Interfacial ferroelectricity in marginally twisted 2D semiconductors

Weston, Astrid and Castanon, Eli and Enaldiev, Vladimir and Ferreira, Fabio and Bhatacharjee, Shubhadeep and Xu, Shuigang and Corte-Leon, Hector and Wu, Zefei and Clark, Nickolas and Summerfield, Alex and Hashimoto, Teruo and Gao, Yunze and Wang, Wendong and Hamer, Matthew and Read, Harriet and Fumagalli, Laura and Kretinin, Andrey and Haigh, Sarah and Kazakova, Olga and Geim, Andre and Falko, Vladimir and Gorbachev, Roman (2021) Interfacial ferroelectricity in marginally twisted 2D semiconductors. arXiv. ISSN 2331-8422

Abstract

Twisted heterostructures of two-dimensional crystals offer almost unlimited scope for the design of novel metamaterials. Here we demonstrate a room-temperature ferroelectric semiconductor that is assembled using mono- or few- layer MoS2. These van der Waals heterostructures feature broken inversion symmetry, which, together with the asymmetry of atomic arrangement at the interface of two 2D crystals, enables ferroelectric domains with alternating out-of-plane polarisation arranged into a twist-controlled network. The latter can be moved by applying out-of-plane electrical fields, as visualized in situ using channelling contrast electron microscopy. The interfacial charge transfer for the observed ferroelectric domains is quantified using Kelvin probe force microscopy and agrees well with theoretical calculations. The movement of domain walls and their bending rigidity also agrees well with our modelling results. Furthermore, we demonstrate proof-of-principle field-effect transistors, where the channel resistance exhibits a pronounced hysteresis governed by pinning of ferroelectric domain walls. Our results show a potential venue towards room temperature electronic and optoelectronic semiconductor devices with built-in ferroelectric memory functions.