通过作者查论文: Patrick Desperrier

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作者: Roland Püsche, Martin Hundhausen, Lothar Ley, Kurt Semmelroth, Gerhard Pensl, Patrick Desperrier, Peter J. Wellmann, Eugene E. Haller, J.W. Ager, Ulrich Starke
摘要: We study electronic Raman scattering of phosphorus and nitrogen doped silicon carbide (SiC) as a function of temperature in the range 7K < T < 300K. We observe a series of peaks in the Raman spectra which we assign to electronic transitions at nitrogen and phosphorus donors on different lattice sites. These transitions are identified as valley orbit transitions of the 1s donor ground state. From the polarization dependence of the observed peaks, we find that all electronic Raman signals have E2-symmetry of C6v for the hexagonal polytypes (6H-SiC and 4H-SiC) and E-symmetry of C3v for 15R-SiC. We find a reduction of the intensities of all valley-orbit Raman signals with increasing temperature and ascribe this reduction to the decreasing occupation of donor states.
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作者: Patrick Desperrier, Ralf Müller, Albrecht Winnacker, Peter J. Wellmann
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作者: Ralf Müller, Ulrike Künecke, Roland Weingärtner, Holger Schmitt, Patrick Desperrier, Peter J. Wellmann
摘要: Several highly aluminum doped SiC bulk crystals were grown with a modified PVT (MPVT) method. To facilitate 4H-SiC formation, growth was conducted on the C-face. The samples were investigated using Hall measurements in the Van-der-Pauw geometry. Lowest room temperature values for specific resistivities were 0.09 Ωcm for 6H-SiC and 0.2 Ωcm for 4H-SiC, which are to our knowledge the lowest values yet reported in literature. Thus, resistivity values of < 0.2 Ωcm, which are required for substrates in high power device applications, could be demonstrated for 4HSiC. Remarkably, in very highly doped samples the type of conduction could not be determined by Hall measurements.
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作者: Ralf Müller, Patrick Desperrier, Christoph Seitz, Matthias Weisser, Andreas Magerl, Manfred Maier, Albrecht Winnacker, Peter J. Wellmann
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作者: Peter J. Wellmann, Thomas L. Straubinger, Patrick Desperrier, Ralf Müller, Ulrike Künecke, Sakwe Aloysius Sakwe, Holger Schmitt, Albrecht Winnacker, Elisabeth Blanquet, Jean Marc Dedulle, Michel Pons
摘要: We review the development of a modified physical vapor transport (M-PVT) growth technique for the preparation of SiC single crystals which makes use of an additional gas pipe into the growth cell. While the gas phase composition is basically fixed in conventional physical vapor transport (PVT) growth by crucible design and temperature field, the gas inlet of the MPVT configuration allows the direct tuning of the gas phase composition for improved growth conditions. The phrase "additional" means that only small amounts of extra gases are supplied in order to fine-tune the gas phase composition. We discuss the experimental implementation of the extra gas pipe and present numerical simulations of temperature field and mass transport in the new growth configuration. The potential of the growth technique will be outlined by showing the improvements achieved for p-type doping of 4H-SiC with aluminum, i.e. [Al]=9⋅1019cm-3 and ρ<0.2Ωcm, and n-type doping of SiC with phosphorous, i.e. [P]=7.8⋅1017cm-3.
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