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

Lead Research Organisation: University College London
Department Name: Physics and Astronomy


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.

Planned Impact

This research programme will address fundamental questions pertaining to the fascinating and technologically useful phenomenon of negative capacitance, which is currently actively explored by both academia and industry for applications in low power electronics. Although the focus of the proposed research is primarily on the fundamental physics of this phenomenon, we expect it to have important practical implications and therefore the impact of this work is likely to filter through to industrial research and commercial applications relatively quickly. The results will be directly relevant for the design of novel devices, presenting a significant potential for generation of new intellectual property and all efforts will be made to maximise the exploitation of the knowledge gained.
An important area of impact will be the training of highly skilled professionals. The researchers employed for this project will acquire a wide range of new technical skills (including advanced experimental and theoretical/computational techniques) that will enhance their employability in both the academic and industrial sectors. They will also gain visibility through their dissemination activities, and acquire a variety of new transferable skills that will further widen their career prospects and contribute valuable, highly skilled workforce to the UK and EU economy.
Impact in the education sector will be generated not only through the involvement of university staff and students in the research and its dissemination, but also by communicating our work more widely to engage the general public and inspire the next generation of young scientists. A variety of outreach activities, including well-established as well as new programmes such as summer internships, summer schools and work experience placements will be aimed at engaging young people in physical sciences.


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Description Using a combination of different experimental techniques and theoretical simulations, we have found that under certain conditions, artificially layered crystals (or superlattices) composed of ferroelectric and non-ferroelectric oxides, develop complex, 3-dimensionally ordered domain patterns. As well as leading to enhanced dielectric properties in the ferroelectric layers, the complex, periodic domain structure was found to generate large local cuvature in the crystalline lattice of the non-ferroelectric component.
We have also investigated how domain structures accommodate macroscopic curvature in free-standing superlattices that have been detached from their rigid support.
Exploitation Route The possibility of using such superlattices to create large lattice curvatures that can be manipulated using electric fields opens new directions for the investigation of curvature-induced phenomena in a variety of materials.
Sectors Electronics

URL https://www.london-nano.com/research/superlattices-supercrystals
Description Bilateral partnership with LIST 
Organisation Luxembourg Institute of Science and Technology
Country Luxembourg 
Sector Academic/University 
PI Contribution This grant is part of the EPSRC-FNR (Luxembourg) bilateral scheme
Collaborator Contribution Luxembourg partners perform DFT-based second-principles atomistic simulations of negative capacitance in ferroelectric-dielectric heterostructures to support and guide our experimental studies at UCL.
Impact Article currently under review (https://arxiv.org/abs/2201.07104)
Start Year 2019