Collaborative Research: Programmable Metal-Assisted Chemical Etching for Three-Dimensional Functional Metamaterials

超材料是一种人工结构的材料，具有不寻常的，但有利的电磁特性，不容易在自然界中发现。这些特殊性质来自于以周期性排列组织起来的复杂结构特征区域。目前，光学超材料的制造主要基于本征二维图案化工艺，三维光学超材料的展示主要基于聚合物结构。目前还没有直接制造三维晶体超导体基超材料的制造技术。该奖项探索了一种独特的可编程金属辅助化学蚀刻工艺，用于三维功能超材料的可扩展纳米制造。这种方法将克服目前基于功能超材料的集成光子学的障碍，以实现对光的完全控制。多功能的制造方法和材料功能将不可避免地影响三维电子和光子学，组织工程和能量转换/存储的生产。通过让包括妇女和少数民族在内的学生参与这一新兴研究领域，该奖项活动将有助于确保他们在当今全球环境中的能力和领导力。针对高中教师、学生和公众的外展活动将提高认识，并为我们未来的劳动力做好准备，以迎接新兴的美国纳米制造业。金属辅助化学蚀刻是一种基于各向异性溶液的蚀刻方法，违背了教科书对湿法蚀刻的定义。通过这种技术，通过将图案化的金属模板雕刻到半导体的主体中来形成三维高纵横比半导体纳米结构。在受控条件下，蚀刻仅发生在金属和半导体之间的界面处。结果，当下面的半导体被侵蚀时，金属层下降或嵌入半导体中。在这项研究中，随着蚀刻的进行，磁场被编程以引导铁磁金属催化剂的运动，并且通过编程金属催化剂的轨迹形成任意三维曲线纳米结构，因为它雕刻到Si或更高指数的III-V族半导体的主体中。由于其与集成电路制造的兼容性，该方法可扩展用于高度期望的功能光学超材料的大批量制造。在纳米纤维和光子学领域的互补专业知识的合作努力，分别定位于提供制造三维微纳米尺度半导体和金属介电结构的能力的跨越式发展，具有前所未有的形状和尺寸控制，以及开发新型功能光学和其他材料和器件。

Metamaterials are artificially structured materials that exhibit unusual, but advantageous, electromagnetic properties not readily found in nature. The special properties arise from regions of complex structural features organized in a periodic arrangement. Currently, the fabrication of the optical metamaterials is largely based on intrinsic two-dimensional patterning processes, with limited demonstrations of three-dimensional optical metamaterials mostly based on polymer structures. There are no manufacturing techniques for direct fabrication of three-dimensional crystalline semiconductor-based metamaterials. This award explores a unique programmable metal-assisted chemical etching process for the scalable nano-manufacturing of three-dimensional functional metamaterials. Such an approach will overcome the current roadblocks towards integrated photonics based on functional metamaterials to enable complete control of light. The versatile fabrication methodology and materials functionalities will inevitably impact the production of three-dimensional electronics and photonics, tissue engineering, and energy conversion/storage. By engaging students including women and minorities in this emerging field of research, the award activities will help ensure their competence and leadership in today's global environment. Outreach activities targeting high school teachers, students, and the general public will raise awareness and prepare our future workforce to embrace the emerging US nano-manufacturing industry.Metal-assisted chemical etching is an anisotropic solution-based etching method that defies the textbook definition of wet etching. By this technique, three-dimensional high aspect-ratio semiconductor nanostructures are formed by engraving patterned metal template into the body of the semiconductor. Under controlled conditions, etching occurs only at the interface between the metal and the semiconductor. As a result, the metal layer descends or digs into the semiconductor as the underlying semiconductor is eroded. In this study, as etching proceeds, a magnetic field is programmed to guide the movement of ferromagnetic-metal catalyst and arbitrary three-dimensional curvilinear nanostructures are formed by programming the trajectory of the metal catalyst as it engraves into the body of Si or higher index III-V semiconductors. Because of its compatibility with integrated circuit manufacturing, this method is scalable for high-volume manufacturing of highly desired functional optical metamaterials. The collaborative effort with complementary expertise in nanofabrication and photonics, respectively, is positioned to provide a leap-ahead advance in capabilities for manufacturing three-dimensional micro- and nano-scale semiconductor and metallo-dielectric structures with unprecedented control of shape and dimensions, and for development of novel functional optical and other materials and devices.