Influence of interfacial stress on the stability of epitaxial films

界面应力对外延膜稳定性的影响

• 批准号: 0706460
• 负责人: Eliot Fried
• 金额: $ 20.24万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0706460&HistoricalAwards=false
• 关键词: Influence; interfacial; stress; stability; epitaxial

Fried0706460 Epitaxially-grown thin alloy films are essential componentsin many nano- and microscale devices used in the electronics andother industries. Unfortunately, the growth of planar strainedfilms is susceptible to instabilities. These instabilities areoften manifested by the formation of surface ripples, surfacecusps, and island-like mounds such as quantum dots and quantumwires. The demand for films with precisely tailored micro- andnanostructures has led to an extensive literature concerned withmorphological instabilities during the epitaxy of thin alloyfilms. To date, attention has focused primarily on instabilitiesthat arise from a mismatch in lattice parameters between the filmand the substrate and surface diffusion. However, interfacialstress, which may strongly influence the formation of surfacepatterns, has received almost no attention. Moreover, because ofthe geometric complications associated with the description ofevolving surfaces in three space dimensions, studies ofgrowth-stress interactions have thus far confined attention totwo-dimensional theories, wherein the interface is a curve. Additionally, no theory yet accounts for the influence of surfacestress on phase segregation and related pattern formation,processes that occur during epitaxy. In this project, theinvestigator and colleagues: 1. Perform stability analyses and numerical simulations designed to explore the role of surface stress in the stability of epitaxially growing films. 2. Extend the existing two-dimensional theory to three space dimensions. 3. Develop a theory that describes the interaction of growth and phase segregation during the epitaxy of alloys. The investigator and his colleagues develop and analyzemathematical models, and carry out numerical simulations, of thebehavior and characteristics of epitaxially grown thin films. Anincreased understanding of the morphological stability of thesefilms allows for progress and innovation in a variety ofstrategically important applications. For instance, in theelectronics industry, epitaxially grown multi-layers have beenused to increase the storage capacity of hard drives and are nowbeing studied for possible improvements. Progress rests directlyon the ability to control small-scale features that form duringgrowth. Another compelling example of the importance ofepitaxial films is provided by recently proposed hybridorganic/inorganic devices capable of detecting airbornecontaminants. These devices combine a monolayer of sensingmolecules on a semiconductor transducer grown via molecular beamepitaxy. A precisely tailored surface structure is necessary toensure that the sensing molecules adhere correctly to thetransducer and perform reliably. Epitaxial films also havepotential in the development of optical semiconductors forapplications such as variable wavelength lasers. The deviceshave a wide range of potential applications, including thedetection of toxic gases from vehicle exhaust, factories,accidents, fires, natural disasters, etc. With a variablewavelength laser, it is possible to shorten measurement timesfrom 1-2 minutes to 1 second, allowing for more rapid containmentand evacuation during emergencies.

联系人：李经理 外延生长的合金薄膜是电子等工业中许多纳米和微米级器件的重要组成部分。 不幸的是，平面应变膜的生长易受不稳定性的影响。 这些不稳定性通常表现为表面波纹，表面尖峰和岛状土丘的形成，如量子点和量子线。 对具有精确定制的微米和纳米结构的薄膜的需求导致了大量的文献关注薄合金薄膜外延过程中的形态不稳定性。 到目前为止，注意力主要集中在不稳定性所产生的晶格参数之间的薄膜和基板和表面扩散的不匹配。 然而，界面应力对表面张力的形成有着重要的影响，却几乎没有引起人们的注意。 此外，由于在三维空间中描述旋转表面的几何复杂性，生长-应力相互作用的研究迄今为止仅限于二维理论，其中界面是曲线。此外，还没有理论解释表面应力对相分离和相关图案形成的影响，这些过程发生在外延过程中。 在本项目中，研究者和同事们：1. 进行稳定性分析和数值模拟，旨在探索表面应力在外延生长薄膜稳定性中的作用。 2. 将现有的二维理论扩展到三维空间。 3. 发展一种理论，描述在合金外延生长过程中生长和相分离的相互作用。 研究人员和他的同事们开发和分析了数学模型，并进行了数值模拟，外延生长薄膜的行为和特性。 对这些薄膜的形态稳定性的进一步了解可以在各种具有重要战略意义的应用中实现进步和创新。 例如，在电子工业中，外延生长的多层已经被用来增加硬盘的存储容量，现在正在研究可能的改进。 进步直接取决于控制生长过程中形成的小尺度特征的能力。 最近提出的能够检测空气污染物的有机/无机混合装置提供了另一个令人信服的例子，说明了外延膜的重要性。 这些装置结合了联合收割机的单层传感分子的半导体传感器通过分子束外延生长。 一个精确定制的表面结构是必要的，以确保传感分子正确地粘附到传感器和可靠地执行。 外延薄膜在光学半导体的发展中也有潜力，例如用于可变波长激光器。 这些设备具有广泛的潜在应用，包括检测汽车尾气、工厂、事故、火灾、自然灾害等产生的有毒气体。使用可变波长激光器，可以将测量时间从1-2分钟缩短到1秒，从而在紧急情况下更快地进行控制和疏散。