Effects of step bunching on CuPt-B ordered structures in Ga In P grown by MOVPE

The effects of step bunching on a CuPt-B ordered structure in Ga0.5In0.5P grown on 118.B and 1 1 13.B substrates by metalorganic vapor phase epitaxy MOVPE.were studied. The growth was carried out at 6608C with VrIII ratios of 55 and 1500. In the GaInP layers, a CuPt-B ordered structure in thew111xB direction was dominantly formed. The epitaxial growth surfaces were undulated caused by the atomic-step bunching. When GaInP was grown at a VrIII ratio of 55, a disordered region of CuPt-B ordered structure was formed at the step-bunched surface. At a VrIII ratio of 1500, anti-phase domain boundaries of a CuPt-B ordered structure were formed on terraced surfaces, resulting in stretched terrace surfaces. The ordered structure is expected to be caused by the epitaxial growth on the undulated surface which has a distribution of P-dimer coverage. From a transmission electron microscopy lattice image, CuPt-B ordered-structure formation at the lower VrIII ratio was weaker. The difference in the ordered-structure formation between two VrIII ratios indicates that P-dimer coverage of surface reconstructions is a factor that affects the ordering formation intensity. q1998 Elsevier Science B.V. All rights reserved.