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Evaluation of Optical and Electrical Properties on Neutron-Irradiated SiC Semiconductors

中子辐照 SiC 半导体的光学和电学性能评估

基本信息

批准号：
09680480
负责人：
OKADA Moritami
金额：
$ 1.66万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Optical and electrical properties of silicon carbide (4H and 6H-SiC) single crystals irradiated with reactor neutrons have been evaluated by the optical spectroscopy and electric measurement methods. The irradiations were carried out at some temperatures in the low temperature irradiation loop facility of the Kyoto University Reactor (KUR-LTL) and at room temperature in the fast neutron reactor of the Tokyo university (YAYOI), In the irradiated samples, a broad absorption band at 780mm was observed. The origin of the 780mm band was attributed to the defect of silicon vacancy type (V_<si>-type center) because it has similar annealing behavior with the paramagnetic defect center consisting of a Si vacancy and a trapped electron.The production efficiency of the V_<si>-type center in SiC crystals irradiated at several temperatures by the KUR-LTL has a maximum about 200K.The characterization of the irradiation temperature dependence of the V_<si>-type center is evidently different from that of oxides or metals which has negative steep gradient from 20K to 400K.On the other hand, the change of electric resistivity in the neutron-irradiated SiC samples was observed. The resistivity for as-irradiated samples increases with fast neutron fluence. The increase of resistivity can be explained by the decreases of the carrier density. From elevated temperature annealing behaviors, it has been clarified that the electric resistivity and the carrier mobility have two annealing stages (350K 500K). By the 800K annealing, both of them recovered about 40%, whereas the change of the carrier density did not found.Also, the effect of the neutron transmutation doping of SiC has been studied. The result shows that a part of ^<30>P which is produced by ^<29>Si(n, gamma)^<30>Si reaction, can effectually act as the electron donor.

用光谱学和电学测量方法研究了反应堆中子辐照碳化硅（4 H和6 H-SiC）单晶的光学和电学性质。在京都大学反应堆的低温辐照回路装置（KUR-LTL）和东京大学快中子反应堆（YAYOI）中进行了一定温度下的辐照。780 mm带的产生归因于硅空位型缺陷（V<si>型心），因为它与由Si空位和俘获电子组成的顺磁缺陷心具有相似的退火行为。在<si>不同温度下，KUR-LTL辐照SiC晶体中V型心的产生效率在200 K左右有一个最大值。V型心的辐照温度依赖性特征<si>明显不同于具有负陡度的氧化物或金属另一方面，还观察到了中子辐照后SiC样品电阻率的变化。辐照样品的电阻率随快中子注量的增加而增加。电阻率的增加可以用载流子密度的降低来解释。从高温退火行为，它已被澄清，电阻率和载流子迁移率有两个退火阶段（350 K-500 K）。经过800 K退火后，两者均恢复了约40%，而载流子密度没有变化。此外，还研究了SiC的中子嬗变掺杂的影响。结果表明，<30>由^<29>Si（n，γ）^<30>Si反应生成的部分^ P可以有效地作为电子给体。