Raman Piezospectroscopy of Phonons in Bulk 6H-SiC

K. Grodeckia, b, A. Wysmołeka, R. Stępniewski a, J.M. Baranowskia, b, W. Hofmanb, E. Tymickib and K. Graszab, c a Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, 00-681 Warsaw, Poland b Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw, Poland c Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland

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Raman piezospectroscopy of high quality 6H-SiC crystals is presented. The crystals used in experiments were grown by the seeded physical vapor transport method. Uniaxial stress up to 0.9 MPa, obtained using a spring apparatus, was applied along [11-20] and [10-10] directions. It was found that the application of uniaxial stress led to different energy shifts of the observed phonon excitations in the investigated 6H-SiC crystals. The obtained pressure coefficients vary in the range 0.98-5.5 cm-1 GPa-1 for different transverse optical phonon modes. For longitudinal optic phonon modes pressure coefficients in the range 1.6-3.6 cm-1 GPa-1 were found. The data obtained could be useful in evaluation of local strain fields in SiC based structures and devices including epitaxial graphene.

DOI: 10.12693/APhysPolA.116.947 PACS numbers: 62.50.-p, 42.65.Dr, 63.20.-e, 78.30.-j