Name: in situ transmission electron microscopy with biasing and fabrication of asymmetric crossbars based on mixed-phased a-vox
Uploaded: 2020-05-13T13:00:00.000+00:00
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这项工作部分在澳大利亚国家制造设施维多利亚节点RMIT大学的微纳米研究设施进行。作者承认这些设施以及RMIT大学显微镜、微分析设施的科技援助，该设施是澳大利亚显微镜的一个联合实验室。澳大利亚政府澳大利亚研究生奖（APA）/研究培训计划（RTP）计划的奖学金支持得到认可。我们感谢马杜·巴斯卡兰教授、苏米特·瓦利亚副教授、马修·菲尔德博士和布伦顿·库克先生的指导和有益的讨论。

1. 制造工艺和电气特征
<ol><li>使用标准图像反转光刻9 来用以下参数对设备的光电逆器进行底部电极（BE 层 1）的图案:<ol>
<li>旋转涂层的光电图在3000 rpm，软烤它在90°C为60s，暴露与25 mJ/cm2 与405 nm激光，在120°C烘烤120s，执行洪水暴露与21mW/cm2 和400nm激光，开发使用开发人员，并用去离子水冲洗。</li>
	</ol>
</li>
	<li>将 5 纳米钛 （Ti） 用于粘附，将 15 nm 铂金 （Pt） 放在顶部，并配有电子束蒸发器系统，基板图案为第 1 层。</li>
	<li>将基材放入丙酮浴中约 20 分钟，从而解除沉积金属。然后，应用超声波振动2分钟，用丙酮和异丙醇（IPA）冲洗，以完成 BE 模式。如果升空不干净，重复重复（图 1A，步骤 1）。</li>
	<li>将功能氧化物层（第 2 层）与 BE 顶部的光刻成形图案进行图案，如第 1.1 步所述。</li>
	<li>使用溅射系统 10 将 100 nm 的-VOx 和 5 nm 的 Ti 存入第2层之上。</li>
	<li>将基板放入丙酮浴中，用2-3的脉冲手动应用脉冲超声波振动，以最终确定功能氧化物模式，从而提升功能氧化物。如果图案不干净，请重复操作。（图1A、第2步和第3步）</li>
	<li>同样，使用图像反转光刻、电子束蒸发和第 1 步描述的升空过程，以 Ti_20 纳米/Pt_200纳米完成顶部电极 （TE） （第 3 层） 模式。（图 1A， 步骤 4） 注:这完成了交叉点设备图 1B的制造。</li>
	<li>对制造的设备进行电气和温度分析，以了解其电阻切换性能。<ol>
<li>使用带双探头直流 （DC） I-V 测量系统的源计和探头站进行电气测量。</li>
		<li>始终保持相关的当前合规性，以避免损坏设备。</li>
		<li>要分析设备的当前行为，请执行电压控制分析，并应用电压扫描，从正偏置的 0.1 V 的低电压开始，缓慢增加，直到观察到电成形。 注:电成形是一次性事件，在特定电压下，在最初绝缘功能氧化物中形成几纳米宽的导电细丝，这取决于固有材料特性和设备尺寸。此时，由于形成导电路径，电流图上观察到电阻突然下降或电流增加。</li>
		<li>电成形后，应用双向电压扫描以实现挥发阈值切换性能。调整电压以实现高开/关比。在这种情况下，交换比达到~10。</li>
		<li>分析室温到 90 °C 的不同温度下的电流电压特性，在 10 °C 步骤中增加，然后使用温度控制阶段倒回室温。</li>
	</ol>
</li>
</ol>2. 网格条和偏置芯片安装
<ol><li>在 CAD 软件中设计 FIB 优化网格条，并在内部使用标准加工技术进行制造，以安装用于现场 TEM 实验的偏置/加热芯片，如 图 2所示。 注: 图2A 显示网格条的单独部分，在方形战壕中同时安装三个芯片。 图 2B 显示了用于适应 TEM 的现场偏置/加热芯片的放大方形沟槽部分。</li>
	<li>将偏置芯片放入装满丙酮的玻璃培养皿中，轻轻旋转2分钟，清洁偏置芯片。然后取出芯片，放在装满甲醇的培养皿中，轻轻旋转2分钟。最后，用低压氮吹干。 注:商业上购买的偏置芯片，称为电子芯片，具有光抗光涂层保护。</li>
	<li>对齐网格条方形沟中的预清洁偏置芯片，如 图 2C所见。</li>
	<li>用螺丝固定偏置芯片顶部的网格盖，以最终确定电子芯片在网格杆上的位置（图 2D）。</li>
</ol>3. Lamella 准备，使用聚焦离子束安装偏置芯片，并就地传输电子显微镜
<ol><li>如 图 3A中所示，用厚度为 Ti_10 nm/Pt_100 nm 的较厚 BE 分别制作第 1 节中描述的样品。</li>
	<li>使用导电碳胶带将新制备的样品安装在金属存根上，并在 FIB 腔室中装载。在样品上应用额外的胶带进行接地，以避免充电问题。</li>
	<li>以 52° 倾斜度（见 图 3B）在机舱中加载偏置芯片安装的网格条。这将垂直或平行于离子束柱，具体取决于阶段旋转。</li>
	<li>使用显微镜物理控制面板和拉梅拉制备位置的软件对焦、对焦和对齐样品表面上的电子束。</li>
	<li>检查聚焦样本位置的偏心高度和电子束和离子束的光束巧合。 注:偏心高度是样品倾斜时图像不移动的位置。</li>
	<li>单击 自动 TEM 程序 （自动 lamella 准备程序），使用显微镜控制软件在集中的样本位置运行它。自动程序遵循下面描述的顺序。 注:这将完成创建TEM拉梅拉（图4）的过程。可在桌面屏幕上实时观察 AutoTEM 程序的进度。<ol>
<li>使用硅铣削创建交叉对齐标记，并在对齐标记之间的 20 μm x 5 μm 区域内沉积 1.5 μm 厚的碳保护层。</li>
		<li>碳保护层两侧的磨沟与5 nA离子束电流，以创建拉梅拉。</li>
		<li>先用 1 nA 离子束电流稀释拉梅拉，然后用 300 pA 离子束电流将拉梅拉变薄，达到 1μm 厚度。</li>
	</ol></li>
	<li>将样品倾斜到 7°，在拉梅拉上执行 J 切口，以从基板中分离出来。</li>
	<li>将样品倾斜到 0° （即垂直于电子束柱），并使用 Pt （图 5A）将拉梅拉连接到操纵器针头上。</li>
	<li>附着在微操纵器上后，用最后的切口将拉梅拉与基板分离，并慢慢缩回微操纵器（图5B）。</li>
	<li>将光束聚焦在网格杆上偏置芯片的顶部边缘，即拉梅拉安装位置。</li>
	<li>用操纵器针（图6A）缓慢地将拉梅拉带到偏置芯片上。</li>
	<li>将偏置芯片顶部边缘 17 微米间隙中心的拉梅拉对齐。慢慢地向下移动，直到它几乎不接触芯片表面，并用Pt（图6B）焊接拉梅拉的底部边缘到芯片。</li>
	<li>用硅铣削将微操纵器从拉梅拉中分离出，并收回微操纵器。</li>
	<li>将拉梅拉的顶边缘与 Pt 痕迹连接到偏置芯片的两个电极进行连接 （图6C）。 注: 在这一点上， Te 和 Be 在左右两侧都做空了。</li>
	<li>首先使用 300 pA 稀释 lamella 的中心区域，然后使用 100 pA 离子束通过将标本正面和背面倾斜 2° 来使拉梅拉厚度小于 100 nm（图 6D），以确保平行面和均匀厚度。</li>
	<li>抛光离子束损坏层与 Ga 光束加速电压 5 kV 在 5° 的角度到表面的两面。</li>
	<li>删除设备顶部和底部电极之间的短连接，在稀薄区域进行隔离切割，通过活动区域（图 7A）创建从 BE 到 TE 的电流路径。</li>
	<li>将偏置芯片与拉梅拉安装在偏置芯片支架上，然后将偏置芯片支架加载到TEM腔室。</li>
	<li>将偏置芯片支架的电线连接到源计和控制 PC。 注意:在实验过程中，请小心地放置连接线以缓解应变并最大限度地减少任何振动。</li>
	<li>等待 TEM 腔室压力下降到 4e-5 Torr，然后对焦、散射，然后使用 TEM 控制旋钮对齐拉梅拉表面横截面上的电子束。</li>
	<li>在不同的偏置电压上应用电压扫描或恒定电压，并现场收集 TEM 显微图。 注:与衍射模式、电子衍射 X 射线光谱 （EDX） 和电子能量损失光谱 （EELS） 映射相关的数据也可以在不同的偏置电压现场收集。</li>
</ol>

<ol>
	<li>Kozma, R., Pino, R. E., Pazienza, G. E., Kozma, R., Pino, R. E., Pazienza, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Advances in Neuromorphic Memristor Science and Applications. , 9-14 (2012).</li><li>Pan, F., Gao, S., Chen, C., Song, C., Zeng, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+progress+in+resistive+random+access+memories:+Materials,+switching+mechanisms,+and+performance.">Recent progress in resistive random access memories: Materials, switching mechanisms, and performance.</a> Materials Science and Engineering: R: Reports. 83, 1-59 (2014).</li><li>Zhou, Y., Ramanathan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mott+Memory+and+Neuromorphic+Devices.">Mott Memory and Neuromorphic Devices.</a> Proceedings of the IEEE. 103 (8), 1289-1310 (2015).</li><li>Nirantar, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Situ+Nanostructural+Analysis+of+Volatile+Threshold+Switching+and+Non-Volatile+Bipolar+Resistive+Switching+in+Mixed-Phased+a-VOx+Asymmetric+Crossbars.">In Situ Nanostructural Analysis of Volatile Threshold Switching and Non-Volatile Bipolar Resistive Switching in Mixed-Phased a-VOx Asymmetric Crossbars.</a> Advanced Electronic Materials. 5 (12), 1900605 (2019).</li><li>Rupp, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Different+threshold+and+bipolar+resistive+switching+mechanisms+in+reactively+sputtered+amorphous+undoped+and+Cr-doped+vanadium+oxide+thin+films.">Different threshold and bipolar resistive switching mechanisms in reactively sputtered amorphous undoped and Cr-doped vanadium oxide thin films.</a> Journal of Applied Physics. 123 (4), 044502 (2018).</li><li>Ahmed, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inducing+tunable+switching+behavior+in+a+single+memristor.">Inducing tunable switching behavior in a single memristor.</a> Applied Materials Today. 11, 280-290 (2018).</li><li>Nili, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoscale+Resistive+Switching+in+Amorphous+Perovskite+Oxide+(a-SrTiO3)+Memristors.">Nanoscale Resistive Switching in Amorphous Perovskite Oxide (a-SrTiO3) Memristors.</a> Advanced Functional Materials. 24 (43), 6741-6750 (2014).</li><li>Ahmed, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transparent+amorphous+strontium+titanate+resistive+memories+with+transient+photo-response.">Transparent amorphous strontium titanate resistive memories with transient photo-response.</a> Nanoscale. 9 (38), 14690-14702 (2017).</li><li>Reuhman-Huisken, M. E., Vollenbroek, F. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+optimized+image+reversal+process+for+half-micron+lithography.">An optimized image reversal process for half-micron lithography.</a> Microelectronic Engineering. 11 (1), 575-580 (1990).</li><li>Taha, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulator-metal+transition+in+substrate-independent+VO2+thin+film+for+phase-change+devices.">Insulator-metal transition in substrate-independent VO2 thin film for phase-change devices.</a> Scientific Reports. 7 (1), 17899 (2017).</li><li>Booth, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlating+the+Energetics+and+Atomic+Motions+of+the+Metal-Insulator+Transition+of+M1+Vanadium+Dioxide.">Correlating the Energetics and Atomic Motions of the Metal-Insulator Transition of M1 Vanadium Dioxide.</a> Scientific Reports. 6, 26391 (2016).</li><li>Lee, S., Ivanov, I. N., Keum, J. K., Lee, H. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epitaxial+stabilization+and+phase+instability+of+VO2+polymorphs.">Epitaxial stabilization and phase instability of VO2 polymorphs.</a> Scientific Reports. 6, 19621 (2016).</li></ol>

作者没有什么可透露的。

本文解释了使用传输电子显微镜进行原位偏置的方案，包括设备的制造过程、偏置芯片安装的网格杆设计、偏置芯片上的拉梅拉制备和安装，以及具有原位偏置的TEM。
解释了交叉点设备的制造方法，这种方法可以很容易地扩展到横杆结构。氧化铝的 Ti 封盖对于加入非定形氧化铝至关重要，因为它在-VOx沉积后的制造步骤中溶解在水中。设备由两种不同尺?...

电阻变化氧化物记忆由于其兼容的切换速度、更小的细胞结构以及在大容量三维（3D）横杆阵列1中设计的能力，越来越多地被用作新内存和逻辑结构的构建块。迄今为止，已报告了电阻切换设备2、3的多种切换类型。金属氧化物的常见切换行为是单极、双极、互补电阻开关和挥发阈值切换。据报道，单细胞的复杂性增加了，显示多功能电阻开关性能以及4，5，6。
这种变异性意味着需要纳米结构研究来了解不同内存行为的起源和相应的切换机制，以开发明确定义的依赖条件的切换，以达到实际效用。常见的技术，以了解切换机制是深度剖析与X射线光电子光谱（XPS）7，8，纳米级二离子质谱（纳米-SIMS）6，非破坏性光发光光谱（PL）8，不同大小和厚度的电气特征的功能氧化物的设备， 纳米缩影7，传输电子显微镜（TEM），能量分散X射线光谱（EDX），和电子能量损失光谱（EELS）在TEM室6，8的横截面拉梅拉。上述所有技术都为转换机制提供了令人满意的见解。但是，在大多数技术中，需要多个样本进行分析，包括原始、电成型、设置和重置设备，以了解完整的切换行为。这增加了实验的复杂性，而且耗时。此外，故障率很高，因为在尺寸为几微米的设备中定位亚纳米级灯丝比较棘手。因此，就地实验在纳米结构特征中对于理解操作机制非常重要，因为它们在实时实验中提供了证据。
现为金属绝缘体金属 （MIM） 堆栈的不对称电阻开关交叉点设备提供现场 TEM 电气偏置的规程。此协议的主要目标是使用聚焦离子束 （FIB） 和 TEM 和电气偏置的原位实验设置为 lamella 制备提供详细的方法。这个过程是使用基于混合相非晶氧化物（a-VOx）4的不对称交叉点设备的代表性研究来解释的。此外，还介绍了结合-VOx的交叉点设备的制造过程，该装置可以使用标准的微纳米制造工艺轻松放大到横杆。这个制造过程是重要的，因为它纳入横杆-VOx溶解在水中。
该协议的优点是，只有一个拉梅拉，纳米结构的变化可以在TEM中观察到，不像其他技术，其中至少需要三个设备或跛脚。这大大简化了流程，降低了时间、成本和工作量，同时为实时操作中的纳米结构变化提供了可靠的视觉证据。此外，它采用标准的微纳米制造工艺、显微镜技术和仪器，以创新的方式建立其新颖性并解决研究空白。
在此处描述的针对-VOx的交叉点设备的代表性研究中，原位 TEM 协议有助于了解极点和挥发阈值切换4背后的切换机制。用于观察原位偏置期间-VOx中的纳米结构变化的过程和方法可以很容易地扩展到原位温度、原位温度和偏置同时，只需更换拉梅拉安装芯片，以及任何其他材料，包括金属绝缘体金属夹层结构中的两层或两层以上功能材料。它有助于揭示潜在的操作机制，并解释电气或热特性。

<table><tbody><tr><td>Resist processing system</td><td>EV group</td><td>EVG 101</td><td></td></tr><tr><td>Acetone</td><td>Chem-Supply</td><td>AA008</td><td></td></tr><tr><td>Biasing Chip - E-chip</td><td>Protochips</td><td>E-FEF01-A4</td><td></td></tr><tr><td>Developer</td><td>MMRC</td><td>AZ 400K</td><td></td></tr><tr><td>Electron beam evaporator - PVD 75</td><td>Kurt J Leskar</td><td>PRO Line - eKLipse</td><td></td></tr><tr><td>Focused Ion beam system</td><td>Thermo Fisher - FEI</td><td>Scios DualBeam&lt;sup&gt;TM&lt;/sup&gt; system</td><td></td></tr><tr><td>Hot plates</td><td>Brewer Science Inc.</td><td>1300X</td><td></td></tr><tr><td>Magnetron Sputterer</td><td>Kurt J Leskar</td><td>PRO Line</td><td></td></tr><tr><td>Mask aligner</td><td>Karl Suss</td><td>MA6</td><td></td></tr><tr><td>Maskless Aligner</td><td>Heildberg instruments</td><td>MLA150</td><td></td></tr><tr><td>Methanol</td><td>Fisher scientific</td><td>M/4056</td><td></td></tr><tr><td>Phototresist</td><td>MMRC</td><td>AZ 5412E</td><td></td></tr><tr><td>Pt source for e-beam evaporator</td><td>Unicore</td><td></td><td></td></tr><tr><td>The Fusion E-chip holder</td><td>Protochips</td><td>Fusion 350</td><td></td></tr><tr><td>Ti source for e-beam evaporator</td><td>Unicore</td><td></td><td></td></tr><tr><td>Transmission Electron Microscope</td><td>JEOL</td><td>JEM 2100F</td><td></td></tr></tbody></table>

in situ transmission electron microscopy with biasing and fabrication of asymmetric crossbars based on mixed-phased a-vox

由于低成本和高密度的益处，在数字存储记忆领域，电阻式切换横杆架构非常受欢迎。由于所用材料的内在性质，不同材料显示出电阻开关特性的变异性，由于潜在的操作机制，导致该领域的差异。这突出了使用纳米结构观测来理解机制的可靠技术的必要性。该协议解释了使用传输电子显微镜 （TEM） 进行电气偏差的原位纳米结构分析的详细过程和方法。它提供了实时内存操作中潜在的纳米结构变化的视觉和可靠证据。还包括非对称横杆结构的制造方法和电气特征，其中含有非定形氧化铝。此处解释的氧化铝薄膜协议可以轻松地扩展到金属介质金属夹层结构中的任何其他材料。根据对操作机制的理解，电阻开关横杆预计将为下一代存储器设备提供可编程逻辑和神经形态电路。此协议以可靠、及时和经济高效的方式揭示了任何类型的电阻开关材料中的切换机制，从而预测了设备的适用性。

使用此协议为a-VOx交叉点设备取得的结果在图8中解释。图8A显示了完整拉梅拉的TEM显微图。在这里，衍射模式（插入）表示氧化物薄膜的无定形性质。对于原位 TEM 测量，控制电压从 25 mV 到 8 V 在 20 mV 步骤中应用，底部电极 （BE） 为正偏置，顶部电极 （TE） 接地。图8B显示，在4 V时，氧化物层中形成了局部?...

Watch this Scientific Journal Video about In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx at JoVE.com

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

这里介绍了一个协议，用于分析纳米结构的变化，在原位偏置与传输电子显微镜 （TEM） 堆叠金属绝缘体金属结构。它在下一代可编程逻辑电路和神经微敏硬件的电阻开关横杆中具有显著应用，可揭示其基本操作机制和实际适用性。

基于混合相位a-VOx的不对称横杆的偏置和制造现场传输电子显微镜

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different ...

in-situ-transmission-electron-microscopy-with-biasing-fabrication

Research

JoVE Journal

Engineering

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

4.0K 次观看.  RMIT University. 这里介绍了一个协议，用于分析纳米结构的变化，在原位偏置与传输电子显微镜 （TEM） 堆叠金属绝缘体金属结构。它在下一代可编程逻辑电路和神经微敏硬件的电阻开关横杆中具有显著应用，可揭示其基本操作机制和实际适用性。

视频: In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement.

The robust device design of fringing-field electrostatic MEMS actuators results in inherently low squeeze-film damping conditions and long settling times when performing switching operations using conventional step biasing. Real-time switching time improvement with DC-dynamic waveforms reduces the settling time of fringing-field MEMS actuators when transitioning between up-to-down and down-to-up states.

实时直流偏置的动态法切换时间改善严重欠阻尼边缘化场静电MEMS致动器

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input ...

科研

工程学

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

电子通道造影的快速III-V异质特征

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

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 ...

Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due to their long coherence time and their capability to manipulate and detect individual quantum bits (qubits). In more recent years, microfabricated surface ion traps have received more attention for large-scale integrated qubit platforms. This paper presents a microfabrication methodology for ion traps using micro-electro-mechanical system (MEMS) technology, including the fabrication method for a 14 &#181;m-thick dielectric layer and metal overhang structures atop the dielectric layer. In addition, an experimental procedure for trapping ytterbium (Yb) ions of isotope 174 (174Yb+) using 369.5 nm, 399 nm, and 935 nm diode lasers is described. These methodologies and procedures involve many scientific and engineering disciplines, and this paper first presents the detailed experimental procedures. The methods discussed in this paper can easily be extended to the trapping of Yb ions of isotope 171 (171Yb+) and to the manipulation of qubits.

This paper presents a microfabrication methodology for surface ion traps, as well as a detailed experimental procedure for trapping ytterbium ions in a room-temperature environment.

利用 Microfabricated 表面离子阱捕获离子的实验方法

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due ...

Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal structure and probing the hydrogen-bond (H-bond) dynamics of the water molecules adsorbed on solid surfaces are fundamental issues of water science, which remains a great challenge owing to the light mass and small size of hydrogen. Scanning tunneling microscopy (STM) is a promising tool for attacking these problems, thanks to its capabilities of sub-&#197;ngstr&#246;m spatial resolution, single-bond vibrational sensitivity, and atomic/molecular manipulation. The designed experimental system consists of a Cl-terminated tip and a sample fabricated by dosing water molecules in situ onto the Au(111)-supported NaCl(001) surfaces. The insulating NaCl films electronically decouple the water from the metal substrates, so the intrinsic frontier orbitals of water molecules are preserved. The Cl-tip facilitates the manipulation of the single water molecules, as well as gating the orbitals of water to the proximity of Fermi level (EF) via tip-water coupling. This paper outlines the detailed methods of submolecular resolution imaging, molecular/atomic manipulation, and single-bond vibrational spectroscopy of interfacial water. These studies open up a new route for investigating the H-bonded systems at the atomic scale.

Here, we present a protocol to investigate the structure and dynamics of interfacial water at the atomic scale, in terms of submolecular resolution imaging, molecular manipulation, and single-bond vibrational spectroscopy.

用扫描隧穿显微镜和光谱法探讨界面水的结构和动力学

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal ...

化学

Sample Preparation and Experimental Design for In Situ Multi-Beam Transmission Electron Microscopy Irradiation Experiments

There is a need to understand materials exposed to overlapping extreme environments such as high temperature, radiation, or mechanical stress. When these stressors are combined there may be synergistic effects that enable unique microstructural evolution mechanisms to activate. Understanding of these mechanisms is necessary for the input and refinement of predictive models and critical for engineering of next generation materials. The basic physics and underlying mechanisms require advanced tools to be investigated. The in situ ion irradiation transmission electron microscope (I&#179;TEM) is designed to explore these principles.
To quantitatively probe the complex dynamic interactions in materials, careful preparation of samples and consideration of experimental design is required. Particular handling or preparation of samples can easily introduce damage or features that obfuscate the measurements. There is no one correct way to prepare a sample; however, many mistakes can be made. The most common errors and things to consider are highlighted within. The I&#179;TEM has many adjustable variables and a large potential experimental space, therefore it is best to design experiments with a specific scientific question or questions in mind.
Experiments have been performed on large number of sample geometries, material classes, and with many irradiation conditions. The following are a subset of examples that demonstrate unique in situ capabilities utilizing the I3TEM. Au nanoparticles prepared by drop casting have been used to investigate the effects of single ion strikes. Au thin films have been used in studies on the effects of multibeam irradiation on microstructure evolution. Zr films have been exposed to irradiation and mechanical tension to examine creep. Ag nanopillars were subjected to simultaneous high temperature, mechanical compression, and ion irradiation to study irradiation induced creep as well. These results impact fields including: structural materials, nuclear energy, energy storage, catalysis, and microelectronics in space environments.

Sample preparation techniques are outlined with specific considerations for in situ ion irradiation TEM experiments. Ion species, energy, and fluence are discussed with methods for how to select and compute them. Finally, procedures for conducting an experiment are described and accompanied by the representative results.

There is a need to understand materials exposed to overlapping extreme environments such as high temperature, radiation, or mechanical stress. When these ...

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by overlapping two parts of an electron wave, one of which has passed through a region of interest on a specimen and the other is a reference wave. The resulting off-axis electron hologram can be analyzed digitally to recover the phase difference between the two parts of the electron wave, which can then be interpreted to provide quantitative information about local variations in electrostatic potential and magnetic induction within and around the specimen. Off-axis electron holograms can be recorded while a specimen is subjected to external stimuli such as elevated or reduced temperature, voltage, or light. The protocol that is presented here describes the practical steps that are required to record, analyze, and interpret off-axis electron holograms, with a primary focus on the measurement of magnetic fields within and around nanoscale materials and devices. Presented here are the steps involved in the recording, analysis, and processing of off-axis electron holograms, as well as the reconstruction and interpretation of phase images and visualization of the results. Also discussed are the need for optimization of the specimen geometry, the electron optical configuration of the microscope, and the electron hologram acquisition parameters, as well as the need for the use of information from multiple holograms to extract the desired magnetic contributions from the recorded signal. The steps are illustrated through a study of specimens of B20-type FeGe, which contain magnetic skyrmions and were prepared with focused ion beams (FIBs). Prospects for the future development of the technique are discussed.

Guidelines are presented for recording and interpreting off-axis electron holograms to provide quantitative images of magnetic fields in nanoscale materials and devices in the transmission electron microscope.

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by ...

Micropatterning Transmission Electron Microscopy Grids to Direct Cell Positioning within Whole-Cell Cryo-Electron Tomography Workflows

Whole-cell cryo-electron tomography (cryo-ET) is a powerful technology that is used to produce nanometer-level resolution structures of macromolecules present in the cellular context and preserved in a near-native frozen-hydrated state. However, there are challenges associated with culturing and/or adhering cells onto TEM grids in a manner that is suitable for tomography while retaining the cells in their physiological state. Here, a detailed step-by-step protocol is presented on the use of micropatterning to direct and promote eukaryotic cell growth on TEM grids. During micropatterning, cell growth is directed by depositing extra-cellular matrix (ECM) proteins within specified patterns and positions on the foil of the TEM grid while the other areas remain coated with an anti-fouling layer. Flexibility in the choice of surface coating and pattern design makes micropatterning broadly applicable for a wide range of cell types. Micropatterning is useful for studies of structures within individual cells as well as more complex experimental systems such as host-pathogen interactions or differentiated multi-cellular communities. Micropatterning may also be integrated into many downstream whole-cell cryo-ET workflows, including correlative light and electron microscopy (cryo-CLEM) and focused-ion beam milling (cryo-FIB).

The goal of this protocol is to direct cell adhesion and growth to targeted areas of grids for cryo-electron microscopy. This is achieved by applying an anti-fouling layer that is ablated in user-specified patterns followed by deposition of extra-cellular matrix proteins in the patterned areas prior to cell seeding.

微图案透射电子显微镜网格，用于在全细胞冷冻电子断层扫描工作流程中指导细胞定位

Whole-cell cryo-electron tomography (cryo-ET) is a powerful technology that is used to produce nanometer-level resolution structures of macromolecules ...

生物化学

Light-Induced In Situ Transmission Electron Microscopy for Observation of the Liquid-Soft Matter Interaction

The current protocol describes the modifications of the transmission electron microscope (TEM) setup for in situ light-induced observations. A glass optical fiber inserted into the electron column above the objective lens polepiece, and a laser, an adjustable light source, was used to fabricate the device. After the illuminator has been calibrated using an external measuring system, it allows one to adjust the intensity of the lighting to the needs of the observed process. This lighting system was utilized to image antimicrobial photodynamic therapy phenomena, which are currently the subject of intense research. The sample was prepared by spotting a suspension of bacteria on a carbon, graphene, or silicon nitride substrate, blotting the excess solution, spotting the photosensitizer solution, blotting the excess liquid again, and then assembling the liquid cell with a second substrate or graphene film. The process of the imaging experiment itself includes choosing the right place for observation with the use of low magnification and a minimum dose of electrons, and then cyclical activation of the light source to capture subsequent images at specified intervals with the minimum amount of electrons necessary. The electron dose of each exposure and the time and intensity of lighting used need to be carefully recorded due to the complexity of the observed phenomena as, at the same time, the process is both light- and electron-driven. After the actual experiment is performed, additional control observations must be made, in which the same doses of electrons are used but without additional light influence and smaller doses of electrons are used for higher doses of light. This makes it possible to distinguish light-induced microstructural effects from those caused by electrons in both the fields of life and materials science.

Light-Induced In Situ Transmission Electron Microscopy for Observation of the Liquid-Soft Matter Interaction

The present protocol describes transmission electron microscope (TEM) modifications with a light illumination system, the fabrication of liquid cells, and in situ TEM observations of light-induced interactions between bacterial cells and a photosensitizer. The sample preparation methods, electron beam damage, and imaging are also discussed.

光诱导 原 位透射电子显微镜观察液-软物质相互作用

The current protocol describes the modifications of the transmission electron microscope (TEM) setup for in situ light-induced observations. A glass ...

Preparation and Observation of Thick Biological Samples by Scanning Transmission Electron Tomography

This report describes a protocol for preparing thick biological specimens for further observation using a scanning transmission electron microscope. It also describes an imaging method for studying the 3D structure of thick biological specimens by scanning transmission electron tomography. The sample preparation protocol is based on conventional methods in which the sample is fixed using chemical agents, treated with a heavy atom salt contrasting agent, dehydrated in a series of ethanol baths, and embedded in resin. The specific imaging conditions for observing thick samples by scanning transmission electron microscopy are then described. Sections of the sample are observed using a through-focus method involving the collection of several images at various focal planes. This enables the recovery of in-focus information at various heights throughout the sample. This particular collection pattern is performed at each tilt angle during tomography data collection. A single image is then generated, merging the in-focus information from all the different focal planes. A classic tilt-series dataset is then generated. The advantage of the method is that the tilt-series alignment and reconstruction can be performed using standard tools. The collection of through-focal images allows the reconstruction of a 3D volume that contains all of the structural details of the sample in focus.

This report describes a sample preparation protocol and specific imaging conditions for performing scanning transmission electron tomography of thick biological specimens.

准备厚生物样品的观察扫描透射电子断层扫描

This report describes a protocol for preparing thick biological specimens for further observation using a scanning transmission electron microscope. It ...

基于混合相位a-VO_x的不对称横杆的偏置和制造现场传输电子显微镜

摘要

探索更多视频

此视频中的章节

实时直流偏置的动态法切换时间改善严重欠阻尼边缘化场静电MEMS致动器

电子通道造影的快速III-V异质特征

一种新的方法

利用 Microfabricated 表面离子阱捕获离子的实验方法

用扫描隧穿显微镜和光谱法探讨界面水的结构和动力学

Sample Preparation and Experimental Design for In Situ Multi-Beam Transmission Electron Microscopy Irradiation Experiments

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

微图案透射电子显微镜网格，用于在全细胞冷冻电子断层扫描工作流程中指导细胞定位

光诱导原位透射电子显微镜观察液-软物质相互作用

准备厚生物样品的观察扫描透射电子断层扫描

基于混合相位a-VOx的不对称横杆的偏置和制造现场传输电子显微镜

摘要

探索更多视频

此视频中的章节

实时直流偏置的动态法切换时间改善严重欠阻尼边缘化场静电MEMS致动器

电子通道造影的快速III-V异质特征

一种新的方法

利用 Microfabricated 表面离子阱捕获离子的实验方法

用扫描隧穿显微镜和光谱法探讨界面水的结构和动力学

Sample Preparation and Experimental Design for In Situ Multi-Beam Transmission Electron Microscopy Irradiation Experiments

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

微图案透射电子显微镜网格，用于在全细胞冷冻电子断层扫描工作流程中指导细胞定位

光诱导 原 位透射电子显微镜观察液-软物质相互作用

准备厚生物样品的观察扫描透射电子断层扫描

基于混合相位a-VO_x的不对称横杆的偏置和制造现场传输电子显微镜

光诱导原位透射电子显微镜观察液-软物质相互作用