SEM AND EDS CHARACTERIZATION OF GAAS-LAYERS GROWN BY THE CLOSE-SPACEDVAPOR TRANSPORT TECHNIQUE AT 4 DIFFERENT GEOMETRIES USING ATOMIC-HYDROGEN AS INITIAL REACTANT

GaAs layers were grown by the close-spaced vapor transport (CSVT) usin g atomic hydrogen as initial reactant. Scanning electron microscopy (S EM) and energy dispersive spectroscopy (EDS) were used to characterize the layers. It is observed that the variation on the experimental set up of the CSVT system and on some growth parameters (spacer thickness and source-substrate temperature gradient) have a remarkable influence on the surface morphology of the grown layers. It is inferred that th e stoichiometric deviation presented by all layers under study is due to the interaction of the atomic hydrogen with the source and substrat e at high temperatures (greater than or equal to 650 degrees C) during their growth process. The EDS analysis performed on the layers also s hows that the main impurities are Si, O, and C. By an additional exper iment, it was proved that the origin of the Si, and O contaminants is the etching effect of the quartz spacer by atomic hydrogen and it is i nferred that the origin of the C contaminant is mainly due to some con tamination existing in the reactor.