Atomic level studies of step dynamics in the homogeneous growth of metal crystals

金属晶体均匀生长阶梯动力学的原子水平研究

• 批准号: 1507837
• 负责人: Paul Schwoebel
• 金额: $ 38.23万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1507837&HistoricalAwards=false
• 关键词: Atomic; level; studies; step; dynamics

NON-TECHNICAL ABASTRACT:The growth of crystalline materials is the first step in the manufacture of numerous electronic devices including microprocessors for computers, chemical sensors for human health, and biological detectors to counter terrorism threats. Today, individual atoms are being manipulated in attempts to create such processors and sensors at the atomic scale. Improvement in our understanding of atomic scale surface processes, such as atom transport and its role in the growth of crystalline materials, is required so that the manipulation of individual atoms can be routinely employed to enhance the performance of existing devices, as well as develop new devices. This project uniquely combines the ability to view the motion of individual atoms using a microscope with the capability of identifying the atomic species in motion using a mass spectrometer. It thereby allows for a detailed atomic level study of the growth of an elemental crystalline material. This research is serving as the Ph.D. thesis project for one graduate student and employing an undergraduate science major to assist with the experiments. The inherent interdisciplinary nature of the project is training the students in a wide variety of technical areas and thereby helping to thoroughly prepare them to begin a career in the physical sciences. Underrepresented groups have a good opportunity to fill the student positions on this research effort because the University of New Mexico is exceptional in combining a highly rated research program and designated as both a Minority-serving institution and a Hispanic-serving institution. TECHNICAL ABSTRACT: The dynamics of steps on crystal surfaces is one of the most important processes governing atom transport and the resulting crystal growth. In this project, step dynamics at the atomic scale in the prototypic case, elemental crystals, is being investigated for the first time. To enable the study of such homogeneous systems we are employing a novel approach - the use of an adatom that is a stable isotope of the elemental substrate. This preserves the chemical nature of the homogeneous system, yet the isotope adatom is distinguishable due to its known mass and isotopic abundance. The field ion microscope is being used for atomic resolution surface imaging. Possible isotope adatom-substrate atom exchange processes that occur during atom transport are detected by the removal of individual atoms as ions with field evaporation and subsequent time-of-fight-based atom-probe microanalysis to determine their mass. The project is investigating step dynamics on various transition metal surfaces by studies of: Year 1 - The descent of isotope adatoms over steps and the diffusion of isotope adatoms along step edges, Year 2 - Nanosecond-time-scale diffusion initiated by laser pulses to capture any 'non-equilibrium' isotope adatom-substrate configurations, and Year 3 - The impact of the proximity of steps to one another on isotope adatom-step dynamics.

晶体材料的生长是制造许多电子设备的第一步，包括计算机微处理器，人类健康的化学传感器和应对恐怖主义威胁的生物探测器。今天，人们正在操纵单个原子，试图在原子尺度上创造这样的处理器和传感器。我们需要改进对原子尺度表面过程的理解，例如原子输运及其在晶体材料生长中的作用，以便可以常规地使用单个原子的操纵来提高现有器件的性能，以及开发新器件。该项目独特地结合了使用显微镜观察单个原子运动的能力和使用质谱仪识别运动中原子种类的能力。因此，它允许对元素晶体材料的生长进行详细的原子水平研究。这项研究是作为博士。一个研究生的论文项目，并聘请本科科学专业，以协助实验。该项目固有的跨学科性质是在各种技术领域培训学生，从而帮助他们彻底准备开始物理科学的职业生涯。代表性不足的群体有一个很好的机会来填补这个研究工作的学生职位，因为新墨西哥州的大学是在结合一个高度评价的研究计划，并指定为少数民族服务机构和西班牙裔服务机构的特殊。 技术摘要：晶体表面台阶的动力学是控制原子输运和晶体生长的最重要的过程之一。在这个项目中，在原子尺度上的原型情况下，元素晶体的阶跃动力学，正在研究的第一次。为了能够研究这样的均匀系统，我们采用了一种新的方法-使用的吸附原子，是一种稳定的同位素的元素基板。这保留了均相系统的化学性质，但同位素吸附原子由于其已知的质量和同位素丰度而可区分。场离子显微镜用于原子分辨率的表面成像。可能的同位素adatom-substrate原子交换过程中发生的原子传输检测的去除个别原子的离子场蒸发和随后的时间的战斗为基础的原子探针显微分析，以确定其质量。该项目通过研究以下问题来研究各种过渡金属表面上的阶跃动力学：第1年-同位素吸附原子在台阶上的下降以及同位素吸附原子沿着台阶边缘的扩散，第2年-由激光脉冲发起的纳秒时间尺度扩散，以捕获任何“非平衡”同位素吸附原子-衬底配置，和第3年-步骤的邻近同位素adatom步骤动力学的影响。