Propriétés stucturales et magnétiques du 6H-SiC implanté Mn
Auteur / Autrice : | Maya Al-Azri |
Direction : | Salim-Mourad Cherif |
Type : | Thèse de doctorat |
Discipline(s) : | Physique |
Date : | Soutenance en 2013 |
Etablissement(s) : | Paris 13 |
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Résumé
In this study, n-Type 6H-SiC(0001) substrates were implanted with three fluencies of Mn' 5x10¹⁵ Mn/cm² (Mn content : 0. 7%), 1x10¹⁶ (~2 %), and 5x10¹⁶ cm² (7%) with implantation energy of 80 keV and substrate temperature of 365°C. The samples were characterized using Rutherford Backscattering and Channeling Spectroscopy (RBS/C), High Resolution X-Ray Diffraction technique (HRXRD), micro Raman Spectroscopy (μRS) and Superconducting Quantum Interference Device (SQUID) techniques. The aims were to investigate implantation-induced defects upon dose and to study any correlation between disorder-composition and magnetic properties. RBS/C spectra were fitted using McChasy code, and the corresponding results show that 41% of Mn occupy substitutional sites for the lowest dose, 63% for intermediate Mn content, whereas an almost amorphization occurred for the highest dose. The hysteresis loops of the all samples have typical ferromagnetic shapes. The maximum magnetic moments were obtained for the fluence of 1×10¹⁶ Mn/cm² at which the ratio of Mn at substitutional site was maximum. In addition, we investigated the structural and magnetic properties of Mn-doped 6H-SiC using ab-initio calculations. Various configurations of Mn sites and vacancy types were considered. The calculations showed that a substitutional Mn atom at Si site possesses larger magnetic moment than Mn atom at C site. A model is introduced to explain the dependence of the magnetic structure on site occupation. The magnetic properties of ferromagnetically (FM) and antiferromagnetically (AFM) coupled pair of Mn atoms with and without neighboring vacancies have also been explored.