Gate‐Tunable and Multidirection‐Switchable Memristive Phenomena in a Van Der Waals Ferroelectric

Abstract

Memristive devices have been extensively demonstrated for applications in nonvolatile memory, computer logic, and biological synapses. Precise control of the conducting paths associated with the resistance switching in memristive devices is critical for optimizing their performances including ON/OFF ratios. Here, gate tunability and multidirectional switching can be implemented in memristors for modulating the conducting paths using hexagonal α‐In2Se3, a semiconducting van der Waals ferroelectric material. The planar memristor based on in‐plane (IP) polarization of α‐In2Se3 exhibits a pronounced switchable photocurrent, as well as gate tunability of the channel conductance, ferroelectric polarization, and resistance‐switching ratio. The integration of vertical α‐In2Se3 memristors based on out‐of‐plane (OOP) polarization is demonstrated with a device density of 7.1 × 109 in.−2 and a resistance‐switching ratio of well over 103. A multidirectionally operated α‐In2Se3 memristor is also proposed, enabling the control of the OOP (or IP) resistance state directly by an IP (or OOP) programming pulse, which has not been achieved in other reported memristors. The remarkable behavior and diverse functionalities of these ferroelectric α‐In2Se3 memristors suggest opportunities for future logic circuits and complex neuromorphic computing.

Two-dimensional ferroelectric channel transistors integrating ultra-fast memory and neural computing

“…The cross-sectional image and corresponding energy dispersive X-ray spectroscopy (EDS) element mapping at the interface between the multilayer h-BN and α-In2Se3 are shown in Figure 1c, which implies a clean van der Waals heterojunction with negligible interface state trapping effect. Figure 1d shows the Raman spectrum of the channel α-In2Se3 to characterize the material properties, which is consistent with previous reports, 14,18,30 and the peak at 89cm -1 suggests a hexagonal (2H) structure. 18 And the Figure S2b in Supporting Information.…”

“…Figure 1d shows the Raman spectrum of the channel α-In2Se3 to characterize the material properties, which is consistent with previous reports, 14,18,30 and the peak at 89cm -1 suggests a hexagonal (2H) structure. 18 And the Figure S2b in Supporting Information. Crucially, we transferred the channel α-In2Se3 ferroelectrics onto a conductive Au/Al2O3 substrate and determined its ferroelectric polarization by piezoelectric microscopy (PFM).…”

“…16 In addition, the future trend of high-integration artificial intelligence applications is pushing the design of memory and computing elements toward miniaturization. 17,18 Bulk perovskite, 19 oxide, 11,20 or organic ferroelectric polymer 21 are served as the gate dielectric in conventional FeFETs, which is insufficient for continuous scaling both in vertical and planar dimensions. 22 2D layered semiconductors with atomic thickness possess the potential for continuous shrinking, [23][24][25] which is a promising candidate for future high-density memory and computing systems.…”

“…22 2D layered semiconductors with atomic thickness possess the potential for continuous shrinking, [23][24][25] which is a promising candidate for future high-density memory and computing systems. 26,27 Particularly, 2D layered α-In2Se3 exhibits robust ferroelectricity at room temperature (RT) without annealing, 14,28,29 and thanks to the intrinsic interlocking of dipoles in α-In2Se3, 18,22 it can maintain ferroelectric polarization even at atomic scale.…”

Iron-doping induced multiferroic in two-dimensional In2Se3

“…Especially for In 2 Se 3 , it is reported that it still maintains its ferroelectricity and piezoelectricity even down to monolayer [13]. Its excellent sustainability and performance prompt people to use it in ferroelectric applications such as non-volatile memristor [14]. Furthermore, the coexistence of out-of-plane and inplane piezoelectricity in In 2 Se 3 makes it promising in energy harvesting system and self-power nanodevice responding to strain from all directions [15].…”