Investigation Of Irradiation Effects Induced By Ions Bombardment In Single Crystals Of 6H-SiC And 4H-SiC

In this dissertation,high-performance Si C materials and their application in radiation environment were used as traction,the effects of N ions,Ar ions,and protons on Si C crystals were studied systematically.The structural evolution and defect behavior of the material under different irradiation conditions were characterized to provide theoretical support for the effect of irradiation.In this dissertation,two kinds of hexagonal materials(6H-Si C and 4H-Si C),were selected as the research object which were irradiated with N ion,Ar ion and proton(110 ke V and 150 ke V).EPR,SEM,XPS,XRD,Raman and other test methods have been investigated the morphology,composition and free radicals of the samples before and after irradiation.The results show that,when the ion energy is 150 ke V and the fluences are 1E14cm-2,1E15cm-2,and 1E16cm-2,The above-mentioned ion irradiation will induce the breaking Si-C bond and lead the formation of radicals(g=2.003),which are mainly composed of carbon vacancies by displacement damage effect.Compared with proton irradiation,N ion and Ar ion irradiation have higher yield than proton radiation radical defect.For different structures of 6H-Si C and 4H-Si C,the effects of ion irradiation on their structure are basically similar.No new phases is produced after irradiation and C-C bond shows an upward trend.It was found that Si(LA+LO)mode was formed at260 cm-1 in Raman of 6H-Si C irradiated by N ion,The lattice damage such as disconnection and atomic displacement caused the decrease of the polarization tensor of Raman;Ar ion irradiation resulted in the formation of disordered lattice structures related to bond angle distortion;long-range orderliness of the lattice in the sample and translational symmetry have little effect after proton irradiation.The long-range orderliness of lattice is destroyed in 4H-Si C irradiated by N ion and Ar ion;the longitudinal optical phonon-plasmon coupled mode decays significantly after proton irradiation.