硅纳米晶微观结构缺陷的高分辨电子显微学研究

HRTEM investigation of microstructural defects in Si nanocrystals

利用离子注入结合后续高温退火的方法成功地制备出包埋在二氧化硅(SiO2)基质中的硅纳米晶。利用透射电子显微学对所制备的硅纳米晶(离子注入浓度为3×1017cm-2)的微观结构缺陷进行了详细的研究。通过高分辨像分析发现:较大的纳米晶(直径>6nm)中存在很多面缺陷,主要为孪晶与层错。孪晶包括一次孪晶、二重孪晶、三重孪晶及五重孪晶。层错分为内禀和外禀两种类型,并讨论了内禀层错占多数的原因。除了面缺陷以外,还有一部分纳米晶中存在位错。

Si nanoerystals （Si nc） have been successfully fabricated in SiO2 film using Si^＋ ion implantation followed by high-temperature annealing. The microstructural defects inside the Sinc （the implantation dose is 3×10^17cm^-2） have been thoroughly investigated using transmission electron microscopy. High-resolution transmis- sion electron microscopy （HRTEM） observations showed that planar defects such as twinning and stacking faults are dominant. The twins include single-twin,double-twin, triple-twin and five-fold twinning. The stacking faults include intrinsic and extrinsic. More intrinsic stacking faults have been found,and the possible reasons are discussed. Besides the planar defects,mismatch dislocations are also found to exist in some Si nc.