ANTIPHASING MECHANISM OF ORDERED GA0.5IN0.5P LAYERS GROWN ON GAAS(001)

Ga0.5In0.5P layers grown by metal-organic chemical-vapor deposition on (001)-oriented GaAs substrates have been studied using transmission e lectron microscopy. Additional extra diffraction spots found in severa l projections around the [001] pole and a streaking parallel to the [0 01] direction observed in the [110] projection are interpreted as due to a laminar structure of the samples consisting of two variants of th e CuPt structure with orderings on the ((1) over bar 11) and (1 (1) ov er bar 1) planes distributed in alternating (001)-oriented laminae. Th e results of our valence-force-field calculations, including-in an app roximate way-the surface reconstruction, suggest a possible origin of the laminar growth. The band-gap reduction of the simplest laminar str uctures relative to the average gap of the binaries has been calculate d by means of the relativistic linear-muffin-tin-orbital method, and f ound to be significantly lower than that of the CuPt phase. [S0163-182 9(98)05607-0].