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3 Acta Physica Polonica A

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Raman Piezospectroscopy of Phonons in Bulk 6H-SiC

100%

Grodecki K. , Wysmołek A. , Stępniewski R. , Baranowski J. , Hofman W. , Tymicki E. , Grasza K.

Acta Physica Polonica A

2009

tom 116

nr 5

947-949

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.

Magneto-Luminescence Study of Silicon-Vacancy in 6HSi

100%

Wysmołek A. , Wardak K. , Stępniewski R. , Baranowski J. , Potemski M. , Tymicki E. , Grasza K.

Acta Physica Polonica A

2006

tom 110

nr 3

437-442

The magneto-spectroscopy studies of luminescence related to silicon-vacancy, in high quality 6H-SiC crystals grown by the seeded physical vapor transport method, are presented. The superior optical quality of these crystals allowed us to resolve a doublet structure of the 1.398 eV emission line (V_2 line), commonly assigned to the transitions involving two singlet states of the silicon-vacancy. Experiments performed in magnetic fields up to 20 T showed that each doublet constituent of the V_2 line splits into four components for the magnetic field parallel to the c-axis of the 6H-SiC crystals. This result could be hardly explained in terms of a singlet to singlet transition. The analysis of the angle-resolved luminescence experiments in high magnetic fields serves us to discuss the symmetry of the defect states responsible for the V_2-line in silicon carbide.

Structural and Electrical Properties of SiC Grown by PVT Method in the Presence of the Cerium Vapor

100%

Avdonin A. , Racka K. , Tymicki E. , Grasza K. , Jakieła R. , Pisarek M. , Dobrowolski W.

Acta Physica Polonica A

2013

tom 124

nr 5

761-764

The results of investigation of structural and electrical properties of bulk SiC crystals, which were grown by physical vapor transport method with different Ce impurity content added to the SiC source material, are presented. The gradual dosage of cerium from the SiC source and continuous presence of the cerium vapor over the SiC crystallization fronts during the crystal growth processes are confirmed. The cerium influences the overall concentration of structural defects. The increase of the concentration of both, donors and acceptors, and appearance of new shallow donors (15-32 meV) in 4H-SiC crystals are observed.