MEMORY DEVICE BASED ON HETEROSTRUCTURES OF FERROELECTRIC AND TWO - DIMENSIONAL MATERIALS

A ferroelectric random-access memory structure and processes for fabricating a ferroelectric random-access memory structure are described that includes using a molybdenum sulfide layer. In an implementation, a ferroelectric random access memory structure in accordance with an exemplary embodiment includes at least one FeFET, which further includes a substrate; a back gate electrode formed on the substrate, the back gate electrode including a conductive layer; a gate dielectric substrate formed on the back gate electrode; a source electrode formed on the gate dielectric substrate; a drain electrode formed on the gate dielectric substrate; and a layered transition metal dichalcogenide disposed on the gate dielectric substrate and contacting the source electrode and the drain electrode

MEMORY DEVICE BASED ON HETEROSTRUCTURES OF FERROELECTRIC AND TWO - DIMENSIONAL MATERIALS

A ferroelectric random-access memory structure and processes for fabricating a ferroelectric random-access memory structure are described that includes using a molybdenum sulfide layer. In an implementation, a ferroelectric random access memory structure in accordance with an exemplary embodiment includes at least one FeFET, which further includes a substrate; a back gate electrode formed on the substrate, the back gate electrode including a conductive layer; a gate dielectric substrate formed on the back gate electrode; a source electrode formed on the gate dielectric substrate; a drain electrode formed on the gate dielectric substrate; and a layered transition metal dichalcogenide disposed on the gate dielectric substrate and contacting the source electrode and the drain electrode

POLYMER ON GRAPHENE

A top - gated graphene field effect transistor can be fabricated by forming a layer of graphene on a substrate, and applying an electrochemical deposition process to deposit a layer of dielectric polymer on the graphene layer. An electric potential between the graphene layer and a reference electrode is cycled between a lower potential and a higher potential. A top gate is formed above the polymer

Negative photoresponse in Ti\u3csub\u3e3\u3c/sub\u3eC\u3csub\u3e2\u3c/sub\u3eT\u3csub\u3ex\u3c/sub\u3e MXene monolayers

Two-dimensional transition metal carbides, nitrides, and carbonitrides, collectively known as MXenes, are finding numerous applications in many different areas, including optoelectronics and photonics, but there is limited information about their intrinsic photoresponse. In this study, we investigated the visible and near-infrared range photoresponse of Ti3C2Tx, the most popular MXene material to date. The electrical measurements were performed on devices based on individual monolayer Ti3C2Tx MXene flakes, which were characterized by a variety of microscopic and spectroscopic methods. For MXene devices with different electrode layouts, the current reproducibly decreased under illumination with either white light or lasers with different wavelengths in the visible and near-infrared region, thus demonstrating a negative photoresponse. The understanding of the intrinsic photoresponse of Ti3C2Tx should facilitate the optoelectronic and photonic applications of MXenes

Diffusion-controlled on-surface synthesis of graphene nanoribbon heterojunctions

We report a new diffusion-controlled on-surface synthesis approach for graphene nanoribbons (GNR) consisting of two types of precursor molecules, which exploits distinct differences in the surface mobilities of the precursors. This approach is a step towards a more controlled fabrication of complex GNR heterostructures and should be applicable to the on-surface synthesis of a variety of GNR heterojunctions

What happens when transition metal trichalcogenides are interfaced with gold?

Transition metal trichalcogenides (TMTs) are two-dimensional (2D) systems with quasi-one-dimensional (quasi-1D) chains. These 2D materials are less susceptible to undesirable edge defects, which enhances their promise for low-dimensional optical and electronic device applications. However, so far, the performance of 2D devices based on TMTs has been hampered by contact-related issues. Therefore, in this review, a diligent effort has been made to both elucidate and summarize the interfacial interactions between gold and various TMTs, namely, In4Se3, TiS3, ZrS3, HfS3, and HfSe3. X-ray photoemission spectroscopy data, supported by the results of electrical transport measurements, provide insights into the nature of interactions at the Au/In4Se3, Au/TiS3, Au/ZrS3, Au/HfS3, and Au/HfSe3 interfaces. This may help identify and pave a path toward resolving the contemporary contact-related problems that have plagued the performance of TMT-based nanodevices

Elastic properties of 2D Ti3C2Tx MXene monolayers and bilayers

Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, are a large class of materials that are finding numerous applications ranging from energy storage and electromagnetic interference shielding to water purification and antibacterial coatings. Yet, despite the fact thatmore than 20 different MXenes have been synthesized, the mechanical properties of a MXene monolayer have not been experimentally studied. We measured the elastic properties of monolayers and bilayers of the most important MXene material to date, Ti3C2Tx (Tx stands for surface termination).We developed amethod for preparingwell-strainedmembranes of Ti3C2Tx monolayers and bilayers, and performed their nanoindentation with the tip of an atomic force microscope to record the force-displacement curves. The effective Young’s modulus of a single layer of Ti3C2Tx was found to be 0.33 ± 0.03 TPa, which is the highest among the mean values reported in nanoindentation experiments for other solution-processed 2D materials, including graphene oxide. This work opens a pathway for investigating the mechanical properties of monolayers and bilayers of other MXenes and extends the already broad range of MXenes’ applications to structural composites, protective coatings, nanoresonators, and membranes that require materials with exceptional mechanical properties

Resistive switching in nanogap systems on SiO2 substrates

Voltage-controlled resistive switching is demonstrated in various gap systems on SiO2 substrate. The nanosized gaps are made by different means using different materials including metal, semiconductor, and metallic nonmetal. The switching site is further reduced by using multi-walled carbon nanotubes and single-walled carbon nanotubes. The switching in all the gap systems shares the same characteristics. This independence of switching on the material compositions of the electrodes, accompanied by observable damage to the SiO2 substrate at the gap region, bespeaks the intrinsic switching from post-breakdown SiO2. It calls for caution when studying resistive switching in nanosystems on oxide substrates, since oxide breakdown extrinsic to the nanosystem can mimic resistive switching. Meanwhile, the high ON/OFF ratio (10E5), fast switching time (2 us, test limit), durable cycles demonstrated show promising memory properties. The intermediate states observed reveal the filamentary conduction nature.Comment: 7 pages, 7 figure