我们的研究是由处长，科学办，能源SP2计划美国能源部基础能源科学办公室根据合同不支持。 DE-AC02-05CH11231（STM仪器仪表的开发和设备集成）;海军研究办公室（器件特性），以及美国国家科学基金会奖没有。 CMMI-1235361（DI / DV摄像）。 STM数据进行了分析，并使用WSxM软件渲染。33 DW和AJB是由美国国防部（DOD）通过国防科学与工程研究生奖学金（NDSEG）程序，32 CFR 168A支持。

的Cu箔22,23 1.电化学抛光注意：电化学抛光暴露出裸铜表面的石墨烯生长除去保护表面涂层，并控制生长种子密度。 <ol><li>通过混合100毫升超纯水，加入50ml乙醇，加入50ml磷酸，将10毫升异丙醇和1g尿素制备的电化学抛光溶液。 </li><li>切铜箔成多个3厘米3厘米箔。注意：每个箔用作阳极或阴极。 </li><li>通过垂直剪裁的Cu箔上保持器和将其连接到电源的相应的终端设置了阳极/阴极。 注：阳极（正极）将电化学抛光的石墨烯生长。 </li><li>抛光开始之前，设定为4.8伏在电源恒定电压。 </li><li>一旦接通电源作为阳极和阴极同时浸入electrochemiCAL抛光液。由约2厘米分开的电极。检查得到的电流是1-2 A之间</li><li>通过关闭电源2分钟后停止电化学抛光。取出阳极，并立即用超纯水，丙酮和异丙醇分别冲洗。 </li><li>吹干漂洗铜箔与N 2气体，并将其存放在干燥的容器中。 </li></ol>石墨烯的2化学气相沉积（CVD）在Cu箔22-25 <ol><li>将石英管CVD炉和管连接到与KF配件气行的其余部分。 </li><li>将电化学抛光的铜箔上的石英舟顶部。使用长棒，推石英舟放入石英管，直到Cu箔被放置在CVD炉的中心。封闭系统KF配件。 </li><li>抽空与低真空泵系统。清扫该系统用H 2。 </li><li>斜坡最高温度10506下以200 SCCM的H 2。退火在1050℃下进行2小时，以同一气流。 注：温度是通过测量内置K型热电偶在管式炉。 </li><li>降温至1030℃，使用相同的气体流量。生长石墨烯10分钟并以40sccm的CH 4和10sccm的H 2。 </li><li>只要增长已经过去，开辟炉罩下来侵权迅速冷却。保持相同的气流。 </li><li>一旦温度低于100℃时，关闭气流。 </li><li>关掉泵。由气体管线和N 2气缸之间缓慢打开计量阀放空系统用N 2气。 </li><li>取出样品。切Cu箔与所需尺寸件。 </li><li>样品存放在干燥器内干燥的容器。 </li></ol> H-BN 3.机械剥离19-21一上SiO 2的芯片<ol><li>清洁的SiO 2芯片。注：在S供氧浓度芯片由一个大致285纳米厚的SiO 2层上的体Si的顶部。 <ol><li>通过使用金刚石划线1厘米芯片切割的SiO 2晶片切割成约1厘米。 </li><li>冲洗的SiO 2芯片与水和异丙醇。保持SiO 2的表面覆盖着每次冲洗后的水/异丙醇。 </li><li>放置在旋涂机中的SiO 2芯片以从其表面除去液体。旋芯片3000转，15秒。 </li><li>检查芯片的清洁利用光学显微镜的暗视野下的设置。注：在暗场设置，固体杂质出现明亮的颗粒。 </li></ol></li><li>放置一个干净的SiO 2芯片，剥离胶带，并在干净的表的h-BN的晶体用光学显微镜。 </li><li>准备两个条带：父带和第二带。其两侧粘在桌子上都放置了。将一个H-BN液晶父带粘贴面。 </li><li>请将S第二带过在父磁带上的h-BN晶体的ticky侧（使得第二和父带粘侧面是接触）。擦在晶体轻轻去除气泡。 </li><li>剥开第二个磁带掉去角质的H-BN液晶到第二个磁带。存储父磁带以供将来使用。 </li><li>折叠第二个磁带本身上，轻轻揉搓过的晶体，并剥离胶带。重复此过程10次，折叠第二带，使得的h-BN的晶体转移到每次第二带的一个全新的区域。 </li><li>放置在显微镜下一个干净的SiO 2芯片。粘含有的h-BN晶体第二带的区域上的SiO 2芯片。确保磁带也坚持显微镜支架为在即将到来的剥离步骤确保芯片。 </li><li>慢慢剥下胶带，在显微镜下监测该过程。由于磁带几乎剥落，使用镊子举行的SiO 2 </suB&gt;芯片到位。注意：剥离太快将导致在芯片上较少的h-BN薄片。 </li><li>一旦将胶带剥离，放置的CVD炉内的芯片。退火在空气中的芯片，在500℃进行2小时。 </li></ol> 4.聚甲基丙烯酸甲酯（PMMA）26-28石墨烯转移到对H-BN / SiO 2的<ol><li>把一滴PMMA（A4）对石墨烯/铜/石墨烯薄片。旋涂用3000转在30秒箔。注意：作为的FeCl 3（水溶液）蚀刻掉在即将到来的蚀刻步骤中的Cu层，背面石墨烯会脱落而PMMA /石墨烯层将保持未反应（ 图2）。 </li><li>使用的FeCl 3耐勺，让在下列顺序的溶液旋涂Cu箔浮动：1.5分钟上的FeCl 3（水溶液），5分钟的超纯水，上的FeCl 3（水溶液），5 1分钟分上超纯水，上的FeCl 3（水溶液），5分钟的超纯水，5分钟的超纯水：15分钟r和对超纯水30分钟。制备各超纯水浴在一个单独的烧杯中。 </li><li>鱼与H-BN / SiO 2的芯片的PMMA /石墨烯样品。将其放置在热板上在80℃下进行10分钟，以去除水并在180℃下进行15分钟至27放松的PMMA膜。 </li><li>将聚甲基丙烯酸甲酯/石墨烯/的h-BN / SiO 2的芯片在CH 2 Cl 2 O / N以溶解的PMMA层。 </li></ol> 5.氩气/ H 2退火29,30 <ol><li>放置在石英管上的CVD炉和管连接到与KF接头的气体管线的其余部分。 </li><li>将石墨烯/ BN / SiO 2的芯片上的石英舟。使用长棒，推石英舟放入石英管，直到该芯片被放置在CVD炉的中心。封闭系统KF配件。 </li><li>抽空与低真空泵系统。清扫该系统用H 2和Ar。 </li><li>建立压力为1个大气压，100 SC厘米的H 2和200sccm的氩有计量阀。一旦压力达到1个大气压，调节计量阀的开口大小，以稳定的压力在1个大气压。 </li><li>斜坡上升的温度为350℃，退火5小时用相同的气流。 </li><li>冷却至RT用相同的气流。 </li><li>一旦温度低于100℃时，关闭气流。关闭所有阀门。 </li><li>关掉泵。由气体管线和N 2气缸之间缓慢打开计量阀放空系统用N 2气。 </li><li>取出样品。检查的石墨烯层，用拉曼光谱32缺陷等级的数目。检查光学显微镜下的清洁/均匀性。该光学显微镜的原子力显微镜（AFM）下出现清洁扫描多个区域，以确保样本出现清洁/均匀以小的长度尺度（&lt;500纳米）为好。 </li><li>它存储在内部的干燥容器干燥器。 </li></ol> 6.组装门可调石墨烯器件的STM测量2-5 <ol><li>蒸发一个50微米×50微米的Au / Ti的接触垫到的Ar / H 2 -annealed CVD石墨烯/的h-BN / SiO 2的样品。 <ol><li>样品用胶带到上一个显微顶部上的阶段。 </li><li>同时用光学显微镜监测，对准石墨使用显微使得对Au / Ti接触将感兴趣的区域附近沉积，而不覆盖所述表面上的模板掩模。 </li><li>与模板掩模的样品转移到电子束蒸发器。蒸发的Ti为10nm以3埃/秒。掩盖Ti层通过不破坏真空中同一蒸发会话蒸发的Au 30-50纳米的3埃/秒。注：另外，铬为1纳米是一个很好的替代钛的10纳米。 </li><li>与模板掩模样品传输回显微去除阶段。 </li></ol></li> &lt;LI&gt;安装样品到一个超高真空（UHV）样板。 <ol><li>将薄薄的一片蓝宝石在特高压样板。注意：蓝宝石作为防止所述Si和STM地面之间的电接触的绝缘层。此外，蓝宝石是样品退火的目的的优异的热导体。 </li><li>放置在蓝宝石顶部的样品。放置另一个薄片蓝宝石在样品上。确保该蓝宝石不覆盖石墨表​​面。 </li><li>用金属夹固定蓝宝石/样品/蓝宝石结构。确保整个结构是刚性的，否则它会震动一STM内。 </li></ol></li><li>引线键合的特高压样板终端到合适的石墨烯设备上的联系人。注意：淀积的Au / Ti的电极引线接合到接地而生成的硅本体是引线键合到所述栅电极（ 图1）。 <ol><li>放置在接地引线接合阶段上的样品。 </li><li>识别使用光学显微镜在Au / Ti的触点的位置。 </li><li>打开的线键合机。如果线键合机是气动，打开N 2气。将线键合机进行两次债券。 </li><li>使用引线接合臂，放置引线接合器的前端上的特高压样品板的适当端子的顶部。下移，轻轻按下引线键合机的前端到终端，直至线焊机表示该键完成。 </li><li>螺纹导线到对Au / Ti接触石墨烯器件。下移，轻轻按下引线键合机的前端到对Au / Ti接触，直到线焊机表明粘结完成。 </li><li>用金刚石划线刮开一些的SiO 2在SiO 2芯片的边缘，以暴露将被用作背栅极的硅。重复两接合工艺对已曝光的硅。 </li><li>样本内插入一个特高压（10 -10托）准备室和退火引线键合摹raphene设备在约300℃。该设备转移到STM室。 注：直到其表面STM下出现清洁石墨烯设备应进行退火处理（见二段议定书8）。退火时间将根据该装置的初始清洁度而变化。 </li></ol></li></ol> 7. STM针尖对校准金（111）表面31 <ol><li>退火/溅射的Au（111）上的加热器阶段样品在超高真空腔室清洁/平坦化的Au表面。退火5分钟，在375℃，溅射5分钟，用Ar +束加速到500 V转移的Au（111）样品的STM扫描的阶段。 </li><li>接近的Au（111）的表面与一个STM针尖。申请10伏脉冲的STM针尖直到由Au（111）的人字形重建是清晰可见。 </li><li>通过调节尖端的形状和微分电导的dI /的dV谱比较标准的Au（111） 的dI / DV频谱校准小费。31 </suP&gt; <ol><li>通过40纳米帧扫描金（111）面与40纳米，以确定一个清洁/平坦区域。如果表面具有台阶边缘的高密度，移动到用于扫描一个新的领域。 </li><li> STM针尖0.4轻轻崩溃到1.0纳米到在Au（111）表面的一个清洁区;这个控制崩溃被称为一个“戳。”关掉反馈并点击“取光谱”按钮经由锁定采取的dI / DV光谱上的交流调制电压的电流响应（6毫伏和613.7赫兹）加入到尖端偏压。 注意：一旦交流调制电压（6毫伏和613.7赫兹）设置在前端，将所得隧道电流进入锁定放大器，其中隔离同频的当前的分量和返回的dI / DV信号。通过记录这种信号作为样本偏压从-1.0扫到1.0V， 的dI / DV频谱被产生。因为这个光谱方案是家庭写，指令采取能谱将不同的程序之间变化。 </li><li>检查对一个标准的Au（111） 的dI /的dV谱（ 图4）所获得的的dI /的dV曲线。确保在Au（111）的表面状态存在于的dI /的dV曲线和该光谱不存在的任何异常的特征。如果测得的dI /的dV曲线是不能接受的，重复在步骤7.3.2捅直到的dI /的dV曲线看起来像图4中所示的那个。 </li><li>一旦笔尖形状和DI / DV频谱进行了优化，等待15至30分钟;如果STM针尖是不稳定的，二/ DV频谱将这个时间间隔内发生变化。夺回的 dl / DV光谱在不同的位置，以确认STM针尖是否稳定与否。 </li><li>重复捅在步骤7.3.2 如果 DI / DV曲线发生了变化。开始扫描石墨烯如果 DI / DV曲线不变。 </li></ol></li></ol> 8.扫描石墨烯<ol><li> TRansfer石墨烯器件到的STM扫描的阶段。 </li><li>使用一个长途光学显微镜看STM针尖和石墨烯器件。后横向对准尖端和利益的h-BN片状，接近石墨烯。 </li><li>启动扫描2纳米2纳米的区域。慢慢由5纳米，10纳米15纳米，20纳米20纳米， 等放大扫描窗口至5nm，10纳米，15纳米。如果一个大的杂质（&gt; 100时在高度）遇到，撤回的前端并移动到不同的区域。 </li><li>取的dI / DV光谱，并比较在石墨烯/的h-BN衬底的标准的dI /的dV谱（见参考文献21）。如果频谱是没有可比性的，在重新校准的Au（111）表面的尖端（见秒议定书7）。 </li><li>扫描多个领域获得的频率大的杂质（&gt; 100时在高度）遇到感。根据这些统计数据，推断样品的清洁度。 </li></ol>在石墨烯面传热9.存入库仑杂质Ë2-4 <ol><li>获取钙源。校准Ca原子的蒸发用的残留气体分析仪（RGA）和石英晶体微天平（QCM）在特高压试验室中。注：RGA评估的钙沉积的纯度，同时QCM衡量一个钙沉积速率。 <ol><li>运行电流通过钙源。 </li><li>增加电流直到10 -10乇的RGA质谱中检测到的Ca分压。需要注意的一个事实，即Ca和Ar具有相同的质量，因此，是无法区分的RGA。 </li><li>测量钙沉积速度（层/秒）与QCM。 <ol><li>输入的密度（ 例如，1.55克/厘米3为钙离子）的存款的转换频移值在沉积速率。 </li><li>沉积速率监控为QCM读取/ s的沉积速率;将此转换层/秒通过假设一个单层的厚度等于离子直径（ 例如，0.228埃为钙离子）的存款。 </li></ol></li><li>确定最佳的电流通过调节电流，直到沉积速率监视器显示一个所需的沉积速率（ 例如，3.33×10 -5层/秒）。 </li></ol></li><li>给出的沉积速率（ 例如，3.33×10 -5层/秒），在步骤9.1.3，计算的时间（秒）用于沉积所需量（ 例如，0.01单层）的Ca.在STM，沉积的Ca在Cu（100）表面就地与来自步骤9.1.3最佳电流设置。检查CA覆盖后沉积和清洁铜（100）表面STM（见步骤8.5）;直到STM在铜（100）表面状态出现如预期重新调整当前设置。 注意：沉积参数进行了优化的Cu（100）的第一，以尽量减少污染控制不良沉积的石墨烯器件的风险。 </li><li> 原位沉积在石墨烯器件转移到STM为4 K. </li><li>存款收取钙原子上的石墨烯表面。 <ol><li>在石墨烯上的钙沉积，outgass的钙源。直到在步骤9.2所需的电流达到缓慢增加的源上的电流0.25 A每次5-10分钟。关闭快门的石墨烯和Ca源之间，以防止脱气污染物到达石墨烯。 </li><li>让蒸发通量打开快门之前稳定20分钟。 </li><li>打开快门和存款理想（ 例如，0.01单层）适量钙离子到石墨烯表面。确保该石墨烯器件具有线的视线与钙源。确保STM针尖是脱节的视线的钙源，以防止钙原子粘到STM针尖的。 </li></ol></li><li>检查CA覆盖率和沉积后的石墨烯表面STM清洁度（见步骤8.5）。请参阅参考。 2，3和4的库仑杂质对石墨烯的研究的进一步协议。 </li></ol>

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L., Kim, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+observation+of+the+quantum+Hall+effect+and+Berry&#8217;s+phase+in+graphene.">Experimental observation of the quantum Hall effect and Berry&#8217;s phase in graphene.</a> Nature. 438 (7065), 201-204 (2005).</li><li>Novoselov, K. 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=Two-dimensional+gas+of+massless+Dirac+fermions+in+graphene.">Two-dimensional gas of massless Dirac fermions in graphene.</a> Nature. 438 (7065), 197-200 (2005).</li><li>Biswas, R. R., Sachdev, S., Son, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coulomb+impurity+in+graphene.">Coulomb impurity in graphene.</a> Phys. Rev. B. 76 (20), 205122 (2007).</li><li>Novikov, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elastic+scattering+theory+and+transport+in+graphene.">Elastic scattering theory and transport in graphene.</a> Phys. Rev. B. 76 (24), 245435 (2007).</li><li>Pereira, V. M., Nilsson, J., Castro Neto, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coulomb+impurity+problem+in+graphene.">Coulomb impurity problem in graphene.</a> Phys. Rev. Lett. 99 (16), 166802 (2007).</li><li>Dean, C. R., 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=Boron+nitride+substrates+for+high-quality+graphene+electronics.">Boron nitride substrates for high-quality graphene electronics.</a> Nat. Nanotechnol. 5 (10), 722-726 (2010).</li><li>Xue, 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=Scanning+tunnelling+microscopy+and+spectroscopy+of+ultra-flat+graphene+on+hexagonal+boron+nitride.">Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride.</a> Nat. 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Chem. Res. 46 (10), 2329-2339 (2013).</li><li>Reina, 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=Transferring+and+identification+of+single-and+few-layer+graphene+on+arbitrary+substrates.">Transferring and identification of single-and few-layer graphene on arbitrary substrates.</a> J. Phys. Chem. C. 112 (46), 17741-17744 (2008).</li><li>Suk, J. 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Authors have nothing to disclose.

对于STM表征，所述石墨烯器件制造的关键目标包括：1）生长单层石墨烯的缺陷最少数量，2）获取一个大的，干净的，均匀的和连续的石墨烯表面上，3）装配用之间的高电阻的石墨烯器件石墨烯和栅极（ 即，没有“栅极泄漏”），以及4）单独库仑杂质沉积。 第一个目标是通过CVD工艺，在此期间，石墨烯生长在Cu箔的管辖。虽然有多个基板的候选（ 例如，镍，钌...

石墨烯是一种具有独特的线性带结构，这产生了其具有卓越的电气，光学和机械性质的二维材料。1,9-16它的低能量的电荷载体被描述为相对论，无质量狄拉克费米子15，其行为从在传统系统非相对论电荷载体显著不同。的各种杂质15-18受控沉积到石墨烯提供了一种简单而通用的平台的这些相对论电荷载体的范围扰动的响应的实验研究。这种系统的调查表明，石墨烯杂质可以转移化学势6,7，改变有效介电常数8，并有可能导致电子介导的超导9。许多这样的研究6-8雇用静电门控，以调整混合impurit的特性的装置Y型石墨烯器件。静电门控可相对于它的费米能级没有滞后2-5此外移位的材料的电子结构，通过调整这些杂质的电荷2或分子5个州，静电门控可以可逆地修改混合杂质石墨烯的特性装置。 背门控石墨烯器件提供了用于调查通过扫描隧道显微镜（STM）的理想系统。扫描隧道显微镜是由从导电表面的几埃客场举行了锋利的金属尖的。通过将两者之间的尖端与表面时，电子隧道之间的偏差。在最常见的方式，恒定电流方式，人们可以通过光栅扫描的前端来回映射样品表面的形貌。此外，样品的局部电子结构可通过检查一个微分电导的dI /的dV谱，它正比于局部去加以研究状态nsity器（LDO）。该测量通常被称为扫描隧道谱（STS）。通过单独控制偏置和背栅极电压，石墨烯的杂质的反应可以通过分析这些的dI / DV光谱的行为进行了研究。2-5 在这份报告中，饰以库仑杂质的背门控石墨烯器件的制造（ 如钙带电原子）概述。该装置由按以下顺序（从顶部到底部）的元素：钙吸附原子和集群，石墨烯，六方氮化硼（的h-BN），二氧化硅（SiO 2）的，与体硅（ 图1）。的h-BN是一种绝缘薄膜，它提供了一个原子级平坦，并电同质衬底用于将石墨烯19-21的h-BN和SiO 2充当电介质，和体Si用作背栅。 为了制造该装置，石墨烯，首先生长在一个electrochemically抛光Cu箔22,23，它作为一个干净的催化表面的化学气相沉积（CVD）石墨22-25。 CVD生长，甲烷（CH 4）和氢（H 2）的前驱物气体发生热解，从而在Cu箔石墨晶体的结构域。将得到的石墨烯转印到目标衬底这些域成长，最终合并在一起，形成一个多晶石墨烯片25中 ，一个的h-BN / SiO 2的芯片（制备的h-BN的机械剥离19-21上的SiO 2 /硅（100）芯片）， 通过聚（甲基丙烯酸甲酯）（PMMA）的传输。26-28在聚甲基丙烯酸甲酯转移，在Cu的石墨烯是第一旋涂上一层聚甲基丙烯酸甲酯。聚甲基丙烯酸甲酯/石墨烯/铜样品，然后在一个蚀刻剂溶液漂浮（ 例如， 氯化铁（AQ）28），该蚀刻掉铜。未反应的聚甲基丙烯酸甲酯/石墨烯样品捕捞用的h-BN / SiO 2的芯片，并随后在一种有机溶剂清洗（ 例如，CH 2 Cl 2中），和Ar / H 2环境29,30去除的PMMA层。所得石墨烯/的h-BN /的SiO 2 / Si的样品是则引线键合到上的超高真空（UHV）样品板的电接触并退火在超高真空腔室中。最后，该石墨烯器件淀积就地与库仑杂质（ 例如，带电荷的钙原子），并研究由STM 2-5

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Cu foil</td>
			<td>Alfa Aesar</td>
			<td>CAS # 7440-50-8</td>
			<td>99.8% Cu</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>Lot # F22X029</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>Stock # 13382</td>
			<td></td>
		</tr>
		<tr>
			<td>Scotch Magic Tape</td>
			<td>Scotch&#174;</td>
			<td>N/A</td>
			<td>for exfoliation of hBN</td>
		</tr>
		<tr>
			<td>PMMA</td>
			<td>Micro Chem</td>
			<td>M23004 0500L 1GL</td>
			<td>A4</td>
		</tr>
		<tr>
			<td>FeCl3 resistant spoon</td>
			<td>Bel-Art ScienceWare</td>
			<td>367300015</td>
			<td>PTFE coated double ended&#160;</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>chemical spoon, 15 cm length</td>
		</tr>
		<tr>
			<td>FeCl3 (aq)</td>
			<td>Ricca Chemical</td>
			<td>3127-16</td>
			<td>40% w/v</td>
		</tr>
		<tr>
			<td>SiO2/Si(100) Chip</td>
			<td>NOVA Electric Materials</td>
			<td>HS39626-OX</td>
			<td>n/a</td>
		</tr>
		<tr>
			<td>h-BN</td>
			<td>K. Watanabe and</td>
			<td>Contact the group</td>
			<td>hexagonal Japanese BN (JBN)</td>
		</tr>
		<tr>
			<td></td>
			<td>T. Taniguchi Group</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Au(111)</td>
			<td>Agilent Technologies</td>
			<td>N9805B-FG</td>
			<td>Au(111) epitaxially grown on mica</td>
		</tr>
		<tr>
			<td>Sapphire</td>
			<td>Precision Ferrites &#38; Ceramic, Inc.</td>
			<td>Contact vendor</td>
			<td>P/N Sapphire Chips</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>0.22 X 0.125 X 0.015&#34;</td>
		</tr>
		<tr>
			<td>Ca source</td>
			<td>Trace Sciences International Corp.</td>
			<td>AS-3-Ca-5-S</td>
			<td>n/a</td>
		</tr>
		<tr>
			<td>Cu(100)</td>
			<td>Princeton Scientific</td>
			<td>Contact vendor</td>
			<td>Cu(100) single crystal</td>
		</tr>
		<tr>
			<td>Methane</td>
			<td>Praxair, Inc.</td>
			<td>ME 5.0RS-K</td>
			<td>Graphene growth precursor gas</td>
		</tr>
		<tr>
			<td>Hydrogen</td>
			<td>Praxair, Inc.</td>
			<td>HY 6.0RS-K</td>
			<td>Graphene growth precursor gas</td>
		</tr>
	</tbody>
</table>

fabrication of gate-tunable graphene devices for scanning tunneling microscopy studies with coulomb impurities

由于其相对论低能量的电荷载体，石墨和各种杂质之间的相互作用导致了大量新的物理和自由度来控制电子设备的。特别是，石墨烯的电荷载体从带电库仑杂质响应于电位的行为被预测为从大多数材料的显著不同。扫描隧道显微镜（STM）和扫描隧道谱（STS）可以提供关于石墨烯的电子结构中带电荷的杂质的存在下既在空间和能源的依赖的详细信息。混合杂质石墨烯器件的设计，制造使用的杂质来控制沉积在背面门控石墨烯表面上，使若干新颖方法，用于可控地调谐石墨烯的电子特性。1-8静电门控使得在石墨烯的电荷载流子密度控制并能够黑白棋布莱调充电2和/或杂质的分子5个状态。本文概述制造装饰有个别库仑杂质为组合的STM / STS研究栅极可调石墨烯器件的方法。2-5这些研究提供了有价值的见解底层物理，以及用于设计杂交石墨烯器件的路标。

图1示出了背门控石墨烯器件的示意图。导线接合对Au / Ti接触到一个超高真空样品板为由石墨电，而引线接合的Si散装于连接到一个外部电路背栅的装置中的电极。通过背门控装置，由库仑杂质的在给定的样品偏压的电荷状态（这是由STM针尖控制）可以被调谐到不同的电荷状态。2-4 图2概述的步骤用于制造栅极可调石墨烯器件。铜箔第一电化?...

Watch this Scientific Journal Video about Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities at JoVE.com

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

This paper details the fabrication process of a gate-tunable graphene device, decorated with Coulomb impurities for scanning tunneling microscopy studies. Mapping the spatially dependent electronic structure of graphene in the presence of charged impurities unveils the unique behavior of its relativistic charge carriers in response to a local Coulomb potential.

对于扫描隧道显微学与库仑杂质制造门可调谐石墨烯器件

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees ...

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JoVE Journal

Engineering

15.3K 次观看.  University of California at Berkeley. This paper details the fabrication process of a gate-tunable graphene device, decorated with Coulomb impurities for scanning tunneling microscopy studies. Mapping the spatially dependent electronic structure of graphene in the presence of charged impurities unveils the unique behavior of its relativistic charge carriers in response to a local Coulomb potential.

视频: Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

全面解决方案处理的无机纳米晶体光伏器件的制造

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

科研

工程学

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

溶剂粘接的PMMA的制备和COP微流体装置

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

基于扫描光散射分析器（SLPS）的方法来量化评估来自眼内镜的前向和后向光散射

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

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

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

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

全电子纳秒分辨扫描隧道显微镜: 促进单一掺杂剂电荷动力学的研究

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

Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO2/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 &#197; and lateral dimensions of about 30 &#181;m &#215; 50 &#181;m were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.

A protocol is presented demonstrating a two-step fabrication technique to grow large-sized single-layer rectangular shaped SnSe flakes on low-cost SiO2/Si dielectrics wafers in an atmospheric pressure quartz tube furnace system.

大型单层矩形 SnSe 片的常压制备

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for ...

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.

A protocol for the fabrication of magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for transmission electron microscopy (TEM) and magnetic transmission x-ray microscopy (MTXM) studies is presented.

用透射显微技术制备氮化硅薄膜磁性纳米结构的研究

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared ...

Fabrication of Refractive-index-matched Devices for Biomedical Microfluidics

The use of microfluidic devices has emerged as a defining tool for biomedical applications. When combined with modern microscopy techniques, these devices can be implemented as part of a robust platform capable of making simultaneous complementary measurements. The primary challenge created by the combination of these two techniques is the mismatch in refractive index between the materials traditionally used to make microfluidic devices and the aqueous solutions typically used in biomedicine. This mismatch can create optical artifacts near the channel or device edges. One solution is to reduce the refractive index of the material used to fabricate the device by using a fluorinated polymer such as MY133-V2000 whose refractive index is similar to that of water (n = 1.33). Here, the construction of a microfluidic device made out of MY133-V2000 using soft lithography techniques is demonstrated, using O2 plasma in conjunction with an acrylic holder to increase the adhesion between the MY133-V2000 fabricated device and the polydimethylsiloxane (PDMS) substrate. The device is then tested by incubating it filled with cell culture media for 24 h to demonstrate the ability of the device to maintain cell culture conditions during the course of a typical imaging experiment. Finally, quantitative phase microscopy (QPM) is used to measure the distribution of mass within the live adherent cells in the microchannel. This way, the increased precision, enabled by fabricating the device from a low index of refraction polymer such as MY133-V2000 in lieu of traditional soft lithography materials such as PDMS, is demonstrated. Overall, this approach for fabricating microfluidic devices can be readily integrated into existing soft lithography workflows in order to reduce optical artifacts and increase measurement precision.

This protocol describes the fabrication of microfluidic devices from MY133-V2000 to eliminate artifacts that often arise in microchannels due to the mismatching refractive indices between microchannel structures and an aqueous solution. This protocol uses an acrylic holder to compress the encapsulated device, improving adhesion both chemically and mechanically.

生物医学微流体折射率匹配器件的研制

The use of microfluidic devices has emerged as a defining tool for biomedical applications. When combined with modern microscopy techniques, these devices ...

Fabrication of Three-Dimensional Graphene-Based Polyhedrons via Origami-Like Self-Folding

The assembly of two-dimensional (2D) graphene into three-dimensional (3D) polyhedral structures while preserving the graphene's excellent inherent properties has been of great interest for the development of novel device applications. Here, fabrication of 3D, microscale, hollow polyhedrons (cubes) consisting of a few layers of 2D graphene or graphene oxide sheets via an origami-like self-folding process is described. This method involves the use of polymer frames and hinges, and aluminum oxide/chromium protection layers that reduce tensile, spatial, and surface tension stresses on the graphene-based membranes when the 2D nets are transformed into 3D cubes. The process offers control of the size and shape of the structures as well as parallel production. In addition, this approach allows the creation of surface modifications by metal patterning on each face of the 3D cubes. Raman spectroscopy studies show the method allows the preservation of the intrinsic properties of the graphene-based membranes, demonstrating the robustness of our method.

Fabrication of Three-Dimensional Graphene-Based Polyhedrons via Origami-Like Self-Folding

Here, we present a protocol for fabrication of 3D graphene-based polyhedrons via origami-like self-folding.

基于折纸式自折叠的三维石墨烯正多面体的制备

The assembly of two-dimensional (2D) graphene into three-dimensional (3D) polyhedral structures while preserving the graphene's excellent inherent ...

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements toward the development of new experimental techniques and methodologies. Here we use a novel home-built uniaxial-strain device integrated into our variable temperature scanning tunneling microscope that enables us to controllably manipulate in-plane uniaxial strain in samples and probe their electronic response at the atomic scale. Using scanning tunneling microscopy (STM) with spin-polarization techniques, we visualize antiferromagnetic (AFM) domains and their atomic structure in Fe1+yTe samples, the parent compound of iron-based superconductors, and demonstrate how these domains respond to applied uniaxial strain. We observe the bidirectional AFM domains in the unstrained sample, with an average domain size of ~50-150 nm, to transition into a single unidirectional domain under applied uniaxial strain. The findings presented here open a new direction to utilize a valuable tuning parameter in STM, as well as other spectroscopic techniques, both for tuning the electronic properties as for inducing symmetry breaking in quantum material systems.

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

Using uniaxial strain combined with spin-polarized scanning tunneling microscopy, we visualize and manipulate the antiferromagnetic domain structure of Fe1+yTe, the parent compound of iron-based superconductors.

利用自旋偏振扫描隧道显微镜对 fe 1+yTe 中的反铁磁领域进行单轴应变操作

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements toward the development of new experimental ...

Fabrication of Nanoheight Channels Incorporating Surface Acoustic Wave Actuation via Lithium Niobate for Acoustic Nanofluidics

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order surface acoustic wave (SAW) devices generate tremendous acceleration on their surface, up to 108 m/s2, in turn responsible for many of the observed effects that have come to define acoustofluidics: acoustic streaming and acoustic radiation forces. These effects have been used for particle, cell, and fluid manipulation at the microscale, although more recently SAW has been used to produce similar phenomena at the nanoscale through an entirely different set of mechanisms. Controllable nanoscale fluid manipulation offers a broad range of opportunities in ultrafast fluid pumping and biomacromolecule dynamics useful for physical and biological applications. Here, we demonstrate nanoscale-height channel fabrication via room-temperature lithium niobate (LN) bonding integrated with a SAW device. We describe the entire experimental process including nano-height channel fabrication via dry etching, plasma-activated bonding on lithium niobate, the appropriate optical setup for subsequent imaging, and SAW actuation. We show representative results for fluid capillary filling and fluid draining in a nanoscale channel induced by SAW. This procedure offers a practical protocol for nanoscale channel fabrication and integration with SAW devices useful to build upon for future nanofluidics applications.

We demonstrate fabrication of nanoheight channels with the integration of surface acoustic wave actuation devices upon lithium niobate for acoustic nanofluidics via liftoff photolithography, nano-depth reactive ion etching, and room-temperature plasma surface-activated multilayer bonding of single-crystal lithium niobate, a process similarly useful for bonding lithium niobate to oxides.

通过用于声学纳米流体的尼奥布精锂结合表面声波驱动纳米高通道的制造

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order ...