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

在过去的40年里，我们已经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年代家庭计算机的出现到偶尔将家里的单个设备连接到互联网上。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、中央暖气，甚至门铃，除了我们的手机、平板电脑和个人电脑外，所有这些设备都通过高速宽带持续连接到互联网。这一趋势将继续下去，智能包装、无处不在的环境监测、可穿戴式健康监测器等新兴技术将变得司空见惯。这种“物联网”的发展预示着新的制造业挑战。在这段时间里，硅基电子学的发展是基于试图将微处理器等电子元件的每晶体管成本降至最低。通过这种方式，微处理器可以用数十亿个晶体管以负担得起的成本来制造。然而，由于成本、外形因素、环境和其他限制，使用硅基电子产品并不适合所有这些新兴应用。大面积电子产品(LAE)是指使用新材料和新工艺制造电子产品的领域，其中单位面积成本最低，而不是每台设备的成本最低。显示器可能是LAE最著名的例子，在整个屏幕上有一层电子设备控制着每个像素的光输出，但其他领域也在涌现，特别是在具有与硅完全不同外形因素的柔性塑料等基板上开发基本微处理器、存储器和逻辑。此外，由于制造成本远低于硅基电子产品，在英国制造是现实。与硅一样，减小LAE设备的物理尺寸会带来性能提升，这将是未来几代智能技术所需要的。但总的来说，制造成本随着特征尺寸的减小而增加，这使得纳米级的制造成本高得令人望而却步。我们一直在研究一种称为粘合光刻(A-Lith)的图案化技术。这使得仅使用金属电极本身的低分辨率图案化就可以在相邻的金属电极之间形成长度约10 nm的间隙的可重复制造。我们已经在https://doi.org/10.17863/CAM.68204上发布了一个工具的设计来实现这一点。然而，要制造像晶体管这样的电子器件，我们需要将材料放入这些金属电极之间的缝隙中。纳米材料，如碳纳米管、硅纳米线、氧化锌纳米线和石墨烯，由于其纳米结构而被证明具有特殊的本征电子性质。然而，通常的挑战是将金属电极放在这些材料上以利用这些特性。在这项工作中，我们建议开发制造工艺，将A-Lith NanoGap制造与这些纳米材料的自下而上生长结合起来，使它们自然地跨越NanoGap生长，以低成本制造新一代电子器件。我们将展示的两个这样的“纳米材料在纳米间隙”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，我们在那里创造电子设备，从大脑的突触中获得灵感来运作。这个项目旨在使这些用于大面积电子设备的新型纳米材料在纳米间隙中的制造成为现实。

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.