Inclined inheritance of interface roughness in semiconductor superlatticesas characterized by x-ray reciprocal space mapping - art. no. 195316

The inclined inheritance of interface roughness is investigated for an AlAs /GaAs superlattice grown by molecular beam epitaxy on a vicinal (001) GaAs substrate. As a consequence of vertical correlation of the roughness of sub sequent interfaces the diffusely scattered x-ray intensity is bunched into resonant diffuse scattering (RDS) sheets in reciprocal space. Inclined inhe ritance leads to corresponding shearing of the RDS sheets. A simple model f or the evaluation of inclined roughness inheritance in three dimensions is presented, where the sheared RDS sheets are modeled by anisotropic sheared ellipsoids. From measurements at different azimuthal sample orientations th e two angles characterizing the inclined inheritance of interface roughness can be determined accurately. At the present sample the inheritance of int erface roughness approximately follows the direction of step flow during gr owth. The results show that a three-dimensional analysis of diffuse scatter ing is necessary for a correct evaluation and interpretation.