Double-crystal spectrometer measurements of lattice parameters and X-ray topography on heterojunctions GaAs-Al_xGa_1-xAs

Heterojunctions GaAs-Al_xGa_1-xAs involved in the elaboration of IR laser diodes have been studied. The difference in lattice parameter between the GaAs substrate and the aluminum-substituted epitaxic layer Al_xGa_1-xAs has been measured accurately on a double-crystal spectrometer for a series of compositions. These data coupled with radius of curvature determination have permitted calculation of the stress in the layer and the bulk lattice parameter of Al_xGa_1-xAs. characterization of the defects introduced during the liquid-phase epitaxy has been performed by X-ray topography.