LATERAL PERIODICITY IN HIGHLY-STRAINED (GAIN)AS GA(PAS) SUPERLATTICESINVESTIGATED BY X-RAY-SCATTERING TECHNIQUES/

In this work we investigate the lateral periodicity of symmetrically s trained (GaIn)As/GaAs/Ga(PAs)/GaAs superlattices by means of X-ray sca ttering techniques. The multilayers were grown by metalorganic Vapour phase epitaxy on (001)GaAs substrates, which were intentionally off-or iented towards the [011]-direction. The substrate off-orientation and the strain distribution was found to affect the structural properties of the superlattices inducing the generation of laterally ordered macr osteps. Several high-resolution triple-crystal reciprocal space maps, which were recorded for different azimuth angles in the vicinity of th e (004) Bragg diffraction and contour maps of the specular reflected b eam collected in the vicinity of the (000) reciprocal lattice point, a re reported and discussed. The reciprocal space maps clearly show a tw o-dimensional periodicity of the X-ray peak intensity distribution whi ch can be ascribed to the superlattice periodicity in the direction of the surface normal and to a lateral periodicity in a crystallographic direction coinciding with the miscut orientation. The distribution an d correlation of the vertical as well as of the lateral interface roug hness was investigated by specular reflectivity and diffuse scattering measurements. Our results show that the morphology of the roughness i s influenced by the off-orientation angle and can be described by a 2- dimensional waviness.