Atomarer Transport und Defekte in Silizium-Germanium

我们计划在同位素控制的Si1-xGex异质结构中，研究x在0（小于）x（小于或等于）1之间的自原子和掺杂原子的同时扩散。在扩散实验中，将采用分子束外延的方法生长出合适的SiGe同位素结构。二次离子质谱法将用于测量退火后的自扩散和掺杂物扩散谱。在层状结构生长或扩散退火过程中可能发生的位错和点缺陷聚集等微观缺陷的形成将通过透射电子显微镜进行研究。首先，我们将关注放松SiGe中的扩散。然后，我们将对应变SiGe结构进行类似的扩散实验。对SiGe中自掺杂原子同时扩散的详细数值分析将提供有关掺杂扩散机制和所涉及的原生点缺陷性质的全面信息。特别是，我们期望确定原生点缺陷的电荷状态和它们各自对自扩散的贡献。总之，扩散研究将揭示Ge含量和应变对SiGe中掺杂物扩散的影响。

We plan to investigate the simultaneous diffusion of self- and dopant atoms in isotopically controlled Si1-xGex heterostructures with x ranging between 0(less than)X(less or equal)1. For the diffusion experiments appropriate SiGe isotope structures will be grown by means of molecular beam epitaxy. Secondary ion mass spectrometry will be performed to measure self- and dopant diffusion profiles after annealing. The formation of microscopic defects such as dislocations and aggregates of point defects, which may occur during the growth of the layer structure or during diffusion annealing, will be investigated by means of transmission electron microskopy. First we will focus on diffusion in relaxed SiGe. Then we will conduct similar diffusion experiments with strained SiGe structures. Detailed numerical analysis of the simultaneous diffusion of self- and dopant atoms in SiGe will provide comprehensive information about the mechanisms of dopant diffusion and the properties of the native point defects involved. In particular, we expect to determine the charge state of the native point defects and their individual contributions to self-diffusion. Altogether the diffusion study will reveal the impact of Ge content and strain on dopant diffusion in SiGe.