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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 17: Microstructure, Real Structure and Crystal Defects
KFM 17.7: Vortrag
Freitag, 20. März 2020, 11:50–12:10, TOE 317
Examination of defects and lattice vibrations in rare and common polytypes of Silicon Carbide — •Maximilian von Roeder, Jurek Lange, Detlev Hofmann, Sangam Chatterjee, and Peter Klar — I. Physikalisches Institut and Zentrum für Materialforschung, Justus-Liebig-Universität, 35392 Gießen, Deutschland
Silicon Carbide is a wide band gap semiconductor existing in multiple polytypes. The most common polytypes are 4H- and 6H-SiC, rare ones are 8H- and 21R-SiC. The polytypism has significant effects on various properties of the material, especially the electronic band gap and thermal stability. The polytypism originates from different stacking of the layers composed of SiC4-tetrahedra. This results in quasi-cubic and quasi-hexagonal lattice sites in the crystal of a polytype. We used Raman-spectroscopy to show the dependence of the A1 acoustic phonon branch on the stacking type. It can be used as a fast and non-destructive way to classify the polytype at room temperature. Point defects (vacancies and impurities) were studied by electron paramagnetic resonance (EPR) spectroscopy. Furthermore, lattice vacancies are created by high-energy (EP=190 MeV) proton radiation vacancies in 4H-SiC-samples with fluxes of 1011 cm−2, 1013 cm−2 and 1014 cm−2. The EPR-spectra were analyzed in terms of the g-tensor, the exchange splitting (D), and the hyperfine interactions. The results of our investigation will be used to discuss the effects on the electrical properties of the silicon carbide polytypes.