Structure and Reactivity of Nano-Scale Holes in Single Sheet BN: Experiment and Theory

非技术描述：本研究的目标是提高对单片氮化硼（BN）中纳米尺寸孔的形成，稳定性和化学反应性的理解，以用作过滤器和生物检测器;并研究这些孔对整个BN片的电气和机械性能的影响。使用原子分辨率电子显微镜，新的洞察力的原子结构的孔和缺陷在单原子厚的BN片将提供。该项目将提高对这些BN片材中存在孔洞和缺陷时电流传导变化的理解，从而评估其在下一代电子应用中的真正潜力。这项研究也将有助于确定使用单个BN片材用于过滤和生物检测应用的可能性。除了培训研究生外，教育部分还包括改进和扩展电子显微镜和计算纳米力学的新课程，为本科生提供夏季研究机会，并与当地高中生一起参加外展计划。技术规格：通过结合扫描透射电子显微镜（STEM）中的几种实验成像和光谱技术与基于第一性原理计算的理论预测，将对单片h-BN中纳米级孔的形成、机械稳定性和化学反应性进行系统的研究。与传统的TEM成像不同，STEM探测电子从样品中原子的静电势散射，并由单电子敏感的环形暗场检测器记录。这为BN的原子分辨率图像提供了直接和明确的原子位置识别。光谱分析将通过使用电子能量损失谱（EELS）的硼和氮的单个原子内的电子激发来测量。两个原子计算的局部态密度的理论预测将与EELS结果进行比较;稍后，将评估机械性能。

NON-TECHNICAL DESCRIPTION: The goal of this research is to improve the understanding of the formation, stability, and chemical reactivity of the nano-size holes in single sheet boron nitride (BN) for use as a filter and biodetector; and to study the effects of those holes on the electrical and mechanical properties of the entire BN sheet. Using atomic-resolution electron microscopy, new insight into the atomic structure of the holes and defects in single-atom-thick BN sheets will be provided. The project will improve the understanding of the changes in current-conduction in these BN sheets in the presence of the holes and defects, allowing evaluation of their true potential for next generation electronics applications. This research will also be instrumental in determining the possibilities of using single BN sheets for filtration and biodetection applications. In addition to training graduate students, the education component includes improving and expanding the new courses on Electron Microscopy and Computational Nanomechanics, providing summer research opportunities for undergraduate students, and participating in outreach programs with local high school students. TECHNICAL DETAILS: A systematic study the formation, mechanical stability and chemical reactivity of the nano-scale holes in the single sheet h-BN will be undertaken by combining several experimental imaging and spectroscopy techniques in scanning transmission electron microscope (STEM) with theoretical predications based on calculations from first principles. Unlike conventional TEM imaging, the STEM probe electrons are scattered from the electrostatic potential of the atoms in the sample and recorded by a single-electron-sensitive annular dark field detector. This provides atomic-resolution images of the BN with direct and unambiguous atomic location identification. The spectroscopic analysis will be measured by electronic excitations inside single atoms of boron and nitrogen using electron energy loss spectroscopy (EELS). Theoretical predictions for the local density-of-states calculated for both atoms will be compared with EELS results; later, mechanical properties will be evaluated.