INTERPRETATION OF DOUBLE-CRYSTAL X-RAY ROCKING CURVES IN RELAXED STRAINED-LAYER STRUCTURES

Double-crystal x-ray rocking curves from metamorphic epitaxial heteros tructures are broadened by the presence of misfit dislocations and thi s vitiates the usual interpretation of rocking curves using simulation software. However, analysis of the moments of the rocking curve can b e useful. Using single layers, we show that the first moment is equiva lent to the peak splitting, so that the average strain and average com position of an inhomogeneous layer can be derived from its first momen ts. The usefulness of the method is demonstrated on complicated hetero structures including graded layers. (C) 1996 American Institute of Phy sics.