This work was supported by the Department of Energy under the FPACE program (DE-EE0005398), the Ohio State University Institute for Materials Research, and the Ohio Office of Technology Investments&#8217; Third Frontier Program.

该协议是写的，读者将有标准SEM操作的工作理解的假设。根据制造商，型号，甚至软件版本，每SEM可以有显著不同的硬件和/或软件接口。同样可以相对于所述仪器的内部结构进行说;以下时这个协议中，因为即使在样本大小/几何形状，样品的取向（倾斜，旋转）相对小的变化，和工作距离，可呈现一个风险用于与磁极片的接触操作者必须谨慎和观察，特别是如果不eucentric高度。这里提供的说明是用来执行这项工作的仪器，一个FEI西连SEM配备了场发射枪和标准，极片装，环形硅背反射传感器。因此，当务之急是读者理解如何在他们自己的特定设备执行等效的操作。 </P&gt; 1.样品制备<ol><li>裂开样品的GaP /硅为这项研究中，将根据不同的扫描电镜样品的尺寸的合适尺寸装载要被使用。注：样品可以是小到5毫米×5mm或大到一个完整的晶片（4英寸长），这取决于所使用的扫描电镜和可用室space.The样品表面的内部几何形状应该是非常干净和无污染，可以扰乱窜（ 如结晶或无定形天然氧化物）。 </li><li>将样品放置到样本SEM坐骑。注意：所述的安装方法可以根据所用扫描电镜存根的种类变化，通常是一个夹子样式或经由一些粘合剂（ 例如 ，碳胶带，银粉漆）。放置的方法中，必须保证样品不会移动，并且它被接地，以防止样品的充电。 </li></ol> 2.装入样品<ol><li>通过单击的“放空”按钮发泄SEM软件接口和插入达到大气压后的样品。 </li><li>在结束前的SEM门，确保样品是在一个适当的高度，以便在没有搬入SEM撞击探测器疯牛病。 </li><li>抽空的SEM通过点击软件界面中的“泵”按钮。等到系统表示该压力足够低来启动测量。 </li></ol> 3.设置适当的工作条件<ol><li>在打开的“梁”控制区通过控制按钮的电子束，并通过在软件界面中的“梁”下拉菜单中设置加速电压。对于这里提出的工作，25千伏，使用。 </li><li>将束流通过“梁”下拉菜单中选择适当的值。这是这里所使用的光点尺寸设定，将其设置为5（大约2.4 nA的）方式的系统内的确定。注：高束电流通常需要because共产国际执行委员会信号一般较弱，较大的电流可以更形象区分。 </li><li>使用二次电子探测器，通过调节软件界面图像焦点和stigmation。注：这是通过右键单击并拖动鼠标在软件界面上这里执行;垂直的焦点，对于水平stigmation。此外，它通常是有帮助找到的小颗粒或表面特征上的样品，以提供用于聚焦/ stigmation调整一个明确的主题。 </li><li>由增量式改变所述阶段的Z位置，并根据需要调整聚焦和stigmation移动样品到垂直的工作距离。 Z位置是通过“Z”下拉菜单中的软件界面的&#39;舞台&#39;控制区改变。对于此处所描述的工作，为5毫米的工作距离放置在同一处eucentric高度和提供一个强有力ECCI信号。 </li></ol> 4.可视化样品ECP &lt;OL&gt; <li>切换到疯牛病模式通过在软件界面中的“检测器”下拉菜单中。 </li><li>放大倍数下降到最低设置（27X），它是通过计算机键盘减号在这里完成的（ - ）键，以可视化的ECP。 </li><li>调整扫描速率，这里通过“扫描”下拉菜单中执行，以提供具有足够的信号-噪声（ 例如 ，慢扫描而非广播模式）的图像。注：平均或积分图像可能是必要的，以获得一个更清晰，更可辨别图像。 </li><li>调整图像对比度和亮度，在这里通过“对比度”和“亮度”滑块来完成，以帮助提升ECP的知名度，注意不要过饱和。 </li><li>调整样品旋转和倾斜，使用&#39;R&#39;和&#39;舞台&#39;控制区在软件界面“T”的条目，以帮助使窜图案的特征更加明显。样品rotat离子将导致在ECP的旋转（ 见图2）和倾斜，将导致在ECP的平移（如图3）。 </li></ol> 5.图像缺陷/功能<ol><li>调整样品倾斜和旋转，如在步骤4.5中所述，以设置所需衍射条件。通过翻译和/或旋转ECP对准目标菊池带边缘做到这一点（ 即亮菊池带及其相关的暗菊池线之间拐点）与SEM光轴。而最大窜实际上发生在菊池线，在此处描述的方法对准提供了与黑暗和明亮的对比度等级的缺陷显示对比度的（ 见图4和5）。 </li><li>一旦所需衍射条件实现时，增加放大倍率，这里通过键盘加（+）键完成。 </li><li>重新聚焦图像并调整为stigmation，如在步骤3.2中描述。注：在这里，FO的CuS和stigmation最好相对于特定的缺陷/特征被成像调整。 </li><li>因为从带的边缘的小偏差可以使在目标缺陷或特征的外观差异大，通过使小（不大于调整到样品倾斜正交于感兴趣的菊池带/线更优化衍射条件，而看为最大对比度特定功能。注意，移向菊池带的内侧将通常降低的“亮”特征的相对对比度，而移向带的外侧（朝向菊池线）通常会降低相对对比度对“黑暗”的特点。 </li><li>一旦获得所需的对比度，减少的倍率，以验证该同一频带仍是上或非常靠近光轴;过多的倾斜可以完全改变衍射条件。 </li></ol>

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The authors have nothing to disclose.

25千伏的加速电压被用于这一研究。加速电压将决定电子束的穿透深度;用更高的加速电压，会有BSE信号从样品中更深处的到来。高的加速电压被选择为这个系统，因为它允许位错是远离所述样品的表面上，埋在界面的可视性。其他类型的缺陷/功能可能或多或少可见取决于样品的种类不同加速电压。 如先前所讨论的，不可见性标准将确定哪些特征具有在使用中的特定衍射条件...

晶体缺陷和微观结构的详细特征是半导体材料和因为这样的缺陷装置研究的一个非常重要的方面，可能对设备性能有显著，不利影响。目前，透射电子显微镜（TEM）是最广泛接受和用于扩展缺陷的详细表征技术 - 位错，堆垛层错，孪晶，反相畴等 - 因为它使各种各样的充足的缺陷的直接成像空间分辨率。不幸的是，TEM是根本低通量的方法，由于长时间的样品制备时间，这可能会导致在研究和开发周期显著延迟和瓶颈。此外，样品的完整性，例如在作为生长应变状态而言，可样品制备过程中改变，留下的机会掺假的结果。 电子通道合作ntrast成像（ECCI）是互补的，并且在一些情况下，潜在的优越，技术TEM，因为它提供用于成像相同的扩展缺陷的替代方案中，高通量的方法。在外延材料的情况下，样品需要很少或几乎没有准备，使得ECCI更多的时间效率。此外有利的是，ECCI只需要一个场致发射扫描电子显微镜（SEM）配备有一个标准的环形磁极片安装背散射电子（BSE）检测器的事实; forescatter几何也可以使用，但需要稍微更专门的设备和这里不讨论。共产国际执行委员会的信号是由已非弹性散射出在持续渠梁（电子波前），并通过多种额外的非弹性散射，能够逃脱样本背面通过表面1类似的两到电子束TEM，也能够通过奥里SEM中执行ECCI在特定衍射条件nting样品，使入射电子束满足晶体布拉格条件（ 即窜），如使用低倍率的电子通道模式（执委会）确定; 1,2参见图1中的例子。简单地说，紧急避孕药提供入射电子束衍射/窜的定向空间表示。低反向散射信号造成3黑线表示布拉格条件得到满足（ 即 ，菊池线）束样本方向，这将产生强烈的窜，而明亮区域表示高后向散射，非衍射条件。相对于菊池图案通过电子背散射衍射（EBSD）或TEM产生，这是通过传出电子衍射形成，左炔诺孕酮丸则入射电子衍射/窜的结果。 在实践中，受控衍射条件ECCI通过调节样品方位实现，VIA倾斜和/或旋转下低倍率，使得代表所关心的良好定义的布拉格条件的ECP特征 - 例如，一个[400]或[220]菊池带/线 - 是一致的扫描电镜的光轴。过渡由于角度范围入射电子束的所得限制到高倍率的话，有效地选择用于理想地只对应于从选择的衍射条件散射BSE信号。以这种方式，可以观察到的缺陷提供衍射对比度，例如位错。正如在TEM中，通过这样的缺陷提出的成像对比度由标准隐形标准确定， 克·（二X U）= 0和g·B = 0，其中g表示衍射载体; b伯格斯矢量， 和 u线的方向。4本因为从飞机的缺陷扭曲将包含有关信息，仅电子衍射所说的故障发生的现象。 迄今为止，ECCI已主要被用于图像特征和缺陷处或附近进行，例如功能性材料如锑化镓，5的SrTiO 3，5的GaN，6-9以及SiC样品表面10,11这种限制的表面的结果100纳米 - 共产国际执行委员会信号本身，其中构成该信号的BSE来自约10的深度范围的敏感的性质。此深度分辨极限最显著贡献是扩大和阻尼的在正在进行电子波前（引导电子），作为深度的函数进入晶体，由于电子的损失，以散射事件，从而降低了最大潜在BSE信号。1尽管如此，一些程度的深度分辨率的已报道在以前的工作在Si 1-X锗的x / Si和的In x Ga的1-x As中 /砷化镓异质结构，12,13以及更近期（以及本文）14，其中ECCI用于埋葬在在晶格失配的异质界面图像失配位错上的GaP / Si的异质结构中，作者深达100纳米（深度较高可能性可能）。 这里详述的工作，ECCI用于研究的GaP外延生长在Si（001），一个复杂的材料集成系统与应用朝向等领域光伏和光电。的GaP / Si是特别令人感兴趣的为变质的整合的潜在途径（晶格失配）的III-V族半导体上成本效益的Si衬底。多年来，在这个方向上的努力一直困扰着失控产生大量的heterovalent核有关的缺陷，包括反相畴，堆垛层错和微孪晶。这种缺陷不利于器件性能，ESPEcially光伏，由于这样的事实，它们可以是电活性，作为载流子复合中心，并且也可阻碍界面位错滑移，从而导致更高的位错密度。15然而，由作者最近的努力和其他人已经导致开发成功能产生间隙对硅薄膜不含这些核有关的缺陷的外延工艺，从而16-19铺平了道路继续前进。 因为的GaP和Si（在RT 0.37％）之间的小的，但不可忽略的，晶格错配的尽管如此，失配位错的产生是不可避免的，并且确实是必要的​​，以产生完全松弛外延层。 GAP，其FCC为基础的闪锌矿结构，往往会产生60°位错型（混合边缘和螺钉）滑移系统，这是glissile，可以通过长网滑行长度释放大量的应变上。额外的复杂性也通过在失配引入的的GaP和Si的热膨胀系数，这导致增加的晶格失配随温度升高（ 即 ，≥0.5％的失配，在典型的生长温度）。20由于穿透位错的段组成的失配位错环的剩余部分（连同界面失配和晶体表面）是众所周知的与其相关的非辐射载流子复合性能，因此降低设备的性能，21它充分理解其性质和演变，使得它们的数量可以最小化是很重要的。界面失配位错的详细的表征可因此提供的关于系统的位错动力学的大量信息。 这里，我们描述的协议利用SEM进行ECCI并提供它的功能和优势的例子。这里有一个重要的区别是使用共产国际执行委员会执行微观characteri排序的矩阵特殊积通常通过TEM进行的，而ECCI提供的等效的数据，但在一个显著较短的时间帧由于显著降低样品制备的需要;在对具有相对光滑表面的外延样品的情况下，没有有效的在所有需要的样品制备。为缺陷和失配位错一般表征使用ECCI的描述，与设置观察结晶缺陷的一些例子。的隐形标准上的界面失配位错的阵列的观察成像对比度的影响，然后说明。这之后是ECCI如何能够被用于执行表征的重要模式示范 - 在这种情况下，研究，以确定的GaP硅上的临界厚度为位错成核 - 提供的TEM状数据，但是从一个方便SEM和显著降低的时间框架。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Sirion Field Emission SEM</td>
			<td>FEI/Phillips</td>
			<td>516113</td>
			<td>Field emission SEM with beam voltage range of 200 V - 30 kV, equipped with a backscattered electron detector</td>
		</tr>
		<tr>
			<td>Sample of Interest</td>
			<td>Internally produced</td>
			<td>N/A</td>
			<td>Synthesized/grown in-house via MOCVD</td>
		</tr>
		<tr>
			<td>PELCO SEMClip</td>
			<td>Ted Pella, Inc.</td>
			<td>16119-10</td>
			<td>Reusable, non-adhesive SEM sample stub (adhesive attachment will also work)</td>
		</tr>
	</tbody>
</table>

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.

间隙/硅样品本研究中通过金属有机化学气相沉积（MOCVD）在Aixtron的3×2紧密耦合喷头反应器以下作者的以前报道的异质外延工艺生长。17全部生长被4英寸硅（执行001）衬底为6°取向差故意（边角料）推向[110]。共产国际执行委员会的所有影像进行作为生长样品没有进一步的样品制备任何（除裂解产生约为1厘米×1厘米件加载到SEM）。 不同衍射条件下捕获的的GaP / Si的样?...

Watch this Scientific Journal Video about Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization at JoVE.com

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

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 ...

electron-channeling-contrast-imaging-for-rapid-iii-v-heteroepitaxial

Research

JoVE Journal

Engineering

10.9K 次观看.  The Ohio State University. 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.

视频: Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Spatial Separation of Molecular Conformers and Clusters

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.

We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.

分子构象器和星团的空间分离

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold ...

科研

工程学

Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by quantum mechanical effects such as tunneling through single dopants, scattering via interface defects, and discrete trap charge states. However, progress in silicon technology has shown that these phenomena can be harnessed and exploited for a new class of quantum-based electronics. Among others, multi-layer-gated silicon metal-oxide-semiconductor (MOS) technology can be used to control single charge or spin confined in electrostatically-defined quantum dots (QD). These QD-based devices are an excellent platform for quantum computing applications and, recently, it has been demonstrated that they can also be used as single-electron pumps, which are accurate sources of quantized current for metrological purposes. Here, we discuss in detail the fabrication protocol for silicon MOS QDs which is relevant to both quantum computing and quantum metrology applications. Moreover, we describe characterization methods to test the integrity of the devices after fabrication. Finally, we give a brief description of the measurement set-up used for charge pumping experiments and show representative results of electric current quantization.

The fabrication process and experimental characterization techniques relevant to single-electron pumps based on silicon metal-oxide-semiconductor quantum dots are discussed.

硅金属 - 氧化物 - 半导体量子点单电子泵

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by ...

Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve the solar conversion efficiency of a concentrated photovoltaic system. The proposed system will also lower the solar cell cost in the concentrated photovoltaic system by replacing the expensive tandem solar cells with the cost-effective single junction solar cells. The structures and the parameters of high contrast gratings for the dispersive elements were numerically optimized. The large-area fabrication of high contrast gratings was experimentally demonstrated using nanoimprint lithography and dry etching. The quality of grating material and the performance of the fabricated device were both experimentally characterized. By analyzing the measurement results, the possible side effects from the fabrication processes are discussed and several methods that have the potential to improve the fabrication processes are proposed, which can help to increase the optical efficiency of the fabricated devices.

The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance.

制造高对比度光栅的频谱分割色散元件的聚光光伏系统

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve ...

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

一个多腔动态单一酶幻影超极化磁共振剂研究的用途

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

The optical, electrical, and structural properties of dislocations and of grain boundaries in semiconductor materials can be determined by experiments performed in a scanning electron microscope. Electron microscopy has been used to investigate cathodoluminescence, electron beam induced current, and diffraction of backscattered electrons.

通过扫描电子显微镜在半导体材料的扩展缺陷的全面表征

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications ...

Characterization of Anisotropic Leaky Mode Modulators for Holovideo

Holovideo displays are based on light-bending spatial light modulators. One such spatial light modulator is the anisotropic leaky mode modulator. This modulator is particularly well suited for holographic video experimentation as it is relatively simple and inexpensive to fabricate1-3. Some additional advantages of leaky mode devices include: large aggregate bandwidth, polarization separation of signal light from noise, large angular deflection and frequency control of color1. In order to realize these advantages, it is necessary to be able to adequately characterize these devices as their operation is strongly dependent on waveguide and transducer parameters4. To characterize the modulators, the authors use a commercial prism coupler as well as a custom characterization apparatus to identify guided modes, calculate waveguide thickness and finally to map the device's frequency input and angular output of leaky mode modulators. This work gives a detailed description of the measurement and characterization of leaky mode modulators suitable for full-color holographic video.

This work describes fabrication and characterization of anisotropic leaky mode modulators for holographic video.

各向异性泄漏模式调制器用于Holovideo的表征

Holovideo displays are based on light-bending spatial light modulators.  One such spatial light modulator is the anisotropic leaky mode modulator.  This ...

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications.

A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

电化学腐蚀和电子碰撞电离夏普场发射点的表征

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by employing an aberration-corrected scanning transmission electron microscope as the exposure tool. Here, we present results of single-digit nanometer patterning of two widely used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. The method achieves sub-5 nanometer features in poly (methyl methacrylate) and sub-10 nanometer resolution in hydrogen silsesquioxane. High-fidelity transfer of these patterns into target materials of choice can be performed using metal lift-off, plasma etch, and resist infiltration with organometallics.

We use an aberration-corrected scanning transmission electron microscope to define single-digit nanometer patterns in two widely-used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. Resist patterns can be replicated in target materials of choice with single-digit nanometer fidelity using liftoff, plasma etching, and resist infiltration by organometallics.

用畸变校正扫描透射电镜进行单数字纳米电子束光刻

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by ...

A Rapid Method for Modeling a Variable Cycle Engine

The variable cycle engines (VCE) that combine the advantages of turbofan and turbojet engines, are widely considered to be the next generation aircraft engines. However, developing VCE requires high costs. Thus, it is essential to build a mathematical model when developing an aircraft engine, which may avoid a large number of real tests and reduce the cost dramatically. Modeling is also crucial in control law development. In this article, based on a graphical simulation environment, a rapid method for modeling a double bypass variable cycle engine using object-oriented modeling technology and modular hierarchical architecture is described. Firstly, the mathematical model of each component is built based on the thermodynamic calculation. Then, a hierarchical engine model is built via the combination of each component mathematical model and the N-R solver module. Finally, the static and dynamic simulations are carried out in the model and the simulation results prove the effectiveness of the modeling method. The VCE model built through this method has the advantages of clear structure and real-time observation.

Here, we present a protocol to build a component-level mathematical model for a variable cycle engine.

可变循环引擎建模的快速方法

The variable cycle engines (VCE) that combine the advantages of turbofan and turbojet engines, are widely considered to be the next generation aircraft ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

纤维素纸非接触式共振腔电谱研究的方法研究

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...