Low Dimensional Electronic Device Fabrication at Low Cost over Large Areas: Follow-on

在过去的40年里，我们看到了我们在日常生活中使用电子设备的方式的转变，从20世纪80年代出现的家庭计算，偶尔将家中的单个设备“拨号”连接到互联网。相比之下，今天我们有太多的智能设备，如电视，扬声器，白色家电，中央供暖，甚至门铃，除了我们的手机，平板电脑和个人电脑，所有这些都通过高速宽带持续连接到互联网上。随着智能包装、无处不在的环境监测、可穿戴健康监测器以及其他新兴技术的普及，这一趋势将继续下去。这种“物联网”的发展预示着新的制造业挑战。在此期间，硅基电子学的发展是基于尽量降低微处理器等电子元件中每个晶体管的成本。通过这种方式，微处理器可以以可承受的成本制造数十亿个晶体管。然而，由于成本、外形因素、环境和其他限制，将硅基电子器件用于所有这些新兴应用是不合适的。大面积电子学（LAE）是使用新材料和新工艺制造电子产品的领域，其中单位面积的成本最小化，而不是每个设备的成本最小化。显示器可能是LAE最著名的例子，在整个屏幕上放置一层电子器件，控制每个像素的光输出，但其他领域正在兴起，特别是在基板上的基本微处理器、存储器和逻辑的发展，如柔性塑料，它们与硅具有完全不同的形状因素。此外，由于制造成本远低于硅基电子产品，在英国制造是一个现实。与硅一样，减小LAE设备的物理尺寸可以提高性能，这将是未来几代智能技术所需要的。但一般来说，随着特征尺寸的减小，制造成本会增加，这使得纳米级的制造成本过高。我们一直在研究一种称为粘合光刻（a - lith）的图案技术。这使得仅使用金属电极本身的低分辨率图像化就可以在相邻的金属电极之间形成长度为10nm的可重复制造的间隙。我们已经在https://doi.org/10.17863/CAM.68204上发布了一个工具的设计。然而，为了制造像晶体管这样的电子器件，我们需要在这些金属电极之间的间隙中放入材料。纳米材料，如碳纳米管、硅纳米线、氧化锌纳米线和石墨烯，由于其纳米结构，已被证明具有特殊的内在电子特性。然而，挑战通常是在这些材料上放置金属电极，以便能够利用这些特性。在这项工作中，我们建议开发制造工艺，将a -锂纳米隙制造与这些纳米材料的自下而上生长结合在一起，使它们自然地在纳米隙中生长，以低成本制造新一代电子器件。我们将展示的两种“纳米材料-纳米隙”器件是晶体管和忆阻器。前者一直是传统电子电路背后的基石。后者被视为未来神经形态电子学背后的基石，在那里我们创造了从大脑突触中获得灵感来操作的电子设备。该项目旨在将这些用于大面积电子产品的新型纳米材料纳米隙器件的制造变为现实。

Over the last 40 years, we have seen a transformation in how we use electronic devices in our everyday lives from the emergence of home computing in the 1980s with occasional 'dial-up' connection of a single device in the home to the internet. In contrast, today we have a plethora of smart devices such as televisions, speakers, white goods, central heating and even doorbells all continuously connected to the internet through high speed broadband in addition to our mobile phones, tablets and personal computers. This trend will continue, with smart packaging, ubiquitous environmental monitoring, wearable wellbeing monitors amongst other emerging technologies becoming commonplace. The development of this 'Internet of Things' portents new manufacturing challenges. Silicon-based electronics has developed over this time based on trying to minimise the cost per transistor in electronic components such as microprocessors. In this way, microprocessors can be fabricated with billions of transistors at an affordable cost point. However, it is just not appropriate to use silicon-based electronics for all of these emerging applications because of cost, form factor, environmental and other limitations.Large-area electronics (LAE) is the field which sees the use of new materials and processes to make electronics where the cost per unit area is minimised rather than the cost per device. Displays are perhaps the best known example of LAE, where a layer of electronics sits over an entire screen controlling the light output from each pixel, but other areas are emerging, and in particular the development of basic microprocessors, memories and logic on substrates such as flexible plastics which have radically different form factors from silicon. Also, as the cost of manufacture is much lower than for silicon-based electronics, manufacturing in the UK is a reality.As with silicon, decreasing the physical size of LAE devices leads to performance enhancements, and these will be needed for future generations of smart technologies. but in general the cost of manufacture increases as feature size is reduced, and this makes fabrication at the nanoscale prohibitively expensive. We have been working on a patterning technique called Adhesion Lithography (A-Lith). This allows the reproducible fabrication of gaps ~10 nm in length to be formed between adjacent metal electrodes using only low resolution patterning of the metal electrodes themselves. We have published the design of a tool to do this at https://doi.org/10.17863/CAM.68204 . However, to make an electronic device such as a transistor, we need to put materials into the gap between these metal electrodes.Nanomaterials, such as carbon nanotubes, silicon nanowires, zinc oxide nanowires and graphene, have been shown to have exceptional intrinsic electronic properties as a result of their nanostructure. However, the challenge is usually to put metal electrodes onto these materials to be able to make use of these properties.In this work, we propose to develop the manufacturing processes to bring together A-Lith nanogap manufacture with the bottom-up growth of these nanomaterials so that they naturally grow across the nanogap to make a new generation of electronic devices at low cost. Two such 'nanomaterial-in-nanogap' devices which we will demonstrate are transistors and memristors. The former have been the building block behind traditional electronic circuits. The latter are seen as the building block behind the neuromorphic electronics of the future, where we create electronic devices which take inspiration from the synapses of the brain to operate.This project aims to bring the manufacture of these new nanomaterial-in-nanogap devices for large-area electronics to reality.