Structure of Ga0.47In0.53As epitaxial layers grown on InP substrates at different temperatures

摘要

The evolution of defect structures and surface reconstruction of Ga0.47In0.53As epitaxial layers grown by molecular beam epitaxy on InP substrate have been investigated by TEM and RHEED over a wide growth temperature range (150thinsp;deg;Cle;Tgle;450thinsp;deg;C) before and after annealing. In the growth temperature range 400thinsp;deg;Cle;Tgle;450thinsp;deg;C, extensive segregation of In near the layer surface takes place. The maximum of In concentration was found to lie under the layer surface. The kinetic of surface pit formation after annealing was explained in terms of surface reconstruction and As clustering. Extensive As clustering was observed after annealing for the growth temperature range 175thinsp;deg;Cle;Tgle;300thinsp;deg;C. Analysis of diffuse scattering and darkhyphen;field images made it possible to propose an atomic model of cluster structure. Precipitate formation close to the interface was observed only for the samples grown at 150thinsp;deg;C and annealed at 500thinsp;deg;C. Differences in electrical properties between LThyphen;grown GaAs and Ga0.47In0.53As are explained in terms of the structural defects.