Thornton Chappel S, Tuttle Blair, Turner Emily, Law Mark E, Pantelides Sokrates T, Wang George T, Jones Kevin S
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, United States.
Department of Physics, The Pennsylvania State University- Behrend, Erie, Pennsylvania 16563, United States.
ACS Appl Mater Interfaces. 2022 Jun 29;14(25):29422-29430. doi: 10.1021/acsami.2c05470. Epub 2022 Jun 15.
A recently discovered, enhanced Ge diffusion mechanism along the oxidizing interface of Si/SiGe nanostructures has enabled the formation of single-crystal Si nanowires and quantum dots embedded in a defect-free, single-crystal SiGe matrix. Here, we report oxidation studies of Si/SiGe nanofins aimed at gaining a better understanding of this novel diffusion mechanism. A superlattice of alternating Si/SiGe layers was grown and patterned into fins. After oxidation of the fins, the rate of Ge diffusion down the Si/SiO interface was measured through the analysis of HAADF-STEM images. The activation energy for the diffusion of Ge down the sidewall was found to be 1.1 eV, which is less than one-quarter of the activation energy previously reported for Ge diffusion in bulk Si. Through a combination of experiments and DFT calculations, we propose that the redistribution of Ge occurs by diffusion along the Si/SiO interface followed by a reintroduction into substitutional positions in the crystalline Si.
最近发现的一种沿Si/SiGe纳米结构氧化界面增强的Ge扩散机制，使得能够形成嵌入无缺陷单晶SiGe基体中的单晶Si纳米线和量子点。在此，我们报告了对Si/SiGe纳米鳍的氧化研究，旨在更好地理解这种新型扩散机制。生长了交替的Si/SiGe层超晶格并将其图案化为鳍状。鳍状结构氧化后，通过分析高角度环形暗场扫描透射电子显微镜（HAADF-STEM）图像来测量Ge沿Si/SiO界面向下的扩散速率。发现Ge沿侧壁扩散的活化能为1.1电子伏特，这不到先前报道的Ge在块状Si中扩散活化能的四分之一。通过实验和密度泛函理论（DFT）计算相结合，我们提出Ge的重新分布是通过沿Si/SiO界面扩散，然后重新引入到晶体Si中的替代位置来实现的。
