Agile electronics through ferroelectric switching of two-dimensional materials

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Atomically thin layers of different two-dimensional materials can be stacked with atomic precision to create 2D heterostructures (2D-HS). This has led to the design of more efficient light emitting diodes for example, and the study of new phenomena such as an insulating to superconducting transition in graphene. In these heterostructures, electric fields perpendicular to the layers can be used to engineer the band alignments, control carrier concentrations, and even switch between metallic, insulating and superconducting states. These fields are usually induced by predefined metallic electrodes which give control over the field strength but are of fixed (microscale) geometry and have limited dynamic response. This project will develop an alternative approach. Strong electric fields can be formed at the surface of thin-film ferroelectric perovskite oxides, with the field patterned with nanoscale precision. The polarity of the field can be switched rapidly and even the spatial arrangement of the field can be controlled dynamically. This presents an exciting opportunity to create agile electronics by integrating perovskite ferroelectrics into 2D-HSs. Creating such a robust platform for electrostatically defining insulating and conducting regions in 2DMs, and for dynamically switching their conductivity, will allow us to explore new physical phenomena and to develop new electronic functionalities. The aim of this project is to explore new artificial heterostructure systems that combine ultrathin ferroelectrics with 2DMs, especially 2D van-der-Waals semiconductors, exploiting reduced dimensionality and interfacial interactions to control the properties and engineer new functionalities in these artificial materials. The project will focus on developing techniques for controlling the interface between the 2D-HSs and high-quality thin-film perovskite oxides grown at Warwick by pulsed laser deposition. Careful characterisation of this interface, and its effect on the electronic properties of the 2D-HSs, will be essential to the wider success of the project. The research will make use of the excellent microscopy and spectroscopy infrastructure at the University of Warwick, as well as international synchrotron-based facilities. It is tied closely to the EPSRC funded responsive mode grant EP/T027207/1, Ferroelectric gating for agile and reconfigurable 2D electronics.