Research On The Mechanism Of SiC Magnetism And Defects

This Silicon carbide(SiC)material is one of the typical wide bandgap semiconductor materials in the third generation of semiconductor materials.It is widely used in high pressure and anti-irradiation environments and plays an important role in aerospace and other important fields.As a semiconductor material,a few amount of ion doping and material defects can have a significant impact on the material properties.Some researchers had found that the magnetic properties of SiC materials are not necessarily related to the magnetic elements contained in the materials themselves,but also have a certain relationship with the external environment and material defects.Based on this,this paper proposes a study of the paramagnetic background of SiC materials and the reasons for the d0 magnetic generation,so as to analyze the relative mechanism between SiC magnetism and its defects.A new method for quantitatively characterizing material defects by using paramagnetic centers density was proposed.Through some certain experiments and software simulations,and comparing the experimental results with the fitting results,the proposed defects characterization method was verified.The reason of d0 magnetics generation was also studied by low-dose injection experiments.The main work is as follows:1.We studied the reasons for the magnetic properties of SiC d0 materials and classified the conditions for d0 magnetic properties generation.After figuring out the advantages and disadvantages of the existing test material damage,we proposed a new method to characterize damage,and the feasibility and premise of the experiment were also analyzed.2.The injection process of the test sample was analyzed by SRIM simulation and the feasibility of the test calculation was also carried out.We Maximums and depths of SiC damage are obtained by using Ar,Xe,Au,C,O,and H ions at injection energies of 200 Ke V,300 Ke V,400 Ke V,500 Ke V,5 Me V,15 Me V,17 Me V and 100 Ke V respectively.3.We implemented magnetic analysis on twenty-three test samples.Two methods were used for this analysis: in the first way,a fitted diamagnetic function based on a non-injected reference material at T=300 K subtracted from the sample magnetic at T=5 K;in the second method,test sample's diamagnetic at T=300 K got a direct subtraction from the magnetic at T=5 K,by this way,reducing the bias of quadratic fitting.Based on the samples observed magnetic in the experiment,the conditions for the presence of magnetic d0 were investigated.4.Implanting SiC with low dose of H ions to obtain a certain amount of point defects,and then the relationship between generation of d0 magnetic and point defects was determined through some related studies.Using Raman spectroscopy,an optical analysis of H ions implanted in SiC was performed,all Raman peak positions were compared and the extent of damage was analyzed.By analyzing the LO phonon plasmon coupling mode(LOPC mode),the carrier concentration's change trend was obtained.The electrical parameters such as carrier density,square resistance and other parameters were measured by Hall.And the defect level was analyzed using deep level transient spectroscopy(DLTS).Finally,the proposed paramagnetic characterization method is compared with commonly used defect characterization methods.The advantages of paramagnetic characterization of material defects are: non-destructive,quantitative,and high test accuracy.At the same time,this method has some disadvantages such as it is difficult to distinguish the very result of paramagnetic if the test observed a variety of magnetic properties,so that it cannot be expressed accurately.