Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 89: Metamorphic structures: Bringing together incompatible materials I (Focus session with DF)

HL 89.7: Talk

Thursday, April 3, 2014, 12:00–12:15, POT 251

Improved X-ray diffraction simulations taking into account inhomogeneities exceeding the coherence length — •Christoph Berger, Dennis Schmidt, Jürgen Bläsing, Armin Dadgar, and Alois Krost — Otto-von-Guericke-Universität, Magdeburg, Deutschland

In many cases simulated diffraction patterns of semiconductor thin films or superlattices differ significantly from experimental data. The reason is that structural imperfections are often neglected in the simulation model. Indeed, many software packages can include the influence of compositional or thickness variations, but these variations occur on a shorter length scale than the coherence length of the diffractometer and have to be treated by dynamical theory. Including these influences often does not improve the simulation result. Due to the large area that is usually probed by the X-ray beam, one has to take into account structural variations larger than the coherence length as well, for instance lateral gradients across the wafer. These variations can be described by a sum of the diffracted intensity from the different parts of the specimen. In our method, a series of ideal simulations, each multiplied with a weighting factor, is summed up by a MATLAB routine that minimizes the deviation between the measurement and the sum of the weighted ideal simulations. The distribution of the weighting factors enables the estimation of the lateral variation width within the sample and the fit between simulated and experimental data is significantly improved.