GaInP ridge structures with ridge-top facet widths in the sub-wavelength region (0.5-0.6 mu m) and aligned along the [1 1 0] direction were successfully fabricated by selective-area metalorganic vapor phase epitaxy on (0 0 1) GaAs substrates using SiO(2) stripes as a mask. An X-ray diffraction study confirmed that the lattice mismatch of GaInP grown on both the (0 0 1) flat and (1 1 1)B sidewall facets of the ridges can be controlled to within about 0.3%, making possible the fabrication of high-efficiency optical devices using the grown structures. Spontaneous atomic ordering similar to that appearing in GaInP layers grown on unpatterned (0 0 1)GaAs substrates was observed on the (0 0 1) flat facet of the ridge structure, while the (1 1 1)B facet was completely disordered. (C) 2011 Elsevier B.V. All rights reserved.