Molecular assembly of spintronic circuits with DNA

设计包括电子设备在内的功能设备的最小尺度是分子尺度(大约是人类头发宽度的10万倍)。这是微型化的终极限制，并激励研究操纵和研究单个分子的性质，以应用于信息技术和传感器等领域。这也是量子现象主宰性质的规模，因此单分子结构提供了一个研究领域，从量子理论的基础测试到为未来的量子技术开发组件。为了实现这样的实验和技术，有必要将单个分子整合到电路中。这是具有挑战性的，因为有用的功能分子的典型尺寸比可能制造的最小导线要小得多，即使使用当今最复杂的光刻系统也是如此。大多数研究人员使用两种方法中的一种。第一种方法是使用电流或机械应变在细电线上形成一个几纳米宽的微小缺口，然后随机放置感兴趣的分子，希望只有一个人能弥合这个缺口。这种方法依赖于偶然性，因此它很少产生工作器件：通常情况下，只有很小一部分制造的器件表现出与缝隙中的单个分子一致的行为，而且由于缝隙的形状和分子的取向是不受控制的，即使是这种“工作”器件也很少表现出可重现的特性。第二种方法使用扫描隧道显微镜来定位和研究沉积在导电表面上的分子。这一过程比断结方法更可靠和可重复性更好，但它涉及庞大的实验设备，并且严格限制了实验几何，排除了开发更复杂的实验或实际设备的可能性。现有方法的这些局限性阻碍了分子尺度设备和技术的发展。这一领域的进一步进展现在需要开发可控制和可靠的方法，这些方法可以规模化地大批量生产。这个项目将提供这种方法并展示一系列原型分子设备。我们的方法基于DNA纳米技术，在过去的十年里，该技术已经证明自己是在分子水平上控制结构自组装的强大工具。我们将使用这些方法来引导直径约100纳米的“组件”的组装。这些组件主要由具有精确编程结构的DNA组成，将以亚纳米级的精度定位金纳米颗粒触点和我们想要利用其电传输特性的“目标”分子组件。我们的方法在试管中一次生产数万亿个封装，并确保每个封装中都有正确的分子准确地结合在触点之间的正确位置和方向上。这些金纳米颗粒触点足够大，我们可以使用标准的纳米光刻技术将它们连接到实验室设备上。这项技术未来有可能在三维器件结构中连接多个分子，并组装大规模集成分子电路。我们建议创建几个器件家族，旨在开发和证明这一全新的分子器件制造方法。这些设备将为我们提供一种前所未有的实验工具来探测分子的电磁性质，但它们也将为我们的技术的工业化部署奠定基础。该项目的核心是与工业伙伴的密切互动和旨在加速商业应用的知识转让活动。

The smallest scale on which it is possible to design functional devices, including electronics, is the molecule scale (about 100,000 times smaller than the width of a human hair). This is the ultimate limit for miniaturisation and motivates research to manipulate and study the properties of individual molecules for applications in, e.g., information technologies and sensors. It is also the scale at which quantum phenomena dominate properties, so single-molecule structures offer a domain for investigations ranging from fundamental tests of quantum theory to developing components for future quantum technologies.To realise such experiments and technologies, it is necessary to incorporate individual molecules into electrical circuits. This is challenging because the typical size of a useful functional molecule is much smaller than the smallest wires that it is possible to fabricate, even with the most sophisticated lithography systems available today. Most researchers use one of two approaches.The first uses an electrical current or mechanical strain to make a tiny gap, a few nanometres across, in a thin wire, and then deposit the molecules of interest randomly, hoping that one and only one bridges the gap. This method relies on chance, and so it very rarely yields a working device: typically, only a very small proportion of devices fabricated show behaviour consistent with a single molecule in the gap and, because the shape of the gap and the orientation of the molecule are uncontrolled, it is rare for even such "working" devices to exhibit reproducible properties. The second method uses a scanning tunnelling microscope to locate and investigate molecules that are deposited on a conducting surface. This process is much more reliable and reproducible than the break junction method but it involves bulky experimental apparatus and it tightly limits the experimental geometry, ruling out the development of more complicated experiments or practical devices. These limitations in the existing methods have hamstrung the development of molecule-scale devices and technologies. Further progress in this field now requires the development of controlled and reliable methods that can be scaled to high volume production. This project will provide this methodology and demonstrate a range of prototype molecular devices.Our approach is based on DNA nanotechnology, which has, over the last decade, proved itself to be a powerful tool for controlled self-assembly of structures at the molecular scale. We will use these methods to direct the assembly of "packages" about 100 nanometres across. Constructed mainly from DNA with a precisely programmed structure, these packages will position gold nanoparticle contacts and the "target" molecular components, whose electrical transport properties we would like to exploit, with sub-nanometre accuracy. Our method produces trillions of packages at a time in a test-tube and ensures that each one has exactly the correct molecules incorporated in the correct positions and orientations between contacts. These gold nanoparticle contacts are large enough that we can connect them to laboratory equipment using standard nanolithography techniques. The technology has the potential for future development to connect multiple molecules in three-dimensional device architectures, and for the assembly of large-scale integrated molecular circuits.We propose to create several families of devices, designed to develop and prove this radically new molecular device fabrication methodology. These devices will give us an unprecedented experimental tool for probing electrical and magnetic properties of molecules, but they will also establish the potential for the industrial deployment of our technology. Central to the project are close interactions with industrial partners and knowledge transfer activities designed to accelerate commercial applications.