Selective-area growth of vertically aligned GaAs and GaAs/AlGaAs core-shell nanowires on Si(111) substrate.

We report on selective-area growth of vertically aligned GaAs nanowires on Si(111) substrate. Modification of the initial Si(111) surface by pretreatment under an AsH(3) atmosphere and low-temperature growth of GaAs were important for controlling the growth orientations of the GaAs nanowire on the Si(111) surface. We also found that the size of openings strongly affected the growth morphology of GaAs nanowires on Si(111). Small diameter openings reduced the antiphase defects and improved the optical properties in the GaAs nanowires. Moreover, we realized coherent growth without misfit dislocation at the GaAs/Si interface. Finally, we demonstrated fabrication of a GaAs/AlGaAs core-shell nanowire array on a Si surface and revealed that the luminescence intensity was markedly enhanced by passivation effects. These results are promising for future III-V nanowire-based optoelectronic integration on Si platforms.