Name: epitaxial nanostructured α-quartz films on silicon: from the material to new devices
Uploaded: 2020-10-06T14:30:00.000+00:00
Duration: 11 min 34 s
Description: Watch this Scientific Journal Video about Epitaxial Nanostructured Î±-Quartz Films on Silicon: From the Material to New Devices at JoVE.com

这项工作由欧洲研究理事会（ERC）根据欧盟的Horizno 2020研究与创新计划（第803004号）资助。

1. 准备解决方案
<ol><li>在将凝胶薄膜放在放置实验室平衡和磁搅拌器的烟雾罩中之前，在 18 小时前准备含有前水解四乙基正石 （TEOS） 的溶液。<ol>
<li>将0.7克聚乙二醇六甲醚（Brij-58）和23.26克乙醇加入50mL瓶中，并关闭瓶子盖，搅拌至Brij完全溶解。</li>
		<li>在步骤 1.1.1 中加入 1.5 克 HCL 35%， 将其关闭并搅拌 20 s。</li>
		<li>在步骤 1.1.2 中将 4.22 克 TEOS 添加到烧瓶中，将其关闭，让它搅拌 18 小时。</li>
	</ol>
</li>
	<li>在凝胶薄膜生产前准备 1 M 水溶液 Sr2+， 因为成熟的溶液容易以 Sr 盐的形式重新沉淀。<ol>
<li>重量 2.67 克 SrCl2+6H2O 在 10 毫升体积烧瓶。</li>
		<li>在步骤 1.2.1 将 10 mL 超纯水（例如 Milli-Q）加入至 10 mL 的烧瓶中，用塑料盖关闭烧瓶，轻轻摇动烧瓶以溶解氯化钛。</li>
	</ol>
</li>
	<li>将 Sr2+ 1 M 水溶液中的 275 μL 添加到包含步骤 1.1 中准备的溶液的 10 mL 瓶中，搅拌溶液 10 分钟。</li>
</ol>2. 制备多二甲基硅氧烷 （PDMS） 模板
<ol><li>第 1.3 步后准备 PDMS 解决方案。<ol>
<li>将固化剂的 1 部分与平衡器中的 10 部分弹性体混合。用玻璃棒搅拌混合物，直到获得气泡的均匀分布，并在真空室中将其取出。</li>
	</ol>
</li>
	<li>使用 PDMS 解决方案复制硅主。请注意，对于此工作，我们使用了由直径、高度和分离距离为 1μm 的柱子组成的硅图案大师。<ol>
<li>将带结构化面罩的硅主放在塑料盒中，并给盒子中填充 PDMS 解决方案。</li>
		<li>将塑料盒在 70 °C 下引入熔炉 2 小时，以获得坚固的 PDMS 模板。</li>
		<li>将 PDMS 模板和硅主板分开。使用刀片将 PDMS 模板切割到所需的尺寸，并将其保存在干净的盒子中。</li>
	</ol>
</li>
</ol>3. 通过浸涂在 SOI （100） 基板上的凝胶薄膜沉积
<ol><li>基材的准备<ol>
<li>通过使用钻石尖端将厚度为 2/0.5/0.67 μm（Si/SiO 2/Si） 的 2 英寸 p 型 SOI 晶圆切割，准备 2 厘米 x6厘米大小的基材。请注意，硅器件层的电导率必须在 1 到 10 Ω/厘米之间。</li>
		<li>在食人鱼溶液中引入基质20分钟，以消除可能的聚合物残留物。</li>
		<li>用DI水清洁，然后用乙醇清洁，让它们干燥或使用氮气流动。此步骤应在步骤 1.3 之后执行。</li>
	</ol>
</li>
	<li>沉积含有前水解四乙基矫形器 （TEOS）、Brij-58 硫化物和 SrCl2 6H2O 的溶液。<ol>
<li>为了获得均匀的二氧化硅薄膜，在相对湿度为40%和25°C的温度条件下设置浸衣机室。</li>
		<li>将大小约为 5 厘米 x 1 厘米 x 8 厘米的烧杯放在悬挂在浸涂臂上的 SOI 基板下方，并在浸入和取款时建立 300 mm/min 的速度的浸涂顺序。将沉浸时间（最终位置的时间）设置为零。</li>
		<li>将第 1.3 步准备的解决方案填充烧杯，等待相对湿度温度稳定，即分别为 40% 和 25 °C。</li>
		<li>执行单浸涂层，并等待，直到薄膜变得均匀。</li>
		<li>将 SOI 基板引入 450 °C 的熔炉中 5 分钟，使凝胶薄膜获得 200 nm 的厚度。</li>
		<li>重复步骤 3.2.3 和 3.2.4 两倍以上，以产生厚度约为 600 nm 的薄膜。为确保解决方案的稳定性，应在 1 小时内执行重复过程。</li>
	</ol>
</li>
</ol>4. 通过软印纹光刻表面微/纳米结构
<ol><li>在相对湿度为 40% 和 25 °C 的温度条件下，在薄膜表面准备微/纳米结构。<ol>
<li>重复步骤 3.2.3 将新胶片存放在 SOI 基板上。</li>
		<li>将第 3.2.1 步之后的 SOI 基板放在平坦的表面上，并在溶胶蒸发时将第 2.2 步制备的 PDMS 模具放在 SOI 基板上。</li>
		<li>将带有 PDMS 模具的 SOI 基板放入 70 °C 的熔炉中 1 分钟，然后在 140 °C 下放入第二个熔炉中 2 分钟。然后，让它冷却下来。</li>
		<li>取出 PDMS 模具，在 SOI 基板上获取微/纳米结构凝胶薄膜。</li>
		<li>将 SOI 基板引入 450 °C 的熔炉中 5 分钟，以巩固 600 nm 高度的微/纳米结构凝胶薄膜。</li>
	</ol>
</li>
</ol>5. 热处理凝胶薄膜结晶
<ol><li>对 SOI 上的凝胶薄膜进行热处理（100）。<ol>
<li>将管状炉子加热从室温到 1000 °C。</li>
		<li>将放置在陶瓷船中的样品引入 1000 °C 的熔炉 5 小时。在整个热处理过程中，不要覆盖管状工作管，以便用空气使炉子饱和。最后，在没有任何编程坡道的情况下冷却炉子，达到室温。</li>
	</ol>
</li>
</ol>6. 光刻面罩布局设计
此工艺中使用的面膜专为 SOI 基板上的设备制造而设计，带有表观纳米结构石英。所有的制造过程都在石英一侧进行。该面罩的设计方式是，每一步都需要使用负色调抵抗。面罩按照以下解释分为四个不同的步骤。
<ol><li>为石英图案，以确定悬臂的形状，以及 30 μm x 30 μm 方形接触区域。例如，120 μm x 160 μm 区域中的 40 μm x 100 μm 大小矩形悬臂区域使用负抗性保护，其余区域蚀刻至硅层。</li>
	<li>实现顶部和底部电极。顶部电极在矩形悬臂区域上图案，底部电极在 30 μm x 30 μm 蚀刻区域的 2 μm 厚硅层上图案。顶部接触的宽度比图案悬臂区域小 4 μm，底部接触的大小大于第 1 步中的 30 μm x 30 μm 方形蚀刻区域。</li>
	<li>在矩形悬臂周围 120μm x 160 μm U 形区域中蚀刻所有 2 μm 厚的硅层。蚀刻区域再次为 U 形，但每侧小 4 μm，以保护悬臂区域免受最后一步的 HF 攻击。</li>
	<li>释放悬臂与BOE蚀刻的SiO2。受保护的悬臂面积比实际悬臂区域大 2 μm。最重要的是保护悬臂的表面和空白。</li>
</ol>7. 用食人鱼溶液清洁悬臂微压加工过程中的石英样品
<ol><li>在环境温度下，将10毫升过氧化氢（H2O2）加入20毫升硫酸（H2SO4），准备食人鱼溶液。这种混合物产生热反应。<ol>
<li>将样品放入此溶液中 10 分钟，以清洁所有有机残留物。</li>
		<li>用DI水冲洗样品，用氮干燥。</li>
	</ol>
</li>
</ol>8. 第 1 步:石英薄膜上图案悬臂形状
<ol><li>第一个光刻过程<ol>
<li>用丙酮、IPA 冲洗样品，然后吹干氮。</li>
		<li>将样品放在 140°C 的热板上，进行 10 分钟的除湿。</li>
		<li>旋转AZ2070负光照面以4000 rpm的速度为30s。</li>
		<li>将样品放在热板上，在 115 °C 下软化 60 s。</li>
		<li>以 37.5 mJ.cm-2 紫外线剂量暴露样品 5s。</li>
		<li>将样品放在热板上，在 60 s 的 115 °C 下进行暴露后烘烤。</li>
		<li>在 MIF 726 开发中开发 100s 在环境温度下，然后冲洗 DI 水并吹干氮。预期厚度为 5.5 μm。</li>
		<li>将样品放在 125 °C 的加热板上 10 分钟，以硬化电阻。</li>
	</ol>
</li>
	<li>石英层的活性离子蚀刻 （RIE）<ol>
<li>使用 RIE 的石英直到硅层，气体流速为 60 sccm CHF3、20sccm 02和 10 sccm Ar，功率为 100 W RF。</li>
	</ol>
</li>
	<li>清洁电阻残留物<ol>
<li>用等离子体以 90 sccm 02 的流速清洁 5 分钟。</li>
		<li>如果第一个清洁步骤不够，请将样品留在 80 °C 的去除器 PG 中，直到删除所有电阻。</li>
		<li>然后，将样品放入食人鱼溶液中（20毫升硫酸H2SO4 + 10 mL 过氧化氢H2O2）10分钟。然后，冲洗 DI 水，用氮气吹干。</li>
	</ol>
</li>
</ol>9. 第 2 步:实现底部和顶部电极
<ol><li>第二个光刻过程<ol>
<li>用丙酮、IPA 冲洗样品，然后吹干氮。</li>
		<li>将样品放在 140 °C 的热板上，进行 10 分钟的除湿。</li>
		<li>旋转AZ2020负光照面以4000 rpm的速度为30s。</li>
		<li>将样品放在热板上，在 115 °C 下软化 60 s。</li>
		<li>以 23.25 mJ.cm-2 紫外线剂量暴露样品 3s。</li>
		<li>将样品放在热板上，在 60 s 的 115 °C 下进行暴露后烘烤。</li>
		<li>在 MIF 726 开发中开发，在环境温度下达到 50 s，然后冲洗 DI 水并吹干氮。预期厚度为 1.7 μm。</li>
	</ol>
</li>
	<li>顶部和底部电极的金属沉积。<ol>
<li>以 4 A/s 和 120 nm 铂金的速率在 2.5 A/s 下沉积 50 nm 铬，电子束蒸发在 10-6 mbar。</li>
	</ol>
</li>
	<li>金属升空<ol>
<li>先将样品留在丙酮中，然后留在 IPA 中，直到金属升空成功。</li>
		<li>用光学显微镜检查样品，如有必要，将样品留在 80 °C 的去除器 PG 中，直到所有金属升空。然后，冲洗 DI 水并吹干氮。</li>
		<li>如果步骤 9.3.2 不够，将样品放入丙酮中的超声波清洁剂中 5 分钟。在必要时重复此操作的次数。</li>
		<li>用丙酮（IPA）冲洗样品，然后用氮气吹干。</li>
	</ol>
</li>
</ol>10. 第 3 步:将样本图案为蚀刻 Si （100） 层
<ol><li>第三个光刻过程<ol>
<li>用丙酮、IPA 冲洗样品，然后吹干氮。</li>
		<li>将样品放在 140 °C 的热板上，进行 10 分钟的除湿。</li>
		<li>旋转AZ2070负光照面以2000 rpm的速度为30s。</li>
		<li>将样品放在60 s的115°C软巴克热板上。</li>
		<li>以 37.5 mJ.cm-2 紫外线剂量暴露样品 5s。</li>
		<li>将样品放在加热板上，在 115 °C 下烘烤 60 s。</li>
		<li>在 MIF 726 中开发，在环境温度下为 110 s，然后冲洗 DI 水，用氮气吹干。预期厚度为 5.9 μm。</li>
		<li>将样品放在 125 °C 的热板上 10 分钟，以硬化电阻。</li>
	</ol>
</li>
	<li>硅层的活性离子蚀刻<ol>
<li>蚀刻硅层，直到 SiO2 层使用 RIE，气体流速为 60 sccm CHF3，20sccm0 2 和 10 sccm Ar 在 100W RF 功率下。</li>
	</ol>
</li>
	<li>清洁电阻残留物<ol>
<li>首先用等离子体清洁，流速为 90 sccm0 2 5 分钟。</li>
		<li>将样品保留在 80 °C 的去除器 PG 中，直到删除所有电阻。然后，冲洗 DI 水并吹干氮。</li>
	</ol>
</li>
</ol>11. 第 4 步:通过 SiO2的湿化学蚀刻释放悬臂
<ol><li>第四个光刻过程<ol>
<li>用丙酮、IPA 冲洗样品，然后吹干氮。</li>
		<li>将样品放在 140 °C 的热板上，进行 10 分钟的除湿。</li>
		<li>旋转AZ2020负光照面以2000 rpm的速度为30s。</li>
		<li>将样品放在加热板上，在115°C下进行60s的软烘烤。</li>
		<li>以 37.5 mJ.cm-2 紫外线剂量暴露样品 5s。</li>
		<li>将样品放在加热板上，在 115 °C 下烘烤 60 s。</li>
		<li>在 MIF 726 中开发，在环境温度下为 65 s。冲洗 DI 水，然后吹干氮。预期厚度为 2.3 μm。</li>
		<li>将样品放在 125 °C 的加热板上 10 分钟，以硬化电阻。</li>
	</ol>
</li>
	<li>带缓冲氧化物蚀刻的 SiO2 层湿蚀刻 （BOE）<ol>
<li>将 BOE 7:1 溶液放入基于聚四氟乙烯 （PTFE） 的容器中。</li>
		<li>将样品放入此溶液中，并将其保持在环境温度，直到所有 SiO2 层都蚀刻在悬臂下。然后冲洗 DI 水并吹干氮。</li>
	</ol>
</li>
	<li>清洁电阻残留物<ol>
<li>用丙酮、IPA 冲洗样品，然后吹干氮。</li>
		<li>如有必要，用等离子体以90 sccm O2 的流速清洁电阻残留物5分钟。</li>
	</ol>
</li>
</ol>

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(106), e53543 (2015).</li><li>Zhang, Q., 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=Tailoring+the+crystal+growth+of+quartz+on+silicon+for+patterning+epitaxial+piezoelectric+films.">Tailoring the crystal growth of quartz on silicon for patterning epitaxial piezoelectric films.</a> Nanoscale Advances. 1 (9), 3741-3752 (2019).</li><li>Zhang, Q., 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=Micro/nanostructure+engineering+of+epitaxial+piezoelectric+&#945;-quartz+thin+films+on+silicon.">Micro/nanostructure engineering of epitaxial piezoelectric &#945;-quartz thin films on silicon.</a> ACS Applied Materials &amp; Interfaces. 12 (4), 4732-4740 (2020).</li><li>Sansen, T., 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=Mapping+cell+membrane+organization+and+dynamics+using+soft+nanoimprint+lithography.">Mapping cell membrane organization and dynamics using soft nanoimprint lithography.</a> ACS Applied Materials &amp; Interfaces. 12 (26), 29000-29012 (2020).</li><li>Jolly, C., 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=Soft+chemistry+assisted+on-chip+integration+of+nanostructured+quartz-based+piezoelectric+microelectromechanical+system.">Soft chemistry assisted on-chip integration of nanostructured quartz-based piezoelectric microelectromechanical system.</a> arXiv:2007.07566 [physics.app-ph]. , (2020).</li></ol>

作者没有什么可透露的。

该方法采用自下而上的方法，在 Si. 石英/Si-MEMS 技术上生产纳米结构压电石英微悬臂，在尺寸、功耗和集成成本方面比散装石英具有重大优势。事实上，表观石英/Si MEMS 是与 CMOS 兼容的工艺生产的。这可促进未来为多频设备制造单芯片解决方案，同时保持小型化和具有成本效益的流程。与目前制造的石英器件相比，该技术基于大型水热晶体的切割和抛光，协议中描述的方法允许在SOSI基板上获得相?...

具有压电特性的氧化物纳米材料对于设计MEMS传感器、微型能量收割机或储存1、2、3等设备至关重要。随着CMOS技术的进步，优质表观压电薄膜和纳米结构整体集成硅成为新设备扩展的一个值得关注的主题。此外，需要更好地控制这些设备的小型化，以实现高性能5，6。电子、生物和医学领域的新传感器应用是由微和纳米制剂技术的进步所推动的。
特别是，α石英被广泛用作压电材料，并显示出突出的特性，使用户能够为不同的应用制造。虽然机电耦合系数低，限制了其能量收集的应用领域，但其化学稳定性和高机械质量系数使其成为频率控制装置和传感器技术的良好应用。然而，这些设备是从散装单石英晶体微加工而来的，具有制造设备10的理想特性。石英晶体的厚度应该以这样的方式配置，以便从设备获得最高的共振频率，现在，最低可实现的厚度是10μm11。到目前为止，一些微量晶体的技术，如法拉第笼斜蚀11，激光干扰光刻12，和聚焦离子束（FIB）13报道。
最近，化学溶液沉积（CSD）14、15开发出将（100）α石英薄膜直接和自下而上地整合成硅基板（100）。这种方法为克服上述挑战打开了大门，也为未来的传感器应用开发基于压电的设备打开了大门。实现了硅基板上α石英薄膜的结构，控制了薄膜的质地、密度和厚度。α石英薄膜的厚度从几百纳米扩大到微米范围，比散装晶体自上而下技术获得的薄10至50倍。优化浸涂沉积条件，湿度和温度，通过一套自上而下的石刻技术17的组合，实现了连续的纳米结构晶体石英薄膜和完美的纳米印花模式。具体来说，软纳米印花光刻（NIL）是一种低成本、大规模制造和台面设备为基础的工艺。软NIL的应用结合了自上而下的方法，是生产硅上表观石英纳米柱阵列的关键，能够精确控制柱径、高度和柱间距离。此外，在有机硅玻璃上制造具有可控形状、直径和周期性的硅纳米柱，用于生物应用，并定制了表观石英薄膜18的软NIL。
到目前为止，压电纳米结构α石英MEMS的片上集成是不可能的。在这里，我们绘制了从材料到设备制造的详细工程路线。我们解释了材料合成的所有步骤，软NIL和设备的微压压，以释放在SOI基板19 上的压电石英悬臂，并讨论其作为压电材料的反应与一些描述结果。

<table><tbody><tr><td>Acetone</td><td>Honeywell Riedel de Ha&amp;euml;n</td><td>UN 1090</td><td></td></tr><tr><td>AZnLOF 2020 negative resist</td><td>Microchemicals</td><td>USAW176488-1BLO</td><td></td></tr><tr><td>AZnLOF 2070 negative resist</td><td>Microchemicals</td><td>USAW211327-1FK6</td><td></td></tr><tr><td>AZ 726 MIF developer</td><td>Merck</td><td>DEAA195539</td><td></td></tr><tr><td>BOE (7:1)</td><td>Technic</td><td>AF 87.5-12.5</td><td></td></tr><tr><td>Brij-58</td><td>Sigma</td><td>9004-95-9</td><td></td></tr><tr><td>Chromium</td><td>Neyco</td><td>FCRID1T00004N-F53-062317/FC79271</td><td></td></tr><tr><td>Dip Coater ND-R 11/2 F</td><td>Nadetec</td><td>ND-R 11/2 F</td><td></td></tr><tr><td>Hydrogen peroxide solution 30%</td><td>Carlo Erka Reagents DasitGroup</td><td>UN 2014</td><td></td></tr><tr><td>H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;</td><td>Honeywell Fluka</td><td>UN 1830</td><td></td></tr><tr><td>Isopropyl alcohol</td><td>Honeywell Riedel de Ha&amp;euml;n</td><td>UN 1219</td><td></td></tr><tr><td>Mask aligner</td><td>EV Group</td><td>EVG620</td><td></td></tr><tr><td>PG remover</td><td>MicroChem</td><td>18111026</td><td></td></tr><tr><td>Platinum</td><td>Neyco</td><td>INO272308/F14508</td><td></td></tr><tr><td>PTFE based container</td><td>Teflon</td><td></td><td></td></tr><tr><td>Reactive ion etching (RIE)</td><td>Corial</td><td>ICP Corial 200 IL</td><td></td></tr><tr><td>SEMFEG</td><td>Hitachi</td><td>Su-70</td><td></td></tr><tr><td>SOI substrate</td><td>University Wafer</td><td>ID :3213</td><td></td></tr><tr><td>Strontium chloride hexahydrate</td><td>Sigma-Aldrich</td><td>10025-70-4</td><td></td></tr><tr><td>SYLGARD TM 184 Silicone Elastomer Kit</td><td>Dow</td><td>.000000840559</td><td></td></tr><tr><td>SYLGARD TM 184 Silicone Elastomer Curring Agent</td><td>Dow</td><td>.000000840559</td><td></td></tr><tr><td>Tetraethyl orthosilicate</td><td>Aldrich</td><td>78-10-4</td><td></td></tr><tr><td>Tubular Furnace</td><td>Carbolite</td><td>PTF 14/75/450</td><td></td></tr><tr><td>Vibrometer</td><td>Polytec</td><td>OFV-500D</td><td></td></tr><tr><td>2D XRD</td><td>Bruker</td><td>D8 Discover</td><td>Equipped with a Eiger2 R 500 K 2D detector</td></tr></tbody></table>

epitaxial nanostructured &alpha;-quartz films on silicon: from the material to new devices

在这项工作中，我们展示了第一台压电纳米结构表观石英微扫描器的详细工程路线。我们将解释从材料到设备制造过程中的所有步骤。SOI （100） 基板上α石英薄膜的表观增生始于制备掺杂硅溶胶，并利用室温下大气条件下的浸涂技术，以薄膜形式将这种凝胶沉积到 SOI 基板中。在凝胶薄膜结晶之前，纳米结构通过纳米印刷石刻（NIL）在薄膜表面进行。表皮膜生长达到1000°C，诱导图案凝胶薄膜的完美结晶。石英晶体悬臂装置的制造是一个基于微制造技术的四步过程。这个过程从塑造石英表面开始，然后电极的金属沉积跟随它。去除硅胶后，悬臂从 SOI 基板中释放出来，消除硅和石英之间的 SiO2。 通过非接触式激光振动计 （LDV） 和原子力显微镜 （AFM） 分析设备性能。在制造芯片中包含的不同悬臂尺寸中， 本作品中分析的纳米结构悬臂尺寸为 40μm 大，长 100μm，由 600 nm 厚的图案石英层（纳米柱直径和分离距离分别为 400 nm 和 1 μm）制成，在 2 μm 厚的 Si 设备层上呈表观增长。测得的共振频率为267千赫，整个机械结构的估计质量因子Q在低真空条件下为Q~398。我们用两种技术（即AFM接触测量和LDV）观察了悬臂的电压依赖线性位移。因此，证明这些设备可以通过间接压电效应激活。

材料合成和设备制造的进展（见图1）通过用真实图像监测不同的步骤来描述。在微制造过程之后，我们使用现场发射扫描电子显微镜 （FEG-SEM） 图像（图 2a-c）观察了纳米结构悬臂的各个方面。2D微X射线衍射控制了悬臂不同堆叠层的晶体（图2d）。我们还利用电子衍射技术和后散电子模式（图2<s...

Watch this Scientific Journal Video about Epitaxial Nanostructured Î±-Quartz Films on Silicon: From the Material to New Devices at JoVE.com

Epitaxial Nanostructured &#945;-Quartz Films on Silicon: From the Material to New Devices

本工作为纳米结构α石英悬臂在绝缘硅（SOI）技术基板上的微压造提供了详细的协议，从石英薄膜的表观生长开始，采用浸涂法，然后通过纳米印花石刻技术对薄膜进行纳米结构处理。

硅上显性纳米结构α石英薄膜:从材料到新设备

In this work, we show a detailed engineering route of the first piezoelectric nanostructured epitaxial quartz-based microcantilever. We will explain all ...

epitaxial-nanostructured-quartz-films-on-silicon-from-material-to-new

Research

JoVE Journal

Engineering

Epitaxial Nanostructured &alpha;-Quartz Films on Silicon: From the Material to New Devices

5.3K 次观看.  Université de Montpellier. 本工作为纳米结构α石英悬臂在绝缘硅（SOI）技术基板上的微压造提供了详细的协议，从石英薄膜的表观生长开始，采用浸涂法，然后通过纳米印花石刻技术对薄膜进行纳米结构处理。

视频: Epitaxial Nanostructured α-Quartz Films on Silicon: From the Material to New Devices

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach.
The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles.
To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 &mu;m thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm2, which can be increased up to 17-18 mA/cm2 (~25% higher) after application of a simple diffuse back reflector made of a white paint.
To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23&deg;C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF2, and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF2, and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm2, up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.
Introduction
Light-trapping in silicon solar cells is commonly achieved via light scattering at textured interfaces. Scattered light travels through a cell at oblique angles for a longer distance and when such angles exceed the critical angle at the cell interfaces the light is permanently trapped in the cell by total internal reflection (Animation 1: Light-trapping). Although this scheme works well for most solar cells, there are developing technologies where ultra-thin Si layers are produced planar (e.g. layer-transfer technologies and epitaxial c-Si layers) 1 and or when such layers are not compatible with textures substrates (e.g. evaporated silicon) 2. For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3, silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.
Metal nanoparticles can effectively scatter incident light into a higher refractive index material, like silicon, due to the surface plasmon resonance effect 6. They also can be easily formed on the planar silicon cell surface thus offering a light-trapping approach alternative to texturing. For a nanoparticle located at the air-silicon interface the scattered light fraction coupled into silicon exceeds 95% and a large faction of that light is scattered at angles above critical providing nearly ideal light-trapping condition (Animation 2: Plasmons on NP). The resonance can be tuned to the wavelength region, which is most important for a particular cell material and design, by varying the nanoparticle average size, surface coverage and local dielectric environment 6,7. Theoretical design principles of plasmonic nanoparticle solar cells have been suggested 8. In practice, Ag nanoparticle array is an ideal light-trapping partner for poly-Si thin-film solar cells because most of these design principle are naturally met. The simplest way of forming nanoparticles by thermal annealing of a thin precursor Ag film results in a random array with a relatively wide size and shape distribution, which is particularly suitable for light-trapping because such an array has a wide resonance peak, covering the wavelength range of 700-900 nm, important for poly-Si solar cell performance. The nanoparticle array can only be located on the rear poly-Si cell surface thus avoiding destructive interference between incident and scattered light which occurs for front-located nanoparticles 9. Moreover, poly-Si thin-film cells do not requires a passivating layer and the flat base-shaped nanoparticles (that naturally result from thermal annealing of a metal film) can be directly placed on silicon further increases plasmonic scattering efficiency due to surface plasmon-polariton resonance 10.
The cell with the plasmonic nanoparticle array as described above can have a photocurrent about 28% higher than the original cell. However, the array still transmits a significant amount of light which escapes through the rear of the cell and does not contribute into the current. This loss can be mitigated by adding a rear reflector to allow catching transmitted light and re-directing it back to the cell. Providing sufficient distance between the reflector and the nanoparticles (a few hundred nanometers) the reflected light will then experience one more plasmonic scattering event while passing through the nanoparticle array on re-entering the cell and the reflector itself can be made diffuse - both effects further facilitating light scattering and hence light-trapping. Importantly, the Ag nanoparticles have to be encapsulated with an inert and low refractive index dielectric, like MgF2 or SiO2, from the rear reflector to avoid mechanical and chemical damage 7. Low refractive index for this cladding layer is required to maintain a high coupling fraction into silicon and larger scattering angles, which are ensured by the high optical contrast between the media on both sides of the nanoparticle, silicon and dielectric 6. The photocurrent of the plasmonic cell with the diffuse rear reflector can be up to 45% higher than the current of the original cell or up to 25% higher than the current of an equivalent cell with the diffuse reflector only.

Polycrystalline silicon thin-film solar cells on glass are fabricated by deposition of boron and phosphorous doped silicon layers followed by crystallisation, defect passivation and metallisation. Plasmonic light-trapping is introduced by forming Ag nanoparticles on the silicon cell surface capped with a diffused reflector resulting in ~45% photocurrent enhancement.

多晶硅薄膜太阳能电池电浆增强光捕获

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To ...

科研

工程学

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 ...

化学

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Atomically Traceable Nanostructure Fabrication

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

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

原子纳米结构可追溯制造

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

Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition

This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol. However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr2+ act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.

A protocol is presented for the preparation of piezoelectric macroporous epitaxial films of quartz on silicon by solution chemistry using dip-coating and thermal treatments in air.

化学溶液沉积在硅外延大孔石英薄膜的制备

This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

锗通过原子层沉积钙钛矿型钛酸锶的外延生长

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on Their Photocatalytic NOx Abatement Performance

The chemical bonding of particulate photocatalysts to supporting material surfaces is of great importance in engineering more efficient and practical photocatalytic structures. However, the influence of such chemical bonding on the optical and surface properties of the photocatalyst and thus its photocatalytic activity/reaction selectivity behavior has not been systematically studied. In this investigation, TiO2 has been supported on the surface of SiO2 by means of two different methods: (i) by the in situ formation of TiO2 in the presence of sand quartz via a sol-gel method employing tetrabutyl orthotitanium (TBOT); and (ii) by binding the commercial TiO2 powder to quartz on a surface silica gel layer formed from the reaction of quartz with tetraethylorthosilicate (TEOS). For comparison, TiO2 nanoparticles were also deposited on the surfaces of a more reactive SiO2 prepared by a hydrolysis-controlled sol-gel technique as well as through a sol-gel route from TiO2 and SiO2 precursors. The combination of TiO2 and SiO2, through interfacial Ti-O-Si bonds, was confirmed by FTIR spectroscopy and the photocatalytic activities of the obtained composites were tested for photocatalytic degradation of NO according to the ISO standard method (ISO 22197&#8722;1). The electron microscope images of the obtained materials showed that variable photocatalyst coverage of the support surface can successfully be achieved but the photocatalytic activity towards NO removal was found to be affected by the preparation method and the nitrate selectivity is adversely affected by Ti-O-Si bonding.

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on Their Photocatalytic NOx Abatement Performance

The focus of the present work is to establish means to generate and quantify levels of Ti-O-Si linkages and to correlate these with the photocatalytic properties of the supported TiO2.

界面化学键合在TiO中的作用<sub&gt; 2</sub&gt; -SiO<sub&gt; 2</sub&gt;复合材料对其光催化NOx消除性能的影响

The chemical bonding of particulate photocatalysts to supporting material surfaces is of great importance in engineering more efficient and practical ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

一种新的方法<em&gt;原位</em&gt;纳米级样品的机电表征

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

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 ...

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

The synthesis of high quality bulk and thin film (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O entropy-stabilized oxides is presented.

组分变熵稳定氧化物的体积和薄膜合成

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...

硅上显性纳米结构α石英薄膜:从材料到新设备

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