The medical research fraternity is imagining a future where nanoelectronic devicescould detect the concentrations of biomolecules in real time for use as medical diagnostics or interact with single cells for use in basic biological research. Such miniaturization to nanoscale 3D structures and devices would open up possibilities to enable new approaches for health monitoring, surveillance, computer processing, energy research, defense technology and many more applications.
这些未来派的纳米驱动器是由一种新技术通过称为聚焦电子束诱导沉积（febid）的新技术，这是一种用于纳米和微型结构的直接光束写作技术，这是当今3D打印过程的纳米级版本。类似于启用3D打印的添加剂制造技术，Febid AIDS快速逐个原子“直接编写”雷电竞充值具有控制形状和拓扑的材料。这导致纳米结构降至100 nm量表，这是在传统过程中极不可能实现的。
Although first used in 1976 for demonstrating the nano-patterning capabilities of focused electron beam, FEBID has garnered the interest of researchers only in the last decade, evident from the fact that the number of citations for “FEBID” in academic and scientific journals has increased by a factor of 15 as compared with the 1980’s. The augmented interest in the subject can be attributed to the availability of high-resolution tools, combined with focused ion beam (FIB) processing techniques. Also available is the technology for focused electron beam induced etching, now routinely used in high-end tools for photolithographic (process of transferring geometric shapes) mask repair in the semiconductor industry.
Realizing the impetus of this promising new technology, the Department of Energy grant will fund research to advance an additive manufacturing technique for fabricating 3D nano-scale structures from a variety of materials. The research will focus on dramatically accelerating growth, improving the purity and increasing the aspect ratio of the 3D structures. Researchers expect the three-year $660,000 grant will help them to develop a fundamental understanding of how the process works, accelerate the rate of materials growth and provide improved control over the process. The research will include both theoretical modelling and experimental evaluation.
The FEBID technique delivers a tightly-focused beam of high energy electrons and an energetic jet of thermally excited precursor gases – both confined to the same spot on a substrate. Secondary electrons generated when the electron beam strikes the substrate cause decomposition of the precursor molecules, forming nano-scale 3D structures whose size, shape and location can be precisely controlled.
该项目的负责人兼乔治亚理工学院乔治·W·伍德拉夫机械工程学院的教授安德烈·费多罗夫（Andrei Fedorov）解释说：“无论电子在任何地方都可以增加押金。”“这提供了一种工具，可从各种纳米纳米的各种材料中生长出复杂的三维结构。”
This process is parallel to the commercially popular “additive manufacturing“ process where a laser-sintering device applies thin layers of the powder material to the building platform followed by a powerful laser beam that fuses the powder at exactly the points defined by the computer-generated component design data. The material is fused so as to bond with the layer below at the predefined points forming components using 3D printing at a macro-scale.
尽管先驱dvancements, the FEBID process is not free from challenges, namely (i) increasing the rate of deposition, (ii) eliminating the unwanted deposits of carbon that are formed as part of the process, and (iii) availability of micron-scale focused jets to release thermally energized precursor molecules. Through experimentation with inert gasses and playing with new substrate materials, scientists are developing solutions to deal with the hurdles. However, one major limitation to this technology remains — overcoming the scalability barriers to produce nano-devices for mass production, as economies of scales do not play a persuasive role in controlling costs in an additive manufacturing process.
The FEBID process of nano-scale additive manufacturing so far has successfully yielded about two-dozen materials on different substrates, including semiconductors, dielectrics, metals and even plastics. The researchers also plan to create nanostructures containing more than one material, allowing them to craft unique properties not available in each individual material. Examples might include new types of ferromagnetic materials and photonic bandgap structures with unique properties. As Dr. Federov puts it, not uniquely, “the possibilities are almost limitless.”
References:
1. “Grant Funds Development of Improved Nanoscale Additive Manufacturing” http://www.news.gatech.edu/2013/10/21/grant-funds-development-improved-nanoscale-additive-manufacturing
2.德国Goethe-Universita的Physikalisches Institut Michael Huth的“聚焦电子束引起的沉积 - 原理和应用”。www.beilstein-institut.de/bozen2010/proceedings/huth/huth.pdf
