Stach EA, Hull R, Bean JC, Jones KS, Nejim A
Department of Materials Science and Engineering, University of Virginia, Thornton Hall, Charlottesville, VA 22903-2442
Microsc Microanal. 1998 May;4(3):294-307. doi: 10.1017/s1431927698980308.
: Strained layer heterostructures provide ideal systems with which to study the dynamics of dislocation motion via in situ transmission electron microscopy, as the geometry, strain state, and kinetics can be characterized and directly controlled. We discuss how these structures are used to study dislocation-point defect interactions, emphasizing the experimental requirements necessary for quantification of dislocation motion. Following ion implantation, different concentrations and types of point defects are introduced within the SiGe epilayer depending on the implantation species, energy, and current density. By annealing samples in situ in the transmission electron microscope (TEM) following implantation, we can directly observe dislocation motion and quantify the effect of dislocation-point defect interactions on dislocation velocities. We find that dislocation motion is impeded if the implantation dose peak lies within the epilayer, as dislocations pin at point defect atmospheres. Shallow BF2 implantation into the sample capping layer results in more complicated behavior. For low current density implants, dislocation velocities may be dramatically increased; at higher current densities the magnitude of this increase is significantly smaller. Implantation of different ions separately implicates fluorine as the species responsible for the observed increases in dislocation velocities, presumably due to an electrical effect on the rate of dislocation kink nucleation.
应变层异质结构提供了理想的系统，通过原位透射电子显微镜来研究位错运动的动力学，因为其几何结构、应变状态和动力学可以被表征并直接控制。我们讨论了这些结构如何用于研究位错-点缺陷相互作用，强调了量化位错运动所需的实验要求。离子注入后，根据注入物种、能量和电流密度的不同，在SiGe外延层中引入不同浓度和类型的点缺陷。通过在注入后在透射电子显微镜（TEM）中对样品进行原位退火，我们可以直接观察位错运动，并量化位错-点缺陷相互作用对位错速度的影响。我们发现，如果注入剂量峰值位于外延层内，位错运动会受到阻碍，因为位错会钉扎在点缺陷气氛中。向样品覆盖层中浅注入BF2会导致更复杂的行为。对于低电流密度注入，位错速度可能会显著增加；在较高电流密度下，这种增加的幅度明显较小。分别注入不同离子表明氟是导致观察到的位错速度增加的物种，这可能是由于对位错扭折成核速率的电效应。
