Nanometre-sized GaAs wires grown by organo-metallic vapour-phase epitaxy

Abstract

We grew GaAs wires as thin as 20 nm on a GaAs(111)B substrate using organo-metallicvapour-phase epitaxy (OMVPE), with Au as a growth catalyst. To investigate the growthcharacteristics, we compared two methods of depositing Au. In the first, Au was depositedby vacuum evaporation, and the deposition thickness was varied to form a planar Au layer.We found that an Au layer thickness of 1 nm was best for forming cylindrical shaped wires.Next, a new method of injecting Au onto an area of a few micrometres was testedusing a focused ion beam (FIB), and this method was found to be effective forgrowing wires as thin as 30–80 nm. However, the wire width did not depend on theinjected density of Au. We based our analysis of the results on an ion implantationmodel. GaAs wires with a p–n junction along the direction were formed by changing dopants from silicon to carbon during growth. Weobserved an optical emission with a peak intensity at the wavelength of 910–920 nm duringcontinuous current injection into the wires at 300 K. A spectral blue-shift in the lightemission and a polarization along the wire growth direction were also revealed at 77 K.