DIFFUSE-X-RAY SCATTERING FROM MISFIT DISLOCATIONS IN SIGE EPITAXIAL LAYERS WITH GRADED GE CONTENT

A theory has been developed describing x-ray diffuse scattering from m isfit dislocations in epitaxial layers. This approach has been used fo r explaining the origins of diffuse x-ray scattering from SiGe layers with linearly graded Ge content. The distribution of the diffusely sca ttered intensity in reciprocal plane measured by triple-axis x-ray dif fractometry has been compared with theoretical predictions and a good agreement has been achieved. It is demonstrated that the main part of the diffusely scattered intensity originates from random strains cause d by misfit dislocations at the substrate-epilayer interface or in the relaxed part of the compositionally graded layers. The contribution o f the threading dislocation segments to the diffuse scattering is rath er small. (C) 1995 American Institute of Physics.