Name: ohmic contact fabrication using a focused-ion beam technique and electrical characterization for layer semiconductor nanostructures
Uploaded: 2015-12-05T14:00:00.000+00:00
Duration: 8 min 12 s
Description: Watch this Scientific Journal Video about Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures at JoVE.com

RSC thanks the support of the National Science Council (NSC) of Taiwan under Project NSC 102-2112-M-011-001-MY3. YSH acknowledges the support of the NSC of Taiwan under Project NSC 100-2112-M-011-001-MY3.

莫塞的2层晶体（见第1步中的图1）1.结构表征<ol><li> X射线衍射测量程序<ol><li>装入摩西2层晶体（具有5×5×0.1-10×10×0.5毫米3大小范围）或晶体粉末在支架上（该混合有石英粉末和粘合剂，并涂抹在载玻片）。 </li><li>按保持器由一个载玻片以确保层晶面平行于托面。 </li><li>样品架装载到衍射仪。 </li><li>关闭衍射仪的门。 </li><li>因此校准光束线制造商的说明。 </li><li>输入测量参数，如2扫描范围（10-80°），增量（0.004°），和停留时间（0.1秒）。 </li><li>启动DIFFRAC.Measurement Center程序附加到衍射仪在计算机上，然后根据制造商的原保存数据和名称数据文件山坳。 </li><li>通过识别的衍射峰的位置使用的软件分析的X射线衍射图案，然后与来自JCPDS卡片数据库中的标准数据进行比较，以确认摩西2层的晶体32,33的单外的面取向和单晶质量。 </li></ol></li><li>显微拉曼测量程序<ol><li>执行使用硅晶片作为标准样品的拉曼设备校准。硅晶片的测量是相同的，如下所述的感兴趣的摩西2层的晶体的步骤。 </li><li>安装在载玻片上一个摩西2层结晶。 </li><li>加载光学显微镜的保持器在载玻片上，并用白色光源聚焦在样品表面。 </li><li>切换从白色光的光源的激光束（波长在514纳米）。 </li><li>输入测量参数，例如波数扫描范围（150-500厘米-1）时，INTEGR通货膨胀时间（10秒），和扫描的次数（10-30倍）。 </li><li>启动程序在计算机上安装于拉曼光谱仪，然后保存数据，并根据制造商的协议名称的数据文件。 </li><li>通过识别其峰宽，并使用该软件的位置分析拉曼光谱，然后用标准的数据从引用比较以确认摩西2层的晶体34,35的晶体结构类型和质量。 </li></ol></li></ol> 2.制作莫塞2层纳米器件 <ol><li>层晶体的机械剥离<ol><li>清洁镊子用丙酮和醇。 </li><li>挑摩西2层的晶体（4至8个）具有光泽表面（即镜状晶面）和区域大小大于0.5×0.5毫米2的镊子，并把它们在切割带具有的面积大小20×60毫米2。</li><li>折叠带一半去角质层晶体和重复动作约二十次。一般层晶体可以在宽度（参见图 1中的步骤2）被剥离成许多微米大小的晶体。 </li><li>加载切割胶带与该层纳米晶体粉末进入SEM室，观察这些剥离摩西2层微晶的大小和形态。如果该层的纳米晶体的宽度分布是在为1〜20μm，纳米晶体粉末能符合条件的器件制造。 </li></ol></li><li>该层纳米晶对设备模板色散<ol><li>放置切割胶带上的器件模板的纳米晶体层粉末颠倒。模板为SiO 2（300纳米）涂覆的硅与16预图案化的Ti（30纳米）/金（90纳米）在SiO 2表面电极基板（参见图 1中的步骤4）。模板的面积大小是5×5毫米<suP&gt; 2。 </li><li>点击切割用胶带轻轻地做一些纳米晶体（约10至100件）落在模板。 </li><li>检查在模板纳米晶体的数密度及分散状态通过光学显微镜或有时通过SEM如果分散纳米晶体可以通过光学显微镜来观察不到。通常为2〜5个的纳米晶体（面积大小大于2×2微米2）不重叠彼此分散在中心广场（具有80×80微米2区）的模板的是为未来的FIB加工的更好的条件。 </li></ol></li><li>电极的制作由FIB <ol><li>安装模板使用导电铜箔胶带的FIB持有人。通常情况下，被要求进行的3×2.4厘米2带的面积为安装6-8模板。 </li><li>保持器加载到FIB室中。 </li><li>通过点击按钮，抽真空室的真空度降低到10 -5毫巴"泵"。 </li><li>设置电子束电流（41 PA）和加速电压（10千伏）的扫描电镜模式。 </li><li>设置离子束电流（0.1 NA）和加速电压（30千伏）的FIB模式。 </li><li> ，热身离子束系统和气体喷射系统（GIS）通过点击"气体注入"块和按钮"冷"按钮"上的光束"分别。 </li><li>打开电子束通过点击按钮"梁"和聚焦图像以100倍的低倍率。 </li><li>以10毫米用于SEM模式中设置的Z轴工作距离（WD）。 </li><li>设定放大倍数5000倍处和焦点。 </li><li>通过点击按钮"导航"和输入的倾斜角"52"设置到保持器52度的倾斜角。 </li><li>选择具有一定厚度（从5到3000 nm）的莫塞2层纳米晶体和矩形和正方形的形状的电极法布里卡化。 </li><li>通过点击按钮"快照"采取不同的缩放比率电极制造之前有针对性的原始材料的SEM图像（从1000倍到10000）。 </li><li>切换到FIB模式，并采取FIB图像的快照模式，以降低目标材料在离子束轰击的曝光时间。 </li><li>定义电极沉积区域中，选择"铂沉积"模式，并输入厚度沉积的Pt电极（0.2-1.0微米）的价值。 </li><li>通过点击"注气"块框"PT DEP"引进地理信息系统的毛细血管进入室内。 </li><li>再次采取由快照模式的图像和修改电极的位置，如果最初所定义图案略微偏移。 </li><li>通过点击按钮"开始图案"打开FIB沉积。 </li><li>沉积后，回unclicking框"PT d拉伸GIS的毛细管"中的"注气"块EP。 </li><li>切换到SEM模式，并检查在纳米晶体层沉积的Pt电极的结果。 </li><li>取已完成的器件的不同放大率的SEM图像具有两个或四个电极（参见图 1中的步骤3）。 </li><li>通过点击按钮"导航"和输入的倾斜角为"0"设置保持器返回到0度的倾斜角。 </li><li>通过点击按钮"快照"采取不同的缩放比率为素材的宽度和电极间距离的估计顶部观看的SEM图像。 </li><li>关闭电子束和离子束系统，并通过点击"注气"挡按钮"梁关"和按钮"暖"降温GIS系统，分别为。 </li><li>通过点击按钮"放空"，然后采取持有人发泄通过引入氮气室流出该室。它通常需要5到10分钟以完成排气过程。 </li><li>关闭箱门和疏散室。 </li></ol></li></ol> 3.刻画了摩西2层纳米器件 <ol><li>第二层纳米晶的原子力显微镜的厚度测量<ol><li>安装AFM悬臂的探头支架。 </li><li>打开AFM程序，选择"ScanAsyst"模式。 </li><li>加载探头支架和与AFM站的激光二极管头连接。 </li><li>执行校准对准入射激光束的位置，并根据制造商的协议的悬臂。 </li><li>安装在由Cu箔胶带样品架的样本（模板芯片用FIB-制造纳米晶体层的设备）。 </li><li>样品架装载到AFM站。 </li><li>移动样品保持器的位置大约在激光束或原子力显微镜cantilev下方呃。 </li><li>由聚焦层纳米晶体的光学显微镜图像降低下来AFM悬臂至聚焦位置。 </li><li>输入扫描参数，例如扫描区域（6×6月30日×30微米2），频率（0.5-1.5赫兹），分辨率（256-512行）。 </li><li>启动该程序并根据制造商的方案保存数据。 </li><li>提起AFM悬臂，并采取样品架出来。 </li><li>装载第二样品，并重复上述如果需要所述的测量过程。 </li><li>通过使用软件"的NanoScope分析"分析AFM图像和高度轮廓估算层纳米晶体的厚度。选择从AFM图像的横向高度分布和由轮廓的扁平化区域确定的平均厚度值。 （参见图2d和2e） </li></ol></li><li>层纳米晶体的电流对电压 （IV）测量<ol><li>安装由Cu箔胶带云母基板上的样品（模板芯片用FIB-制造纳米晶体层的设备）。 </li><li>结合上由Ag膏在芯片的电极上的漆包线或Cu导线。 （参见图 1中的步骤4）。 </li><li>加载在探针台室已完成的样品，并修复它由铜铝箔胶带样品架。低温探针台位于在黑暗环境中。 （见步骤5 在图1中）。 </li><li>焊接试样的电线和的探针逐个金属电极。 </li><li>盖上腔顶部和疏散室下降到10 -4毫巴。降温样品到77K的引入液氮到探针台。设定的温度范围内（通常从80至320 K），间隔，和停留时间为温度控制。 （仅适用于温度变化的测量必要）。 </li><li>置所施加的电压扫描范围（通常从-1到1伏），电压INTErval中（0.01 V）中，并在一个超高阻抗多功能静电用于两终端IV测量的有限最大电流（10或者100μA）。对于四端子测量时，设定所施加的电流扫描范围（通常为-100至100μA）和当前时间间隔（1微安）。 </li><li>启动程序，并保存IV数据在室温下或在不同的温度。 </li><li>如有必要，打开腔室盖和取样品流出该室。 </li><li>装载第二样品，如果需要，并重复上述过程。 </li><li>通过绘制所测量的电流与使用该软件施加的电压数据分析IV曲线 。通过选择线性拟合函数拟合IV曲线。检查IV曲线的线性和得到的斜率值 （即电导值）。 （ 参见图1步骤6）。 </li><li>重复步骤3.2.10的IV曲线米easured在不同温度下，如果需要的。 </li><li>根据公式σ= G（吨/总重量）采用由四 ，SEM获得的参数计算出电导率（σ）值，和AFM测量，包括电导（G），厚度 （t）， 宽度 （w）和长度（ 升层纳米晶体）。 </li><li>积的电导性和导电性值对纳米晶体层的厚度的曲线。 </li></ol></li></ol>

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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disorder+effects+in+focused-ion-beam-deposited+Pt+contacts+on+GaN+nanowires.">Disorder effects in focused-ion-beam-deposited Pt contacts on GaN nanowires.</a> Nano Lett. 5 (10), 2029-2033 (2005).</li><li>Chen, R. 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=Anomalous+quantum+efficiency+for+photoconduction+and+its+power+dependence+in+metal+oxide+semiconductor+nanowires.">Anomalous quantum efficiency for photoconduction and its power dependence in metal oxide semiconductor nanowires.</a> Nanoscale. 5 (15), 6867-6873 (2013).</li><li>Chen, R. S., Tang, C. C., Shen, W. C., Huang, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thickness-dependent+electrical+conductivities+and+ohmic+contacts+in+transition+metal+dichalcogenides+multilayers.">Thickness-dependent electrical conductivities and ohmic contacts in transition metal dichalcogenides multilayers.</a> Nanotechnology. 25 (41), (2014).</li><li>Huang, Y. H., Peng, C. C., Chen, R. S., Huang, Y. S., Ho, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport+properties+in+semiconducting+NbS2+nanoflakes.">Transport properties in semiconducting NbS2 nanoflakes.</a> Appl. Phys. Lett. 105 (9), (2014).</li><li>Hu, S. Y., Liang, C. H., Tiong, K. K., Lee, Y. C., Huang, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+characterization+of+large+niobium-doped+MoSe2+single+crystals.">Preparation and characterization of large niobium-doped MoSe2 single crystals.</a> J. Crystal Growth. 285 (3), 408-414 (2005).</li><li>Das, S., Appenzeller, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Where+does+the+current+flow+in+two-dimensional+layered+systems.">Where does the current flow in two-dimensional layered systems.</a> Nano Lett. 13 (7), 3396-3402 (2013).</li><li>Cullity, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Elements of X-ray Diffraction. , (1978).</li><li>Jadczak, J., 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=Composition+dependent+lattice+dynamics+in+MoSxSe(2-x)+alloys.">Composition dependent lattice dynamics in MoSxSe(2-x) alloys.</a> J. Appl. Phys. 116 (19), 193505 (2014).</li><li>Weber, W. H., Merlin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Raman Scattering in Materials Science. , (2000).</li><li>Tonndorf, P., 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=Photoluminescence+emission+and+Raman+response+of+monolayer+MoS2,+MoSe2,+and+WSe2.">Photoluminescence emission and Raman response of monolayer MoS2, MoSe2, and WSe2.</a> Opt. Express. 21 (4), 4908-4916 (2013).</li><li>Hu, S. Y., Liang, C. H., Tiong, K. K., Lee, Y. C., Huang, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+characterization+of+large+niobium-doped+MoSe2+single+crystals.">Preparation and characterization of large niobium-doped MoSe2 single crystals.</a> J. Crystal Growth. 285 (3), 408-414 (2005).</li><li>Hu, S. Y., Liang, C. H., Tiong, K. K., Huang, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Re+dopant+on+the+electrical+and+optical+properties+of+MoSe2+single+crystals.">Effect of Re dopant on the electrical and optical properties of MoSe2 single crystals.</a> J. Alloys Compounds. 442 (1-2), 1-2 (2007).</li><li>Bougouma, 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=Growth+and+characterization+of+large,+high+quality+MoSe2+single+crystals.">Growth and characterization of large, high quality MoSe2 single crystals.</a> J. Crystal Growth. 363, 122-127 (2013).</li></ol>

The authors have nothing to disclose.

准确测定的σ值的和它在该层中纳米晶体尺寸的依赖是高度依赖于电触点的质量。用于金属电极沉积的FIB沉积法在整个研究过程中发挥了至关重要的作用。根据电气，结构和组成分析，稳定和高度可再现的欧姆触点的制造中，使用FIB淀积法，在摩西2或二硫化钼的设备提供了便利的非晶态导电性合金的铂金属和摩西2之间形成层的半导体。有缺陷的合金结构在摩西2...

过渡金属二硫属化物（TMDS），诸如二硫化钼，摩西2，WS 2，和WSE 2，有一个有趣的二维（2D）层结构和半导体性能1-3。科学家最近发现， 二硫化钼的单层结构示出了由于量子限制效应基本上提高发光效率。的新的直接带隙半导体材料的发现已引起大量关注4-7。此外，TMDS的易剥离层结构是研究二维的材料的基本性质的一个很好的平台。不像无带隙的金属石墨烯，TMDS具有固有半导体的特性，并具有在1-2电子伏特1,3,8的范围内的带隙。 TMDS 9的三元化合物和这些化合物与石墨烯的一体化的可能性的2D结构提供了前所未有的奥普ortunity开发超薄和柔性电子器件。 不像石墨烯，2D TMDS的室温的电子迁移率的值是在中等水平（1-200厘米2 V - 1秒- 1 二硫化钼十月十七号 ;大约50厘米2 V - 1秒- 1 MOSE 2 18 ）。石墨烯的最优迁移率值已被报道为高于10,000个厘米2 V - 1秒 - 1 19-21日然而，半导体的TMD单层表现出优良的器件性能。例如， 二硫化钼和摩西2单层或多层场效应晶体管显示出极高的开/关比，高达10 6 -10 9 10,12,17,18,22。因此，关键的是要了解的2D TMDS和的基本电性能的IR散装物料。 然而，该层材料的电性能的研究已部分地是由于在形成在层的结晶良好的欧姆接触的困难的阻碍。三种方法，阴影掩模沉积（SMD）23，电子束光刻（EBL）24,25，和聚焦离子束（FIB）沉积，26,27已被用于形成纳米材料电触头。因为贴片通常涉及使用一个铜栅作为掩模，两个接触电极之间的间隔是大多大于10μm。不同于EBL和FIB的沉积，而没有目标或选择在SMD方法的兴趣进行纳米材料在基片上的电极阵列的金属沉积。这种方法不能保证金属图案被正确地沉积在纳米材料个体作为电极。在SMD方法的结果具有偶然性的因素。所述EBL和FIB淀积方法在所使用的扫描电子显微镜（SEM）的系统;纳米材料可以直接观察和选择用于电极沉积。此外，EBL可以用来容易地制造金属电极与线宽度和接触电极间隔小于100nm。然而，残留的抗蚀剂上期间光刻不可避免地导致在金属电极和纳米材料之间的绝缘层的形成左纳米材料表面上。因此，EBL导致高接触电阻。 通过FIB淀积电极制造的主要优点是，它会导致低的接触电阻。因为金属沉积是由有机金属前体的分解通过使用离子束在所规定区域进行的，金属的沉积和离子轰击同时发生。这可能会破坏金属 - 半导体界面和防止的肖特基接触的形成。离子轰击也可以消除表面杂质如烃的丝宝和原生氧化物，从而降低接触电阻。通过FIB沉积欧姆接触的制造已经证明了不同的纳米材料27-29。此外，在FIB淀积方法的整个制造过程比在EBL简单。 作为半导体层通常显示高度各向异性导电，在层与层方向的电导率是几个数量级小于在面内方向30,31更低。这个特性增加制造欧姆接触，并确定导电率的难度。因此，在此研究中，FIB沉积用于研究层半导体纳米结构的电性能。

<table><tbody><tr><td>HRTEM&amp;amp;SEAD</td><td>FEI (http://www.fei.com/products/tem/tecnai-g2/?ind=MS)</td><td>Tecnai&amp;trade; G2 F-20</td><td></td></tr><tr><td>SEM&amp;amp;EDS</td><td>HITACHI (http://www.hitachi-hitec.com/global/em/sem/sem_index.html)</td><td>S-3000H</td><td></td></tr><tr><td>FIB</td><td>FEI (http://www.fei.com/products/dualbeam/versa-3d/)</td><td>Quanta 3D FEG</td><td></td></tr><tr><td>AFM</td><td>BRUKER (http://www.bruker.com/products/surface-analysis/atomic-force-microscopy/dimension-icon/overview.html)</td><td>Dimension Icon</td><td></td></tr><tr><td>XRD</td><td>Bruker (https://www.bruker.com/products/x-ray-diffraction-and-elemental-analysis/x-ray-diffraction/d2-phaser/learn-more.html)</td><td>D2 PHASER X-ray Diffractometer</td><td></td></tr><tr><td>Raman</td><td>Renishaw (http://www.renishaw.com/en/renishaw-enhancing-efficiency-in-manufacturing-and-healthcare--1030)</td><td>inVia Raman microscope system</td><td></td></tr><tr><td>Keithley-4200</td><td>keithley (http://www.keithley.com.tw/products/dcac/currentvoltage/4200scs)</td><td>4200scs</td><td></td></tr><tr><td>ultralow current leakage cryogenic probe station</td><td>Lakeshore Cryotronics (http://www.lakeshore.com/)</td><td>TTP4</td><td></td></tr><tr><td>copper foil tape</td><td>3M (http://solutions.3m.com/wps/portal/3M/en_US/Electronics_NA/Electronics/Products/Product_Catalog/~/3M-Copper-Foil-Shielding-Tape-1182?N=4294300025+5153906&amp;amp;&amp;amp;Nr=AND%28hrcy_id%3A8CQ27CX0WMgs_F2LMWMM6M6_N2RL3FHWVK_GPD0K8BC31gv%29&amp;amp;rt=d)</td><td>1182</td><td></td></tr><tr><td>Ag paste</td><td>Well-Being (http://www.gredmann.com/about.htm)</td><td>MS-5000</td><td></td></tr><tr><td>Cu wire</td><td>Guv Team (http://www.guvteam.com)</td><td>ICUD0D01N</td><td></td></tr><tr><td>dicing tape</td><td>Nexteck (http://www.nexteck-corp.com/tw/product-tape.html)</td><td>contact vender</td><td></td></tr><tr><td>mica</td><td>Centenary Electronic (http://100y.diytrade.com/sdp/307600/4/pl-1175840/0.html)</td><td>T0-200</td><td></td></tr><tr><td>enamel wire</td><td>Light-Tech Electronics (http://www.ltc.com.tw/product_info.php/products_id/57631)</td><td>S.W.G #38</td><td></td></tr></tbody></table>

ohmic contact fabrication using a focused-ion beam technique and electrical characterization for layer semiconductor nanostructures

层半导体用容易加工的二维（2D）结构表现出间接到直接带隙跃迁和优越的晶体管性能，这表明用于下一代超薄和灵活的光子和电子设备的发展的新方向。增强发光量子效率得到了广泛的观察，这些原子薄的二维晶体。然而，除了量子限制厚度或甚至微米尺度尺寸效应预计不会与很少被观察到。在这项研究中，钼二硒化物（摩西2）层晶体纳米被制造为两个或四个终端设备的厚度范围的6-2,700。欧姆接触的形成，成功通过使用铂（Pt）作为接触金属的聚焦离子束（FIB）沉积方法来实现的。层的晶体具有各种厚度通过简单的机械剥离通过使用切割带制备。电流 - 电压曲线measuremenTS进行，以确定层纳米晶体的电导率值。此外，高分辨率透射电子显微镜，选择区域电子衍射仪和能量色散X射线光谱进行了表征的金属-半导体的FIB-制造MOSE 2设备的接触界面。施加的方法之后，在很宽的厚度范围为摩西2 -layer半导体实质厚度依赖性的导电性进行了观察。电导率增加从4.6以上两个数量级到1500Ω - 1厘米- 1，从2700至6nm的降低的厚度。另外，温度依赖性的导电性表明，薄摩西2多层膜表现出与3.5-8.5兆电子伏的活化能，其中比大部分（36-38兆电子伏）小得多相当弱半导体行为。普罗巴竹叶提取表面主导的运输性质和在摩西2的高表面电子浓度的存在下提出。类似的结果可以为其他层的半导体材料，例如二硫化钼和WS 2来获得。

纳米材料层具有不同厚度的电导（G）和电导率（σ）的所确定的值是高度依赖于电触点的质量。的FIB-沉积制造的双端摩西的欧姆触点 2的设备的特征在于测量电流-电压（I - V）的曲线。室温我 - V曲线为具有不同厚度的二端摩西2纳米片的设备示于图2a。 该 I - V曲线遵循线性关系。这证实了摩西2器件的欧姆?...

Watch this Scientific Journal Video about Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures at JoVE.com

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

We describe the approaches for the device fabrication and electrical characterization of molybdenum diselenide (MoSe2) layer semiconductor nanostructures with different thicknesses. In addition, the fabrication of ohmic contacts for MoSe2-layer nanocrystals by the focused-ion beam deposition method using platinum (Pt) as a contact metal is described.

欧姆接触制造用聚焦离子束技术和电气特性的半导体层的纳米结构

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor ...

ohmic-contact-fabrication-using-focused-ion-beam-technique-electrical

Research

JoVE Journal

Engineering

12.2K 次观看.  National Taiwan University of Science and Technology. We describe the approaches for the device fabrication and electrical characterization of molybdenum diselenide (MoSe2) layer semiconductor nanostructures with different thicknesses. In addition, the fabrication of ohmic contacts for MoSe2-layer nanocrystals by the focused-ion beam deposition method using platinum (Pt) as a contact metal is described. 

视频: Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

科研

工程学

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

写作和氧化物纳米结构的低温特性

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

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 ...

Atomically Traceable Nanostructure Fabrication

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

We report a protocol for combining the atomic metrology of the Scanning Tunneling Microscope for surface patterning with selective Atomic Layer Deposition and Reactive Ion Etching. Using a robust process involving numerous atmospheric exposures and transport, 3D nanostructures with atomic metrology are fabricated.

原子纳米结构可追溯制造

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process ...

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has been attributed to statistical fluctuations in the number of photons/electrons arriving at a given nano-region arising from shot-noise (SN). The SN varies inversely to the square root of a number of photons/electrons. For a fixed dosage, the SN is larger in EUV and E-beam lithographies than for traditional (193 nm) optical lithography. Bottom-up and top-down patterning approaches are combined to minimize the effects of shot noise in nano-hole patterning. Specifically, an amino-silane surfactant self-assembles on a silicon wafer that is subsequently spin-coated with a 100 nm film of a PMMA-based E-beam photoresist. Exposure to the E-beam and the subsequent development uncover the underlying surfactant film at the bottoms of the holes. Dipping the wafer in a suspension of negatively charged, citrate-capped, 20 nm gold nanoparticles (GNP) deposits one particle per hole. The exposed positively charged surfactant film in the hole electrostatically funnels the negatively charged nanoparticle to the center of an exposed hole, which permanently fixes the positional registry. Next, by heating near the glass transition temperature of the photoresist polymer, the photoresist film reflows and engulfs the nanoparticles. This process erases the holes affected by SN but leaves the deposited GNPs locked in place by strong electrostatic binding. Treatment with oxygen plasma exposes the GNPs by etching a thin layer of the photoresist. Wet-etching the exposed GNPs with a solution of I2/KI yields uniform holes located at the center of indentations patterned by E-beam lithography. The experiments presented show that the approach reduces the variation in the size of the holes caused by SN from 35% to below 10%. The method extends the patterning limits of transistor contact holes to below 20 nm.

Uniformly sized nanoparticles can remove fluctuations in contact hole dimensions patterned in poly(methyl methacrylate) (PMMA) photoresist films by electron beam (E-beam) lithography. The process involves electrostatic funneling to center and deposit nanoparticles in contact holes, followed by photoresist reflow and plasma- and wet-etching steps.

牺牲纳米颗粒使用删除散粒噪声的影响通过电子束光刻装配式接触孔

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has ...

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 ...

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

基于 LiPON 的固态锂离子 Nanobatteries 的聚焦离子束制备方法在原位测试中的研究

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

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

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different materials show variability in resistive switching properties due to the intrinsic nature of the material used, leading to discrepancies in the field because of underlying operation mechanisms. This highlights a need for a reliable technique to understand mechanisms using nanostructural observations. This protocol explains a detailed process and methodology of in&#160;situ nanostructural analysis as a result of electrical biasing using transmission electron microscopy (TEM). It provides visual and reliable evidence of underlying nanostructural changes in real time memory operations. Also included is the methodology of fabrication and electrical characterizations for asymmetric crossbar structures incorporating amorphous vanadium oxide. The protocol explained here for vanadium oxide films can be easily extended to any other materials in a metal-dielectric-metal sandwiched structure. Resistive switching crossbars are predicted to serve the programmable logic and neuromorphic circuits for next-generation memory devices, given the understanding of the operation mechanisms. This protocol reveals the switching mechanism in a reliable, timely, and cost-effective way in any type of resistive switching materials, and thereby predicts the device&#39;s applicability.

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

Presented here is a protocol for analyzing nanostructural changes during in&#160;situ biasing with transmission electron microscopy (TEM) for a stacked metal-insulator-metal structure. It has significant applications in resistive switching crossbars for the next generation of programmable logic circuits and neuromimicking hardware, to reveal their underlying operation mechanisms and practical applicability.

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 ...

Nanoscale Characterization of Liquid-Solid Interfaces by Coupling Cryo-Focused Ion Beam Milling with Scanning Electron Microscopy and Spectroscopy

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar energy and fuel generation, and electrochemical energy storage. Nanoscale characterization of such interfaces has recently been achieved using cryogenic electron microscopy, thereby providing a new path to advancing our fundamental understanding of interface processes.
This contribution provides a practical guide to mapping the structure and chemistry of solid-liquid interfaces in materials and devices using an integrated cryogenic electron microscopy approach. In this approach, we pair cryogenic sample preparation which allows stabilization of solid-liquid interfaces with cryogenic focused ion beam (cryo-FIB) milling to create cross-sections through these complex buried structures. Cryogenic scanning electron microscopy (cryo-SEM) techniques performed in a dual-beam FIB/SEM enable direct imaging as well as chemical mapping at the nanoscale. We discuss practical challenges, strategies to overcome them, as well as protocols for obtaining optimal results. While we focus in our discussion on interfaces in energy storage devices, the methods outlined are broadly applicable to a range of fields where solid-liquid interface play a key role.

Cryogenic Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques can provide key insights into the chemistry and morphology of intact solid-liquid interfaces. Methods for preparing high quality Energy Dispersive X-ray (EDX) spectroscopic maps of such interfaces are detailed, with a focus on energy storage devices.

通过冷冻聚焦离子束铣削与扫描电子显微镜和光谱学耦合，对液固界面进行纳米级表征

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar ...

Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of sophisticated microelectrodes with greater resolution and expanded capabilities. The progress in fabrication technology has supported the development of biomimetic electrodes, which aim to seamlessly integrate into the brain parenchyma, reduce the neuroinflammatory response observed after electrode insertion and improve the quality and longevity of electrophysiological recordings. Here we describe a protocol to employ a biomimetic approach recently classified as nano-architecture. The use of focused ion beam lithography (FIB) was utilized in this protocol to etch specific nano-architecture features into the surface of non-functional and functional single shank intracortical microelectrodes. Etching nano-architectures into the electrode surface indicated possible improvements of biocompatibility and functionality of the implanted device. One of the benefits of using FIB is the ability to etch on manufactured devices, as opposed to during the fabrication of the device, facilitating boundless possibilities to modify numerous medical devices post-manufacturing. The protocol presented herein can be optimized for various material types, nano-architecture features, and types of devices. Augmenting the surface of implanted medical devices can improve the device performance and integration into the tissue.

We have shown that the etching of nano-architecture into intracortical microelectrode devices may reduce the inflammatory response and has the potential to improve electrophysiological recordings. The methods described herein outline an approach to etch nano-architectures into the surface of non-functional and functional single shank silicon intracortical microelectrodes.

聚焦 Ion 光束平版印刷到蚀刻纳米架构到微电极

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of ...

欧姆接触制造用聚焦离子束技术和电气特性的半导体层的纳米结构

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