这项工作得到了部分支持, 其中大部分是由 105-2221-001-011-MY3 和最多 105-2622-8-002-001 的项目资助, 由科技部, 台湾, 并部分由应用科学研究中心资助的重点项目, 中央研究院,台湾。

1. 单个2D 材料的增长 (MoS2和 WS2)
<ol><li>
用射频溅射系统进行过渡金属沉积
	<ol>
<li>一个干净的 2 x 2 cm2蓝宝石衬底放置在样品持有人与抛光的一面向溅射系统的目标的过渡金属沉积。蓝宝石基板的选择是由于蓝宝石在高温和原子平面表面的化学稳定性。</li>
		<li>泵下溅射室到 3 x 10-6乇依次使用一个机械泵, 其次是扩散泵。</li>
		<li>将 Ar 气体注入溅射系统, 并使用质量流量控制器 (MFC) 使气体流量保持在40毫升/分钟。</li>
		<li>使用手动压力控制阀将腔室压力保持在 5 x 10-2乇上, 并点燃 Ar 等离子体。将输出功率保持在 40 W。</li>
		<li>使用手动轮角锥阀将燃烧室压力降低到 5 x 10-3乇。</li>
		<li>手动打开蓝宝石衬底与2英寸金属靶之间的快门, 并开始金属沉积。在沉积过程中, 将溅射功率保持在 40 w, 用于钼和钨。背景压力保持在 5 x 10-3乇与40毫升/分钟氩气流量。</li>
		<li>控制溅射时间, 沉积不同厚度的过渡金属薄膜。由于金属厚度薄, 溅射时间将提供更好的控制膜厚度比从石英晶体谐振器的读数。 注意: 使用当前原稿所讨论的方法生长的 MoS2和 WS2的层数与 pre-deposited 钼和 W 薄膜的溅射次数成正比。溅射时间的确定获得 MoS2和 WS2与所需的层数是基于横断面高分辨率透射电子显微镜 (HRTEM) 图像的不同溅射时间的样品。然而, 如果 pre-deposited 钼和 w 薄膜太厚, mo 和 w 氧化物的分离将成为主导生长机制, 而不是平面 MoS2和 WS2胶片增长。因此, 层数与溅射时间的比例仅限于少量层 TMDs。随着 mos2在当前原稿中的生长情况, 当 mos2胶片少于10层时, 层数将与溅射时间成正比。溅射时间是三十年代为5层 MoS 的成长2。</li>
	</ol>
</li>
	<li>
过渡金属膜的硫化
	<ol>
<li>将蓝宝石衬底与 pre-deposited 过渡金属薄膜放在热熔炉的中心硫化。</li>
		<li>将硫磺粉放在气流的上游, 距离炉子加热区2厘米。在这个位置, 当基体温度增加到800° c 时, S 粉末的蒸发温度将是120° c。精确控制硫化中不同过渡金属的粉末重量。在工作中, S 粉末重量是1.5 克为 Mo 和 1.0 g 为 W。 注: 我们根据每种用不同的硫粉制备的材料的结果, 确定了用于制备 MoS2和 WS2薄膜的硫粉量。</li>
		<li>保持炉膛压力在0.7 乇。在硫化过程中, 使用130毫升/分钟氩气作为载体气体。</li>
		<li>将加热炉的温度从室温提高到800° c, 在40分钟内将温度提高到20° c/分钟. 将温度保持在800° c, 直到硫粉完全蒸发。之后, 加热器的功率被切断, 以降低炉温。炉子从800° c 到达室温需要大约30到40分钟。</li>
	</ol>
</li>
	<li>使用 488 nm 激光15,16,17执行拉曼光谱测量。获取横截面 HRTEM 图像以验证2D 晶体的层数15、16、17。</li>
</ol>2. WS2/MoS2垂直单杂结构的增长
注: 本节用于创建一个由5层 MoS2和4层 WS2组成的具有蓝宝石层的单异质结构。
<ol><li>按照与步骤1.1 相同的步骤操作。使用三十年代溅射时间的射频溅射系统将 Mo 薄膜沉积在蓝宝石衬底上。</li>
	<li>Sulfurize 的 Mo 薄膜遵循相同的硫化步骤 1.2, 为 MoS2的增长。五层 MoS2将在硫化过程之后获得。</li>
	<li>按照步骤1.1 的相同步骤操作。使用三十年代溅射时间的射频溅射系统将 W 薄膜沉积在 MoS2/蓝宝石衬底上。</li>
	<li>Sulfurize 为 WS2的增长而遵循步骤1.2 的相同硫化过程的 W 胶片。WS2的四层将在硫化过程之后的 MoS2的顶部获得。 注: 金属沉积和硫化过程与个别材料相同。Mo 和 W 薄膜的溅射时间取决于 MoS2和 WS2层所需的层数。可以通过重复相同的生长过程来建立双或 multi-hetero 结构。在垂直异质结构中, TMDs 的序列也可以根据样本结构而改变。</li>
</ol>3. 薄膜传输和器件制作程序
<ol><li>
2D 晶体薄膜的膜传递过程
	<ol>
<li>自旋外套三滴聚 (甲基丙烯酸甲酯) (PMMA) 在 TMD 薄膜上覆盖整个薄膜室温。两级旋转转速的微调是 500 rpm 为十年代和 800 rpm 为十年代。在120° c 固化5分钟后, PMMA 厚度约为3µm。</li>
		<li>将 PMMA/TMD/蓝宝石样品放在充满去离子水的培养皿中。</li>
		<li>利用在 DI 水中的镊子, 从蓝宝石基体上剥离出 PMMA/TMD 薄膜的一角。</li>
		<li>热250毫升的1米 koh 水溶液 (14 克 koh 丸混合250毫升水) 在烧杯到100° c。将样品移动到加热的 KOH 水溶液中, 继续剥离 PMMA/TMD 薄膜, 直到胶片完全从基底剥离。剥皮需要大约1分钟完成。</li>
		<li>使用一个单独的蓝宝石衬底, 从 KOH 溶液中舀出 PMMA/TMD 薄膜。将胶片移至250毫升的烧杯中, 用 DI 水冲洗膜上的残渣。在这一阶段, PMMA/TMD 薄膜与蓝宝石底材之间的附着力很弱。因此, 这部影片将 de-attach 从蓝宝石衬底浸入到 DI 水中。</li>
		<li>重复步骤 3.1.4-3.1.5 三次使用新的 DI 水, 以确保大部分的残留 KOH 是从影片中删除。 注意: 每个 TMD 层之间的附着力要比蓝宝石衬底的 TMDs 强得多。因此, 相同的传输过程可以应用于单个 MoS2/WS2材料或其异质结构。2D 晶体薄膜将被完全剥离的基板, 这是类似于剥离的 MoS2/石墨烯杂-结构在以前的出版物中讨论18。根据转移薄膜的目的, 本步骤中提到的基板可以是蓝宝石衬底或带有 pre-deposited 电极的2/Si 衬底, 如步骤3.2 所述。其他基板也可用于此目的。</li>
	</ol>
</li>
	<li>
2D 晶体晶体管的制造。
	<ol>
<li>使用标准光刻来定义的电极模式, 在2/Si 衬底15,16,17。由 10 nm 钛 (Ti) 或 100 nm 金 (Au) 制成的源和漏极电极是在 300 nm 的2/p 型 Si 衬底上制作的。</li>
		<li>将带 pre-patterned 的源/漏极的2/Si 衬底浸入装满 DI 水的烧杯中, 并将其附加到在步骤3.1 中准备的 PMMA/tmd 薄膜的 tmd 一侧。</li>
		<li>烘烤样品在100° c 为3分钟, 在影片以后附有了一层的2/Si 基体, 去除水残渣。</li>
		<li>滴三滴 pmma 的样品与 pmma/TMD 薄膜覆盖整个表面, 使薄膜更牢固地附着在基板上。</li>
		<li>在移动到下一步骤之前, 将样品放置在电子干柜中至少8小时。</li>
		<li>用丙酮填充两个不同的250毫升烧杯。将与 pmma/TMD 薄膜相连的样品依次浸入两个不同的烧杯, 分别填充丙酮50和10分钟, 除去顶部 pmma 层。</li>
		<li>使用标准的光刻和反应离子蚀刻定义晶体管通道15,16,17。后栅 MoS2和 WS2/mos2杂结构晶体管是捏造的151617。设备的通道长度和宽度分别为5和150μ m。</li>
		<li>使用双通道系统源仪器测量晶体管的电流电压特性15,16,17。</li>
	</ol>
</li>
</ol>

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作者没有什么可透露的。

与传统的半导体材料如 Si 和 GaAs 相比, 2D 材料在器件应用中的优势在于有可能将极薄的物体分解成几个原子层。当 si 产业进入 < 10 纳米技术节点时, si 散热 FET 的高长宽比将使器件结构不适合实际应用。因此, 2D 的材料已经出现, 因为它们有可能取代 Si 的电子器件应用。
虽然最研究的2D 材料, 石墨烯, 预计将表现出高的流动性值, 其零带隙性质已导致没有关闭状态的石墨烯晶体?...

获取2D 晶体薄膜的最常见方法之一是使用散装材料的机械剥离1,2,3,4,5。虽然采用这种方法可以很容易地获得高结晶质量的2D 晶体薄膜, 但这一方法不能获得可伸缩的2D 晶体薄膜, 这对实际应用是不利的。在以前的出版物中已经表明, 使用化学气相沉积 (CVD), 大面积和均匀的2D 晶体薄膜可以准备6,7,8,9。利用 CVD 生长技术10、11, 还演示了通过重复相同的生长周期制备的石墨烯基底和层数可控 MoS2薄膜的直接生长。在最近的一份出版物中, 在平面 WSe2/MoS2杂化结构薄片中也使用 CVD 生长技术12进行制作。尽管 CVD 生长技术有望提供可伸缩的2D 晶体薄膜, 但这种生长技术的主要缺点是不同的前体必须位于不同的2D 晶体中。不同的2D 晶体的生长条件也不尽相同。在这种情况下, 当需求增长2D 晶体异质结构时, 生长过程将变得更加复杂。
与 CVD 生长技术相比, pre-deposited 过渡金属薄膜的硫化为 TMDs1314提供了类似但更简单的增长方法。由于生长过程只涉及金属沉积和以下硫化程序, 有可能通过相同的生长过程生长不同的 TMDs。另一方面, 2D 晶体的层数可控性也可以通过改变 pre-deposited 过渡金属厚度来实现。在这种情况下, 对于不同的 TMDs, 需要将增长优化和层数控制降低到单个层. 利用这种方法, 了解生长机制对复杂 TMD 杂化结构的建立也非常重要。
在本文中, MoS2和 WS2薄膜是在类似的金属沉积生长过程中制备的, 其次是硫化程序。在硫充分和缺陷条件下, 通过硫化钼薄膜的研究得到的结果, 在硫化过程中观察到两种生长机制15。在硫充分条件下, 可在硫化过程后获得均匀、层数可控的 MoS2膜。当样品在硫亏缺条件下硫化时, 背景硫不足以形成完整的 MoS2膜, 从而使钼氧化物的分离和聚结成为早期生长阶段的主要机制。在硫化过程15之后, 将获得由少量 MoS2层覆盖的 Mo 氧化物簇的样品。通过顺序金属沉积和以下硫化程序, WS2/MoS2垂直异质结构的层数可控性下到一个单一的层可以准备15,16。利用该技术, 在四区域的蓝宝石衬底上获得了样品: (I) 空白蓝宝石衬底, (II) 独立 MoS2, (III) ws2/mos2异质结构, (IV) 独立 ws217.结果表明, 生长技术有利于垂直2D 晶体杂化结构的建立, 具有选择性生长能力。2D 晶体异质结构的增强装置性能将标志着2D 晶体实际应用的第一步。

<table>
	<tbody>
		<tr>
			<td>RF sputtering system</td>
			<td>Kao Duen Technology</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Furnace for sulfurization</td>
			<td>Creating Nano Technologies</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Polymethyl methacrylate (PMMA)</td>
			<td>Microchem</td>
			<td>8110788</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>KOH, &#62; 85%</td>
			<td>Sigma-Aldrich</td>
			<td>30603</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone, 99.5%</td>
			<td>Echo Chemical</td>
			<td>CMOS110</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfur (S), 99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>13803</td>
			<td></td>
		</tr>
		<tr>
			<td>Molybdenum (Mo), 99.95%</td>
			<td>Summit-Tech</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten (W), 99.95%</td>
			<td>Summit-Tech</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>C-plane Sapphire substrate</td>
			<td>Summit-Tech</td>
			<td>X171999</td>
			<td>(0001) &#177; 0.2 &#176; one side polished</td>
		</tr>
		<tr>
			<td>300 nm SiO2/Si substrate</td>
			<td>Summit-Tech</td>
			<td>2YCDDM</td>
			<td>P-type Si substrate, resistivity: 1-10 &#937; &#183; cm.</td>
		</tr>
		<tr>
			<td>Sample holder (sputtering system)</td>
			<td>Kao Duen Technology</td>
			<td>N/A</td>
			<td>Ceramic material</td>
		</tr>
		<tr>
			<td>Mechanical pump (sputtering system)</td>
			<td>Ulvac</td>
			<td>D-330DK</td>
			<td></td>
		</tr>
		<tr>
			<td>Diffusion pump (sputtering system)</td>
			<td>Ulvac</td>
			<td>ULK-06A</td>
			<td></td>
		</tr>
		<tr>
			<td>Mass flow controller</td>
			<td>Brooks</td>
			<td>5850E</td>
			<td>The maximum Argon flow is 400 mL/min</td>
		</tr>
		<tr>
			<td>Manual wheel Angle poppet valve</td>
			<td>King Lai</td>
			<td>N/A</td>
			<td>Vacuum range from 2500 ~1 &#215; 10-8 torr</td>
		</tr>
		<tr>
			<td>Raman measurement system</td>
			<td>Horiba</td>
			<td>Jobin Yvon LabRAM HR800</td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission electron microscopy</td>
			<td>Fei</td>
			<td>Tecnai G2 F20</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dish</td>
			<td>Kwo Yi</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezer</td>
			<td>Venus</td>
			<td>2A</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital dry cabinet</td>
			<td>Jwo Ruey Technical</td>
			<td>DRY-60</td>
			<td></td>
		</tr>
		<tr>
			<td>Dual-channel system sourcemeter</td>
			<td>Keithley</td>
			<td>2636B</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of large-area vertical 2d crystal hetero-structures through the sulfurization of transition metal films for device fabrication

我们已经证明, 通过硫化过渡金属薄膜, 如钼 (钼) 和钨 (W), 大面积和均匀过渡金属 dichalcogenides (TMDs) MoS2和 WS2可以在蓝宝石衬底上制备。通过控制金属膜厚度, 可以利用这种生长技术获得良好的层数可控性, 降低到单层 TMDs。根据在硫缺乏条件下钼膜硫化的结果, 在硫化过程中, (a) 平面 MoS2生长和 (b) 钼氧化物的分离有两种机制。当背景硫充足时, 平面 TMD 的生长是主要的生长机制, 在硫化过程后会产生均匀的 MoS2膜。如果背景硫缺乏, 在硫化过程的初始阶段, 钼氧化物的分离将成为主要的生长机制。在这种情况下, 将获得覆盖有少量层 MoS2的 Mo 氧化物簇的样品。在连续 Mo 沉积/硫化和 W 沉积/硫化过程之后, 使用这种生长技术建立了垂直 WS2/MoS2杂化结构。分别对应于 WS2和 MoS2的拉曼峰值, 以及与单个2D 材料求和的异质结构的相同层数, 证实了垂直2D 晶体的成功建立异质结构。在将 WS2/MoS2胶片传输到带 pre-patterned 源/漏极的微晶2/Si 衬底上后, 制作了底栅极晶体管。与仅 mos2通道的晶体管相比, 具有 WS2/mos2异质结构的设备的更高的漏电流显示出, 随着2D 晶体异质结构的引入, 高级器件可以获得性能。研究结果揭示了这种生长技术在2D 晶体实际应用中的潜力。

分别在图 1ab17中显示了使用 pre-deposited 过渡金属硫化制作的单个 MoS2和 WS2的拉曼光谱和横截面 HRTEM 图像。对 MoS2和 WS2的两个特征拉曼峰值分别进行了观测, 它对应于平面内的和2D 晶体中的一个<img alt="Equation 1" src="/files/ftp_upload/56494/56494eq1.jpg"> 1g声子振动模式。mos2样本的?...

Watch this Scientific Journal Video about Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication at JoVE.com

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

通过 pre-deposited 过渡金属的硫化, 可以制备大面积和垂直2D 晶体杂化结构。本报告还演示了薄膜传输和器件制作程序。

硫化过渡金属膜制备大面积垂直2D 晶体杂化结构

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...

preparation-large-area-vertical-2d-crystal-hetero-structures-through

Research

JoVE Journal

Engineering

9.1K 次观看.  National Taiwan University. 通过 pre-deposited 过渡金属的硫化, 可以制备大面积和垂直2D 晶体杂化结构。本报告还演示了薄膜传输和器件制作程序。

视频: Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view and for its considerable potential for practical applications. Slow light photonic crystal waveguides, in particular, have played a major part and have been successfully employed for delaying optical signals1-4 and the enhancement of both linear5-7 and nonlinear devices.8-11
Photonic crystal cavities achieve similar effects to that of slow light waveguides, but over a reduced band-width. These cavities offer high Q-factor/volume ratio, for the realization of optically12 and electrically13 pumped ultra-low threshold lasers and the enhancement of nonlinear effects.14-16 Furthermore, passive filters17 and modulators18-19 have been demonstrated, exhibiting ultra-narrow line-width, high free-spectral range and record values of low energy consumption.
To attain these exciting results, a robust repeatable fabrication protocol must be developed. In this paper we take an in-depth look at our fabrication protocol which employs electron-beam lithography for the definition of photonic crystal patterns and uses wet and dry etching techniques. Our optimised fabrication recipe results in photonic crystals that do not suffer from vertical asymmetry and exhibit very good edge-wall roughness. We discuss the results of varying the etching parameters and the detrimental effects that they can have on a device, leading to a diagnostic route that can be taken to identify and eliminate similar issues.
The key to evaluating slow light waveguides is the passive characterization of transmission and group index spectra. Various methods have been reported, most notably resolving the Fabry-Perot fringes of the transmission spectrum20-21 and interferometric techniques.22-25 Here, we describe a direct, broadband measurement technique combining spectral interferometry with Fourier transform analysis.26 Our method stands out for its simplicity and power, as we can characterise a bare photonic crystal with access waveguides, without need for on-chip interference components, and the setup only consists of a Mach-Zehnder interferometer, with no need for moving parts and delay scans.
When characterising photonic crystal cavities, techniques involving internal sources21 or external waveguides directly coupled to the cavity27 impact on the performance of the cavity itself, thereby distorting the measurement. Here, we describe a novel and non-intrusive technique that makes use of a cross-polarised probe beam and is known as resonant scattering (RS), where the probe is coupled out-of plane into the cavity through an objective. The technique was first demonstrated by McCutcheon et al.28 and further developed by Galli et al.29

Use of photonic crystal slow light waveguides and cavities has been widely adopted by the photonics community in many differing applications. Therefore fabrication and characterization of these devices are of great interest. This paper outlines our fabrication technique and two optical characterization methods, namely: interferometric (waveguides) and resonant scattering (cavities).

光子晶体慢光波导和腔体的制备与表征

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view ...

科研

工程学

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

VB制作<sub&gt; 2</sub&gt; /空气电池电化学测试

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

低温碳纳米管垂直互连的制作兼容半导体技术

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

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 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

1-D光子晶体空穴对纳米纤维使用飞秒激光诱导消融制造

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve desired molecular orientation states in LC displays, the "static" surface property of LCs, so-called surface anchoring, has been intensively studied. As a rule of thumb, once the initial orientation of LCs is "locked" by specific surface treatments, such as rubbing or treatment with a specific alignment layer, it hardly changes with temperature. Here, we present a system exhibiting an orientational transition upon temperature variation, which conflicts with the consensus. Right on the transition, the bulk LC molecules experience the orientational rotation, with 90&#176; between the planar (P) orientation at high temperatures and the vertical (V) orientation at low temperatures in the first-order transitional manner. We have tracked thermodynamic surface anchoring behavior by means of polarizing optical microscopy (POM), dielectric spectroscopy (DS), high-resolution differential scanning calorimetry (HR-DSC), and grazing incidence X-ray diffraction (GI-XRD) and reached a plausible physical explanation: that the transition is triggered by a growth of surface wetting sheets, which impose the V orientation locally against the P orientation in the bulk. This landscape would provide a general link explaining how the equilibrium bulk orientation is affected by surface-localized orientation in many LC systems. In our characterization, POM and DS are advantageous by offering information on the spatial distribution of the orientation of LC molecules. HR-DSC gives information about the precise thermodynamic information on transitions, which cannot be addressed by conventional DSC instruments due to limited resolution. GI-XRD provides information on surface-specific molecular orientation and short-range orderings. The goal of this paper is to present a protocol for preparing a sample that exhibits the transition and to demonstrate how the thermodynamic structural variation, both in the bulk and on surfaces, can be analyzed through the abovementioned methods.

Here, we present a protocol to trigger an orientational transition of a liquid crystal in response to temperature. Methodologies are described for preparing a sample in order to observe the transition and the detailed transitional evolution.

由界面润湿片的热力学生长触发的液晶中的定向转变

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

Scalable Solution-processed Fabrication Strategy for High-performance, Flexible, Transparent Electrodes with Embedded Metal Mesh

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a polymer film. This paper also presents a low-cost, vacuum-free fabrication method for this novel TE; the approach combines lithography, electroplating, and imprint transfer (LEIT) processing. The embedded nature of the EMTEs offers many advantages, such as high surface smoothness, which is essential for organic electronic device production; superior mechanical stability during bending; favorable resistance to chemicals and moisture; and strong adhesion with plastic film. LEIT fabrication features an electroplating process for vacuum-free metal deposition and is favorable for industrial mass production. Furthermore, LEIT allows for the fabrication of metal mesh with a high aspect ratio (i.e., thickness to linewidth), significantly enhancing its electrical conductance without adversely losing optical transmittance. We demonstrate several prototypes of flexible EMTEs, with sheet resistances lower than 1 &#937;/sq and transmittances greater than 90%, resulting in very high figures of merit (FoM) &#8211; up to 1.5 x 104 &#8211; which are amongst the best values in the published literature.

This protocol describes a solution-based fabrication strategy for high-performance, flexible, transparent electrodes with fully-embedded, thick metal mesh. Flexible transparent electrodes fabricated by this process demonstrate among the highest reported performances, including ultra-low sheet resistance, high optical transmittance, mechanical stability under bending, strong substrate adhesion, surface smoothness, and environmental stability.

具有嵌入式金属网的高性能，灵活，透明电极的可扩展解决方案处理制造策略

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

光诱导的宏观振荡运动液晶网络的制备

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

用斜角沉积法制备高吸收介质的超薄彩色薄膜

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

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 ...