单晶6H-SiC经氦离子辐照及退火后的微观组织研究

Microstructural Investigation of Single Crystal 6H-SiC Irradiated by He+ Ions and Annealed after Post-irradiation

摘要:

本文在400 ℃下对单晶6H-SiC进行了400 keV氦离子辐照,辐照剂量为1×10₁₆ He₊/cm₂,随后在1200和1500 ℃退火30分钟。采用透射电子显微镜和扫描电子显微镜对辐照态和退火态SiC进行微观结构观察与分析。实验结果表明,单晶6H-SiC在400 ℃经氦离子辐照后,仅观察到由辐照引起的位移损伤带,而未观察到明显尺寸的氦气泡。但经1200 ℃退火30分钟后,在辐照损伤区域形成了呈血小板状的气泡簇,其主要分布在(0001)晶面上,少量形成在(1 1 -2 0)晶面。辐照未在6H-SiC表面上形成明显尺寸的缺陷,而经1200 ℃退火30分钟后,SiC表面出现大尺寸的起泡和凹坑,进一步提高退火温度至1500 ℃时,表面起泡和形成凹坑更严重,并产生了大量裂纹。本文同时对微观结构演化的机理进行了分析与讨论。

Abstract:

The single crystal 6H-SiC was irradiated by 400 keV He₊ ions with 1×10₁₆ He₊/cm₂ fluence at 400°C and then annealed for 30min at 1200 and 1500°C. The microstructure was observed by using transmission electron microscopy and scanning electron microscopy. Only the damaged layer was observed and no visible helium bubbles were formed in SiC matrix after helium ion irradiation at 400 °C. However, after annealled at 1200 °C for 30 minutes, platelet-like planar bubbles were formed in the irradiated region, which were distributed mainly on the (0001) plane and less on the (1 1 -2 0) crystal plane. There were no visible size defects formed on 6H-SiC surface after helium ion irradiation. But, blisters and craters were formed after annealing at 1200 °C for 30 min and became easier with annealing temperature increase. Some cracks were generated after annealing at 1500 °C. The mechanism of microstructural evolution was also analyzed and discussed.