Observation and analysis of the irradiation temperature dependence in the formation efficiency of the irradiation-induced defects in SiC aid its related materials

单晶碳化硅(SIC)是一种宽禁带半导体材料，在强辐射场(电子、中子、质子等)高温、极低温等恶劣环境下工作，有望成为一种优良的电子器件材料。用反应堆辐射或电子在不同温度下对样品进行辐照。用光谱分析(OS)和电子自旋共振(ESR)的方法观察了辐射效应。还对氮化物、氧化物等相关材料进行了研究，结果总结如下：1)研究发现，n型碳化硅中硅空位型缺陷的形成效率随辐照温度的变化规律与通常的理论不同。OS和ESR都观察到，在10K到370K之间，它在200K左右有最大值。另一方面，在金红石(二氧化钛)和氮化铝中也发现了类似于碳化硅的ITD，这是一种共价键合材料。2)然而，在p型碳化硅中，它不能明显地得到类似的现象。由于对辐照温度的影响被SiC.3中受主B的(n，α)反应引起的核加热所掩盖，因此发现在SiC中引入核相变掺杂对施主的影响是有效的。4)中子辐照使p型碳化硅转变为n型碳化硅。

Single crystalline silicon carbide (SiC), which is one of wide-gap semiconductors (WGS), is expected to be an excellent material by way of electronic devices acting under severe environment such as intense radiation field (electron, neutron, proton, etc) with high temperature and extreme low temperature. Samples were irradiated in various temperatures with reactor radiations or electrons. The radiation effects were observed by using the method of the optical spectroscopy (OS) and the ESR. The related materials such as nitrides, oxides and other WGS's were also examined These results are summarized following.1) It has been found that the irradiation temperature dependence (ITD) of the formation efficiency of the Si-vacancy-type-defect formed in n-type SiC due to the irradiation was different from the usual established theory. It was observed by both of the OS and the ESR that it had the maximum value at about 200K between 10K and 370K. On the other hand, it has been also found that there is the ITD similar to SiC, in rutile (TiO2) and AIN, which are a covalent bonding material. From these facts, we proposed that it does cause to the covalent bonding.2) However, in the p-type SiC it could not clearly get the similar phenomenon. It was thought because the effect on irradiation temperature was covered by a nuclear heating which was caused to the (n, α) reaction of acceptor boron in SiC.3) It has been found that the effect on ^<31>P donor introduced by the nuclear-transformation-doping in SiC is effective.4) The p-type SiC was changed into the n-type one due to neutron irradiation.