这项研究得到1000名中国青年科学家、国家自然科学基金 (51472164 号赠款)、A * 星航标灯方案 (赠款 152 70 00014) 和新加坡国立大学高级2D 技术中心提供的设施支持。材料.

注意: 这项工作中使用的一些化学剂和气体是有毒的、致癌的、易燃的和爆炸性的。在进行蒸汽输送沉积时, 请使用所有适当的安全措施, 包括使用工程控制 (油烟机) 和个人防护设备 (安全眼镜、专业防护口罩、手套、实验室大衣、全长裤子, 和封闭脚趾鞋)。
1. 温度控制器参数的自动调谐功能
注: 在合成 SnSe 片之前, 需要按照制造商的手册来校准炉子的加热系统。
<ol><li>将最常用温度的80% 设置为目标温度。这里, 将 560 oC 设置为1小时, 然后运行熔炉。</li>
	<li>当温度接近 560 oC 时, 按 2 s 的 "设置" 键, 注意参数 "HAL" 弹出, 然后按 1 s 的 "设置" 键转到下一个参数。</li>
	<li>继续按下 "设置" 键。出现 "Cont=3" 后, 将其设置为2。系统启动自动调谐功能, 以算出 Int、Pro 和 it 的值, 然后系统将转到3。当需要重新自动调整时, 将其设置为2。</li>
</ol>2. 石英管和陶瓷船的预处理
注: 在合成 SnSe 片之前, 需要一个高温清洗工艺, 新的陶瓷船和新的石英管被预处理。
<ol><li>在新的1英寸直径的石英管内放置一条新的陶瓷船。将1英寸直径的石英管放在水平管炉内, 用新的2英寸直径的石英管。确保管道两端牢固固定和支持。</li>
	<li>关闭炉盖, 加热管炉至 1000 oC 30 分钟以上。</li>
	<li>当加热炉中心的温度接近 1000 oc 时, 将炉子保持在 1000 oc 上30分钟。然后, 逐渐将管式炉从一端移到另一个端, 以加热整个管的长度, 以清洗石英管壁和陶瓷船。</li>
	<li>在此之后, 让管炉冷却到室温通过关闭炉。当炉冷却到室温, 打开炉盖, 取出新的陶瓷船和新的1英寸直径的石英管, 可用于后续实验。</li>
</ol>3. 预处理- 2 /Si 基板
<ol><li>在重掺杂 Si 上剪切2/Si 硅片 (300 nm 厚的 x2 ) (参见材料表), 使用菱形划线, 将其用作生长基质。</li>
	<li>在丙酮、异丙醇和水中清洁2/Si 基底, 然后氮气吹干。</li>
</ol>4. 大体积矩形 SnSe 片的合成
<ol><li>在清洁的陶瓷船上放置0.010 克 SnSe 粉 (参见材料表)。将干净的2/Si 衬底 (大约1.5 厘米 x 2 厘米) 放到陶瓷船上, 生长侧面对 SnSe 粉末。将陶瓷船放置在一个干净的1英寸直径的石英管内。</li>
	<li>将1英寸直径的石英管放在水平管式炉内, 外部有2英寸直径的石英管, 并确保陶瓷船位于管式炉加热区的上游。拧紧管两端的法兰, 关闭排气阀, 密封2英寸直径的石英管。</li>
	<li>打开连接到石英管的泵, 将管泵成 ~ 1×10-2毫巴的压力, 以去除管内的空气和湿气。压力实现后, 关闭泵。</li>
	<li>然后打开载气阀, 使用气体流量计控制气体流量。将40标准立方厘米每分钟 (sccm) Ar 和 10 sccm H2 (纯度: 99.9%) 引入石英管, 直到大气压达到。打开排气阀, 使石英管中的气体连续流动。</li>
	<li>关闭炉盖, 用 35 oC 每分钟加热速率快速加热管式炉。</li>
	<li>当炉膛中心的温度接近 700 oC 时, 快速移动管式炉, 将 SnSe 粉末放置在炉子的中心。SnSe 粉末将蒸发, 散装 SnSe 片将沉积在2/Si 表面。</li>
	<li>经过15分钟的生长时间, 打开炉盖, 快速冷却管炉的室温。同时, 将 Ar/H2的流量调整为最大值, 这将有助于将反应气体或粒子从管中驱动。当生长过程完成后, 将在2/Si 衬底的表面上获得大块 SnSe 薄片。</li>
</ol>5. 单层矩形 SnSe 片的制作
<ol><li>将已长大的散装 SnSe/2/Si 样品朝上一条新的清洁陶瓷船。将陶瓷船放置在一个新的干净的1英寸直径的石英管内。</li>
	<li>将1寸直径的石英管置于水平管炉内, 直径为2英寸的石英管, 与陶瓷船位于炉管加热区的上游。拧紧管两端的法兰, 并关闭排气阀以密封2英寸直径的石英管。</li>
	<li>打开连接到石英管的泵, 将管子向下泵入至 1×10-2毫巴的压力, 以去除管内的空气和湿气。完成后, 关闭泵。</li>
	<li>打开载气阀, 使用气体流量计控制气体流量。将 50 sccm N2 (纯度: 99.9%) 引入石英管, 直到大气压达到。打开排气阀, 使石英管中的气体连续流动。</li>
	<li>关闭炉盖, 并将管炉快速加热至 700 oC, 20 分钟。</li>
	<li>当加热炉中心的温度接近 700 oC 时, 快速移动管式炉, 将散装 SnSe/输出2/Si 样品放置在炉的中心。</li>
	<li>将炉子保持在 700 oC 的5-20 分钟内以完成蚀刻过程。然后, 打开炉盖, 快速冷却管炉到室温。同时, 将 N2气体的流量保持在最大值, 这将有助于将反应气体或粒子从管中驱动。当蚀刻过程完成后, 观察在2/Si 衬底表面获得的单层矩形 SnSe 片。 注: 蚀刻气体和蚀刻时间是该工艺的主要控制因素。在参考29中对蚀刻机理进行了研究, 因此请参阅参考29以了解更多细节。</li>
</ol>

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我们没有什么可透露的。

本文首次报道了气体输送沉积法和氮气蚀刻技术在常压系统中的结合。在该协议中, 关键步骤是制作单层 SnSe 片的部分。
虽然可以将散装试样蚀刻成高质量的单层样品, 但散装试样的厚度应均匀, 试样的分解温度应高于蚀刻温度。由于大多数散装样品完全蚀刻, 因此所得到的样品的覆盖率很低。
对于扫描隧道显微术 (STM) 的应用, 单层样品的覆盖密度不够。然而, 对于光电器件的应用, 覆盖密度是令人满意的。由于最近对新的2D 组 IV monochalcogenides 材料的兴趣有所增加, 我们认为这一简单的两步制造技术可以推广到其他大型高质量超薄2D 材料。
对 SnSe 片的长期稳定性、XRD 分析和拉曼特性的研究可以在其他地方找到29。

近年来, 由于石墨烯的成功分离, 对二维 (2D) 材料的研究已经绽放, 这是因为2D 材料在其散装对应物上具有优异的电学、光学和机械性能1,2,3,4,5. 2D 材料在光电和电子设备中显示有前途的应用6,7, 催化和水分裂8,9, 表面增强拉曼散射传感10、11、等等可剥离成2D 材料的大量分层材料显示出巨大的多样性, 包括从半金属石墨烯到半导体过渡金属 dichalcogenides (TMDs) 和黑色磷 (BP) 对绝缘六角氮化硼 (h BN)。这些材料及其异质结构近年来得到了很好的研究, 并展示了许多新颖的特性和应用12。其他研究较少, 但同样有希望的2D 分层材料, 在通过 (气体, 气体, 和 InSe)13,14和伊娃通过 (GeS, 考试, 和 SnS)15,16,17家庭有最近也受到关注。
SnSe 属于正交结构, 由在pnma空间群中排列的原子组成, 并在层内屈曲, 就像 phosphorene 的晶体结构一样。SnSe 是一个窄隙半导体与带隙 0.6 eV, 但更著名的是其更独特的热电性能, 因为它被报告有一个非常高的 ZT (热电图的优点) 值2.6 在 923 K18,19, 由于其独特的电子结构和低导热性。虽然散装 SnSe 晶体是商用的, 并且可以通过已知的方法来增长, 如布里奇曼-Stockbarger 方法20或化学蒸气传输方法21, 在介电上生长大尺寸的少量层和单层 SnSe基板更具挑战性。有许多支持2D 材料生长的基板, 如高定向热解石墨 (HOPG)、云母、2、Si3N4和玻璃。低成本的2电介质是最常用的基板, 因为它们允许制造场效应晶体管, 其中介质作为电气后门的一部分。根据我们的经验, 与石墨烯和 TMDs 不同, 很难获得少量层或单层 SnSe 片的微机械剥离方法, 因为散装 SnSe 有一个高夹层结合能22 32 兆伏特/Å2, 这导致厚层, 甚至沿剥落片的边缘。因此, 为了研究少量层和单层 SnSe 的新型电子性质, 需要一种新的、简单的、低成本的合成方法, 在绝缘衬底上制备高质量的大型单层 SnSe 晶体, 特别是由于 SnSe 具有作为热电应用的候选者, 在低和中温范围内的能量转换方面表现出很大的希望19。
一些研究人员开发了合成高质量 SnSe 晶体的方法。刘等。23和 Franzman et 。24使用解决方案阶段方法合成不同形状的 SnSe 纳米晶, 如量子点、nanoplates、单晶薄片、nanoflowers 和 nanopolyhedra, 使用 SnCl2和烷基磷化膦硒或二烷基二diselenium 为前体。Baumgardner et 。25通过将双 [双 (三甲基硅) 氨基] 锡 (II) 注入热 trioctylphosphine, 合成了胶体 SnSe 纳米粒子, 并获得了直径为4-10 纳米的纳米晶。Boscher et 。26使用常压化学气相沉积技术, 利用四氯化锡和硒化二元前体, 在玻璃基底上获得 SnSe 薄膜, 其氯化锡比为硒化二乙酯, 其合成SnSe 薄膜约100纳米厚, 银色黑色的外观。赵等。27在低真空系统中使用了蒸气输送沉积, 在云母基体上合成了单晶 SnSe nanoplates, 得到了1-6 µm 的平方 nanoplates。然而, 使用这些技术不可能获得单层 SnSe 晶体。李等。28使用 SnCl4和 SeO2前体的一壶合成方法成功合成单层单晶 SnSe 薄片。然而, 他们只能获得大约300毫微米的横向大小为他们的薄片。我们最近发布了我们的方法, 以发展高质量的, 大型的单层 SnSe 晶体, 这是阶段纯29。这项详细的协议旨在帮助新的从业者使用这种方法种植其他大型高品质的超薄2D 材料。

<table><tbody><tr><td>SnSe powder</td><td>Sigma-Aldrich</td><td>1315-06-6</td><td>(99.999%) toxic, carcinogenic</td></tr><tr><td>Ar gas</td><td></td><td></td><td>explosive</td></tr><tr><td>H2 gas</td><td></td><td></td><td>flammable, explosive</td></tr><tr><td>SiO&lt;sub&gt;2&lt;/sub&gt;/Si wafer</td><td></td><td></td><td>300 nm thick SiO2 on heavily doped Si</td></tr><tr><td>Acetone</td><td>Sigma-Aldrich</td><td>67-64-1</td><td>toxic, flammable</td></tr><tr><td>Isopropanol</td><td>Sigma-Aldrich</td><td>67-63-0</td><td>flammable</td></tr><tr><td>Quartz tube</td><td>Dongjing Quartz Company, China</td><td></td><td></td></tr><tr><td>Ceramic boat</td><td>Dongjing Quartz Company, China</td><td></td><td></td></tr><tr><td>Optical microscope</td><td>Olympus, BX51</td><td></td><td></td></tr><tr><td>Atomic force microscopy</td><td>Bruker</td><td></td><td>Using FastScan-A probe type and ScanAsyst-air</td></tr><tr><td>Scanning electron microscopy</td><td>JEOL JSM-6700F</td><td></td><td></td></tr><tr><td>transmission electron microscopy</td><td>FEI Titan</td><td></td><td></td></tr><tr><td>Tube furnace</td><td>MTI Corporation</td><td></td><td></td></tr></tbody></table>

atmospheric pressure fabrication of large-sized single-layer rectangular snse flakes

硒化锡 (SnSe) 属于具有 phosphorene 的屈曲结构的层状金属硫材料的家族, 并在二维电子学器件中显示了应用潜力。虽然已经开发了许多合成 SnSe 纳米晶的方法, 但制作大型单层 SnSe 片的简单方法仍然是一个巨大的挑战。在常压石英管中, 采用直接两步法制作方法, 给出了在常用的2/Si 绝缘衬底上使用普通的单层矩形 SnSe 片的实验方法。炉系统。采用气相输送沉积技术和氮蚀刻工艺相结合, 制备了平均厚度为6.8 Å的单层矩形 SnSe 片和大约30µm x 50 µm 的横向尺寸。对矩形 SnSe 片的形貌、显微结构和电学性能进行了表征, 获得了优良的结晶度和良好的电子性能。这篇文章的两步制作方法可以帮助研究人员发展其他类似的二维, 大型, 单层材料使用大气压系统。

实验仪器的示意图, 光学图像, 原子力显微镜 (AFM) 图像, 扫描电子显微镜 (SEM) 图像, 透射电镜 (TEM) 图像的捏造 SnSe 片显示在图 1中,图 2和图 3。光学图像由传统的光学显微镜完成。目镜透镜为 10X, 物镜为20X、50X 和100X。曝光时间约为0.3 秒。得到的光学图像的分辨率是1,376×1,038 的。扫描大小为30µm, 长宽比为1。X 和 Y 偏移和角度都设置为0。扫描速率为3.92 赫兹, 512 个样本/线。积分增益和比例增益分别设置为1.000 和5.000。振幅设定, 驱动频率和振幅设置为 208.9 mv, 1400.789 赫, 85.14 mv, 分别。扫描电镜和 TEM 图像分别在30伏和200伏的电子显微镜下进行。
图 1显示了将前体 SnSe 粉蒸发的过程, 该粉末通过在常压石英上的蒸气传输沉积技术, 沉积在的 2/Si 表面, 以生长大尺寸的矩形大块 SnSe 片.管系统。为了制造单层 SnSe 片, 我们将已长大的散装 SnSe/的 2/Si 样品转移到相邻的氮气蚀刻管炉中.我们没有使用任何热/化学处理方法, 也没有必要后, 生长过程。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57023/57023fig1.jpg"> 图 1: 合成.示意图显示了合成大块矩形 SnSe 片的实验装置和工艺, 并制作了单层矩形 SnSe 片。<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57023/57023fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
图 2显示了合成的大块和单层 SnSe 片的形貌的光学显微学和 AFM 特性。我们发现, 散装和单层 SnSe 片大约是长方形的, 并在2/Si 基底上随机生长。图 2a-d和图 2fi: 我们获得的 SnSe 片约为30µm x 50 µm 大小, 约200倍大, 比单层单晶 SnSe 薄片获得的李等.28图 2e显示了一个 AFM 图像, 其对应的线条轮廓为典型合成的大块 SnSe 片, 露出一个厚度约54.9 到 5.6 nm 的平坦表面。我们测量了超薄矩形 SnSe 片 (图 2j) 的厚度为6.8 到1.4 Å, 接近于5.749 Å18的单层 SnSe 的理论值。
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57023/57023fig2.jpg"> 图 2: SnSe 片的图像.合成的批量 (a d) 和单层 (f i) 矩形形状 SnSe 片的光学图像。SnSe 的典型 AFM 图像 (e) 和单层 (j) 矩形形状的图形, 分别位于 (a) 和 (f) 的片状边缘。版权所有: 眼压出版 (允许复制要求)。此数字已由江et 等修改。29<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57023/57023fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
通过 SEM 和能量色散 X 射线光谱分析 (EDX), 对合成样品的显微结构和化学成分进行了分析, 并对 SnSe 片进行了表征。图 3a-b显示了典型的大容量和单层 SnSe 片的扫描电镜图像, 它们随机分布在的 2/Si 硅片表面上.我们可以看到, 体积和单层 SnSe 片约为矩形, 尺寸约为30µm x 50 µm, 与光学显微图像 (图 2) 获得的结果非常一致。EDX 频谱 (图 3c) 显示了在合成的散装样品中 Sn 和 Se 的 1:0. 92 原子比, 它证实了化学计量 SnSe 而不是 SnSe2。图 3d显示了传输的 SnSe 片段的典型 TEM 图像。单层 SnSe 碎片的选定区域电子衍射模式 (萨德) 清楚地展示了正交对称衍射模式 (图 3e), 表明我们的样品在自然界中是单晶的。单层 SnSe 片通常沿 [100] 平面方向定向, 因为萨德还显示0kl反射的斑点图案。图 3f显示了传输的 SnSe 片段的高分辨率 tem (HR) 图像, 其两个明显的正交格子条纹来自于 0.30 nm 的平面和格子间距。格子条纹之间的角度约为 86.5o, 对应于正交晶体结构, 与理论18一致。
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57023/57023fig3.jpg"> 图 3: SEM 图像(a) 和 EDX 光谱 (c) 的散装 SnSe 片;SEM 图像 (b), TEM 图像 (d), 萨德模式 (e), 和高分辨率 TEM 图像 (f) 的单层矩形 SnSe 片碎片, 分别。版权所有: 眼压出版 (允许复制要求)。此数字已由江et 等修改。29<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57023/57023fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes at JoVE.com

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

提出了一种在常压石英管炉系统中, 在低成本的2/Si 介质晶片上生长大型单层矩形 SnSe 片的两步法制造技术。

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 ...

atmospheric-pressure-fabrication-large-sized-single-layer-rectangular

Nanyang Technological University

Research

JoVE Journal

Engineering

8.1K 次观看.  Shenzhen University. 提出了一种在常压石英管炉系统中, 在低成本的2/Si 介质晶片上生长大型单层矩形 SnSe 片的两步法制造技术。

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

Origami Inspired Self-assembly of Patterned and Reconfigurable Particles

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize.
In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 &mu;m to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to possibly create even smaller nanoscale grasping devices.

We describe experimental details of the synthesis of patterned and reconfigurable particles from two dimensional (2D) precursors. This methodology can be used to create particles in a variety of shapes including polyhedra and grasping devices at length scales ranging from the micro to centimeter scale.

折纸灵感的图案和可重构颗粒自组装

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two ...

科研

化学

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

原子定义模板复合氧化物薄膜的外延生长

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

大面积的制造自立性的超薄聚合物薄膜

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices.

Tin sulfide (SnS) is a candidate material for Earth-abundant, non-toxic solar cells. Here, we demonstrate the fabrication procedure of the SnS solar cells employing atomic layer deposition, which yields 4.36% certified power conversion efficiency, and thermal evaporation which yields 3.88%.

通过热蒸发和原子层沉积使记录效率的SnS太阳能电池

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent ...

工程学

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

对于新材料的低温磁输运测量先进的实验方法

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. Layered crystals of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) are exfoliated in aqueous surfactant solution by sonication. This yields highly polydisperse mixtures containing nanosheets with broad size and thickness distributions. However, for most purposes, specific sizes (in terms of both lateral dimension and thickness) are required. For example, large and thin nanosheets are desired for (opto) electronic applications, while laterally small nanosheets are interesting for catalytic applications. Therefore, post-exfoliation size selection is an important step that we address here. We provide a detailed protocol on the efficient size selection in large quantities by liquid cascade centrifugation and the size and thickness quantification by statistical microscopic analysis (atomic force microscopy and transmission electron microscopy). The comparison of MoS2 and WS2 shows that both materials are size-selected in a similar way by the same procedure. Importantly, the dispersions of size-selected nanosheets show systematic changes in their optical extinction spectra with size due to edge and confinement effects. We show how these optical changes are related quantitatively to the nanosheets dimensions and describe how mean nanosheets length and layer number can be extracted reliably from the extinction spectra. The exfoliation and size selection protocol can be applied to a broad range of layered crystals as we have previously demonstrated for graphene, gallium sulphide (GaS) and black phosphorus.

A protocol for the liquid exfoliation of layered materials to nanosheets, their size selection and size measurement by microscopic and spectroscopic techniques is presented.

与尺寸可控液体剥离的过渡金属二硫属化物纳米片和厚度的制备:艺术议定书的国家

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. ...

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 ...

Exfoliation and Analysis of Large-area, Air-Sensitive Two-Dimensional Materials

We describe methods for producing and analyzing large, thin flakes of air-sensitive two-dimensional materials. Thin flakes of layered or van der Waals crystals are produced using mechanical exfoliation, in which layers are peeled off a bulk crystal using adhesive tape. This method produces high-quality flakes, but they are often small and can be hard to find, particularly for materials with relatively high cleavage energies such as black phosphorus. By heating the substrate and the tape, two-dimensional material adhesion to the substrate is promoted, and the flake yield can be increased by up to a factor of ten. After exfoliation, it is necessary to image or otherwise analyze these flakes but some two-dimensional materials are sensitive to oxygen or water and will degrade when exposed air. We have designed and tested a hermetic transfer cell to temporarily maintain the inert environment of a glovebox so that air-sensitive flakes can be imaged and analyzed with minimal degradation. The compact design of the transfer cell is such that optical analysis of sensitive materials can be performed outside of a glovebox without specialized equipment or modifications to existing equipment.

A method for exfoliating large thin flakes of air sensitive two-dimensional materials and safely transporting them for analysis outside of a glovebox is presented.

大面积空气敏感二维材料的去角质与分析

We describe methods for producing and analyzing large, thin flakes of air-sensitive two-dimensional materials. Thin flakes of layered or van der Waals ...

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 ...

Fabricating van der Waals Heterostructures with Precise Rotational Alignment

In this work we describe a technique for creating new crystals (van der Waals heterostructures) by stacking distinct ultrathin layered 2D materials. We demonstrate not only lateral control but, importantly, also control over the angular alignment of adjacent layers. The core of the technique is represented by a home-built transfer setup which allows the user to control the position of the individual crystals involved in the transfer. This is achieved with sub-micrometer (translational) and sub-degree (angular) precision. Prior to stacking them together, the isolated crystals are individually manipulated by custom-designed moving stages that are controlled by a programmed software interface. Moreover, since the entire transfer setup is computer controlled, the user can remotely create precise heterostructures without coming into direct contact with the transfer setup, labeling this technique as &#8220;hands-free&#8221;. In addition to presenting the transfer set-up, we also describe two techniques for preparing the crystals that are subsequently stacked.

In this work we describe a technique that is used to create new crystals (van der Waals heterostructures) by stacking ultrathin layered 2D materials with precise control over position and relative orientation.

使用精确旋转对齐来制造范德瓦尔斯异构结构

In this work we describe a technique for creating new crystals (van der Waals heterostructures) by stacking distinct ultrathin layered 2D materials. We ...