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

We grew GaAs wires as thin as 20?nm on a GaAs(111)B substrate using organo-metallic vapour-phase epitaxy (OMVPE), with Au as a growth catalyst. To investigate the growth characteristics, we compared two methods of depositing Au. In the first, Au was deposited by 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 tested using a focused ion beam (FIB), and this method was found to be effective for growing wires as thin as 30?80?nm. However, the wire width did not depend on the injected density of Au. We based our analysis of the results on an ion implantation model. GaAs wires with a p?n junction along the direction were formed by changing dopants from silicon to carbon during growth. We observed an optical emission with a peak intensity at the wavelength of 910?920?nm during continuous current injection into the wires at 300?K. A spectral blue-shift in the light emission and a polarization along the wire growth direction were also revealed at 77?K.