Papers by Author: John W. Steeds

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Authors: W. Sullivan, John W. Steeds, Hans Jürgen von Bardeleben, J.L. Cantin
Abstract: Several 4H SiC samples have been electron-irradiated at near threshold energies at low fluence, either along the [0001] or [000-1] direction. PL and EPR techniques have been used to investigate the dependence of the beam direction on defect generation and, together with a sample irradiated at a higher fluence, to correlate differences brought about by irradiating with a change in electron fluence. Attempts are made to correlate the information derived from the two techniques.
Authors: W. Sullivan, John W. Steeds
Abstract: The high-temperature persistent PL defect known as DII is commented on within this study, seen for the first time in low-energy electron irradiated 4H SiC. The local vibrational modes associated with the defect have been identified and the temperature dependence, spatial variation and electron-energy/electron-dose variation of this defect have all been investigated.
Authors: John W. Steeds, N. Peng, W. Sullivan
Abstract: 1 MeV ion implantations of 4H SiC have been performed to various doses with ion probes of 5 µm diameter. Defect introduction has been studied by microscopic photoluminescence.
Authors: John W. Steeds, N.C. Burton, A.R. Lang, D. Pickard, Yu.G. Shreter, James E. Butler
Authors: Yu.G. Shreter, Y.T. Rebane, O.V. Klyavin, P.S. Aplin, C.J. Axon, W.T. Young, John W. Steeds
Authors: John W. Steeds
Abstract: In the course of studying by low temperature photoluminescence spectroscopy a wide range of electron-irradiated samples of p(Al)-type epitaxial layers of 4H SiC, from a variety of different sources of supply, the results were found to fit into two very different categories. The origin of these differences has been explored using a wide range of experimental techniques and found to result from the degree of compensation of the aluminium by nitrogen in the layers. Nitrogen concentrations deduced by SIMS experiments on these materials were found to be unreliable. The two different categories of material, called V and AB here, showed marked differences in their subsequent annealing behaviour and the implications of this distinction are discussed.
Authors: John W. Steeds, S.A. Furkert, J.M. Hayes, W. Sullivan
Authors: Yeon Suk Jang, Sakwe Aloysius Sakwe, Peter J. Wellmann, Sandrine Juillaguet, Hervé Peyre, Jean Camassel, John W. Steeds
Abstract: We have carried out the growth and basic characterization of isotopically enriched 4HSi 13C crystals. In recent years the growth of 13C enriched 6H-SiC has been performed in order to carry out fundamental materials studies (e.g. determination of phonon energies, fundamental bandgap shift, carbon interstitial defect study, analysis of the physical vapor transport (PVT) growth process). For electronic device applications, however, the 4H-SiC polytype is the favored material, because it offers greater electron mobility. In this paper we present the growth of 4H-Si13C single crystals with up to 60% of 13C concentration. From a physical point of view we present first results on phonons as well as the fundamental bandgap energy shift due to 13C incorporation into the SiC lattice.
Authors: Alexander Mattausch, M. Bockstedte, Oleg Pankratov, John W. Steeds, S.A. Furkert, J.M. Hayes, W. Sullivan, Nicolas G. Wright
Abstract: We observe new photoluminescence centers in electron-irradiated 6H-SiC with phonon replicas up to 250 meV and clear threefold isotope splitting of the highest energy mode. Based on ab initio calculations, we discuss the tri-carbon anti-site (C3)Si and the di-interstitial (C2)Hex as models for these centers.
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