INFLUENCE OF 1ST-ORDER APPROXIMATIONS IN THE INCIDENCE PARAMETER ON THE SIMULATION OF SYMMETRICAL AND ASYMMETRIC X-RAY ROCKING CURVES OF HETEROEPITACTIC STRUCTURES

The simulation of the experimental symmetric X-ray rocking curve of a coherent heteroepitactic structure, using first-order expressions in the incidence parameter, is shown to give a strain-depth profile not consistent with asymmetric rocking curves taken on the same sample. Two different expressions are suggested for the incidence parameter to attain internal consistency among all the rocking curves. The former involves second-order approximations and considers both normal and parallel lattice mismatches. The latter is the result of an exact derivation and takes into account only the normal mismatch. These models make the data from rocking-curve simulation reliable, provided that the angle between the surface and the planes corresponding to the nominal crystallographic orientation is not ignored.