Dynamics of Interface Instabilities and Nanostructure Formation on Si and SiGe Alloys

该项目致力于硅和硅锗薄膜生长和表面和界面反应的动力学;该方法包括界面化学，应变效应和表面和界面能量学。本研究的主要目的是发展一个基本的了解界面不稳定性的动态纳米结构形成的Si和SiGe合金。原位测量将采用光电子发射显微镜（PEEM）与自由电子激光器（UV-FEL）的紫外激发。研究目标包括：（1）开发使用FEL PEEM系统在Si和SiGe表面进行原位、真实的时间动态测量的具体方法。LTV-FEL PEEM系统的主要优点是高强度FEL光可以被波长调谐到适当的光阈值，以获得所需表面的图像对比度。(2)发展在矽上制备奈米矽化物岛的方法，以及利用扫描探针技术来表征奈米矽化物岛的电性。研究将涉及聚结和成熟过程和外延岛的形状转变。(3)硅表面液态金属-硅微滴的动力学在M-Si二元相图中，Pd、Pt、Ni和Au都表现出深共晶。研究将探索界面化学平衡如何影响金属沉积或蒸发或Si沉积的各种条件下的表面微观结构的演变。(4)SiGe上金属界面的动力学和稳定性。这项研究将涉及在现场PEEM测量这些不稳定性的动态。避免隔离效应的新方法是基于过程模型。(5)单一取向硅上硅锗外延层应变弛豫和纳米结构形成的动力学。对于Si上的外延SiGe层，通过失配位错的形成和通过表面波纹的发展来松弛应变。本项目将探讨应变松弛过程是否会受到不同台阶和平台结构的衬底表面的影响。该研究还将探索使用纳米结构组织的表面形态。该项目解决了材料科学领域的基础研究问题，具有高度的技术相关性。该计划的一个重要特点是通过在一个基本和技术上重要的领域对学生进行培训来整合研究和教育。一个综合的教育计划已经开发，包括科学研究技术，跨学科的研究方法，实验室安全，并涉及来自不同背景的研究生和本科生。

This project addresses dynamics of film growth and surface and interface reactions on Si and SiGe; the approach encompasses interface chemistry, strain effects and surface and interface energetics. The primary objective of the research is to develop a fundamental understanding of the dynamics of interface instabilities for nanostructure formation on Si and SiGe alloys. In situ measurements will employ photo-electron emission microscopy (PEEM) with UV excitation from a free electron laser (UV-FEL). The research goals include: (1) Development of specific approaches to use the FEL PEEM system for in situ, real time measurements of the dynamics at Si and SiGe surfaces. The major advantage of the LTV-FEL PEEM system is that the high intensity FEL light can be wavelength tuned to the appropriate photo threshold to obtain image contrast of the desired surface. (2) Development of methods to prepare nanoscale silicide islands on Si, and the characterization of the electrical properties of the nanoscale islands using scanning probe techniques. The research will relate coalescence and ripening processes and shape transitions of the epitaxial islands. (3) Dynamics of liquid metal-Si (M-Si) micro-droplets on Si surfaces. The metals of Pd, Pt, Ni and Au all exhibit a deep eutectic in the M-Si binary phase diagram. Research will explore how interface chemical equilibrium affects the evolution of the surface microstructure under various conditions of metal deposition or evaporation, or Si deposition. (4) Dynamics and stability of metallic interfaces on SiGe. This research will involve in situ PEEM measurements of the dynamics of these instabilities. New approaches to avoid segregation effects are based on models of the processes. (5) Dynamics of strain relaxation and nanostructure formation in SiGe epitaxial layers on uniquely oriented Si. For epitaxial SiGe layers on Si, strain is relaxed through the formation of misfit dislocations and through the development of surface corrugations. This project will explore whether the strain relaxation processes are affected by the presence of substrate surfaces with different step and terrace structures. The research will also explore the use of surface morphology for nanostructure organization. %%% The project addresses basic research issues in a topical area of materials science with high technological relevance. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. An integrated educational program has been developed that includes scientific research techniques, interdisciplinary research approaches, and laboratory safety, and involves graduate and undergraduate students from diverse backgrounds.***