Ferroelectricity and other phases in heterostructures of van der Waals coupled 2D crystals of CuInP₂S₆ and MoTe₂

Ferroelectric materials featuring two electrically polarized states can be used to engineer novel material and device properties in the heterostructures. CuInP₂S₆ (CIPS), the only van der Waals transition metal chalcogenide whose ferroelectricity is demonstrated explicitly in the bulk, may be useful for achieving these goals. So far, ferroelectricity in CIPS was found to persist up to room temperature and down to 4 nm in thickness. We have demonstrated previously [1] that atomically thin crystals of CIPS behaves also as a semiconductor featuring a Schottky barrier whose barrier height is controlled not only by the charge transfer between CIPS and the electrode but also the direction of the remnant polarization, yielding a ferroelectric Schottky diode featuring four as opposed to two resistive states. We have extended our work on atomically thin crystals of CIPS to heterostructures of CIPS and MoTe₂, the latter of which is a van der Waals transition metal dichalcogenide featuring two distinct polymorph, the 1T’ and 2H-MoTe₂. While the former was reported to possess both ferroelectricity and superconductivity [2], twisted bilayer 2H-MoTe₂ was found to host the exotic fractional quantum anomalous Hall effect. We will report the progress we made in the material characterization and device preparation and discuss observation in the exploration of the interplay between ferroelectricity and other phases in CIPS/MoTe₂ heterostructures.

[1] Jinyuan Yao et al. Ferroelectric Schottky diodes of CuInP₂S₆ nanosheet. Appl. Phys. Lett. 123, 142903 (2023)

[2] Apoorv Jindal et al. Coupled ferroelectricity and superconductivity in bilayer T_d-MoTe₂. Nature 613, 48–52 (2023).