Antiphasing mechanism of orderedGa0.5In0.5Players grown on GaAs (001)

Abstract
Ga0.5In0.5P layers grown by metal-organic chemical-vapor deposition on (001)-oriented GaAs substrates have been studied using transmission electron microscopy. Additional extra diffraction spots found in several projections around the [001] pole and a streaking parallel to the [001] direction observed in the [110] projection are interpreted as due to a laminar structure of the samples consisting of two variants of the CuPt structure with orderings on the (1¯11) and (11¯1) planes distributed in alternating (001)-oriented laminae. The results of our valence-force-field calculations, including—in an approximate way—the surface reconstruction, suggest a possible origin of the laminar growth. The band-gap reduction of the simplest laminar structures relative to the average gap of the binaries has been calculated by means of the relativistic linear-muffin-tin-orbital method, and found to be significantly lower than that of the CuPt phase.