25 January 2000 Characterization of silicon carbide epitaxial films by differential reflectance spectroscopy
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Proceedings Volume 4064, Third International Workshop on Nondestructive Testing and Computer Simulations in Science and Engineering; (2000) https://doi.org/10.1117/12.375465
Event: Third International Workshop on Nondestructive Testing and Computer Simulations in Science and Engineering, 1999, St. Petersburg, Russian Federation
Abstract
We are presenting a simple non-destructive method for characterizing SiC samples (Lely-crystals, CREE-substrates, and epitaxial films). With our method we observed ultraviolet differential reflection spectra of SiC samples and compared with pure Lely-crystal to estimate their structural quality. Our optical differential method is based on the experimental fact that doping of a crystal leads to appreciable changes of the optical fundamental absorption spectrum, which we interpreted as a uniform broadening and a shift of differential spectra. The broadening of absorption peaks can be caused not only by doping, but also by any defects of the crystal lattice (neutral impurities, clusters, micro-pipes and others), that destroy its periodicity. The shifts of these peaks inform us about the free carrier concentration. The experiment has shown we can detect minimum free carriers concentration up to nmin equals (ND-NA) equals 6 (DOT) 1015 cm-3. Besides we can detect minimal frequency of impacts with lattice defects as vmin equals 3 (DOT) 1012 s-1. Converting to charged centers concentration it equals (ND + NA) equals 5 (DOT) 1016 cm-3. Considering the small depth of light probe (less than 0.1 micrometers ) and delicacy of thin films, our contactless method is mostly applicable for its testing.
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Anatoly V. Shturbin, Anatoly V. Shturbin, Ilya E. Titkov, Ilya E. Titkov, Vadim Yu. Panevin, Vadim Yu. Panevin, Leonid E. Vorobjev, Leonid E. Vorobjev, Renata F. Witman, Renata F. Witman, } "Characterization of silicon carbide epitaxial films by differential reflectance spectroscopy", Proc. SPIE 4064, Third International Workshop on Nondestructive Testing and Computer Simulations in Science and Engineering, (25 January 2000); doi: 10.1117/12.375465; https://doi.org/10.1117/12.375465
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