| EPSRC Reference: |
EP/H047093/1 |
| Title: |
Critical Scaling of Domain Dynamics in Ferroelectric Nanoelements |
| Principal Investigator: |
Gregg, Professor J |
| Other Investigators: |
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| Researcher Co-Investigators: |
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| Department: |
Sch of Mathematics and Physics |
| Organisation: |
Queen's University of Belfast |
| Scheme: |
Standard Research |
| Starts: |
01 December 2010 |
Ends: |
30 November 2013 |
Value (£): |
324,494
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| EPSRC Research Topic Classifications: |
| Materials Characterisation |
Materials Synthesis & Growth |
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Summary on Grant Application Form |
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The potential for ferroelectric materials to influence the future of small scale electronics cannot be overstated. At a basic level, this is because ferroelectric surfaces are charged, and so interact strongly with charge-carrying metals and semiconductors - the building blocks for all electronic systems. Since the electrical polarity of the ferroelectric can be reversed, it can both attract and repel charges in nearby materials, exerting complete control over both the charge distribution and movement within the device. It should be no surprise, therefore, that microelectronics industries have already looked very seriously at harnessing ferroelectric materials in a variety of applications, from solid state memory chips (ferroelectric random access memories, or FeRAMs) to field effect transistors (ferroelectric field effect transisitors, or FeFETs). In all such applications, switching of the direction of the polarity of the ferroelectric is the most important aspect of functional behaviour. The mechanism for switching invariably involves the field-induced nucleation and growth of domains. Domain coarsening, through domain wall propagation, eventually causes the entire ferroelectric to switch its polar direction. It is therefore the existence and behaviour of domains under the influence of an external bias field that determine the switching response, and ultimately the performance of the ferroelectric in any given electronic device. Understanding domains and domain dynamics is therefore the key to fully understanding switching behaviour and eventually rationalizing and predicting device performance.However, integrating ferroelectrics into commercial devices has not been altogether straightforward. One of the major issues has been that the properties associated with ferroelectrics, in bulk form, appear to change quite dramatically and unpredictably when at the nanoscale: new modes of behaviour, and different functional characteristics appear. For domains, in particular, the proximity of surfaces and boundaries has a dramatic effect: surface tension and depolarizing fields both serve to increase the equilibrium density of domains, and domain walls, such that minor changes in scale or morphology at the nanoscale can have major ramifications for domain redistribution. Given the importance of domains in dictating the overall switching characteristics of a device, the need to fully understand how size and morphology affect domain behaviour in small scale ferroelectrics is obvious. That the near future plans for microelectronic ferroelectric devices are to move from simple planar 2D to more complex 3D architectures, only increases the imperative for study. This proposal seeks to map and understand the manner in which reduced size and increased morphological complexity affect the switching behaviour of small scale ferroelectrics. Our revolutionary approach will be to make devices in which single crystal ferroelectric material has been machined to thin film dimensions using focused ion beam milling (FIB). 'Stroboscopic Piezo-Force Microscopy (PFM)' will be used to map the dynamics of domain wall motion during in-plane switching, induced by an external electric field dropped between coplanar electrodes. Observations made on nanoscale domain dynamics can then be meaningfully correlated to the measured 'macroscopic' functional behaviour of the devices. Using FIB to machine holes and slits into the thin ferroelectric slabs will allow us to directly investigate the manner in which physical defects alter the nucleation and propagation of domain walls. The study will also be extended to investigate axial switching of discrete FIBed single crystal ferroelectric nanowires with and without topographic complexity (in terms of notches, antinotches and kinks). Prior support on static domain states in passive ferroelectric nanoshapes has enabled this research, but there is no overlap - this new work concerns domain dynamics in active devices.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
| Summary |
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| Date Materialised |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.qub.ac.uk |