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

本计画的目的之一，是发展一种影像处理方法，从半导体位错的高解析度电子显微镜（HREM）平面影像中，以远高于传统弱束技术的解析度，撷取出部分位错的线形。利用这种新的技术，我们研究了沿着位错线的扭结运动，并试图推导出扭结迁移能，这是半导体中位错滑移运动的基本参数之一。对Ge和GaAs所做的实验表明，用于显微观察的电子束辐照引起的电子激发增强了30°部分位错上扭结的迁移。对于Ge，电子激发下的扭结迁移能为0.75eV。虽然没有通过高分辨电子显微镜观察，电子辐照对六方GaN单晶中位错滑移的影响也进行了研究。结果表明，在位错滑移面上的基底位错和刃位错的活动性增强。从凹部和凸部都受到影响的事实可以得出结论，电子激发增强了扭结对的形成以及扭结的迁移。

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.