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4 Acta Physica Polonica A

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CVD Growth of Graphene Stacks on 4H-SiC (0001) Surface - X-ray Diffraction and Raman Spectroscopy Study

100%

Tokarczyk M. , Kowalski G. , Grodecki K. , Urban J. , Strupiński W.

Acta Physica Polonica A

2013

tom 124

nr 5

768-771

Features associated with short and prolonged growth time in the chemical vapor deposition process of growth of graphene stacks on SiC (0001) substrate are reported. In particular general bimodal (as far as d_{002} interlayer spacing is concerned) distribution of graphene species across the surface of the samples is observed. It consists of thin few layer graphene coverage of most of the sample surface accompanied by thick graphite-like island distribution. It points to the two independent channels of graphene stacks growth with two characteristic growth rates.

Raman Piezospectroscopy of Phonons in Bulk 6H-SiC

86%

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.

Raman Studies of Defects in Graphene Grown on SiC

86%

Grodecki K. , Bożek R. , Borysiuk J. , Strupinski W. , Wysmolek A. , Stępniewski R. , Baranowski J.

Acta Physica Polonica A

2011

tom 119

nr 5

595-596

The Raman scattering studies of multi-layer graphene obtained by high temperature annealing of carbon terminated face of 4H-SiC(000-1) substrates are presented. Intensity ratio of the D and G bands was used to estimate the average size of the graphene flakes constituting carbon structures. The obtained estimates were compared with flake sizes from atomic force microscopy data. We found that even the smallest structures observed by atomic force microscopy images are much bigger than the estimates obtained from the Raman scattering data. The obtained results are discussed in terms of different average flake sizes inside and on the surface of the multi-layer graphene structure, as well as different type of defects which would be present in the investigated structures apart from edge defects.

Optical Absorption and Raman Scattering Studies of Few-Layer Epitaxial Graphene Grown on 4H-SiC Substrates

72%

Grodecki K. , Drabińska A. , Bożek R. , Wysmołek A. , Korona K. , Strupiński W. , Borysiuk J. , Stępniewski R. , Baranowski J.

Acta Physica Polonica A

2009

tom 116

nr 5

835-837

Optical absorption and Raman scattering studies of few-layer epitaxial graphene obtained by high temperature annealing of carbon terminated face of 4H-SiC(000-1) on-axis substrates are presented. Changing the pressure and annealing time, different stages of the graphene formation were achieved. Optical absorption measurements enabled us to establish average number of graphene layers covering the SiC substrate. Raman scattering experiments showed that integrated intensity of the characteristic 2D peak positively correlated with the number of graphene layers deposited on the SiC substrate. The spectral width of the 2D peak was found to decrease with the number of the deposited graphene layers.