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Maximizing light‐to‐electricity conversion efficiency is a crucial challenge for the practical applications of 2D material photodetectors. However, due to the lack of stable and precise electronic structure control methods for 2D materials, the driving force of photogenerated carriers is insufficient that severely hinders the efficiency of separation and transport. Herein, a gradient‐modulated, stable and precise strain applied strategy for 2D materials is designed and constructed, which results in a significant improvement in the detect efficiency of ZnO/WSe2/graphene van der Waals heterojunction photodetectors. Different from the overall strain of all‐component materials in typical photodetectors, biaxial tensile strain is applied to WSe2 that can be precisely modulated by controlling the height of ZnO nanorods, while the strain is nearly unaffected to ZnO. As the strain modulation increases from 1.3% to 4.0%, the external quantum efficiency (EQE) of the heterojunction increases from 11.4% to 35.3%, representing a threefold increase. Furthermore, with increasing strain, the EQE can reach higher levels. Moreover, the strain‐enhanced conversion efficiency mechanism is elucidated that results from the synergistic effect of the strain‐induced WSe2 exciton convergence and the strain‐increased ZnO/WSe2 interface barrier, which enhances the carrier interface separation efficiency. [ABSTRACT FROM AUTHOR]

Although 2D material van der Waals heterostructures (vdWHs) exhibit many novel properties and applications, 2D homojunctions have unique advantages in interface lattice matching, band continuity, and charge transfer efficiency. However, the rectification performances of 2D homojunction diodes are severely limited by the small junction barrier, mainly due to inefficient charge doping. In this work, an ultrahigh‐rectification‐ratio WSe2 homojunction diode achieved by the semi‐floating gate doping of graphdiyne oxide (GDYO) is reported. Utilizing the WSe2/GDYO direct charge trapping mode can free the inhibition of charge capturing efficiency by removing conventional insulating barriers and thus improve the rectification ratio. The C─C(sp) and oxygen‐containing functional groups in the GDYO layer can provide outstanding charge‐trapping ability due to their unsaturation. Furthermore, the oxygen plasma treatment used for oxidizing graphdiyne (GDY) into GDYO can make GDYO a flatter surface, thus creating strong‐coupling WSe2/GDYO interfaces to improve the charge transfer efficiency and enhance the electrostatic doping effect. Besides, the WSe2/GDYO interfaces are confirmed to possess a higher junction barrier than that of the WSe2/GDY interfaces. This research proposes a brand‐new approach to building p–n junctions via charge trapping and the homojunction diode with a record‐highest rectification ratio of up to 106 is obtained. [ABSTRACT FROM AUTHOR]

Metal–semiconductor contacts are crucial components in semiconductor devices. Ultrathin two‐dimensional transition‐metal dichalcogenide semiconductors can sustain transistor scaling for next‐generation integrated circuits. However, their performance is often degraded by conventional metal deposition, which results in a high barrier due to chemical disorder and Fermi‐level pinning (FLP). Although, transferring electrodes can address these issues, they are limited in achieving universal transfer of full‐class metals due to strong adhesion between pre‐deposited metals and substrates. Here, we propose a nanobelt‐assisted transfer strategy that can avoid the adhesion limitation and enables the universal transfer of over 20 different types of electrodes. Our contacts obey the Schottky–Mott rule and exhibit a FLP of S = 0.99. Both the electron and hole contacts show record‐low Schottky barriers of 4.2 and 11.2 meV, respectively. As a demonstration, we construct a doping‐free WSe2 inverter with these high‐performance contacts, which exhibits a static power consumption of only 58 pW. This strategy provides a universal method of electrode preparation for building high‐performance post‐Moore electronic devices. [ABSTRACT FROM AUTHOR]

Field‐effect transistors (FETs) made of monolayer 2D semiconductors (e.g., MoS2) are among the basis of the future modern wafer chip industry. However, unusually high contact resistances at the metal‐semiconductor interfaces have seriously limited the improvement of monolayer 2D semiconductor FETs so far. Here, a high‐scale processable strategy is reported to achieve ohmic contact between the metal and monolayer MoS2 with a large number of sulfur vacancies (SVs) by using simple sulfur‐vacancy engineering. Due to the successful doping of the contact regions by introducing SVs, the contact resistance of monolayer MoS2 FET is as low as 1.7 kΩ·µm. This low contact resistance enables high‐performance MoS2 FETs with ultrahigh carrier mobility of 153 cm2 V−1 s−1, a large on/off ratio of 4 × 109, and high saturation current of 342 µA µm−1. With the comprehensive investigation of different SV concentrations by adjusting the plasma duration, it is also demonstrated that the SV‐increased electron doping, with its resulting reduced Schottky barrier, is the dominant factor driving enhanced electrical performance. The work provides a simple method to promote the development of industrialized atomically thin integrated circuits. [ABSTRACT FROM AUTHOR]

Tea polyphenols (TP) are one of the most functional and bioactive substances in tea. The interactions between TP and intestinal microbiota suggest that probiotics intervention is a useful method to ameliorate neurological diseases. Now, numerous researches have suggested that TP plays a significant role in modulating intestinal bacteria, especially in the area of sustaining a stable state of intestinal microbial function and abundance. Furthermore, homeostatic intestinal bacteria can enhance the immunity of the host. The close reciprocity between intestinal microbiota and the central nervous system provides a new chance for TP to modulate neural‐related diseases depending on intestinal microbiota. Therefore, based on the bidirectional relationship between the brain and the intestines, this review provides a new clue to solve insomnia symptoms and related neurological diseases that will enable us to better study the bidirectional effects of TP and intestinal microbiota on the improvement of host health. Practical applications: This review provides a new clue to solve insomnia symptoms and related neurological diseases that will enable us to better study bidirectional effects of TP and intestinal microbiota on the improvement of host health. [ABSTRACT FROM AUTHOR]

Direct charge trapping memory, a new concept memory without any dielectric, has begun to attract attention. However, such memory is still at the incipient stage, of which the charge‐trapping capability depends on localized electronic states that originated from the limited surface functional groups. To further advance such memory, a material with rich hybrid states is highly desired. Here, a van der Waals heterostructure design is proposed utilizing the 2D graphdiyne (GDY) which possesses abundant hybrid states with different chemical groups. In order to form the desirable van der Waals coupling, the plasma etching method is used to rapidly achieve the ultrathin 2D GDY with smooth surface for the first time. With the plasma‐treated 2D GDY as charge‐trapping layer, a direct charge‐trapping memory based on GDY/MoS2 is constructed. This bilayer memory is featured with large memory window (90 V) and high degree of modulation (on/off ratio around 8 × 107). Two operating mode can be achieved and data storage capability of 9 and 10 current levels can be obtained, respectively, in electronic and opto‐electronic mode. This GDY/MoS2 memory introduces a novel application of GDY as rich states charge‐trapping center and offers a new strategy of realizing high performance dielectric‐free electronics, such as optical memories and artificial synaptic. [ABSTRACT FROM AUTHOR]

Universal van der Waals integrated metal electrode approach drives integrated circuit advanced process development [ABSTRACT FROM AUTHOR]

Flexible optoelectronics, as promising components hold shape‐adaptive features and dynamic strain response under strain engineering for various intelligent applications. 2D materials with atomically thin layers are ideal for flexible optoelectronics because of their high flexibility and strain sensitivity. However, how the strain affects the performance of 2D materials‐based flexible optoelectronics is confused due to their hypersensitive features to external strain changes. It is necessary to establish an evaluation system to comprehend the influence of the external strain on the intrinsic properties of 2D materials and the photoresponse performance of their flexible optoelectronics. Here, a focused review of strain engineering in 2D materials‐based flexible optoelectronics is provided. The first attention is on the mechanical properties and the strain‐engineered electronic properties of 2D semiconductors. An evaluation system with relatively comprehensive parameters in functionality and service capability is summarized to develop 2D materials‐based flexible optoelectronics in practical application. Based on the parameters, some strategies to improve the functionality and service capability are proposed. Finally, combining with strain engineering in future intelligence devices, the challenges and future perspective developing 2D materials‐based flexible optoelectronics are expounded. [ABSTRACT FROM AUTHOR]

Field-effect transistors (FETs) made of monolayer 2D semiconductors (e.g., MoS 2 ) are among the basis of the future modern wafer chip industry. However, unusually high contact resistances at the metal-semiconductor interfaces have seriously limited the improvement of monolayer 2D semiconductor FETs so far. Here, a high-scale processable strategy is reported to achieve ohmic contact between the metal and monolayer MoS 2 with a large number of sulfur vacancies (SVs) by using simple sulfur-vacancy engineering. Due to the successful doping of the contact regions by introducing SVs, the contact resistance of monolayer MoS 2 FET is as low as 1.7 kΩ·µm. This low contact resistance enables high-performance MoS 2 FETs with ultrahigh carrier mobility of 153 cm 2 V -1 s -1 , a large on/off ratio of 4 × 10 9 , and high saturation current of 342 µA µm -1 . With the comprehensive investigation of different SV concentrations by adjusting the plasma duration, it is also demonstrated that the SV-increased electron doping, with its resulting reduced Schottky barrier, is the dominant factor driving enhanced electrical performance. The work provides a simple method to promote the development of industrialized atomically thin integrated circuits., (© 2023 Wiley-VCH GmbH.)

Two-dimensional (2D) MoS 2 is an excellent candidate channel material for next-generation integrated circuit (IC) transistors. However, the reliability of MoS 2 is of great concern due to the serious threat of vacancy defects, such as sulfur vacancies (V S ). Evaluating the impact of vacancy defects on the service reliability of MoS 2 transistors is crucial, but it has always been limited by the difficulty in systematically tracking and analyzing the changes and effects of vacancy defects in the service environment. Here, a simulated initiator is established for deciphering the evolution of vacancy defects in MoS 2 and their influence on the reliability of transistors. The results indicate that V S below 1.3% are isolated by slow enrichment during initiation. Over 1.3% of V S tend to enrich in pairs and over 3.5% of the enriched V S easily evolve into nanopores. The enriched V S with electron doping in the channel cause the threshold voltage (V th ) negative drift approaching 6 V, while the expanded nanopores initiate the V th roll-off and punch-through of transistors. Finally, sulfur steam deposition has been proposed to constrain V S enrichment, and reliable MoS 2 transistors are constructed. Our research provides a new method for deciphering and identifying the impact of defects.

Considerable evidence indicates the important role of gut microbiota in human health. Through the interaction with the host and diet, it secretes a myriad of metabolites to modulate biological processes essential for health. Cognitive impairment is a common feature of psychiatric and neurological disorders, which may seriously damage the quality of patients' life. Studies have found that cognitive impairment has a close relationship with gut microbiota, and plant polysaccharides intervention to maintain intestinal micro-ecological balance has a great impact on ameliorating cognitive impairment. This review introduced the interaction between gut microbiota and plant polysaccharides, and focused on signaling pathogenesis of gut microbiota in cognitive impairment. The effect of plant polysaccharides intervention on regulation of gut microbiota was also discussed, so as to provide a promising strategy for ameliorating cognitive impairment., Competing Interests: The authors have no conflicts of interest to declare., (© 2022 Center for Food and Biomolecules, National Taiwan University. Production and hosting by Elsevier Taiwan LLC.)

Special surface plays a crucial role in nature as well as in industry. Here, the surface morphology evolution of ZnO during wet etching is studied by in situ liquid cell transmission electron microscopy and ex situ wet chemical etching. Many hillocks are observed on the (000 1 ¯ ) O-terminated surface of ZnO nano/micro belts during in situ etching. Nanoparticles on the apex of the hillocks are observed to be essential for the formation of the hillocks, providing direct experimental evidence of the micromasking mechanism. The surfaces of the hillocks are identified to be {01 1 ¯ 3 ¯ } crystal facets, which is different from the known fact that {01 1 ¯ 1 ¯ } crystal facets appear on the (000 1 ¯ ) O-terminated surface of ZnO after wet chemical etching. O 2 plasma treatment is found to be the key factor for the appearance of {01 1 ¯ 3 ¯ } instead of {01 1 ¯ 1 ¯ } crystal facets after etching for both ZnO nano/micro belts and bulk materials. The synergistic effect of acidic etching and O-rich surface caused by O 2 plasma treatment is proposed to be the cause of the appearance of {01 1 ¯ 3 ¯ } crystal facets. This method can be extended to control the surface morphology of other materials during wet chemical etching., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)