Collaborative Research: Large-Scale Patterning of Germanium Quantum Dots by Stress Transfer

该合作研究项目的目标是研究和开发一种高通量、基于模板的方法，用于在硅-锗系统中生长高度有序的半导体量子点阵列。本研究将采用理论、多尺度计算机模拟和实验相结合的研究方法。原子尺度的计算机模拟技术，如蒙特卡罗方法，将被用来确定在硅-锗衬底中使用通过图案化的可重复使用的模板施加的应力来产生微图案化成分分布的最佳条件。然后，将在使用分子束外延在衬底上生长有序的Ge纳米结构的背景下，研究衬底内诱导的成分变化的适宜性以及由此产生的表面应变图案。将制造一种专用的实验装置，用于执行基于模板的衬底硅-锗晶片的成分图案化。为了与原子尺度和多尺度模拟预测建立直接联系，本研究将在整个研究过程中使用高分辨率电子显微镜。这项研究将建立成功实现概念上简单、成本效益高的基于模板的方法在硅-锗衬底上生长高度有序的二维锗纳米结构阵列所需的材料和操作条件标准。这项工作的主要目标是定量地理解在外加应力下支配成分图案化的基本原子机制以及这种应力与纳米结构有序的耦合，然后利用这种理解来实验地演示Ge量子点阵列的形成。如果这项工作成功，这项工作可能会为制造高密度纳米结构阵列提供一条实用的路线，这些阵列具有从传感器到数据存储再到量子计算等各种潜在的重要应用。此外，将研究的许多基本原子化子过程，以及将开发的相关计算和实验技术，可能与广泛的材料加工应用有关。

The goal of this collaborative research project is aimed at studying and developing a high-throughput, template-based method for the growth of highly ordered arrays of semiconductor quantum dots in the silicon-germanium system. An integrated approach based on theory, multiscale computer simulation, and experiments will be utilized to perform the study. Atomic-scale computer simulation techniques such as the Monte Carlo method will be employed to identify optimal conditions for generating micro-patterned compositional distributions in a silicon-germanium substrate using stress applied via a patterned, reusable template. The suitability of the compositional variations induced within the substrate, and the resultant surface strain patterns, will then be investigated in the context of growing ordered germanium nanostructures on the substrate using molecular beam epitaxy. A dedicated experimental apparatus will be fabricated for performing the template-based compositional patterning of a substrate silicon-germanium wafer. High-resolution electron microscopy will be performed and used throughout this study in order to establish direct connections with atomic-scale and multiscale simulation predictions.This research will establish materials and operating-condition criteria required for successfully realizing a conceptually simple, cost-effective, template-based method for growing a highly ordered two-dimensional array of germanium nanostructures on silicon-germanium substrates. The primary goals of this work are to understand quantitatively the basic atomistic mechanisms that govern compositional patterning under applied stress and the coupling of this stress to nanostructure ordering, and then the use of this understanding to demonstrate experimentally the germanium quantum dot array formation. If successful, this work could lead to a practical route for fabrication of high-density nanostructure arrays with a variety of potentially important applications, ranging from sensors, to data storage, to quantum computing. Moreover, many of the basic atomistic sub-processes that will be studied, along with the associated computational and experimental techniques that will be developed, may be relevant to a wide range of materials processing applications.