Ferroelectric field‐effect transistors (FeFETs) are one of the most interesting ferroelectric devices; however, they, usually suffer from low interface quality. The recently discovered 2D layered ferroelectric materials, combining with the advantages of van der Waals heterostructures (vdWHs), may be promising to fabricate high‐quality FeFETs with atomically thin thickness. Here, dual‐gated 2D ferroelectric vdWHs are constructed using MoS2, hexagonal boron nitride (h‐BN), and CuInP2S6 (CIPS), which act as a high‐performance nonvolatile memory and programmable rectifier. It is first noted that the insertion of h‐BN and dual‐gated coupling device configuration can significantly stabilize and effectively polarize ferroelectric CIPS. Through this design, the device shows a record‐high performance with a large memory window, large on/off ratio (107), ultralow programming state current (10−13 A), and long‐time endurance (104 s) as nonvolatile memory. As for programmable rectifier, a wide range of gate‐tunable rectification behavior is observed. Moreover, the device exhibits a large rectification ratio (3 × 105) with stable retention under the programming state. This demonstrates the promising potential of ferroelectric vdWHs for new multifunctional ferroelectric devices.

Two-dimensional materials have been widely used in electronics due to their electrical properties that are not accessible in traditional materials.Here, we present the first demonstration of logic functions of unipolar memristors made of functionalized HfSe 2−x O x flakes and memtransistors made of MoS 2 /graphene/HfSe 2−x O x van der Waals heterostructures. The twoterminal memristors exhibit stable unipolar switching behavior with high switching ratio (>10 6 ), high operating temperature (106 °C), long-term endurance (>10 4 s), and multibit data storage and can operate as memory latches and logic gates. Benefiting from these superior memristive properties, the three-terminal heterostructure memtransistors show wide tunability in electrical switching behaviors, which can simultaneously implement logic operation and data storage. Finally, we investigate their application prospect in logical units with memory capability, such as D-type flip-flop. These results demonstrate the potential of twodimensional materials for resistive switching applications and open up an avenue for future in-memory computing.

Nonvolatile resistive random access memories based on synthesized two-dimensional α-MoO3 crystals are demonstrated with high performances.

A method to prepare nano-composite phase change material was proposed and demonstrated by oxygen doping into Si2Sb2Te5 material. According to transmission electron microscope images, Si-Sb-Te-rich domains are separated from each other by SiOx-rich domains within the material. A proper dose of O-doping into Si2Sb2Te5 significantly reduces the grain size of the phase change material. Average size of Si-Sb-Te-rich domains is about 10 nm. Such separation will limit the phase-change to a relatively small volume. The reduction of grain size further results in the promotion of data retention and thermal stability of the material. Memory device based on O-doped Si2Sb2Te5 nano-composite phase change material, with a bottom electrode contact of 260 nm in diameter, was fabricated and characterized. The memory cell shows a better electrical performance compared with the Ge2Sb2Te5 based one.

No abstract