这项工作得到了来自紧急救济协调员赠款 #615759 "薄荷", 区域 le-de 法国昏暗的 "Oxymore" (项目 "NEIMO") 和美国抵抗组织项目 "NOMILOPS" 的支持。h.n 的部分支持 EPSRC--jsp 核心核心计划, 即 jsp 的科研资助 (B) (#15H03548)。问得到德意志 Forschungsgemeinschaft (HO 53461-1; 博士后奖学金, 问)。D.C.V. 感谢法国高等教育和研究部和 CNRS 为他的博士论文融资。感谢巴黎大学 Saclay (达朗伯计划) 和 CNRS 为他在 CNRS/泰雷兹的逗留提供资金。

注意:本协议中描述的所有5步骤都可以在任何时候暂停和重新启动, 唯一的条件是, 该示例在步骤3.4 到5的高真空下保持不中断。
1. 停止 (001) 基板的终止:
<ol><li>填充超声波清洗剂 (用40赫变换器) 与水和热它到60° c。用丙酮填充硼硅酸盐玻璃烧杯。独立的烧杯大小, 一定要填补至少20% 的最大体积, 以确保基板是很好地淹没。<ol>
<li>放置一个出箱混合终止单面抛光 (001) 定向停止单晶衬底 (55 毫米2在横向尺寸, 0.5 毫米的厚度, miscut 角之间的0.01°和 0.02°) 内硼硅酸盐玻璃烧杯。</li>
		<li>在丙酮中几种基材, 用氮气吹枪将基体干燥3分钟左右, 操作压力约 5 bar。</li>
	</ol>
</li>
	<li>重复步骤 1.1, 但使用异丙醇, 然后去离子水。</li>
	<li>将清洁的衬底放在由聚偏氟乙烯 (PVDF) 制成的样品架上, 带有 "北斗" 形状 (图 1a)。用运行的去离子水填充第二个硼硅酸盐玻璃烧杯 (图 1b)。 注意:烧杯应足够大, 使样品持有人适合它。</li>
	<li>将基板放置在样品夹中。</li>
	<li>穿戴适当的保护, 填满烧杯 (图 1b), 通常由聚四氟乙烯、PTFE 制成, 其最大体积约 20%, 具有缓冲氢氟酸 (hf) 解决方案 (hf: NH4F = 1:7)。与步骤1.3 中使用的大小烧杯大致相同。</li>
	<li>将样品持有人淹没在 HF 中整整三十年代, 并立即将其移动到去离子自来水中, 以阻止随后的化学反应。轻轻地搅动它。</li>
	<li>2分钟后, 从去离子水中取出样品夹。取出衬底, 用氮气吹枪擦干。 注意:更多的细节可以在川崎的食谱11中找到。 警告:使用的 HF 溶液具有极强的腐蚀性和毒性。在适当的工作环境中, 始终对已使用的 HF 解决方案进行操作和处理。与身体部位接触后中毒的症状可能在接触后一天内开始可见, 在最初的几个小时可能不会造成任何疼痛。还可以使用基于 HCl-硝酸3酸性溶液12或无酸性终止配方13的替代终止过程。</li>
	<li>将衬底插入管式炉 (图 1c) 在20° c。将炉膛部分压力设置为约1的氧气自动取款机。将温度提高到1000° c, 以20° c/分钟的速度退火基板, 在1000° c 下3小时。3小时后, 让样品冷却到20° c。卸下纸张。关闭氧气源</li>
	<li>重复步骤 1.1, 去除退火过程中促进的后续表面污染物。</li>
</ol>2. 单晶老挝目标的制备:
<ol><li>机械抛光一个单晶老挝目标 (1 英寸直径) 轻轻使用砂纸和异丙醇溶液作为润滑剂。用氮气吹枪擦干</li>
	<li>在传送带上安装目标。 注意:确保旋转木马允许目标轮换。</li>
	<li>在 loadlock 腔中插入旋转木马 (图 2)。让目标在真空中加气, 同时不断泵腔 (直到它达到 10-8毫巴范围内的压力)。将传送带传送到 PLD 室 (图 3a和3b)。等待基本压力在 10-9毫巴范围内。 注意:在无 loadlock 室和真空传输系统中, 典型的等待时间和基本压力会受到严重影响。</li>
	<li>使用准分子激光能量计检查激光能量。为此, 使用矩形狭缝 (6 毫米 x 16 mm) 和外部衰减器的权利后, 激光源调节的形状和能量的光束 (图 4a和4b)。将能量计放置在激光束的路径中, 在第二会聚透镜和石英窗之间。然后, 以任意频率拍摄激光器, 并使用电能表读取能量。</li>
	<li>将能量设置为相同 (或稍高), 就像在成长过程中使用的那样 (步骤 3.12)。 注意:激光能量的绝对值可能会因设置的几何形状而异。然而, 对于老靶消融, 使用激光注量约 1 J/厘米2 (注: 能量/光斑面积)。此外, 使用脉冲 KrF 准分子激光器的波长λ = 248 nm, 具有特征脉冲持续时间为 25 ns 和操作在最低限度的 21 kV (为改善脉冲-脉冲再现性)。</li>
	<li>旋转老挝目标约 10 rpm (使用卡鲁塞尔的旋转平台, 在那里的目标是安装)。<ol>
<li>将目标转速调整到光斑大小和激光重复率, 避免两个连续重叠的镜头, 可能导致局部过热或熔化的目标和随后的非化学计量。图 4c中提供了一个可视化描述。</li>
	</ol>
</li>
	<li>在燃烧室内插入氧气, 直到达到 2x10-4毫巴的氧分压。卸下电能表。前蚀3或4赫兹的老挝目标为20000脉冲。 注意:应设置激光器, 使光束和目标之间的夹角为45° (图 4d)。这一相对较长的老单靶消融被发现在老/停样重现性中具有决定性的作用。</li>
</ol>3. PLD 的成长:
<ol><li>对先前终止的基板表面进行原子力显微镜 (AFM) 扫描, 以验证终止、形貌和清洁 (图 5)。</li>
	<li>使用银浆, 胶水的基板, 与终止表面指向向上, 样品持有人。虽然基板的方向不相关, 但请确保它放在刀柄的中心 (图 6a)。</li>
	<li>加热到大约100° c 为10分钟, 以便溶剂蒸发和浆糊变硬 (为优选的热量传导)。让样品架冷却下来。</li>
	<li>在 loadlock 中插入样品夹。使用在集群内的手臂, 转移样品持有人到 XPS 室分析氧, 碳和钛峰 (参考步骤5的详细信息)。</li>
	<li>将样品架转移到 PLD 室, 基板朝向老挝目标 (图 6b)。</li>
	<li>在腔室内插入氧气以达到 2x10-4毫巴的氧分压。将样品架的温度提高到730° c (在25° c/分钟)。</li>
	<li>利用反射高能电子衍射 (高能), 使电子束在掠角 (°和3之间) 与基体表面对齐, 从而在荧光屏上观察到衍射斑点。使用 CCD 摄像机和图像分析软件实时监控每个点的强度。使用 30 kV 和40µA 电流的源电压。</li>
	<li>将样品架放在离目标63毫米远的地方。 注意:根据所使用的 PLD 设置的几何形状, 目标到基板距离可能需要某种程度的优化。</li>
	<li>拍摄激光, 以校准的能量, 使其匹配约 1 J/cm2 (与步骤2.4 相同的方式)。再次, 使用矩形狭缝 (6 毫米 x 16 mm) 和外部衰减器的权利后, 激光出口调节的形状和能量的光束 (图 4a和4b)。</li>
	<li>将激光频率设置为1赫兹. 停止拍摄激光和删除能量表。</li>
	<li>启动老挝目标的旋转 (与步骤2.6 相同的方式)。启动高能振荡读数。等待它稳定。</li>
	<li>开始拍摄激光。观察羽流 (图 6c) 和高能振荡 (图 6d)。根据所需的厚度, 停止激光在一个振荡的峰值。 注意:请记住, 每个振荡表示一个单元格 (uc) 的增长。为了本实验的目的, 分别生长1和 2 uc 进行运输和光谱实验。</li>
	<li>增长完成后, 关闭高能枪并进行后退火步骤。 注意:后退火步骤是在生长完成后进行的。<ol>
<li>开始后退火, 增加氧气分压在会议厅从 2x10-4毫巴 (增长压力), 以 1x10-1毫巴和降低样品持有人的温度从730° c (生长温度) 到500° c。</li>
		<li>在温度和压力稳定后, 引入一个静态氧分压约300毫巴, 同时保持样品持有人的温度在500° c。将样品留在这些条件下60分钟。</li>
	</ol>
</li>
	<li>冷却样品在25° c/分钟, 同时保持它在相同的氧分压, 直到它达到室温。</li>
	<li>将样品转移到 XPS 室, 以研究钛峰值或相对镧/铝浓度可能发生的价态变化 (有关详细信息, 请参阅步骤 5)。</li>
	<li>为确保老挝表面保持原始, 请将示例在真空中传输到溅射室 (图 7a), 该样本在 10-8毫巴范围内的压力下始终保持不移。 注意:执行这些实验时,原位将导致碳和水在表面的积聚, 最终导致改变结果。</li>
</ol>4. 金属 Overlayers 磁控溅射:
注意:根据所需的金属, 诸如 Ar 压力、沉积电流和靶向衬底距离的参数可能稍有不同。根据所用溅射装置的几何形状, 建议对每个沉积过程进行优化。下面的过程描述了沉积 3 nm 的 Co。
<ol><li>将样品表面朝下朝向目标。</li>
	<li>在溅射腔内插入纯 Ar, 以达到 4.5x10-4毫巴 (约 100 sccm) 的气氛。</li>
	<li>将基板放置在离 Co 目标大约7厘米的位置。</li>
	<li>随着快门关闭, 坡道的电流高达约100毫安 (36 W), 使等离子体被点燃。</li>
	<li>与稳定的血浆 (图 7b), 降低电流到80毫安 (沉积电流) 以及 Ar 到 5.2 sccm 的流入。确保等离子体保持稳定。</li>
	<li>预溅射 Co 靶约5分钟, 除去任何可能在其表面形成的氧化层。</li>
	<li>与样品在室温下, 打开快门和存款二十五年代. 关闭快门结束沉积。<ol>
<li>在运输实验中, 沉积一个随后的上限层约 3 nm Al (其表面钝化, 形成一个 AlOx 保护层后, 暴露在空气), 以防止氧化的基础金属层。 注意:生长率不直接地在会议厅内测量。为了做到这一点, 在使用相同的参数时, 用不同的沉积时间生长各种样品。然后, 用 x 射线反射测量每个样品的厚度。对所使用的每个金属靶进行一次此过程。</li>
	</ol>
</li>
	<li>将电流向下斜向零, 关闭 Ar 源并泵入腔室。</li>
	<li>再一次将样品持有者转移到 XPS 室 (图 8a), 以检查在 Ti 2p 水平上可能的价态变化以及在金属/老挝界面上可能发生的氧化反应 (有关详细信息, 请参阅步骤 5)。</li>
</ol>5. 原位 X 射线光电子能谱:
<ol><li>将示例与与电子分析器轴 (图 8b) 平行的曲面法线对齐。</li>
	<li>接近 X 射线枪尽可能靠近样品 (避免机械接触之间的枪端和样品持有人, 以防止损坏), 并打开它。<ol>
<li>在这个实验中, 使用一个 1253.6 eV 的激发能量的 Mg Kα源。将灯丝设置为在15伏的阳极电压下达到20毫安的发射电流。关于分析仪的电子光学, 选择一个2毫米直径的入口狭缝和一个5x11 毫米的长方形形状的出口狭缝。 注意:有关最大发射电流和阳极电压的信息, 请参阅 XPS 设置手册。另外, 对于其他特定设置, 进出卡瓦的大小可能会有所不同。如果分析仪有不同的规格, 选择的狭缝, 以避免过高的强度在电子计数单位。</li>
	</ol>
</li>
	<li>打开 X 射线枪后, 确保该腔室处于超高真空状态 (10-10毫巴范围)。收集测量光谱 (在0和 1200 ev 结合能之间) 与一个选择的步 0.05 ev, 居住时间 0.5 s, 通行证能量在30和 60 ev 之间和一个适当的透镜方式达到最小的斑点大小可能。根据预期的分辨率调整值。<ol>
<li>找到相关峰值的位置 (图 8c)。对于改进的统计, 测量每个峰值数倍和平均收集的光谱。</li>
	</ol>
</li>
	<li>使用适当的 XPS 处理软件分析频谱。<ol>
<li>为了从给定的跃迁中识别电子, 定义一个包括峰值分析的能量范围。</li>
		<li>创建适当的背景曲线 (通常为雪莉背景14) 并将其从原始数据中减去。</li>
		<li>使用书目参考文献15, 找到构成测量峰值的可能峰值。特别注意不同峰值的表距和相对强度。 注意:更深入地了解所收集的 XPS 数据是在 "代表性结果" 部分以及 Ref.7中提供的。</li>
	</ol>
</li>
</ol>6. 磁实验:
<ol><li>使用超声波楔焊机, 金属/老挝/样品与铝或 Au 线联系, 以接触埋接口 (图 9a)。 注意:根据所使用的设置和运输测量支架的类型, 选择合适的楔形-采样距离、力和时间。</li>
	<li>使用8线几何 (4 在 van der 范德堡-渠道 1-和4在霍尔几何-渠道 2-)。要做到这一点, 首先通过接触的一个通道的运输测量持有人的四个角落的样品在 van der 范德堡几何。然后, 与示例中以前完成的联系人联系第二个通道 (图 9b)。</li>
	<li>通过万用表测量电阻, 检查触点是否良好。为了确保样品是均匀的, 验证不同方向测量的电阻是大致相同的, 这样 van der 范德堡 R100≈R010条件得到满足。 注意:如果 r100和 r010明显不同, 则应在两个方向上执行 van der 范德堡测量 (如下 Ref.16)。先前的研究报告了在老挝/在17中强各向异性的电气传输特性。</li>
	<li>在传输设置中装载持有者。<ol>
<li>测量电阻 (通道 1) 下至 2 K。</li>
		<li>在低温下, 通过扫掠外部和垂直磁场 (从-9 到 9 T) 依次测量磁电阻 (通道 1) 和霍尔效应 (通道 2), 为金属/老挝/µA 样品寻找通常10到100的电流。</li>
		<li>重复步骤6.4.2。为 5 k, 10 k, 50 k, 100 k, 200 k 和 300 k, 为了观察磁电阻演化与温度。</li>
	</ol>
</li>
</ol>

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作者没有什么可透露的。

在基板的终止, 你应该非常小心与淹没时间在 HF 解答。我们观察到, 在蚀刻的表面上, 只改变了5秒的原始配方。另外, 我们观察了基片步长和淹没时间的依赖性。对于较小的步长 (小于 100 nm) 淹没三十年代可能导致过度蚀刻, 即使事后退火程序可能足以适当地重建表面。由于使用 HF 基酸的风险, 我们还建议优化的 HCl-硝酸3酸性解决方案终止12或无酸终止技术13</...

准2D 电子系统 (q2DES) 被广泛用作研究大量的低维和量子现象的操场。从 LaAlO3/SrTiO3系统的开创性论文 (老挝语/停用)1开始, 创建了一个不同系统的新界面电子阶段的爆发。结合不同的材料导致发现的 q2DESs 与其他性质, 如电场可调谐自旋极化2, 极高的电子迁移3或铁耦合现象4。虽然大量的工作已经致力于解开这些系统的创造和操纵, 但一些实验和技术却显示出矛盾的结果, 即使是在相当相似的条件下。此外, 在静电和化学相互作用之间的平衡被发现是必不可少的正确理解的物理在玩5,6,7。
在本文中, 我们详细描述了不同的金属/老挝/异的增长, 使用脉冲激光沉积 (PLD) 和原位磁控溅射的组合。然后, 通过传输和电子光谱实验, 了解在老挝/q2DES 界面上不同表面条件对埋地的影响, 进行了电子和化学研究。
由于以前使用过多种方法来生长结晶型老挝, 因此选择合适的沉积技术是制备高质量氧化物异 (除了可能的成本和时间限制) 的关键步骤。在 PLD 中, 强烈的和短的激光脉冲命中所需材料的目标, 然后消融, 并获得沉积在基底上作为一个薄膜。这项技术的主要优点之一是能够可靠地将目标的化学计量性转移到胶片上, 这是一个关键因素, 以达到所需的相形成。此外, 通过大量复杂氧化物的反射高能电子衍射-高能进行层状生长 (实时监测) 的能力, 同时在腔室内有多个目标的可能性 (允许不同材料的生长, 而不打破真空) 和简单的设置使这项技术是最有效的和多才多艺的。
然而, 其他技术, 如分子束外延 (外延), 允许生长更高质量的外延生长。而不是有一个特定的材料的目标, 在外延, 每个特定的元素是升华对基板, 在那里他们相互反应, 形成良好的定义原子层。此外, 缺乏高能量的物种和更均匀的能量分布, 使得极尖锐的界面的制作成为8。然而, 在氧化物的生长过程中, 这一技术比 PLD 要复杂得多, 因为它必须在超高真空条件下执行 (这样, 长的平均自由路径就不会被破坏), 而且一般需要更大的投资、成本和时间。尽管在第一批老挝/其他出版物中使用的增长过程是 PLD, 但具有相似特性的样品却是由 "9" 的外延生长的。还值得注意的是, 老挝/异已经使用溅射10来增长。虽然在高温 (920 ° c) 和高氧压力 (0.8 毫巴) 上实现了原子性尖锐的界面, 但没有达到界面电导率。
对于金属盖层的生长, 我们使用磁控溅射, 因为它在质量和柔韧性之间提供了良好的平衡。然而, 其他化学气相沉积技术也可用于获得类似的结果。
最后, 运输和光谱学技术结合在这篇文章中展示了一个系统的方法来探测电子和化学的相互作用, 强调对照不同的方法的重要性, 以充分理解这些类型的系统的许多功能。

<table border="0" cellpadding="0" cellspacing="0" style="width:1433px;" width="1433">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Pulsed Laser Deposition</td>
			<td style="width:200px;">SURFACE</td>
			<td style="width:305px;">PLD Workstation + UHV Cluster System</td>
			<td style="width:521px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">KrF Excimer Laser</td>
			<td style="width:200px;">Coherent</td>
			<td style="width:305px;">Compex Pro 201F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Reflection High-Energy Electron Diffraction (electron gun)</td>
			<td style="width:200px;">R-Dec Co., Ltd.</td>
			<td style="width:305px;">RDA-003G</td>
			<td>Distributed in Europe by SURFACE.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Reflection High-Energy Electron Diffraction (CCD camera)</td>
			<td style="width:200px;">k-Space Associates, Inc.</td>
			<td style="width:305px;">kSA 400</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Variable Laser Beam Attenuator</td>
			<td style="width:200px;">Metrolux</td>
			<td style="width:305px;">ML 2100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Excimer Laser Sensor</td>
			<td style="width:200px;">Coherent</td>
			<td style="width:305px;">J-50MUV-248</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:407px;">LaAlO3 target</td>
			<td style="width:200px;">CrysTec</td>
			<td style="width:305px;"></td>
			<td>Single-crystal target</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:407px;">SrTiO3 subtrates</td>
			<td style="width:200px;">CrysTec</td>
			<td style="width:305px;"></td>
			<td>Several different sizes. Possibility to order TiO2 terminated.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Buffered HF Acid</td>
			<td style="width:200px;">Technic</td>
			<td style="width:305px;">BOE 7:1</td>
			<td>buffered hydrofluoric acid = BOE 7:1 (HF : NH4F = 12.5 : 87.5%) in&#160;VLSI-quality.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Silver Paste</td>
			<td style="width:200px;">DuPont</td>
			<td style="width:305px;">4929N</td>
			<td>Conductive Silver Composite.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Ultrasonic Cleaner</td>
			<td style="width:200px;">Bransonic</td>
			<td style="width:305px;">12</td>
			<td>Ultrasonic Cleaning Bath</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Tube Furnace</td>
			<td style="width:200px;">AET Technologies</td>
			<td style="width:305px;">Heat Treatment Furnace</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Borosilicate Glass Beaker</td>
			<td style="width:200px;">VWR</td>
			<td>213-1128</td>
			<td>Iow form</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">PTFE Beaker</td>
			<td style="width:200px;">Dynalon</td>
			<td style="width:305px;">PTFE Beaker</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Substrate holder &#34;dipper&#34;</td>
			<td style="width:200px;">Eberl&#233;</td>
			<td style="width:305px;"></td>
			<td>Custom made dipper</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Magnetron Sputtering</td>
			<td style="width:200px;">PLASSYS</td>
			<td style="width:305px;">Sputtering system</td>
			<td>5 chambers for targets.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Metal targets</td>
			<td style="width:200px;">Neyco S.A.</td>
			<td style="width:305px;"></td>
			<td>Purity &#62; 99.9%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">X-Ray Photoelectron Spectroscopy System</td>
			<td style="width:200px;">Omicron</td>
			<td style="width:305px;">Custom XPS System</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">X-Ray Source</td>
			<td style="width:200px;">Omicron</td>
			<td style="width:305px;">DAR 400</td>
			<td>Twin Anode X-Ray Source.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Energy Analyser</td>
			<td style="width:200px;">Omicron</td>
			<td style="width:305px;">EA 125</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Atomic Force Microscopy</td>
			<td style="width:200px;">Bruker</td>
			<td style="width:305px;">Innova AFM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Atomic Force Microscopy Probes</td>
			<td style="width:200px;">Olympus</td>
			<td style="width:305px;">OMCL-AC160TS-R3</td>
			<td>Micro Cantilevers</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">Wire bonding</td>
			<td style="width:200px;">Kulicke &#38; Soffa</td>
			<td style="width:305px;">4523AD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:407px;">PPMS</td>
			<td style="width:200px;">Quantum Design</td>
			<td style="width:305px;">PPMS Dynacool</td>
			<td>9T magnet.</td>
		</tr>
	</tbody>
</table>

growth and electrostatic/chemical properties of metal/laalo3/srtio3 heterostructures

在 LaAlO3 (老挝) 和 SrTiO3 (q2DES) 之间的接口上形成的准2D 电子系统引起了氧化物电子学界的广泛关注。其特征之一是存在一个关键的老挝厚度4单元细胞 (uc) 的界面电导率出现。虽然过去已经提出了静电机制来描述这种临界厚度的存在, 但化学缺陷的重要性最近得到了加强。在这里, 我们描述了金属/老挝/异的增长, 在一个超高真空 (特高压) 集群系统结合脉冲激光沉积 (增长老挝), 磁控溅射 (增长金属) 和 X 射线光电子能谱 (XPS)。我们逐步研究了金属和 q2DES 之间的化学相互作用的形成和演化。此外, 磁实验阐明了 q2DES 的传输和电子性质。这一系统的工作不仅证明了一种研究 q2DES 及其环境之间的静电和化学相互作用的方法, 而且也解开了在二维电子系统, 允许制造新类型的设备。

用于增长和特性描述的完整实验系统显示在图 2中。强烈建议通过配电室在特高压中连接不同的设置, 以确保每个生长过程后样品的表面保持原始状态。还详细描述了 PLD 室 (图 3)、磁控溅射 (图 7) 和 XPS 室 (图 8)。有关 PLD 设置中的光学路径的其他信息, 将显示在图 4</st...

Watch this Scientific Journal Video about Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures at JoVE.com

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

我们制造金属/LaAlO3/SrTiO3异使用脉冲激光沉积和原位磁控溅射组合。通过磁和原位X 射线光电子能谱实验, 研究了该系统中所形成的准二维电子气体的静电与化学现象之间的相互作用。

金属/LaAlO 的生长和静电/化学性质3/SrTiO3异

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide ...

growth-electrostaticchemical-properties-metallaalo3srtio3

Research

JoVE Journal

Engineering

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

10.2K 次观看.  Université Paris-Saclay. 我们制造金属/LaAlO3/SrTiO3异使用脉冲激光沉积和原位磁控溅射组合。通过磁和原位X 射线光电子能谱实验, 研究了该系统中所形成的准二维电子气体的静电与化学现象之间的相互作用。

视频: Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

Concurrent Quantitative Conductivity and Mechanical Properties Measurements of Organic Photovoltaic Materials using AFM

Organic photovoltaic (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale inhomogeneity of OPV materials affects performance of photovoltaic devices. Thus, understanding of spatial variations in composition as well as electrical properties of OPV materials is of paramount importance for moving PV technology forward.1,2 In this paper, we describe a protocol for quantitative measurements of electrical and mechanical properties of OPV materials with sub-100 nm resolution. Currently, materials properties measurements performed using commercially available AFM-based techniques (PeakForce, conductive AFM) generally provide only qualitative information. The values for resistance as well as Young's modulus measured using our method on the prototypical ITO/PEDOT:PSS/P3HT:PC61BM system correspond well with literature data. The P3HT:PC61BM blend separates onto PC61BM-rich and P3HT-rich domains. Mechanical properties of PC61BM-rich and P3HT-rich domains are different, which allows for domain attribution on the surface of the film. Importantly, combining mechanical and electrical data allows for correlation of the domain structure on the surface of the film with electrical properties variation measured through the thickness of the film.

Organic photovoltaic (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale inhomogeneity of OPV materials affects performance of photovoltaic devices. In this paper, we describe a protocol for quantitative measurements of electrical and mechanical properties of OPV materials with sub-100 nm resolution.

并行定量的导电性和力学性能测试的有机光伏材料利用原子力显微镜

Organic photovoltaic  (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale  inhomogeneity of OPV materials affects performance ...

科研

工程学

Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays

In this article, we describe a simple method to reversibly tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays. Here, CNT arrays are defined as densely packed multi-walled carbon nanotubes oriented perpendicular to the growth substrate as a result of a growth process by the standard thermal chemical vapor deposition (CVD) technique.1,2 These CNT arrays are then exposed to vacuum annealing treatment to make them more hydrophobic or to dry oxidation treatment to render them more hydrophilic. The hydrophobic CNT arrays can be turned hydrophilic by exposing them to dry oxidation treatment, while the hydrophilic CNT arrays can be turned hydrophobic by exposing them to vacuum annealing treatment. Using a combination of both treatments, CNT arrays can be repeatedly switched between hydrophilic and hydrophobic.2 Therefore, such combination show a very high potential in many industrial and consumer applications, including drug delivery system and high power density supercapacitors.3-5
The key to vary the wettability of CNT arrays is to control the surface concentration of oxygen adsorbates. Basically oxygen adsorbates can be introduced by exposing the CNT arrays to any oxidation treatment. Here we use dry oxidation treatments, such as oxygen plasma and UV/ozone, to functionalize the surface of CNT with oxygenated functional groups. These oxygenated functional groups allow hydrogen bond between the surface of CNT and water molecules to form, rendering the CNT hydrophilic. To turn them hydrophobic, adsorbed oxygen must be removed from the surface of CNT. Here we employ vacuum annealing treatment to induce oxygen desorption process. CNT arrays with extremely low surface concentration of oxygen adsorbates exhibit a superhydrophobic behavior.

This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.

干式氧化及真空退火处理调整的润湿性能的碳纳米管阵列

In this article, we describe a simple method to reversibly  tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays.  Here, CNT ...

Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph cross-sections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected.

A method to prepare epitaxial layers of ordered alloys by sputtering is described. The B2-ordered FeRh compound is used as an example, as it displays a metamagnetic transition that depends sensitively on the degree of chemical order and the exact composition of the alloy.

变磁B2有序化的FeRh外延层溅射生​​长和表征

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using ...

Using Microwave and Macroscopic Samples of Dielectric Solids to Study the Photonic Properties of Disordered Photonic Bandgap Materials

Recently, disordered photonic materials have been suggested as an alternative to periodic crystals for the formation of a complete photonic bandgap (PBG). In this article we will describe the methods for constructing and characterizing macroscopic disordered photonic structures using microwaves. The microwave regime offers the most convenient experimental sample size to build and test PBG media. Easily manipulated dielectric lattice components extend flexibility in building various 2D structures on top of pre-printed plastic templates. Once built, the structures could be quickly modified with point and line defects to make freeform waveguides and filters. Testing is done using a widely available Vector Network Analyzer and pairs of microwave horn antennas. Due to the scale invariance property of electromagnetic fields, the results we obtained in the microwave region can be directly applied to infrared and optical regions. Our approach is simple but delivers exciting new insight into the nature of light and disordered matter interaction.

Our representative results include the first experimental demonstration of the existence of a complete and isotropic PBG in a two-dimensional (2D) hyperuniform disordered dielectric structure. Additionally we demonstrate experimentally the ability of this novel photonic structure to guide electromagnetic waves (EM) through freeform waveguides of arbitrary shape.

Disordered structures offer new mechanisms for forming photonic bandgaps and unprecedented freedom in functional-defect designs. To circumvent the computational challenges of disordered systems, we construct modular macroscopic samples of the new class of PBG materials and use microwaves to characterize their scale-invariant photonic properties, in an easy and inexpensive manner.

利用微波和电介质固体的宏观样本，研究无序光子带隙材料的光子特性

Recently, disordered photonic materials have been suggested as an alternative to periodic crystals for the formation of a complete photonic bandgap (PBG). ...

Seedless Growth of Bismuth Nanowire Array via Vacuum Thermal Evaporation

Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. Conventionally reserved for the fabrication of metal thin films, thermal evaporation deposits bismuth into an array of vertical single crystalline nanowires over a flat thin film of vanadium held at RT, which is freshly deposited by magnetron sputtering or thermal evaporation. By controlling the temperature of the growth substrate the length and width of the nanowires can be tuned over a wide range. Responsible for this novel technique is a previously unknown nanowire growth mechanism that roots in the mild porosity of the vanadium thin film. Infiltrated into the vanadium pores, the bismuth domains (~ 1 nm) carry excessive surface energy that suppresses their melting point and continuously expels them out of the vanadium matrix to form nanowires. This discovery demonstrates the feasibility of scalable vapor phase synthesis of high purity nanomaterials without using any catalysts.

A protocol for seedless and high yield growth of bismuth nanowire arrays through vacuum thermal evaporation technique is presented.

铋纳米线阵列通过真空热蒸发无核增长

Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. ...

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

电活性聚合物纳米粒子参展光热特性

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement during previous phase changes and applied shear. To determine the extent of these changes, we have developed a microfluidic device that enables repeated phase transitions induced by exchange of the surrounding fluid and microrheological characterization while limiting shear on the sample. This technique is &#181;2rheology, the combination of microfluidics and microrheology. The microfluidic device is a two-layer design with symmetric inlet streams entering a sample chamber that traps the gel sample in place during fluid exchange. Suction can be applied far away from the sample chamber to pull fluids into the sample chamber. Material rheological properties are characterized using multiple particle tracking microrheology (MPT). In MPT, fluorescent probe particles are embedded into the material and the Brownian motion of the probes is recorded using video microscopy. The movement of the particles is tracked and the mean-squared displacement (MSD) is calculated. The MSD is related to macroscopic rheological properties, using the Generalized Stokes-Einstein Relation. The phase of the material is identified by comparison to the critical relaxation exponent, determined using time-cure superposition. Measurements of a fibrous colloidal gel illustrate the utility of the technique. This gel has a delicate structure that can be irreversibly changed when shear is applied. &#181;2rheology data shows that the material repeatedly equilibrates to the same rheological properties after each phase transition, indicating that phase transitions do not play a role in microstructural changes. To determine the role of shear, samples can be sheared prior to injection into our microfluidic device. &#181;2rheology is a widely applicable technique for the characterization of soft matter enabling the determination of rheological properties of delicate microstructures in a single sample during phase transitions in response to repeated changes in the surrounding environmental conditions.

We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.

微流体和 Microrheology 相结合测定软物质在重复相变过程中的流变特性

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement ...

Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that characterize the transport phenomena in a rotating channel are identified via the parametric analysis of the momentum and energy equations referring to a rotating frame of reference. Based on these dimensionless flow equations, an experimental strategy that links the design of the test module, the experimental program and the data analysis is formulated with the attempt to reveal the isolated Coriolis-force and buoyancy effects on heat transfer performances. The effects of Coriolis force and rotating buoyancy are illustrated using the selective results measured from rotating channels with various geometries. While the Coriolis-force and rotating-buoyancy impacts share several common features among the various rotating channels, the unique heat transfer signatures are found in association with the flow direction, the channel shape and the arrangement of heat transfer enhancement devices. Regardless of the flow configurations of the rotating channels, the presented experimental method enables the development of physically consistent heat transfer correlations that permit the evaluation of isolated and interdependent Coriolis-force and rotating-buoyancy effects on the heat transfer properties of rotating channels.

Here, we present an experimental method for decoupling the interdependent Coriolis-force and rotating-buoyancy effects on full-field heat transfer distributions of a rotating channel.

解耦科里奥利力和旋转浮力对旋转通道全场传热性能的影响

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that ...

Plasma-Assisted Molecular Beam Epitaxy Growth of Mg3N2 and Zn3N2 Thin Films

This article describes a procedure for growing Mg3N2 and Zn3N2 films by plasma-assisted molecular beam epitaxy (MBE). The films are grown on 100 oriented MgO substrates with N2 gas as the nitrogen source. The method for preparing the substrates and the MBE growth process are described. The orientation and crystalline order of the substrate and film surface are monitored by the reflection high energy electron diffraction (RHEED) before and during growth. The specular reflectivity of the sample surface is measured during growth with an Ar-ion laser with a wavelength of 488 nm. By fitting the time dependence of the reflectivity to a mathematical model, the refractive index, optical extinction coefficient, and growth rate of the film are determined. The metal fluxes are measured independently as a function of the effusion cell temperatures using a quartz crystal monitor. Typical growth rates are 0.028 nm/s at growth temperatures of 150 &#176;C and 330 &#176;C for Mg3N2 and Zn3N2 films, respectively.

Plasma-Assisted Molecular Beam Epitaxy Growth of Mg3N2 and Zn3N2 Thin Films

This article describes the growth of epitaxial films of Mg3N2 and Zn3N2 on MgO substrates by plasma-assisted molecular beam epitaxy with N2 gas as the nitrogen source and optical growth monitoring.

Mg3N2和 Zn3N2薄膜的等离子辅助分子束外延生长

This article describes a procedure for growing Mg3N2 and Zn3N2 films by plasma-assisted molecular beam epitaxy (MBE). The films are grown on 100 oriented ...

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 ...

金属/LaAlO 的生长和静电/化学性质₃/SrTiO₃异

摘要

探索更多视频

此视频中的章节

并行定量的导电性和力学性能测试的有机光伏材料利用原子力显微镜

干式氧化及真空退火处理调整的润湿性能的碳纳米管阵列

变磁B2有序化的FeRh外延层溅射生长和表征

利用微波和电介质固体的宏观样本，研究无序光子带隙材料的光子特性

铋纳米线阵列通过真空热蒸发无核增长

电活性聚合物纳米粒子参展光热特性

微流体和 Microrheology 相结合测定软物质在重复相变过程中的流变特性

解耦科里奥利力和旋转浮力对旋转通道全场传热性能的影响

Mg₃N₂和 Zn₃N₂薄膜的等离子辅助分子束外延生长

使用精确旋转对齐来制造范德瓦尔斯异构结构

金属/LaAlO 的生长和静电/化学性质3/SrTiO3异

摘要

探索更多视频

此视频中的章节

并行定量的导电性和力学性能测试的有机光伏材料利用原子力显微镜

干式氧化及真空退火处理调整的润湿性能的碳纳米管阵列

变磁B2有序化的FeRh外延层溅射生​​长和表征

利用微波和电介质固体的宏观样本，研究无序光子带隙材料的光子特性

铋纳米线阵列通过真空热蒸发无核增长

电活性聚合物纳米粒子参展光热特性

微流体和 Microrheology 相结合测定软物质在重复相变过程中的流变特性

解耦科里奥利力和旋转浮力对旋转通道全场传热性能的影响

Mg3N2和 Zn3N2薄膜的等离子辅助分子束外延生长

使用精确旋转对齐来制造范德瓦尔斯异构结构

金属/LaAlO 的生长和静电/化学性质₃/SrTiO₃异

变磁B2有序化的FeRh外延层溅射生长和表征

Mg₃N₂和 Zn₃N₂薄膜的等离子辅助分子束外延生长