Ferroelectric field effect transistors based on two-dimensional CuInP₂S₆ (CIPS) and graphene heterostructures

Heterostructures of two-dimensional (2D) materials comprise clean van der Waals (vdW) interfaces that can facilitate charge or energy transfer. Recently, the 2D ferroelectric CuInP₂S₆ (CIPS) has been integrated with graphene and other 2D materials to realize potentially novel low energy electronic devices. However, the influence of 2D CIPS on the properties of graphene and doping across the vdW interface has not been studied in detail. Here, we study graphene field effect transistors (FETs) with CIPS as the top gate. We find that CIPS leads to modulation of the graphene Fermi level due to local doping. We also find polarization-induced hysteresis in CIPS-gated graphene FETs. Electrical transport measurements from 50 to300 K show that above 200 K, the ferroelectric response decreases. As a result, the hysteresis voltage windows in the graphene ferroelectric FETs (FeFET) transfer curves decrease above 200 K. Our results show that interfacial remote doping affects the macroscopic polarization and performance of CIPS-based graphene FeFETs.

This research studies the temperature-dependent local doping across a vdW ferroelectric/2D channel interface that affects the transport properties of ferroelectric field effect transistors (FeFETs).Experimental findings showed ferroelectric polarization switching-based hysteresis in CuInP₂S₆-gated graphene FeFETs.

vdW ferroelectrics that can be scaled to atomic layer thicknesses are useful for miniaturised low energy electronics.Understanding the interface charge or energy transfer in vdW ferroelectrics is essential for their integration into current or future technologies.

The online version contains supplementary material available at 10.1557/s43581-024-00109-y.