摘要:
实验采用300 keV的He2+辐照6H-SiC,辐照温度分别为室温,450,600和750?C,辐照剂量范围为1×1015-1×1017 cm-2,辐照完成后对样品进行拉曼散射和紫外可见透射光谱测试与研究。这两种分析方法的实验结果表明, He离子辐照产生的缺陷以及缺陷的恢复与辐照剂量和辐照温度有着直接关系。室温下辐照会使晶体出现非晶化,体现在拉曼特征峰消失,相对拉曼强度达到饱和(同时出现了较强的Si-Si峰)；高温下辐照伴随着晶体缺陷的恢复过程,当氦泡未存在时,高温辐照很容易导致Frenkel对、缺陷团簇等缺陷恢复,当氦泡存在时,氦泡会抑制缺陷恢复,体现在相对拉曼强度和相对吸收系数曲线斜率的变化趋势上。本文重点讨论了高温辐照情况下氦泡对缺陷聚集与恢复的影响,并与高温下硅离子辐照碳化硅结果进行了对比。
Abstract:
Specimens of 6H-SiC were irradiated by 300keV He ions at temperatures of RT, 450, 600 and 750 ?C with fluences ranging from 1 × 1015 to 1 × 1017 cm-2. Post-irradiation, virgin and irradiated 6H-SiC specimens are measured and studied by microscopic laser confocal Raman spectrometer and UV-visible transmission apparatus. Analyses of both experimental results shown that production and recovery of defects caused by irradiation are directly related to the fluences and temperatures. Amorphization of 6H-SiC irradiated at RT occurrs, which is reflected by the disappearance of the Raman peaks and the saturation of the relative Raman intensity(simultaneously a strong Si-Si peak appears). Recovery of defects may exist in high-temperature irradiation, when helium bubbles do not exist, so that irradiation-induced defects can be easily recovered during irradiation process at elevated temperatures; but when helium bubbles are present, they can inhibit defects to recover, as shown in the trend of slopes of curves representing the relative Raman intensity and the relative absorption coefficients. This paper mainly focuses on the effects of helium bubbles on defect accumulation and recovery under the condition of high temperature irradiation, and then the comparison with the results of 6H-SiC irradiated by Si ions at elevated temperatures.
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