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用作过滤器和生物探测器的单层氮化硼(BN)中纳米孔的形成、稳定性和化学反应的了解；并研究这些孔对整个BN片材的电气和机械性能的影响。使用原子分辨电子显微镜，将提供对单原子厚度的BN薄膜中空穴和缺陷的原子结构的新见解。该项目将提高对存在空洞和缺陷时这些BN薄膜中电流传导变化的了解，从而能够评估它们在下一代电子应用中的真正潜力。这项研究还将有助于确定将单一氮化硼薄膜用于过滤和生物检测应用的可能性。除了培养研究生，教育部分还包括改进和扩大电子显微镜和计算纳米力学的新课程，为本科生提供暑期研究机会，以及参加与当地高中生的外展计划。技术细节：通过将扫描电子显微镜(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相结合，将对单层h-BN中纳米级空穴的形成、机械稳定性和化学反应活性进行系统的研究。与传统的电子显微镜成像不同，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探测器记录下来。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)在单个硼和氮原子内部的电子激发来测量。对两个原子计算的局域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.