Hybrid axial and radial Si-GaAs heterostructures in nanowires.

Hybrid structures are formed from materials of different families. Traditionally, group IV and III-V semiconductors have not been integrated together in the same device or application. In this work we present a new approach for obtaining Si-GaAs hybrid heterostructures in nanowires based on a combination of molecular beam epitaxy and plasma enhanced chemical vapor deposition. Crystalline Si segments are integrated into GaAs nanowires grown by the Ga-assisted growth method at temperatures as low as 250 °C. We find that one of the most important factors leading to the successful growth of Si segments on GaAs is the silane-hydrogen dilution, which affects the concentration of silicon and hydrogen-based radicals (SiHx with x < 3) in the plasma, and determines if the Si shell is amorphous, polycrystalline or crystalline, and also if the growth takes place in the axial and/or radial directions. This work opens the path for the successful integration of silicon and III-V materials in one single nanowire.