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Two-dimensional (2D) bismuth oxyselenide (Bi2O2Se) with high electron mobility shows great potential for nanoelectronics. Although the in-plane properties of Bi2O2Se have been widely studied, its out-of-plane electrical transport behavior remains elusive, despite its importance in fabricating devices with new functionality and high integration density. Here, the out-of-plane electrical properties of 2D Bi2O2Se at nanoscale are revealed by conductive atomic force microscope. This work finds that hillocks with tunable heights and sizes are formed on Bi2O2Se after applying a vertical electric field. Intriguingly, such hillocks are conductive in the vertical direction, resulting in a previously unknown out-of-plane resistance switching in thick Bi2O2Se flakes while ohmic conductive characteristic in thin ones. Furthermore, the transformation is observed from bipolar to stable unipolar conduction in thick Bi2O2Se flake possessing such hillocks, suggesting its potential to function as a selector in vertical devices. This work reveals the unique out-of-plane transport behavior of 2D Bi2O2Se, providing the basis for fabricating vertical devices based on this emerging 2D material. 相似文献
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Lei Tang Runzhang Xu Junyang Tan Yuting Luo Jingyun Zou Zongteng Zhang Rongjie Zhang Yue Zhao Junhao Lin Xiaolong Zou Bilu Liu Hui-Ming Cheng 《Advanced functional materials》2021,31(5):2006941
Modulating electronic structure of monolayer transition metal dichalcogenides (TMDCs) is important for many applications, and doping is an effective way toward this goal, yet is challenging to control. Here, the in situ substitutional doping of niobium (Nb) into TMDCs with tunable concentrations during chemical vapor deposition is reported. Taking monolayer WS2 as an example, doping Nb into its lattice leads to bandgap changes in the range of 1.98–1.65 eV. Noteworthy, electrical transport measurements and density functional theory calculations show that the 4d electron orbitals of the Nb dopants contribute to the density of states of Nb-doped WS2 around the Fermi level, resulting in an n- to p-type conversion. Nb-doping also reduces the energy barrier of hydrogen absorption in WS2, leading to an improved electrocatalytic hydrogen evolution performance. These results highlight the effectiveness of controlled doping in modulating the electronic structure of TMDCs and their use in electronic related applications. 相似文献
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Wen‐Bin Liu Songfeng Pei Jinhong Du Bilu Liu Libo Gao Yang Su Chang Liu Hui‐Ming Cheng 《Advanced functional materials》2011,21(12):2330-2337
A good dispersion of single‐walled carbon nanotubes (SWCNTs) in liquid media is a prerequisite to fulfill many of their applications. This contribution reports an efficient approach to additive‐free dispersion of SWCNTs with the aid of functionalized carbonaceous byproducts (CBs, e.g., amorphous carbon, carbon nanoparticles, and carbonaceous fragments) in SWCNT products. SWCNT bundles are treated by oleum intercalation and nitric acid oxidation in sequence, which leads to the selective functionalization of the CBs while the structure and properties of the SWCNTs are well preserved. These functionalized CBs can improve the subsequent dispersion of SWCNTs and the majority of SWCNTs in the suspension are present in small bundles or individually. Moreover, SWCNT transparent conductive films (TCFs) are fabricated by using these suspensions. The SWCNT TCFs obtained can achieve a low sheet resistance of 76 and 133 Ω sq?1, with optical transmittance of 82% and 90% at 550 nm, respectively. 相似文献
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Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapour deposition 总被引:8,自引:0,他引:8
Integration of individual two-dimensional graphene sheets into macroscopic structures is essential for the application of graphene. A series of graphene-based composites and macroscopic structures have been recently fabricated using chemically derived graphene sheets. However, these composites and structures suffer from poor electrical conductivity because of the low quality and/or high inter-sheet junction contact resistance of the chemically derived graphene sheets. Here we report the direct synthesis of three-dimensional foam-like graphene macrostructures, which we call graphene foams (GFs), by template-directed chemical vapour deposition. A GF consists of an interconnected flexible network of graphene as the fast transport channel of charge carriers for high electrical conductivity. Even with a GF loading as low as ~0.5 wt%, GF/poly(dimethyl siloxane) composites show a very high electrical conductivity of ~10 S cm(-1), which is ~6 orders of magnitude higher than chemically derived graphene-based composites. Using this unique network structure and the outstanding electrical and mechanical properties of GFs, as an example, we demonstrate the great potential of GF/poly(dimethyl siloxane) composites for flexible, foldable and stretchable conductors. 相似文献
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Different measuring methods relating to the prerotation flow in the entrance pipe of radial pumps are analyzed. The appearance of the prerotation flow is a result of the complicated fluid flow model, which appears as a consequence of the pump operating out of design limits and reduces pump efficiency. The goal of this contribution is in estimating the best measuring method, taking into account the inconvenience of conventional hot-wire and laser-Doppler anemometry. Therefore, two measuring systems—multiblade (ASB) and single blade (ASSB) anemometer—are introduced, analyzed and compared. The advantages of the introduced measuring system—ASB—are in its simple construction and simple use and its low price. The direction and swirl flow intensity in the entrance pipe of radial pumps and fans could be measured using this method. 相似文献
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