Printed Logic Supply Chain (FlexIC) - TSB App. No. 155

在过去的五十年里，基于晶体硅的晶体管作为支撑逻辑器件的技术一直占据主导地位，微处理器就是其中的终极例子。虽然将处理能力打包成高性能单元的结果适合许多电子系统的发展，例如计算机，处理能力自然集中，但它不适合未来的普适计算目标。在无处不在的计算世界中，处理能力以较低的级别分布到需要它的地方。其结果是，人类不再通过特定的电子设备与数字世界互动，而是以一种对所有人开放的直观方式不断地联系在一起——最近的“数字英国”报告表达了这一观点。这将需要开发一种新技术，使高性能电子器件（如晶体管）能够在包括塑料在内的各种廉价基板上以极低的成本制造。有几种技术正在争夺这一领域，包括薄膜硅、有机半导体和金属氧化物。每种技术都有其相对的优点和缺点，很明显，没有一种技术将占主导地位，而是不同的技术将根据特定的需求（性能、寿命、成本、操作环境等）解决不同的应用领域。金属氧化物材料将在这一领域发挥明确的作用，因为它们具有其他技术所不具备的特殊特性——最显著的是（同时）透明度、高载流子迁移率、非晶结构、出色的均匀性和长寿命。然而，为了满足这些应用，必须能够将金属氧化物材料与低成本的图案化技术结合起来。要实现这一目标，需要多种技能的结合，从材料表征到设备测试和故障分析。正是出于这个原因，材料科学与工程系将在这个项目上进行合作。该项目将使该大学继续发展其在多种金属氧化物材料沉积方面的专业知识，包括n型半导体（氧化锌、氧化铟锌和氧化锌锡）、p型半导体（氧化亚铜）和绝缘体（氧化铪和氧化铝）。这些材料将应用于各种离散电子器件、逻辑器件和电路中，使用基于印刷技术的新型自对准图形技术。然后，该大学将通过更广泛的项目合作伙伴加入英国公司的完整供应链。作为一个联盟，我们将开发一种基于薄片的流程来提供打印逻辑组件，这些组件将用于演示和开辟分布式逻辑（泛在计算）的新应用领域。这将集中在交互式消费产品，允许品牌增强，品牌保护和改进产品选择。要实现这一目标，牛津大学需要研究金属氧化物材料的物理、材料科学和工程的一些非常基础的方面。特别是，金属氧化物的能带结构的性质使得生产稳定的p型半导体非常困难。金属氧化物材料之间的界面性质——特别是半导体和电介质之间以及半导体和导体之间的界面，这两者都是功能器件的关键——还没有得到很好的理解。有许多关于这些材料的各种降解机制的报道，特别是在高温和紫外线照射下的应用，但对降解机制没有共识。大学将致力于解决这些关键问题，使项目合作伙伴能够在项目期限内成功利用金属氧化物材料。

Transistors based on crystalline silicon have dominated as the technology underpinning logic devices for the last fifty years, and the microprocessor is the ultimate example of this. Whilst the consequential packaging of processing power into high performance units has suited the development many electronic systems, such as computers, where processing power is naturally concentrated, it does not suit the future aim of ubiquitous computing. In a ubiquitous computing world, processing power is distributed at a low level to the places where it is required. The consequence of this is that humans no longer interact with specific electronic devices to engage with the digital world, but are constantly connected in an intuitive way that is open to all - a view that is expressed through the recent 'Digital Britain' reports.This will require the development of a new technology that allows high performance electronic devices (such as transistors) to be fabricated at very low cost on a diversity of cheap substrates including plastics. There are several technologies vying for this space, including thin film silicon, organic semiconductors and metal oxides. Each have their relative merits and demerits, and it is clear that no single technology will dominate, but rather that different technologies will address different application areas depending on the specific requirements (performance, lifetime, cost, operating environment, etc.). Metal oxide materials will have a clear role to play in this space as they offer particular features that the other technologies do not - most notably (and simultaneously) transparency, high carrier mobility, an amorphous structure, excellent uniformity and long lifetimes. However, in order to meet these applications, it is necessary to be able to marry metal oxide materials with a low cost patterning technology. To achive this will require a combination of diverse skills from materials characterisation to device testing and failure analysis. It is for this reason that the the Departments of Materials Science and Engineering will be collaborating on this project.This project will see the University continue to develop its expertise in the deposition of a diversity of metal oxide materials including n-type semiconductors (zinc oxide, indium zinc oxide and zinc tin oxide), p-type semiconductors (cuprous oxide) and insulators (hafnium oxide and aluminium oxide). These materials will be applied in a variety of discrete electronic devices, logic devices and circuits using a novel self-aligned patterning technology based on printing techniques. The University will then plug into a complete supply chain of UK companies through the wider project partners.As a consortium, we will develop a sheet-based process to provide printed logic components which will be employed to demonstrate and open up new application areas of distributed logic (ubiquitous computing). This will focus on interactive consumer products that allow brand enhancement, brand protection and improved product choice.Achieving this will require the University to research some very fundamental aspects of the physics, materials science and engineering of metal oxide materials. In particular, the nature of the band structure of metal oxides makes it very difficult to produce a stable, p-type semiconductor. The nature of the interface between metal oxide materials - particularly between semiconductors and dielectrics and between semiconductors and conductors, both of which are key for a functional device - is not well understood. There are numerous reports of a variety of degradation mechanisms operating in these materials, particularly under the application of elevated temperatures and under ultraviolet light illumination, but no consensus on degradation mechanisms. The University will aim to address these key issues to enable the project partners to utilise the metal oxide materials successfully within the time frame of the project.