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，而微处理器就是这方面的最终例子。虽然相应地将处理能力打包到高性能单元中适合许多电子系统的发展，例如计算机，其中处理能力自然地集中，但它不适合泛在计算的未来目标。在无处不在的计算世界中，处理能力以较低的水平分配到需要它的地方。其结果是，人类不再与特定的电子设备互动，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连接--这一观点在最近的《数字英国》报告中得到了表达。这将需要开发一种新技术，允许在包括塑料在内的各种廉价衬底上以非常低的成本制造高性能电子设备(如晶体管)。有几种技术在争夺这一领域，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缺点，显然不会有单一的技术占据主导地位，而是不同的技术将根据具体要求(性能、寿命、成本、运行环境等)满足不同的应用领域。金属氧化物材料将在这一领域发挥明显的作用，因为它们提供了其他技术所不具备的特殊功能--最显著的(也是同时)透明、高载流子迁移率、无定形结构、出色的一致性和长寿命。然而，为了满足这些应用，有必要将金属氧化物材料与低成本的图案化技术相结合。要做到这一点，将需要多种技能的结合，从材料特性到设备测试和故障分析。正因为如此，材料科学系和工程学系将在这个项目上合作。这个项目将看到大学继续发展其在沉积各种金属氧化物材料方面的专业知识，包括n型半导体(氧化锌、氧化铟和氧化锡)、p型半导体(氧化亚铜)和绝缘体(氧化汞和氧化铝)。这些材料将应用于各种分立的电子器件、逻辑器件和电路中，使用基于印刷技术的新型自对准图案化技术。然后，该大学将通过更广泛的项目合作伙伴，接入英国公司的完整供应链。作为一个联合体，我们将开发一种基于工作表的过程，以提供打印的逻辑组件，这些组件将用于演示和开辟分布式逻辑(普适计算)的新应用领域。这将侧重于互动式消费产品，以提高品牌、保护品牌和改进产品选择。要实现这一点，该大学将需要研究金属氧化物材料的物理、材料科学和工程方面的一些非常基本的方面。特别是，金属氧化物的能带结构的性质使得生产稳定的p型半导体变得非常困难。金属氧化物材料之间的界面的性质--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--这两个都是功能器件的关键，目前还没有很好的理解。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光照射下，但关于降解机制还没有达成共识。该大学将致力于解决这些关键问题，使项目伙伴能够在项目的时间范围内成功地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.