Catalyst-free growth of GaAs nanowires by selective-area metalorganic vapor-phase epitaxy

We report on the fabrication of GaAs hexagonal nanowires surrounded by {110} vertical facets on a GaAs (111) B substrate using selective-area (SA) metalorganic vapor-phase epitaxial (MOVPE) growth. The substrate for SA growth was partially covered with thin SiO2, and a circular mask opening with a diameter d(0) of 50-200 nm was defined. After SA-MOVPE, GaAs nanowires with a typical diameter d ranging from 50 to 200 nm and a height from 2 to 9 μ m were formed vertically on the substrate without any catalysts. The size of the nanowire depends on the growth conditions and the opening size of the masked substrate. A possible growth mechanism is also discussed. © 2005 American Institute of Physics.