Name: probing c84-embedded si substrate using scanning probe microscopy and molecular dynamics
Uploaded: 2016-09-28T12:30:00.000+00:00
Duration: 13 min 58 s
Description: Watch this Scientific Journal Video about Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics at JoVE.com

The authors would like to thank the Ministry of Science and Technology of Taiwan, for their financial support of this research under Contract Nos. MOST-102-2923-E-492- 001-MY3 (W. J. Lee) and NSC-102- 2112-M-005-003-MY3 (M. S. Ho). Support from the High-performance Computing of Taiwan in providing huge computing resources to facilitate this research is also gratefully acknowledged.

注:本文概述在一个半导体衬底的表面上的自组装富勒烯阵列的形成中使用的方法。具体地讲，我们提出了用作微电子机械系统（MEMS），以及在高温，高功率光电器件，应用的场致发射体或基底富勒烯嵌入硅衬底的制备的新方法，以及在高-频率器件9-13。 在Si衬底1的制作六角形封闭封装（HCP）加铺结构Ç84 <ol><li>准备清洁的Si（111）基板<ol><li>主体的Si衬底的RCA清洗（美国无线电公司），涉及随后加热在超高真空系统中除去从基板的表面上的氧化物层和杂质的溶剂的应用（见辅助材料）。 注意:在这里，术语"UHV-超高真空系统"是指到低于1×10的真空-8帕中的Si（111）的制备中使用。 </li></ol></li><li>存款ç84硅表面以特高压系统使用热蒸发<ol><li>通过加热丝至500℃的预加热用外部电源的K细胞蒸发器，以促进杂质的放气。 </li><li>载荷C 84纳米到K-电池容器。电阻加热的K细胞至650℃。汽化ç84纳米粒子为C 84纳米粒子在容器组成蒸汽。蒸发下在直线84纳米至纳米颗粒通过一个控制阀在低于5×10 -8帕压力取得一个Si衬底。 </li></ol></li><li>嵌入Ç84通过自组装机理Si表面分子内<ol><li>在一个超高真空系统的预退火的Si（111）基片，在900℃，得到（1×1）结构。降低温度至650℃用于该depos 30分钟在衬底的表面的C 84纳米的银行足球比赛。 </li><li>在〜750退火在Si基板 ℃下12小时，在此期间，粉状-C的84纳米自组装成在Si（111）基板的表面上的高度均匀的富勒烯阵列。 注意:在这里，术语"高度均匀的富勒烯阵列"是指富勒烯的基板上的均匀分布，其中大部分的纳米颗粒在垂直于衬底的表面取向在一个紧凑的布置。这种配置有助于确保富勒烯阵列的垂直高度为所有样本中基本上是相同的。 </li></ol></li></ol> 2.Ç84电子性能的测量-嵌入式硅衬底<ol><li>衡量各国的本地电子密度使用超高真空扫描隧道显微镜<ol><li>测量使用UHV-SPM特定原子的IV曲线</li><li>将C 84 </子&gt;在SPM样品架 - 嵌入式硅衬底。引进的持有人到UHV-STM（扫描隧道显微镜）扫描头系统。扫描应用样本偏差-5 V至5 V </li><li>点击"IV"测量项目测量隧道电流我在原子分辨率。选择进行测量的C 84 -嵌入式Si衬底上至少20的特定位置。计算隧道电流I 20的特定位置的平均值。派生我作为电压的一个函数。情节IV曲线。 </li><li>对于V.计算的I（V）的衍生物转换IV曲线到的dI / DV作为电压的函数，以便确定的C- 84的本地电子状态-嵌入式Si衬底。 </li></ol></li><li>测量带隙能量<ol><li>根据从以下2.1.2和2.1.3的程序获得IV曲线:SI（111）-7x7表面的Si（111）-1x1表面，单一个体Ç84纳米粒子在Si，7-19Ç84在Si集群，20-50Ç84簇在Si和嵌入式硅表面内Ç84单层。 </li><li>对于V.计算的I（V）的衍生物转换IV曲线到的dI / DV曲线来测量的HOMO-LUMO能级差异（称为带隙能量）在每个测量位置， 如图2a中 。 </li></ol></li><li>获取场发射（FE）属性<ol><li>将C 84在FE样品架-嵌入式硅衬底。将支架插入有限元分析室。抽空腔室，以约5×10 -5 Pa的是FE测量的压力。 注意:C 84 -嵌入式硅衬底充当阴极和与〜0.71毫米2充当阳极的横截面面积的铜探针。在阴极和阳极之间的距离为大约590微米。 </li><li>在衬底手动增加施加电压从100伏到1,100 V.测量对应ING场发射电流作为使用高电压源测量单元与电流放大器一个施加电压的功能。 </li><li>根据如图2b所示的功函数〜5 eV的计算福勒-诺德海姆场发射的相关性。 </li><li>具有约4,383一个β值F（场）=β（V / D）:得到的几何场增强因子（β）如下。 </li><li>获取基于所述自然对数的斜率（J / E 2）与（1 / E），这给了我们的〜4.0×10 6 V / cm的为C 84 -嵌入式Si衬底的值在真空下的击穿电场如图2c所示。 </li></ol></li><li>光电性能<ol><li>传输测试衬底的光学发射测量系统。注重与位于样品室的中心在基板上325纳米的排放He-Cd激光器光源。设置在适当的位置上的光谱仪。使用SPEctrometer通过收集和分析发射光子以获得光致发光光谱。光电结果示于图2d。 </li></ol></li></ol> 3.表面磁性测量<ol><li>获得MFM（磁力显微镜）地形。 <ol><li>磁化的Ç84样品-嵌入式硅前MFM测量通过施加磁铁用约2千奥斯特的磁场强度。 </li><li>广场上的MFM样品台的磁化样本。点击"获取MFM地志"项目。观察在嵌入升降模式中使用MFM与磁化垂直于样品的表面上的应用在硅衬底内的磁畴的富勒烯的微观结构。 </li><li>使用MFM测量纳米级PPP-MFMR悬臂（ 图3a）。确定表面磁性如果MFM地形显得较暗（亮）时尖的磁矩是在SAM基材时刻E（对面）的方向。 </li></ol></li><li> SQUID（超导量子干涉器件）测量<ol><li>准备Ç84单层-嵌入式基于C 84嵌入硅衬底硅衬底和C 84簇。 </li><li>磁化的ç84样品嵌入硅衬底之前SQUID实验通过应用磁铁约2千奥斯特的磁场强度-嵌入式Si和C 84簇基于C 84。 </li><li>将在SQUID样品。在一系列〜2千奥斯特应用扫描磁场。获得作图在室温下于SQUID测量的外部磁场的磁化循环。 注:如如图3b中所示为铁磁性材料的典型MH曲线可以得到。 </li></ol></li></ol> 4. AFM纳米力学性能的测量注:原子力显微镜（AFM）提供在微观和材料和机械性能在空气中的纳米尺度的特征，以及在一个UHV环境强大的工具<ol><li>衡量Ç84嵌入式硅衬底在大气条件下的刚度<ol><li>上放置的AFM样品台的基板。将一个锋利的尖端在使用扫描仪的基材。监视尖端的位移作为针尖 - 样品的相互作用力的量度。点击"力测量"项记录在某一位置沿垂直方向的许多针尖样的距离运动。 </li><li>获得使用来自天然氧化物的2-3纳米的层一个RCA清洗Si基板以及从C 84大气压条件下的AFM测力-嵌入式Si衬底和涂覆有碳化硅的薄膜的Si基片。 </li><li>使用AFM软件，绘制大气条件下力 - 距离曲线。 注:AFM悬臂是硅探针的尖端半径〜〜的40牛顿/米5-20纳米和弹簧常数。 </li></ol></li><li>衡量Ç84的刚度嵌入式硅基特高压室<ol><li>根据4.1.1在从一个RCA清洗Si基板，一个干净的Si（111）-7x7表面的超高真空系统中使用的AFM指导获得力的测量，一个C 84 -嵌入式Si衬底，衬底和一个硅衬底涂覆的与碳化硅的薄膜。 </li><li>剧情以特高压系统力 - 距离曲线。注:AFM悬臂是硅探头的〜5-20 nm和弹簧常数〜40牛顿/米的尖端半径图4给出无序硅表面的力-距离分析，7×7表面的，独立的自章C 84嵌入Si表面和Si表面组装内层，如使用UHV-AFM决定。 </li></ol></li></ol>通过分子动力学模拟纳米力学性能的5.测量注:在模拟部分，OVITO 16（开源visualizati上的软件），并且OSSD 17（开放面结构数据库）用于创建仿真模型和结果可视化。 LAMMPS 14（一个开源的分子动力学（MD）模拟包）被用来进行纳米压痕模拟和分析模拟结果15。所有仿真作业是用在先进的大型并行超星系的NCHC（ALPS），并行计算执行。 注意:要使用MD模拟研究的C 84单层/ Si衬底异质结，应准备几个步骤，一个模拟模型来获得嵌入到Si衬底严格的C 84单层。需要注意的是它难以产生一个恰好从实验数据相同的结构，因为该间结构的Ç84单层和Si（111）衬底异质结之间的复杂的。其结果是，我们使用一个人工的方式与程序的若干步骤，生成模拟模型，其在图5中示出。细节在以下协议说明。我们描述的MD在LAMMPS参数如何设置，建立嵌入到衬底的严格的C 84富勒烯单层，执行一个缩进过程，并分析模拟结果。 <ol><li>在LAMMPS输入文件参数设置<ol><li>使用边界命令设置在x周期性边界条件和y方向。 </li><li>用"固定速度"命令给初始速度与系统的各原子的高斯分布分配，随机。 </li><li>使用"修复pair_style"命令来指定Tersoff 18和19 AIREBO潜力来形容的Si-Si和Si-C相互作用和CC的互动，分别为。 </li><li>使用"修正NVT"和"固定的npt"命令来采取鼻胡佛方法20，以确保系统保持在所需的温度和压力下，以基因评价规范和等温等压系综20，在该系统中，速度- verlet的算法20被用来预测原子的轨迹。同时使用"修复NVT"和"运行"命令来设置3 K /皮秒退火过程的冷却速度。 </li><li>使用"时间步"命令来设置0.2 FSEC的时间积分的时间步长。 </li><li>使用"修复墙/体现"命令采用反射墙来限制自由（5.3.2）的程度。 </li><li>使用"区"和"基团"的基片成不同的控制层（5.4.3）分成:牛顿原子层，热控制层和底部固定层，其可以通过使用"修正NVE"成立，"修复NVT"和"修复setforce"命令，分别。 </li><li>使用"区域"和"create_atoms"命令来创建一个球形探头。 </li><li>使用"修复移动"命令来嵌入C84单分子层到基板（5.4。2）与模拟（5.5.2）中移动探针。 </li><li>使用"运行"命令来执行分子动力学模拟。 </li><li>使用"计算力"（5.6.1）和"计算应力/原子"（5.6.4）命令来评价原子应力和压痕力。 注意:在下文中，除了结构建立，所有的步骤被LAMMPS脚本完成的。 </li></ol></li><li>使用OSSD和OVITO到硅（111）7×7表面的制备。 <ol><li>打开OSSD软件。点击"搜索"按钮。 "搜索条件"面板呈现。之所以选择Si衬底，元素类型，重建的结构，半导体ELEC，菱形格，111脸和7×7的模式。点击"搜索"和"接受"按钮。 "结构列表"面板呈现。单击所需的结构（ 即 ，硅（111）7×7）。点击"文件"按钮。保存协调文件名为.xyz文件。 注:我们指出的结构从OSSD抽取的数据库是不是我们的压痕模拟足够大。其结果是，我们通过以下步骤重建较大和较厚衬底。 </li><li>打开OVITO软件。加载名为.xyz文件到OVITO。使用"切片"命令来捕获所述Si的（111）7×7表面在x和y方向26.878点¯x46.554埃2的尺寸的超晶胞。导出的数据文件。使用"切片"命令来捕捉底部的Si（111）衬底与3的26.878点¯x46.554点¯x9.7大小的超级。使用"查看定期图像"命令来复制超级12倍z方向。导出的数据文件。 </li><li>结合Si的数据文件（111）7×7表面和Si（111）衬底模型通过记事本+ +（一个免费的源代码编辑器）。最后，将合并的数据加载到OVITO。使用"查看周期性图像"复制在x和y方向上具有5×3超元放大基板的大小。 </li><li>使用LAMMPS执行20微秒MD模拟时间放宽仿真模型。在下文中，1550ķ执行淬火处理至室温以500微秒仿真时间。最后，执行一个10皮秒的模拟时间进行最后的放松过程。 </li></ol></li><li>章C 84富勒烯单分子膜制备方法<ol><li>从网络21下载C 84富勒烯的结构优化的协调文件，并写入FORTRAN程序复制安排在一个蜂窝结构49℃84富勒烯。 </li><li>使用LAMMPS设置反映壁在与下面的C 84单层以确保该分子留在一个计划。执行MD模拟时间为200皮秒放松仿真模型。在下文中，执行从700 K A淬火过程到室温，以获得500微秒仿真时间水珠最小状态。最后，执行一个10皮秒的模拟时间进行最后的放松过程。 </li></ol></li><li>建立Indenta在硅ç84富勒烯单分子膜化模型（111）7×7表面。 <ol><li>写FORTRAN代码躺在硅的C 84单层（111）7×7表面3的距离，建立压痕模型。 </li><li>使用LAMMPS嵌入的C 84单层与2〜3埃的深度的基板。在下文中，运行一个40微秒的模拟时间为系统的放松。最后，退火系统至室温。 </li><li>划分硅衬底成上层牛顿原子层，热控制层和底部固定层，分别是0.7，2，和厚度5.3纳米。的C 84单层也建模为牛顿原子。 </li></ol></li><li> MD压痕工艺<ol><li>使用LAMMPS与基于C 84 / SI（111）7×7表面的模式直径5纳米（ 图5）创建一个球形探头。探头设定为刚体。指定的PR 10米/秒的恒定速度OBE向下朝向缩进过程试样移动。 </li><li>向下移动探针与样品以恒定的速度，直到特定装载深度（ 即，包括1.5的情况下，2.5，4.5，10，15，20，和30埃，以便探索的C 84富勒烯单层的效果在装载过程中的Si衬底，其中C 84富勒烯的尺寸为11埃）上。持探针在夹持过程基板以允许原子的松弛。最后，在缩回过程的恒定速度提取从该衬底的探针。 </li></ol></li><li>计算与分析<ol><li>总结根据下列公式在探针原子的垂直力计算压痕力: <img alt="方程" src="/files/ftp_upload/54235/54235eq1.jpg" /> （1） </li><li>萃取从压痕的力 - 距离曲线的还原模量和硬度。基于奥利弗和法尔＆＃39氏方法22，线性关系可以的杨氏模量和卸载刚度之间的。刚度（ 即 ，初始部分的斜率）的卸载曲线的定义为 <img alt="方程" src="/files/ftp_upload/54235/54235eq2.jpg" /> （2） 其中，P，H，A和E r为压痕负荷，探针的弹性位移，压痕投影面积，降低了模量。 β（= 1为圆形压头）是形状修正因子。降低模量和杨氏模量之间的关系可以写成 <img alt="方程" src="/files/ftp_upload/54235/54235eq3.jpg" /> （3） 其中E和v是杨氏模量和泊松比的样品和E I和V i是杨氏模量和泊松比的压头。 </li><li>的H定义计算硬度= P 马X / A，其中P 最大和A是最大压痕力和探头的投影面积。 </li><li>计算由在所述n -方向基板的m面的维里原子应力22 <img alt="方程" src="/files/ftp_upload/54235/54235eq4.jpg" /> （4） 其中m i为原子i的质量; <img alt="方程" src="/files/ftp_upload/54235/54235eq_vmi.jpg" />和<img alt="方程" src="/files/ftp_upload/54235/54235eq_vni.jpg" />是在第m原子i的速度分量-和n -directions分别; V I是围绕原子我分配体积; N s是包含区域S，其中S是指原子的相互作用的区域内的粒子数;Φ（R IJ）是潜在的功能; R ij是原子i和之间的距离<em&gt; j和<img alt="方程" src="/files/ftp_upload/54235/54235eq_xmij.jpg" />和<img alt="方程" src="/files/ftp_upload/54235/54235eq_xnij.jpg" />就在M -从原子到我的Atom j中的向量的n个晶向组件。 </li><li>使用OVITO表示根据下列公式每个原子不变的冯米塞斯应力: <img alt="方程" src="/files/ftp_upload/54235/54235eq5.jpg" /> （5） </li></ol></li></ol>

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作者什么都没有透露。

<html>在这项研究中，我们证明Ç84的Si衬底上的自组装单层的通过新颖的退火工艺的制造（ 图1）。这个方法也可以用于制备其它种类的纳米颗粒的嵌埋半导体基板。的C 84 -嵌入式Si衬底，其特征在用UHV-STM（ 图2），场发射光谱仪，光致发光光谱，MFM和SQUID（ 图3）的原子比例。 对应的C- 84纳米力学性能（ 即 ，应力）的附着强度-嵌入式Si衬底可以用原子力显微镜（ 图4）来测量。我们的结果表明，该Ç84的硬度-嵌入式Si衬底比得上碳化硅和硅的表面，使之适用作为用于切削工具，以及在MEMS器件的薄膜研磨材料。 jove_content"&gt;在模拟部分中，冯米塞斯应变（εVM）分析能够探测原子结构，这是在实验中观察到非常困难的局部变形。但是，这是不可能表征相变。这里，我们提出了一些有用的指数，如配位数和HA索引23以检查相变，在压痕模型的设置，我们要指出的是，在俯视方向上的衬底的尺寸必须至少大三倍比探头用于消除尺寸效应和边界条件的限制，这将影响到动态和原子力流动的直径。 另外，由于MD模拟的时间限制，来研究缩进的过程中，探头应以非常快的速度相比，在实验施加试样。我们注意到，这样的加载速度过高出来的长时间在OMIC扩散和迁移行为，但它仍然是合适的观察和根据机械负载24描述的塑性变形行为和材料性能，因为这些结果可以作为大致准静态的性质25被识别。一种替代理论，命名为并行副本动力学（PRD）26，已经发展到基本上加速仿真时间，但它需要大量的计算资源。 从MD模拟研究获得的数据与所述AFM压痕试验（ 图8）的协议;另外，将C 84的硬度和模量减小-嵌入式Si衬底比得上其它的Si衬底。这些数据表明，Ç84 -嵌入式Si衬底可以具有在光电显著影响和稀磁性半导体（DMS）纳米器件。

富勒烯分子和它们包含有纳米材料之间独特的，由于其优异的结构特点，电子传导性，机械强度，化学性能1-4复合材料。这些材料已被证明在一个范围内的领域，如电子，电脑，燃料电池技术，太阳能电池，以及场致发射技术5,6非常有益的。 在这些材料中，碳化硅（SiC）纳米粒子的复合材料已经受到了特别的关注由于它们的宽带隙，高导热性和稳定性，高电击穿能力，和化学惰性。这些好处是在光电器件特别明显，金属氧化物半导体场效应晶体管（MOSFET），发光二极管（LED），和高功率，高频率，和高温应用。然而，高密度的缺陷通常conventi的表面上观察到的Onal地区碳化硅可以对电子结构的不利影响，甚至导致器件失效7,8。尽管碳化硅的应用程序已自1960年以来研究的事实，这个特殊的未解决的问题仍然存在。 本研究的目的是一个C 84的制造-嵌入式Si衬底异质结和随后的分析，得到所得到的材料的电子，光电，机械，磁性，和场发射性能的全面理解。我们还讨论通过数值模拟来预测纳米材料的特性，通过分子动力学计算得到新的应用的问题。

<table><tbody><tr><td>Silicon wafer</td><td></td><td></td><td>Si(111). Type/Dopant: P/Boron; Resistivity: 0.05-0.1 Ohm&amp;#183;cm</td></tr><tr><td>Carbon, C&lt;sub&gt;84&lt;/sub&gt;</td><td>Legend Star</td><td></td><td>C&lt;sub&gt;84&lt;/sub&gt; powder, 98%</td></tr><tr><td>Hydrochloric acid</td><td>Sigma-Aldrich</td><td>84422</td><td>RCA, 37%</td></tr><tr><td>Ammonium</td><td>Choneye Pure Chemical</td><td></td><td>RCA, 25%</td></tr><tr><td>Hydrogen peroxide</td><td>Choneye Pure Chemical</td><td></td><td>RCA, 35%</td></tr><tr><td>Nitrogen</td><td>Ni Ni Air</td><td></td><td>high-pressure bottle, 95%</td></tr><tr><td>Tungsten</td><td>Nilaco</td><td>461327</td><td>wire, diameter 0.3 mm, tip</td></tr><tr><td>Sodium hydroxide</td><td>UCW</td><td>85765</td><td>etching Tungsten wire for tip</td></tr><tr><td>Acetone</td><td>Marcon Fine Chemicals</td><td>99920</td><td>suitable for liquid chromatography and UV-spectrophotometry</td></tr><tr><td>Methanol</td><td>Marcon Fine Chemicals</td><td>64837</td><td>suitable for liquid chromatography and UV-spectrophotometry</td></tr><tr><td>UHV-SPM</td><td>JEOL Ltd</td><td>JSPM-4500A</td><td>Ultrahigh Vacuum Scanning Tunneling Microscope and Ultrahigh Vacuum Atomic Force Microscope</td></tr><tr><td>Power supply</td><td>Keithley</td><td>237</td><td>High-Voltage Source-Measure Unit</td></tr><tr><td>SQUID</td><td>Quantum desigh</td><td>MPMS-7</td><td>Magnetic field strength: &amp;plusmn;7.0 Tesla, Temperature range: 2&amp;#8211;400 K, Magnetic-dipole range: 5&amp;nbsp;&amp;times;&amp;nbsp;10&lt;sup&gt;-7&lt;/sup&gt; &amp;#8211; 300 emu</td></tr><tr><td>ALPS</td><td>National Center for High-performance Computing, Taiwan</td><td></td><td>Advanced Large-scale Parallel Supercluster, 177Tflops; 25,600 CPU cores; 73,728 GB RAM; 1,074 TB storage</td></tr></tbody></table>

probing c84-embedded si substrate using scanning probe microscopy and molecular dynamics

本文的阵列设计Ç84 -嵌入式Si衬底捏造使用受控的自组装方法中的超高真空室的报告。的C- 84的特性-嵌入式Si表面，如原子分辨率地形，态本地电子密度，带隙能量，场发射性能，纳米机械刚度，以及表面磁性，使用各种表面分析技术下超进行了检查，在高真空（UHV）条件下，以及在一个大气压的系统。实验结果表明的C- 84的高度均匀性-嵌入式Si表面捏造使用受控的自组装纳米机制，表示场发射显示器（FED），光电器件制造，微机电系统的应用的一个重要发展切削工具，并在努力找到硬质合金半导体合适的替代者。分子动力学（MD）方法，半经验潜力b用于研究的ç84纳米压痕ê -嵌入式硅衬底。执行MD模拟详细描述这里提出。对MD模拟的力学分析，如压痕力，杨氏模量，表面硬度，原子应力，应变原子的综合研究的细节都包括在内。压痕模型的基本应力和冯·米塞斯应变分布可以计算出监测与原子级别时间评估变形机制。

Ç84分子的无序的Si（111）面A单层使用受控的自组装过程中一个超高真空腔室制造图1示出了一系列通过UHV-STM不同程度的覆盖率的测量地形图像:（一） 0.01毫升，（b）0.2毫升，（C）0.7毫升，和（d）0.9毫升。的C 84嵌入Si衬底的电子和光学性质使用各种表面分析技术，如STM和PL（ 图2）还研究。得到的样品的优异材料性质证明纳米技术可以如何用于物质在atomic-和纳米尺度上的控制。 图3中的MFM和SQUID结果表明Ç84嵌入基片的表面的磁性。 图4给出了参考提出衬底的纳米机械的UHV-AFM结果。我们的实验结果表明，中C 84的潜力</sUB&gt;嵌入硅衬底作为替代在高温，高功率纳米电子器件的半导体，碳化硅，高频率的应用，以及在磁性和MEMS装置（ 图4中）。 在模拟部分，所有的程序都用LAMMPS进行MD模拟完成。富勒烯埋置基板的机械性能（压痕力和接触应力）的计算，并在图6中示出。在不同的时间步原子的冯米塞斯应变分析用于表征局部变形。相应的快照作为压痕深度的函数可以在图6的插入件，其分别计算与由OVITO可视看到。的压痕力作为压痕深度的函数的结果被用来计算硬度H（ 图7a），减少的模量E &lt;子&gt; R（ 图7b），并装载刚度S的C 84单层（ 图8）。结果可以与由实验确定被比较和提供的观点更详细地点来解释的机械性能的变化。 <img alt="图1" src="/files/ftp_upload/54235/54235fig1.jpg" /> 图1:C 84 嵌入式Si衬底具有不同的覆盖的STM地形图（40×40纳米2）表示ç吸附在Si 84分子的系列（111）面以2伏的负样本偏置，如通过UHV-STM测量。不同程度的覆盖范围:（1）0.01毫升，（b）0.2毫升，（C）0.7毫升，和（d）0.9毫升。 <img alt="图2" src="/files/ftp_upload/54235/54235fig2.jpg" /><br/&gt; 图2: 电子属性第C 84 测量 嵌入式Si衬底 （ 一个 ）IV曲线和差分衍生物电导（DI / DV）与章C 84单自组装层的电压曲线，如通过UHV-STM确定。 ; （ 二 ）场发射电流密度VS电场曲线; （ 三 ）对应的表面的FN情节与嵌入式C 84，如使用源测量单元测量; （ 四 ）Ç84单自组装层的光致发光光谱。重新打印与基准12的许可。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/54235/54235fig3.jpg" /> 图3: </str翁&gt; 第C 84 表面磁性 嵌入式Si衬底 （ 一个 ）嵌入用C 84 Si基的MFM图像。 （ 二 ）磁化循环暗算外部磁场<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/54235/54235fig4.jpg" /> 图4:第C 84纳米机械调查嵌入式Si衬底无序的Si表面的力-距离分析，7×7的表面，或C 84嵌入Si表面内，并且Si表面单自组装层，如使用UHV-AFM测定。重新打印与基准11的许可。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig4large.jpg" target="_blank">请点击此处</a>查看该图的放大版本。 <img alt="图5" src="/files/ftp_upload/54235/54235fig5.jpg" /> 图5: 流程图建立仿真模型的戏剧性说明在MD模拟的设置从单个C层84和Si（111）7×7表面嵌入到硅（111）7×7型为C 84单层。详细步骤可以在协议的第5节中看到。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图6" src="/files/ftp_upload/54235/54235fig6.jpg" /> 图6: 缩进力和接触应力分析压痕力（黑色）和联系的Ç84应力（蓝色）为压痕深度的函数。插入显示相应的快照，其中不同的颜色表示的所有原子的相应的冯米塞斯应变（εVM）。要清除显示应变局部化，只能用εVM原子&gt; 0.08快照所示。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图7" src="/files/ftp_upload/54235/54235fig7.jpg" /> 图7:。 硬度和模量减小分析 （ 一 ）硬度和（b）模量减小的变化作为压痕深度对Si表面的C 84单层功能<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig7large.jpg" target="_blank">，请点击这里查看该图的放大版本。</a> 图8: 加载刚度分析 。载入刚度与用AFM实验对于C 84 / Si的比较由MD模拟确定的距离的函数。从参考16修改。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54235/54235fig8large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics at JoVE.com

Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics

This paper reports the nanomaterial fabrication of a fullerene Si substrate inspected and verified by nanomeasurements and molecular dynamic simulation.

探测ç<sub&gt; 84</sub&gt; - 嵌入式硅衬底利用扫描探针显微镜和分子动力学

This paper reports an array-designed C84-embedded Si substrate fabricated using a controlled self-assembly method in an ultra-high vacuum chamber. The ...

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Nanyang Technological University

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Engineering

Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics

11.7K 次观看.  National Chung Hsing University. This paper reports the nanomaterial fabrication of a fullerene Si substrate inspected and verified by nanomeasurements and molecular dynamic simulation.

视频: Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics

Scanning-probe Single-electron Capacitance Spectroscopy

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the electronic quantum structure of small systems - including individual atomic dopants in semiconductors. Here we present a capacitance-based method, known as Subsurface Charge Accumulation (SCA) imaging, which is capable of resolving single-electron charging while achieving sufficient spatial resolution to image individual atomic dopants. The use of a capacitance technique enables observation of subsurface features, such as dopants buried many nanometers beneath the surface of a semiconductor material1,2,3. In principle, this technique can be applied to any system to resolve electron motion below an insulating surface.
As in other electric-field-sensitive scanned-probe techniques4, the lateral spatial resolution of the measurement depends in part on the radius of curvature of the probe tip. Using tips with a small radius of curvature can enable spatial resolution of a few tens of nanometers. This fine spatial resolution allows investigations of small numbers (down to one) of subsurface dopants1,2. The charge resolution depends greatly on the sensitivity of the charge detection circuitry; using high electron mobility transistors (HEMT) in such circuits at cryogenic temperatures enables a sensitivity of approximately 0.01 electrons/Hz&frac12; at 0.3 K 5.

Scanning-probe single-electron capacitance spectroscopy facilitates the study of single-electron motion in localized subsurface regions. A sensitive charge-detection circuit is incorporated into a cryogenic scanning probe microscope to investigate small systems of dopant atoms beneath the surface of semiconductor samples.

扫描探针单电子电容谱

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the ...

科研

工程学

Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. At the same time the AFM tip is passivated to prevent unspecific interactions between the tip and the substrate, which is a prerequisite to study single molecules attached to the AFM tip. Analyses to determine the adhesion force, the adhesion length, and the free energy of these molecules on solid surfaces and bio-interfaces are shortly presented and external references for further reading are provided. Example molecules are the poly(amino acid) polytyrosine, the graft polymer PI-g-PS and the phospholipid POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine). These molecules are desorbed from different surfaces like CH3-SAMs, hydrogen terminated diamond and supported lipid bilayers under various solvent conditions. Finally, the advantages of force spectroscopic single molecule experiments are discussed including means to decide if truly a single molecule has been studied in the experiment.

A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

调查单分子粘附的原子力谱

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single ...

Hand Controlled Manipulation of Single Molecules via a Scanning Probe Microscope with a 3D Virtual Reality Interface

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer. For intuitive and efficient manipulation we therefore couple a low-temperature non-contact atomic force/scanning tunneling microscope (LT NC-AFM/STM) to a motion capture system and fully immersive virtual reality goggles. This setup permits &#34;hand controlled manipulation&#34; (HCM), in which the SPM tip is moved according to the motion of the experimenter&#39;s hand, while the tip trajectories as well as the response of the SPM junction are visualized in 3D. HCM paves the way to the development of complex manipulation protocols, potentially leading to a better fundamental understanding of nanoscale interactions acting between molecules on surfaces. Here we describe the setup and the steps needed to achieve successful hand-controlled molecular manipulation within the virtual reality environment.

We demonstrate the precise manipulation of individual organic molecules on a metal surface with the tip of a scanning probe microscope driven in 3D by the experimenter's hand using a motion capture system and fully immersive virtual reality goggles.

通过手扫描探针显微镜用三维虚拟现实接口控制单分子的操作

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building ...

Probing The Structure And Dynamics Of Nucleosomes Using Atomic Force Microscopy Imaging

Chromatin, which is a long chain of nucleosome subunits, is a dynamic system that allows for such critical processes as DNA replication and transcription to take place in eukaryotic cells. The dynamics of nucleosomes provides access to the DNA by replication and transcription machineries, and critically contributes to the molecular mechanisms underlying chromatin functions. Single-molecule studies such as atomic force microscopy (AFM) imaging have contributed significantly to our current understanding of the role of nucleosome structure and dynamics. The current protocol describes the steps enabling high-resolution AFM imaging techniques to study the structural and dynamic properties of nucleosomes. The protocol is illustrated by AFM data obtained for the centromere nucleosomes in which H3 histone is replaced with its counterpart centromere protein A (CENP-A). The protocol starts with the assembly of mono-nucleosomes using a continuous dilution method. The preparation of the mica substrate functionalized with aminopropyl silatrane (APS-mica) that is used for the nucleosome imaging is critical for the AFM visualization of nucleosomes described and the procedure to prepare the substrate is provided. Nucleosomes deposited on the APS-mica surface are first imaged using static AFM, which captures a snapshot of the nucleosome population. From analyses of these images, such parameters as the size of DNA wrapped around the nucleosomes can be measured and this process is also detailed. The time-lapse AFM imaging procedure in the liquid is described for the high-speed time-lapse AFM that can capture several frames of nucleosome dynamics per second. Finally, the analysis of nucleosome dynamics enabling the quantitative characterization of the dynamic processes is described and illustrated.

Here, we present a protocol to characterize nucleosome particles at the single-molecule level using static and time-lapse atomic force microscopy (AFM) imaging techniques. The surface functionalization method described allows for the capture of the structure and dynamics of nucleosomes in high-resolution at the nanoscale.

原子力显微镜成像在核细胞结构和动力学研究中的应用

Chromatin, which is a long chain of nucleosome subunits, is a dynamic system that allows for such critical processes as DNA replication and transcription ...

生物化学

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

一种新的方法<em&gt;原位</em&gt;纳米级样品的机电表征

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution. Several methods have been developed to overcome this shortcoming, including all-electronic time-resolved STM, which is used in this study to examine dopant dynamics in silicon with nanosecond resolution. The methods presented here are widely accessible and allow for local measurement of a wide variety of dynamics at the atomic scale. A novel time-resolved scanning tunneling spectroscopy technique is presented and used to efficiently search for dynamics.

We demonstrate an all-electronic method to observe nanosecond-resolved charge dynamics of dopant atoms in silicon with a scanning tunneling microscope.

全电子纳秒分辨扫描隧道显微镜: 促进单一掺杂剂电荷动力学的研究

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new ...

Characterizing Individual Protein Aggregates by Infrared Nanospectroscopy and Atomic Force Microscopy

The phenomenon of protein misfolding and aggregation results in the formation of highly heterogeneous protein aggregates, which are associated with neurodegenerative conditions such as Alzheimer&#8217;s and Parkinson&#8217;s diseases. In particular low molecular weight aggregates, amyloid oligomers, have been shown to possess generic cytotoxic properties and are implicated as neurotoxins in many forms of dementia. We illustrate the use of methods based on atomic force microscopy (AFM) to address the challenging task of characterizing the morphological, structural and chemical properties of these aggregates, which are difficult to study using conventional structural methods or bulk biophysical methods because of their heterogeneity and transient nature. Scanning probe microscopy approaches are now capable of investigating the morphology of amyloid aggregates with sub-nanometer resolution. We show here that infrared (IR) nanospectroscopy (AFM-IR), which simultaneously exploits the high resolution of AFM and the chemical recognition power of IR spectroscopy, can go further and enable the characterization of the structural properties of individual protein aggregates, and thus offer insights into the aggregation mechanisms. Since the approach that we describe can be applied also to the investigations of the interactions of protein assemblies with small molecules and antibodies, it can deliver fundamental information to develop new therapeutic compounds to diagnose or treat neurodegenerative disorders.

We describe the application of infrared nanospectroscopy and high-resolution atomic force microscopy to visualize the process of protein self-assembly into oligomeric aggregates and amyloid fibrils, which is closely associated with the onset and development of a wide range of human neurodegenerative disorders.

通过红外纳米光谱和原子力显微镜对单个蛋白质聚合进行特征化

The phenomenon of protein misfolding and aggregation results in the formation of highly heterogeneous protein aggregates, which are associated with ...

Probing Surface Electrochemical Activity of Nanomaterials using a Hybrid Atomic Force Microscope-Scanning Electrochemical Microscope (AFM-SECM)

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. Atomic force microscopy (AFM) is a versatile tool to characterize micro- and nanostructure in terms of topography and mechanical properties. However, conventional SECM or AFM provides limited laterally resolved information on electrical or electrochemical properties at nanoscale. For instance, the activity of a nanomaterial surface at crystal facet levels is difficult to resolve by conventional electrochemistry methods. This paper reports the application of a combination of AFM and SECM, namely, AFM-SECM, to probe nanoscale surface electrochemical activity while acquiring high-resolution topographical data. Such measurements are critical to understanding the relationship between nanostructure and reaction activity, which is relevant to a wide range of applications in material science, life science and chemical processes. The versatility of the combined AFM-SECM is demonstrated by mapping topographical and electrochemical properties of faceted nanoparticles (NPs) and nanobubbles (NBs), respectively. Compared to previously reported SECM imaging of nanostructures, this AFM-SECM enables quantitative assessment of local surface activity or reactivity with higher resolution of surface mapping.

Probing Surface Electrochemical Activity of Nanomaterials using a Hybrid Atomic Force Microscope-Scanning Electrochemical Microscope AFM-SECM

Atomic force microscopy (AFM) combined with scanning electrochemical microscopy (SECM), namely, AFM-SECM, can be used to simultaneously acquire high-resolution topographical and electrochemical information on material surfaces at nanoscale. Such information is critical to understanding heterogeneous properties (e.g., reactivity, defects, and reaction sites) on local surfaces of nanomaterials, electrodes and biomaterials.

使用混合原子力显微镜扫描电化学显微镜（AFM-SECM）探测纳米材料的表面电化学活性

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. ...

化学

Microscopic Visualization of Porous Nanographenes Synthesized through a Combination of Solution and On-Surface Chemistry

On-surface synthesis has recently been regarded as a promising approach for the generation of new molecular structures. It has been particularly successful in the synthesis of graphene nanoribbons, nanographenes and intrinsically reactive and instable, yet attractive species. It is based on the combination of solution chemistry aimed at preparation of appropriate molecular precursors for further ultra-high vacuum surface assisted transformations. This approach also owes its success to an incredible development of characterization techniques, such as scanning tunneling/atomic force microscopy and related methods, which allow detailed, local characterization at atomic scale. While the surface-assisted synthesis can provide molecular nanostructures with outstanding precision, down to single atoms, it suffers from basing on metallic surfaces and often limited yield. Therefore, the extension of the approach away from metals and the struggle to increase productivity seem to be significant challenges toward wider applications. Herein, we demonstrate the on-surface synthesis approach for generation of non-planar nanographenes, which are synthesized through a combination of solution chemistry and sequential surface-assisted processes, together with the detailed characterization by scanning probe microscopy methods.

<meta charset="utf8"></head><body>通过溶液和表面化学相结合合成的多孔纳米石墨烯的微观可视化

A combination of solution and surface assisted synthesis opens new directions in the atomically precise synthesis of nanostructures. Scanning tunneling microscopy (STM) supplemented by non-contact atomic force microscopy (nc-AFM) enables detailed characterization of newly designed and generated carbon-based nano-objects.

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