Determination of the optical properties of a-SixGe1-X facilitated by micro-combinatory

The traditional “multiple-sample concept” combinatorial techniques produce numerous different samples, very effectively, however, handling and measuring dozens of samples is definitely not effective. We worked out the method “one-sample concept” micro-combinatory that provides extreme throughput in both preparation and measurement of composition dependent properties of binary films. Due to its technological importance gradient amorphous SiGe was studied to reveal the correlations between composition, structure, and optical properties. SiGe micro-combinatorial samples were deposited by DC magnetron sputtering and scanned by a Woollam M-2000DI rotating compensator spectroscopic ellipsometer. The dispersion of the layer was modeled using the Tauc-Lorentz (TL) approach. This approach allows that the total number of fitted parameters are kept at a reasonable value (thicknesses of the roughness layer and the film, and the TL parameters). The spectra measured at each position (each composition) have been fitted. To shorten the time of calculations of the fitting procedure we used the calculated parameters of the previous point as starting data to find the best match between the measured and calculated ellipsometry spectra.