Sub-Surface Structural Damages in Laser-assisted Surface Nanostructuring: Experimental Characterization and Atomistic Modeling

激光辅助扫描隧道显微镜（STM）作为一种自上而下的纳米加工技术，在表面纳米修复、纳米到微米尺度集成纳米电子学和纳米光子学的制造和表征、纳米粒子和纳米管/线的加工和排列等方面具有广泛的应用前景。利用激光辅助STM制造的表面纳米结构中的纳米级残余应力/应变和结构损伤可以显著改变局部的机械、热、光学和电子特性，从而降低表面纳米结构的功能性和可靠性。针对这一关键问题，本项目的目标是（1）开发有关激光辅助STM表面纳米结构中亚表面纳米结构损伤形成的基础物理知识库，以及（2）探索和确定实验参数如何以及在多大程度上影响亚表面纳米结构损伤的形成。 激光辅助STM纳米结构化的分子/原子水平上的应变和结构损伤的显着见解将获得使用扫描隧道光谱和高分辨率透射电子显微镜。这代表了早期的尝试，定量探索的残余应变和结构损伤的特点，在这样一个小规模。这种大规模的分子动力学模拟将提供基本的和动态的理解的发展和传播/迁移的应力/应变和结构损伤的表面纳米结构与激光辅助STM。这些实验和数值研究的结合将揭示残余应变和结构损伤与不同实验参数之间的相关性，预期的结果将有助于减少残余应力/应变和结构损伤，提高微/纳米系统的功能/性能和可靠性。对纳米结构损伤形成的机制和驱动力的充分了解将有助于建立成功开发激光辅助STM纳米结构技术及其在工业中的应用所需的基本知识构建模块。 研究结果将通过在专业会议上的演讲，在高度知名的期刊上的出版物，跨部门研讨会和专门的项目网站广泛传播。研究成果将被整合到新课程“纳米尺度和超短时域传热”和“纳米技术导论”中。“广泛的本科生参与将涉及通过夏季研究就业。将特别努力从传统上在高等教育中代表性不足的群体，特别是妇女和少数民族中招收研究生和本科生。一个专门设计的网站将开发为K-12学生的教学功能。

As a top-down nanofabrication technique, the laser-assisted scanning tunneling microscope (STM) provides a wide variety of potential applications in surface nano-repair, fabrication and characterization of nano- to microscale integrated nanoelectronics and nanophotonics, and machining and aligning of nanoparticles and nanotubes/wires. The nanoscale residual stress/strain and structural damages in surface nanostructures fabricated using laser-assisted STM can significantly change the local mechanical, thermal, optical, and electronic characteristics, thereby degrading the functionality and reliability of surface nanostructures. Targeting this critical problem, the objectives of the project are to (1) develop the knowledge base about the underlying physics in the formation of sub-surface nanoscale structural damages in surface nanostructuring with laser-assisted STM, and (2) explore and identify how and to what extent the experimental parameters affect the formation of sub-surface nanoscale structural damages. Significant insights into strain and structural damages at molecular/atomic levels in nanostructuring by laser-assisted STM will be attained using both scanning tunneling spectroscopy and high-resolution transmission electron microscopy. This represents the early attempts to quantitatively explore the characteristics of the residual strain and structural damages at such a small scale. This large-scale molecular dynamics simulation will provide fundamental and dynamic understanding of the development and propagation/migration of both stress/strain and structural damages in surface nanostructuring with laser-assisted STM. These strategically combined experimental and numerical investigations will reveal the correlations between residual strain and structural damages and varied experimental parameters.The anticipated outcomes are instrumental for minimizing residual stress/strain and structural damages and improving the function/performance and dependability of micro/nanoscale systems. Sufficient insights into the mechanisms and driving forces behind the formation of nanoscale structural damages will lead to the establishment of basic knowledge building blocks required for successful development of the nanostructuring technology with laser-assisted STM and its implementation to industries. Results of the research will be broadly disseminated through presentations at professional conferences, publications in highly visible refereed journals, across-department seminars, and a dedicated project website. The research results will be integrated into new courses "Heat Transfer at Nanoscales and in Ultra-short Time Domain" and "Introduction to Nanotechnology." Extensive undergraduate participation will be involved via summer research employment. Special efforts will be taken to recruit graduate and undergraduate students from groups traditionally underrepresented in higher education, particularly women and minorities. A specially designed website will be developed for instructional functions for K-12 students.