Papers by Author: W. Sullivan

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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, S.A. Furkert, J.M. Hayes, W. Sullivan
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.
Authors: W. Sullivan, John W. Steeds
Abstract: Samples of 4H SiC, both n- and p-doped, have been irradiated with low-energy electrons in a transmission electron microscope. The dependence of the silicon vacancy-related V1 ZPL doublet (~860nm) on electron energy and electron dose has been investigated by low temperature photoluminescence spectroscopy. Furthermore, this luminescence centre has been studied across a broad range of samples of various doping levels. Some annealing characteristics of this centre are reported.
Authors: Giovanni Alfieri, Ulrike Grossner, Edouard V. Monakhov, Bengt Gunnar Svensson, John W. Steeds, W. Sullivan
Abstract: The migration of carbon interstitials in n-type 4H-SiC has been revealed with optical and electrical measurements. Furthermore, clear evidence is found that carbon interstitials are involved in the formation of the Z- and S-centers detected by DLTS within the electronic band gap of n-type 4H-SiC.
Authors: John W. Steeds, S.A. Furkert, J.M. Hayes, W. Sullivan
Authors: John W. Steeds, S.A. Furkert, W. Sullivan, J.M. Hayes, Nicolas G. Wright
Abstract: New results are presented concerning several optical centres having local vibrational modes in electron irradiated and annealed 4H and 6H SiC. Some of these centres are common to both polytypes, others have only been found in 6H SiC. They appear, typically, after annealing in the range 1000°C - 1300°C. Additional results have been obtained about mode splitting from 13C isotope enriched 6H SiC.
Authors: John W. Steeds, S.A. Furkert, W. Sullivan, Günter Wagner
Abstract: The unusual behaviour of two optical centres with zero phonon lines close to 463nm has been investigated by means of low-temperature photoluminescence microscopy using 488nm and 325nm laser excitation. The experiments were performed on as-irradiated samples and also after annealing isochronally to various temperatures up to 1300°C.
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