Direct Measurements of Kink Diffusion Barrier Height by Plan-view High Resolution Electron Microscopy

该项目的目的之一是开发一种图像处理方案，从半导体中位错的高分辨率电子显微镜(HREM)平面图中提取部分位错的线形，其分辨率远远高于传统的弱束技术。利用这一新技术，我们研究了位错线上的扭结运动，并试图推导出扭结迁移能，它是位错滑动运动的基本参数之一。对Ge和GaAs所做的实验表明，用于显微镜观察的电子束辐照诱导的电子激发增强了30°部分位错上的扭结迁移。对于Ge，测得电子激发下的扭结迁移能约为0.75 eV。虽然没有用高分辨电子显微镜观察，但也研究了电子辐照对六方GaN单晶中位错滑移的影响。研究发现，锥体滑移面上的基面位错和刃位错的迁移性增强。从凹部和凸部都受到影响的事实可以看出，电子激发促进了扭结对的形成和扭结的迁移。

One of the aims of this Project is to develop an image-processing scheme to extract from a high resolution electron microscopic (HREM) plan-view image of a dislocation in semiconductor the line shape of the partial dislocations with a resolution far higher than the conventional weak beam technique. With this novel technique, we investigate the kink motion along a dislocation line and tried to deduce the kink migration energy, which is one of the fundamental parameters in dislocation glide motion in semiconductors. Experiments done for Ge and GaAs revealed that the migration of kinks on 30° partial dislocations is enhanced by electronic excitation induced by electron beam irradiation used for microscopic observations. For Ge, the kink migration energy under electronic excitation wag measured to be about 0.75 eV. Although not by HREM observations, effects of electron irradiation on dislocation glides in hexagonal GaN single crystals were also investigated. It was found that the mobility of basal dislocations and edge dislocations on a pyramida1 slip plane is enhanced. From the fact that concave parts and convex parts are both affected, it was concluded that kink pair formation as well as kink migration is enhanced by electronic excitation.