INVESTIGATION OF THE ROUGHNESS REPLICATION IN MULTILAYERS BY DIFFUSE X-RAY REFLECTION V. Holy, Dept. of Solid State Phys., Masaryk University, Kotlarska 2, 611 37 Brno, Czech Republic, G. Bauer, A. Darhuber, J. Stangl, and S. Zerlauth, Inst. of Semiconductor Physics, Kepler University, Altenbergerstr. 69, 4040 Linz, Austria.

The correlation properties of the interface roughness in a multilayer can be investigated by measuring the diffuse (off-specular) component of the reflected x-ray intensity. From the distribution of the diffuse scattering in reciprocal plane, the correlation function of a rough interface (in-plane correlation) as well as the correlation function of a pair of interfaces (inter-plane correlation) can be deduced. The in-plane correlation is decisive for the intensity distribution along the axis parallel to the surface, the inter-plane correlation affects the intensity distribution in the perpendicular direction. Inter-plane correlations give rise to distinct sheet-like maxima in reciprocal space oriented perpendicular to the direction of maximum correlation. From the width of the maxima, the inter-plane correlation length can be stated. In the case of single crystalline multilayers grown on misoriented substrates, the miscut of the vicinal surface affects the diffuse scattering introducing an asymmetry of the intensity distribution with respect to the surface normal. All these features have been demonstrated by measurements of diffuse x-ray reflection from SiGe/Si superlattices. We have found a well pronounced inter-plane correlation, whose direction differs substantially from the growth direction. The in-plane correlation function could be modelled by means of the Markov random chains using either two-level or many-level models.