Gate‐Deterministic Remote Doping Enables Highly Retentive Graphene‐MXene Hybrid Memory Devices on Plastic

Abstract

In this work, a highly retentive and synaptic-functional transistor memory device architecture based on the gate-deterministic remote doping of graphene via surface-oxidized Ti 3 C 2 T X MXene nano-floating-gates (NFG) is presented. By using solution-phase size-sorting followed by controlled surface oxidation process, a regulated distribution of MXene nanoflakes comprising metallic Ti 3 C 2 T X as the core surrounded by TiO 2 -a high dielectric constant insulator-as the shell is achieved. The size-sorted core/shell-like MXene nanoflakes show a self-sustainable charge trapping/detrapping behavior, which is highly feasible for realizing non-embed NFGs for transistor memory devices. Interestingly, unlike the conventional NFG-embedded architecture, the introduction of core/shell-like MXene under an electrolyte-gated graphene field-effect transistor (GFET) architecture induces a cooperative evolution of the hysteresis loop associated with ionic motion in the electrolyte gates and charge trapping/detrapping in the nanoflakes, resulting in a deterministic remote doping of the graphene layer. The resulting device exhibited a highly retentive memory behavior, which can be optimized by the nanoflake size distribution. In addition, synaptic functions having mechanical flexibility can be successfully emulated using MXene-based GFETs fabricated on a flexible polyethylene naphthalate substrate.

Coaxial Graphene/MXene Microfibers with Interfacial Buffer-Based Lightweight Distance Sensors Assisting Lossless Grasping of Fragile and Deformable Objects

“…Among the fresh generation of intelligent electrosensing materials, two-dimensional (2D) materials with a foam structure have attracted great attention in the field of intelligent sensing because of their low cost and light weight. − Graphene and MXene as the typical carbon-based 2D materials show great application prospects in piezoresistive sensors with flexibility and compressibility performance. − However, it is difficult for pure graphene foam to achieve high sensitivity and stability without additional additives or structural design due to poor conductivity and mechanical strength. , Although the pure MXene material itself has good electrical conductivity, it is difficult to process it into self-supporting foam because of its intrinsic weak gelation capability, which remarkably limits its wide application . Here, by combining the advantages of reduced graphene oxide (rGO) and MXene materials with the coaxial structure design, we constructed an ultra-fine and lightweight coaxial heterogeneous microfiber.…”

“…Graphene oxide (GO) was prepared by the Hummers method previously reported. 43 Briefly, 2 g of graphite powder was added to 92 g of concentrated sulfuric acid with continuous stirring for 24 h. Then, 1 g of NaNO 3 and 6 g of KMnO 4 were slowly added at 4 °C and stirred for 10 min. The mixture was stirred at 200 rpm for 30 min at 35 °C, and deionized water and 30% H 2 O 2 were successively added.…”

Revisiting Solution-Based Processing of van der Waals Layered Materials for Electronics

“…Since the discovery of monolayer graphene isolated from bulk graphite by breaking weak van der Waals (vdW) interactions, − post-graphene two-dimensional (2D) vdW layered materials have been extensively explored for more than a decade for use in electronic applications owing to their atomically thin structure and unique electronic properties. − Various electronic classes of 2D vdW materials with structural analogy, such as metallic MXene, − semimetallic graphene, ,, semiconducting transition metal dichalcogenides (TMDCs) and black phosphorus, − and insulating hexagonal boron nitride (h-BN) and montmorillonite, ,,, have been explored for use in electronic components (e.g., electrodes, channels, and dielectric layers). Furthermore, the synthesis of vdW heterostructures has been successfully demonstrated through the assembly of two or more vdW layered materials as building blocks with desired electronic properties. ,− Most importantly, the atomically clean, dangling-bond-free surface of 2D samples enables the demonstration of numerous fundamental prototypes that rely on achieving efficient charge transport between the neighboring layers at vdW interfaces. − Despite having prototyped high-performance electronics based on vdW heterostructures which push the intrinsic limits of such 2D materials, the complicated processes for vdW device fabrication (which include micromechanical cleavage-based monolayer sample preparations and microscopy-assisted precise transfer for heterostructure formations) hinder the scaling up of such devices while maintaining their performance for industrial-scale applications.…”

“…Since the discovery of monolayer graphene isolated from bulk graphite by breaking weak van der Waals (vdW) interactions, 1 − 3 post-graphene two-dimensional (2D) vdW layered materials have been extensively explored for more than a decade for use in electronic applications owing to their atomically thin structure and unique electronic properties. 4 − 11 Various electronic classes of 2D vdW materials with structural analogy, such as metallic MXene, 12 − 14 semimetallic graphene, 3 , 15 , 16 semiconducting transition metal dichalcogenides (TMDCs) and black phosphorus, 4 − 7 and insulating hexagonal boron nitride (h-BN) and montmorillonite, 3 , 8 , 11 , 17 have been explored for use in electronic components (e.g., electrodes, channels, and dielectric layers). Furthermore, the synthesis of vdW heterostructures has been successfully demonstrated through the assembly of two or more vdW layered materials as building blocks with desired electronic properties.…”

Solution-Processed MoS2-Based Back-to-Back Diodes Circuit Applications for Signal Demodulators and Envelope Detectors

“…Moreover, the scalability and throughput of the fabrication process were highly limited because TMDC microflakes had to be transferred onto electrodes via a microscope-assisted precise alignment procedure because of their small lateral size (tens of micrometers). Liquid-phase exfoliation has been alternatively pursued for large-scale synthesis of TMDCs. − In particular, MoS 2 nanosheets can be mass-produced via ultrasonication-assisted exfoliation of MoS 2 crystals. The resulting nanosheets, however, exhibit a broad thickness distribution and small lateral size (typically <100 nm), which leads to poor electrical properties of their thin-film assemblies because of nonuniformity in film thickness and intersheet junction resistances.…”