FNR - Fundamentals of Negative Capacitance: Towards New Low Power Electronics

构成我们日常电子产品的晶体管等电子元件的持续升级一直是这些设备不断提高性能的核心。然而，继续这一趋势带来了越来越复杂的挑战，需要新的材料解决方案，超越目前的硅技术。最大的挑战之一是功耗和散热--随着晶体管变得越来越小，越来越多的晶体管被封装在芯片上，它们产生的热量变得越来越难以管理。一种可能的解决方案是用铁电材料代替用于控制晶体管中半导体沟道的导电性的栅极电介质。铁电体是在一定温度下自发获得电极化的材料，并且已经广泛用于从超声换能器到非易失性随机存取存储器的许多应用中。在铁电体的许多迷人特性中，目前吸引半导体界注意力的是它在某些条件下表现为具有负电容的电容器的能力，即在与普通电容器相反的意义上充电的电容器。这种负电容行为可以用来放大晶体管内部的内部电位，使其能够在较低的电压下工作。然而，尽管在过去的几年里，对负电容器件的研究有了令人难以置信的增长，但对这种现象的基本物理学仍然知之甚少。到目前为止，人们对负电容的内在机制、其全部潜力和局限性、如何在实验上最好地消除这种现象以及如何优化材料参数和器件几何形状以获得最佳性能知之甚少。该项目的目的是解决这些基本问题，使用实验技术和国家的最先进的理论模拟相结合。

Continued miniaturisation of electronic components such as transistors that make up our everyday electronics has been at the heart of the ever-improving performance of these devices. Yet continuing this trend presents ever more complex challenges that require new materials solutions, beyond current silicon technology. One of the big challenges is power consumption and heat dissipation--as transistors get smaller and more of them are packed on a chip, the heat they produce becomes increasingly unmanageable. One possible solution is to replace the gate dielectric, which is used to control the conductivity of the semiconducting channel in the transistor, with a ferroelectric material. Ferroelectrics are materials that spontaneously acquire an electrical polarisation at some temperature and are already widely used in many applications ranging from ultrasound transducers to non-volatile random access memories. Among the many fascinating properties of ferroelectrics, the one that is currently captivating the attention of the semiconductor community is its ability to behave, under certain conditions, as a capacitor with a negative capacitance, i.e. one that charges up in the opposite sense to an ordinary capacitor. Such negative capacitance behaviour can be exploited to amplify the internal potential inside a transistor, allowing it to operate at lower voltages. However, despite an incredible increase in research on negative capacitance devices over the last few years, the fundamental physics of this phenomenon is still very poorly understood. As yet, little is known about the intrinsic mechanism of negative capacitance, its full potential and limitations, how to best characterise this phenomenon experimentally, and how to optimise the materials parameters and device geometries for the best performance. The aim of this project is to address these fundamental questions using a combination of experimental techniques and state-of-the-art theoretical simulations.