting that equilibrium thermodynamics plays a dominant role in Bi incorporation during VLS growth. Additionally, Bi incorporation facilitates a material bandgap reduction, which is confirmed theoretically and experimentally. Thus, the proposed approach enables a promising route for the monolithic integration of high-performance mid-infrared devices in silicon photonics.