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Propriétés des défauts ponctuels natifs et induits par irradiation dans les polytypes 3C et 6H du carbure de silicium déterminées par annihilation de positons et RPE

Abstract : Potential applications of silicon carbide (SiC) in micro-electronics have justified many studies on point defects, which play an important role in the electrical compensation. Moreover, this material has many assets to take part in the fissile materials confining in the gas cooled reactors of the future (4th generation). In this thesis, we have used Electronic Paramagnetic Resonance and Positron Annihilation Spectroscopy to study the properties of point defects (nature, size, charge state, migration and agglomeration during annealing), either native or induced by irradiation with various particles (H+, e-, carbon ions), in the 3C and 6H polytypes of SiC. The positron annihilation study of native defects in 6H-SiC has shown the presence of a strong concentration of non-vacancy traps of acceptor type, which are not present in the 3C-SiC crystals. The nature of the defects detected after irradiation with low energy electrons (190keV) depends on the polytype. Indeed, while silicon Frenkel pairs and carbon monovacancies are detected in the 6H crystals, only carbon monovacancies are detected in the 3C crystals. We propose that these differences concerning the populations of detected point defects result from different values of the silicon displacement threshold energy for the two polytypes (approximately 20eV for 6H and 25V for 3C). In addition, the irradiations with 12MeV protons and 132MeV carbon ions have created silicon monovacancies as well as VSi-VC divacancies. Neither the particle (protons or ions carbon), nor the polytype (3C or 6H) influence the nature of the generated defects. Finally the study of the annealing of 6H-SiC monocrystals irradiated with 12MeV protons have revealed several successive processes. The most original result is the agglomeration of the silicon monovacancies with the VSi-VC divacancies which leads to the formation of VSi-VC-VSi trivacancies.
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Contributor : Xavier Kerbiriou <>
Submitted on : Sunday, October 29, 2006 - 9:04:16 AM
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  • HAL Id : tel-00110421, version 1

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Xavier Kerbiriou. Propriétés des défauts ponctuels natifs et induits par irradiation dans les polytypes 3C et 6H du carbure de silicium déterminées par annihilation de positons et RPE. Physique [physics]. Université d'Orléans, 2006. Français. ⟨tel-00110421⟩

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