Low Temperature Photoluminescence Of Irradiated Defects In 4H-SiC

Due to its wide bandgap,high thermal conductivity,high carrier mobility and high breakdown electric field,silicon carbide?SiC?is considered to be an ideal semiconducting material for optoelectronic devices,high-power electronic devices and solid-state microwave power devices that have been widely used in radar,5G communications,rail transit,new energy vehicles and other fields.It is precisely because of the important military value and broad market prospects of SiC materials that the United States imposed a technical blockade and product embargo on China.During the Twelfth Five-Year Plan,China has invested a lot of scientific research funds to develop R&D layout,partially solving the key technical problems of SiC materials and devices.At the beginning of the Thirteenth Five-Year Plan,many ministries and commissions issued policies to promote the rapid progress of research and development of basic materials,and the research of SiC materials has entered the fast lane.At present,electron irradiation is often employed to introduce intrinsic defects into SiC materials in order to adjust their semiconducting properties.However,there are few reports on the structure and properties of irradiated defects in SiC materials.In this paper,the irradiated defects of 4H-SiC crystals were studied by low temperature photoluminescence spectroscopy,and the dependence of irradiated defects on test temperature,laser power,irradiation time,annealing temperature and their spatial distribution in crystals were also investigated and analyzed.Results showed that after irradiation with 10 Me V energy for 3t holding time,the carbon vacancy-carbon antisite pair defects(V_CC_Si)⁺and neutral Si vacancies were successfully introduced into 4H-SiC crystal with maintaining the original crystal structure.The axial configuration of hh/kk with C_3Vsymmetry and hk/kh basal surface configuration with C_1hsymmetry had different excitation energies for different configurations,resulting in different distribution along depth direction.Among them,the maximum of A1 strength appeared at the surface and extended to the depth of 60?m,while the maximum of B3strength located at the depth of 30-40?m below the surface and extended to the depth of 75?m.The strength of Si vacancies reached their maximum at 500?and disappeared after 700?atoms.The reason was that the interstitials,created by irradiation recombined with Si vacancies.In addition,the C atoms around the Si vacancies moved into the position of vacancies to produce the(V_CC_Si)⁺defects.