Effects of step bunching on CuPt-B ordered structures in Ga0.5In0.5P grown by MOVPE

The effects of step bunching on a CuPt-B ordered structure in Ga(0.5)In(0.5)P grown on ((1) over bar 18)B and((1) over bar 1 13)B substrates by metalorganic vapor phase epitaxy (MOVPE) were studied. The growth was carried out at 660 degrees C with V/III ratios of 55 and 1500. In the GaInP layers, a CuPt-B ordered structure in the [(1) over bar 11]B direction was dominantly formed. The epitaxial growth surfaces were undulated caused by the atomic-step bunching. When GaInP was grown at a V/III ratio of 55, a disordered region of CuPt-B ordered structure was formed at the step-bunched surface. At a V/III 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 V/III ratio was weaker. The difference in the ordered-structure formation between two V/III ratios indicates that P-dimer coverage of surface reconstructions is a factor that affects the ordering formation intensity. (C) 1998 Elsevier Science B.V. All rights reserved.