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Quantum materials research at NPL underpins the UK National Quantum Technologies Programme, providing a powerful unifying concept across diverse fields of materials science and engineering as well as a metrological approach and measurement reliability.
In new research, published in Nature Nanotechnology, scientists from NPL and the University of Manchester demonstrated the existence of ferroelectric behaviour in bi-layer MoS2. This research opens the possibility to room temperature electronic and optoelectronic semiconductor devices with built-in ferroelectric memory functions being used to enable the performing of logic operations within a sensor or offering the possibility of buffering data between a sensor and a processing unit, thus enabling the speeding up of operations.
Twisted heterostructures of two-dimensional (2D) crystals offer almost unlimited scope for the design of novel metamaterials (e.g. by varying the twist angle it is possible to tune the optical properties of the material). Recently a new trend in creating truly 2D ferroelectrics has emerged, which exploits interfacial charge transfer in stacked heterostructures of 2D materials. In this study, the team demonstrates that switchable ferroelectric behaviour is a generic property of heterostructures assembled from atomically thin layered semiconductors with small twist angles.
These observations pave a way towards novel electronic devices with memory effects integrated with optoelectronic devices (e.g. an atomically thin MoS2 detector coupled to a bi-layer MoS2 ferroelectric memory).
In this article, NPL performed quantitative traceable nanoscale measurements of surface potential distribution in the ferroelectric domains. This was achieved using a technique called Kelvin-probe force microscopy, which is an imaging tool, for which calibration standards have yet to be written, and thus can only be realized with confidence at National Metrology Institutes like NPL. Such confidence in the quantitative values has been provided by the expertise and the measurement protocols developed at NPL. NPL scientists demonstrated the traceability of such measurements, triggered a re-evaluation of the theoretical model, and provided the unique experimental demonstration of the ferroelectric nature of the effect on the nanoscale.
The future plans include developing routes for the scalability of the new devices and characterisation of such important device performance parameters, as e.g. threshold current to switch the ferroelectric domains.
Find out more about NPL’s work in Quantum material
07 Mar 2022