中子辐照的6H-SiC单晶的退火回复特性

Annealing Characteristics of Neutron-irradiated 6H-SiC Single Crystal

对6H-SiC单晶进行中子辐照(中子总剂量为2.85×1020 n/cm^2)后对其进行200~1 700℃的等时退火处理,利用X线衍射技术(XRD)观察和分析中子辐照对样品造成的损伤及其回复规律.通过研究(0001)晶面衍射峰的峰形和峰位置发现,等时退火处理后,辐照缺陷逐渐消失,晶体衍射峰的半高宽在200~600℃回复明显,在600~1 400℃没有明显变化,但在1 400℃之后又开始明显减小,最后接近辐照前的数值.而晶面间距d在200~1 400℃时持续减小,之后又随退火温度的升高而变大,最后接近辐照前的数值.通过对辐照损伤回复规律的分析认为,中子辐照使样品内部出现了大量点缺陷和线缺陷,而这些缺陷大多可以通过高温退火消除.

The 6H-SiC single crystals was irradiated with a total neutron dose of 2.85 × 1020 n/cm2 , then were treated with isochronal annealing from 200 ℃ to 1 700 ℃, and the irradiation-damage-recovery law were observed and analyzed by X-ray-diffraction （XRD）. By the observing the shape and position of the diffraction peak of （0001） crystal plane after isochronal annealing,we found that the full width half maxi- mum （FWHM） of diffraction peak decreased obviously when the annealing temperature varier from 600 ℃ to 1 from 200 ℃ to 600 ℃ ,and it has no obvious change 400 ℃. However, the FWHM is close to that of the pre-irradiation sample when the temperature is higher than 1 400 ℃. Meanwhile, the interplanar distance decreases continuously from 200 ℃ to 1 400 ℃ ,then increases with the increase of annealing temperature, and finally approaches that of pre-irradiation sample. It is believed that a large number of point defects and line defect are produced within the sample by neutron irradiation. Hawever most of these defects can be eliminated by high temperature annealing.