Using Nanoscale Patterning to Reveal the Atomic-scale Effects which Drive Unstable Growth on GaAs(001)

利用纳米级图案揭示驱动 GaAs(001) 不稳定生长的原子级效应

• 批准号: 0705447
• 负责人: Raymond Phaneuf
• 金额: $ 50.76万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0705447&HistoricalAwards=false
• 关键词: Using; Nanoscale; Patterning; Reveal; Atomic

Technical: Lithographic patterning followed by epitaxial growth provides a viable candidate to achieve rapid fabrication of large arrays of nanometer scale structures. Recent research reveals a transient instability in molecular beam epitaxial (MBE) growth of GaAs(001) on patterned substrate surfaces. Structures whose lateral dimensions exceed a thickness-dependent critical value increase in height, while those smaller than this value decay. This project is to investigate the effects responsible for growth instabilities of GaAs(001) surfaces patterned at various lateral length scales. The research bridges the gap in the scale between micrometers, where a continuum description is valid, and nanometers, where atomic scale processes enter more directly into the evolution. The project uses an integrated experimental/theoretical approach. In experiments, electron beam lithography is used to produce groove structures of dimensions as small as a few 10's of nanometers on substrates, which are used to grow GaAs at controlled temperatures, growth rates and As2/Ga flux ratios. A combination of photo lithography and electron beam lithography is utilized to fabricate hybrid nanometer/micrometer structures. Kinetic Monte Carlo (KMC) calculations are to be carried out for comparison with observations of the evolution during growth on the smaller structures. The goal is to understand the physical significance of the coefficients of the terms in the continuum equation. A second, more ambitious theoretical goal is to find an equation which has the CKPZ form in the continuum limit, but with correction terms that manifest themselves at the atomic scale. The research adopts a multi-scale approach in determining the rate and energy parameters for use in the KMC calculations, taking advantage of the existence of accurate quantum molecular dynamics (ab initio) methods based on density functional theory (DFT) that can accurately predict these parameters.Non-technical: The project addresses basic research issues in a topical area of materials science with high technological relevance. It aims at achieving a predictive capability for directed self organization and roughness control at the surface of a model substrate, GaAs, for applications in electronic, optoelectronic and spintronic devices. Through this project, graduate and undergraduate students will receive training in an interdisciplinary field. The results from this research projects will be introduced into the curriculum of two undergraduate courses, including one for a newly created Interdisciplinary NanoScience and Technology Minor program at the University of Maryland.

技术：光刻图案，然后外延生长为快速制造大量纳米尺度结构提供了可行的候选者。最近的研究揭示了GAA（001）在图案化的底物表面上的分子束外延（MBE）生长的短暂不稳定性。横向尺寸超过厚度依赖性临界值的结构的高度增加，而小于此值衰减的结构。该项目是为了调查导致GAAS（001）表面生长不稳定性的影响，该表面在各种横向尺度上模式化。该研究桥接了微米之间的尺度上的差距，其中连续描述是有效的，而原子量表过程更直接地进入进化。该项目采用综合实验/理论方法。在实验中，电子束光刻用于产生尺寸的凹槽结构，其底物上的纳米含量很小至10纳米，这些纳米用于在受控的温度，生长速率和AS2/GA通量比下生长GAAS。光刻和电子束光刻的组合用于制造杂化纳米/千分尺结构。要进行动力学蒙特卡洛（KMC）计算，以与较小结构生长过程中的演化观察进行比较。目的是了解连续方程中术语系数的物理意义。第二，更雄心勃勃的理论目标是找到一个具有CKPZ形式在连续限制中的方程式，但具有在原子规模上表现出来的校正术语。该研究采用了一种多尺度方法来确定在KMC计算中使用的速率和能量参数，利用基于密度功能理论（DFT）的精确量子分子动力学（AB始于）的存在，可以准确预测这些方法参数。非技术：该项目解决了具有高技术相关性的材料科学主题领域的基础研究问题。它旨在实现模型底物GAA表面的定向自组织和粗糙度控制的预测能力，用于电子，光电和自旋设备的应用。通过这个项目，毕业生和本科生将在跨学科领域接受培训。该研究项目的结果将被引入两个本科课程的课程中，其中包括一项针对马里兰州大学新创建的跨学科纳米科学和技术次要计划的课程。