6H-SiC中子辐照肿胀高温回复及光学特性研究  

High Temperature Recovery of Neutron Irradiation-induced Swelling and Optical Property of 6H-SiC

作　　者：张守超 陈洪雨 刘洪飞 杨羽 李欣[2] 刘德峰[2] ZHANG Shouchao;CHEN Hongyu;LIU Hongfei;YANG Yu;LI Xin;LIU Defeng(School of Science,Tianjin Chengjian University,Tianjin 300384,China;Aviation Key Laboratory of Science and Technology on Special Condition Monitoring Sensor Technology,Beijing Changcheng Aeronautic Measurement and Control Technology Research Institute,Beijing 101111,China)

机构地区：[1]天津城建大学理学院,天津300384 [2]北京长城航空测控技术研究所状态监测特种传感技术航空科技重点实验室,北京101111

出　　处：《无机材料学报》2023年第6期678-686,共9页Journal of Inorganic Materials

基　　金：天津市自然科学基金(20YDTPJC01540);天津市研究生科研创新项目(2021YJSO2S20);国防项目(KJ-2021-01)。

摘　　要：高能粒子轰击不可避免地会造成SiC材料内部缺陷的产生、积累,晶格紊乱等,导致其物理性能的显著变化,继而影响基于SiC材料的半导体器件使用寿命。因此,有必要对SiC在不同的辐射环境下的损伤行为进行系统研究。本工作对6H-SiC中子辐照肿胀高温回复及光学特性开展研究,辐照剂量范围5.74×10^(18)~1.27×10^(21)n/cm^(2),退火温度在500~1650℃。利用X射线单晶衍射技术分析测试样品的晶体结构及晶胞参数,结果表明:SiC仍为六方结构,晶体未发生非晶化,晶格肿胀及高温回复行为具有各向同性特征,表明辐照缺陷以点缺陷为主。本征缺陷及辐照缺陷均可引入缺陷能级,空位型缺陷是缺陷能级引入的主要因素。缺陷能级导致SiC吸收带边红移,带隙宽度降低,光吸收增强。利用吸收光谱、光致发光谱和拉曼光谱,并结合第一性原理计算对缺陷能级分布开展研究,结果表明硅空位在价带顶上方引入了新的缺陷能级,而碳空位则是在导带底下方引入了新的缺陷能级。未辐照晶体在1382和1685 nm红外波段光吸收以及550 nm光发射主要源于本征碳空位及其相关缺陷构型;辐照SiC晶体在415、440和470nm处的发光主要源于辐照产生的硅空位及其相关缺陷构型。研究还利用电荷态和缺陷能级分布对SiC晶体发光机理行了讨论。High energy particle bombardment of silicon carbide can lead to the accumulation of defects and lattice disorder,which can negatively affect physical property and reduce lifetime of SiC devices.Thus,it is essential to systematically study the damage of SiC in different radiation environment.Herein,6H-SiC was irradiated by neutrons at the fluence of 5.74×10^(18),1.74×10^(19),2.58×10^(20) and 1.27×10^(21) n/cm^(2),and then annealed.Changes in lattice parameters from post-irradiation isochronal annealing for 30 min in the range of 500–1650℃were measured using X-ray single crystal diffraction.The results showed that the lattice swelling and recovery behavior were isotropic.Based on the swelling data,it was concluded that the neutron irradiation-induced defects in 6H-SiC were primarity point defects.Both intrinsic and irradiation defects can introduce defect energy levels,which were mainly caused by vacancies and led to the absorption band edge redshift and band gap narrowing of SiC.The defect energy levels of these vacancies and vacancy-associated defects were determined by absorption spectra,luminescence spectra and Raman spectra.Experiments and first principles calculation showed that the silicon vacancies introduced defect levels above the valence band,while the carbon vacancies introduced levels below the conduction band.The infrared absorption at 1382 nm and 1685 nm and the emission at 550 nm of unirradiated 6H-SiC were mainly due to the intrinsic carbon vacancies.The luminescence of post-irradiated SiC at 415,440 and 470 nm was mainly due to the silicon vacancy produced by irradiation and its related defect configuration.All above data revealed the luminescence mechanism of SiC based on the charge state and the defect energy level distribution.

关 键 词：X射线单晶衍射 拉曼光谱 第一性原理 退火 带隙调控 缺陷 

分 类 号：O734[理学—晶体学]