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排序方式: 共有466条查询结果,搜索用时 93 毫秒
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Tunneling Photocurrent Assisted by Interlayer Excitons in Staggered van der Waals Hetero‐Bilayers 下载免费PDF全文
Dinh Hoa Luong Hyun Seok Lee Guru Prakash Neupane Shrawan Roy Ganesh Ghimire Jin Hee Lee Quoc An Vu Young Hee Lee 《Advanced materials (Deerfield Beach, Fla.)》2017,29(33)
Vertically stacked van der Waals (vdW) heterostructures have been suggested as a robust platform for studying interfacial phenomena and related electric/optoelectronic devices. While the interlayer Coulomb interaction mediated by the vdW coupling has been extensively studied for carrier recombination processes in a diode transport, its correlation with the interlayer tunneling transport has not been elucidated. Here, a contrast is reported between tunneling and drift photocurrents tailored by the interlayer coupling strength in MoSe2/MoS2 hetero‐bilayers (HBs). The interfacial coupling modulated by thermal annealing is identified by the interlayer phonon coupling in Raman spectra and the emerging interlayer exciton peak in photoluminescence spectra. In strongly coupled HBs, positive photocurrents are observed owing to the inelastic band‐to‐band tunneling assisted by interlayer excitons that prevail over exciton recombinations. By contrast, weakly coupled HBs exhibit a negative photovoltaic diode behavior, manifested as a drift current without interlayer excitonic emissions. This study sheds light on tailoring the tunneling transport for numerous optoelectronic HB devices. 相似文献
194.
《Advanced Powder Technology》2022,33(11):103836
This paper presents a review of our key advances in model-guided dry coating-based enhancements of poor flow and packing of fine cohesive powders. The existing van der Waals force-based particle-contact models are reviewed to elucidate the main mechanism of flow enhancement through silica dry coating. Our multi-asperity model explains the effect of the amount of silica, insufficient flowability enhancements through conventional blending, and the predominant effect of particle surface roughness on cohesion reduction. Models are presented for the determination of the amount and type of guest particles, and estimation of the granular Bond number, used for cohesion nondimensionalization, based on particle size, particle density, asperity size, surface area coverage, and dispersive surface energy. Selection of the processing conditions for LabRAM, a benchmarking device, is presented followed by key examples of enhancements of flow, packing, agglomeration, and dissolution through the dry coating. Powder agglomeration is shown as a screening indicator of powder flowability. The mixing synergy is identified as a cause for enhanced blend flowability with a minor dry coated constituent at silica < 0.01%. The analysis and outcomes presented in this paper are intended to demonstrate the importance of dry coating as an essential tool for industry practitioners. 相似文献
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B. Bira T. Raja Sekhar G.P. Raja Sekhar 《Computers & Mathematics with Applications》2018,75(11):3873-3883
In this paper, we consider a quasilinear hyperbolic system of partial differential equations (PDEs) governing unsteady planar or radially symmetric motion of an inviscid, perfectly conducting and non-ideal gas in which the effect of magnetic field is significant. A particular exact solution to the governing system, which exhibits space–time dependence, is derived using Lie group symmetry analysis. The evolutionary behavior of a weak discontinuity across the solution curve is discussed. Further, the evolution of a characteristic shock and the corresponding interaction with the weak discontinuity are studied. The amplitudes of the reflected wave, the transmitted wave and the jump in the shock acceleration influenced by the incident wave after interaction are evaluated. Finally, the influence of van der Waals excluded volume in the behavior of the weak discontinuity is completely characterized. 相似文献
197.
Ji‐Hye Lim Jaewoo Shim Beom‐Seok Kang Gicheol Shin Hyeongjun Kim Maksim Andreev Kil‐Su Jung Kwan‐Ho Kim Jae‐Woong Choi Yoonmyung Lee Jin‐Hong Park 《Advanced functional materials》2019,29(48)
Multi‐valued logic (MVL) computing, which uses more than three logical states, is a promising future technology for handling huge amounts of data in the forthcoming “big data” era. The feasibility of MVL computing depends on the development of new concept devices/circuits beyond the complementary metal oxide semiconductor (CMOS) technology. This is because many CMOS devices are required to implement basic MVL functions, such as multilevel NOT, AND, and OR. In this study, a novel MVL device is reported with a complementarily controllable potential well, featuring the negative differential transconductance (NDT) phenomenon. This NDT device implemented on the WS2–graphene–WSe2 van der Waals heterostructure is evolved to a double‐NDT device operating on the basis of two consecutive NDT phenomena via structural engineering and parallel device configuration. This double‐NDT device is intensively analyzed via atomic force microscopy, kelvin probe force microscopy, Raman spectroscopy, and temperature‐dependent electrical measurement to gain a detailed understanding of its operating mechanism. Finally, the operation of a quaternary inverter configured with the double‐peak NDT device and a p‐channel transistor through Cadence circuit simulation is theoretically demonstrated. 相似文献
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Stefano Cecchi Daniele Dragoni Dominik Kriegner Elisa Tisbi Eugenio Zallo Fabrizio Arciprete Vclav Holý Marco Bernasconi Raffaella Calarco 《Advanced functional materials》2019,29(2)
In recent years strain engineering is proposed in chalcogenide superlattices (SLs) to shape in particular the switching functionality for phase change memory applications. This is possible in Sb2Te3/GeTe heterostructures leveraging on the peculiar behavior of Sb2Te3, in between covalently bonded and weakly bonded materials. In the present study, the structural and thermoelectric (TE) properties of epitaxial Sb2+xTe3 films are shown, as they represent an intriguing option to expand the horizon of strain engineering in such SLs. Samples with composition between Sb2Te3 and Sb4Te3 are prepared by molecular beam epitaxy. A combination of X‐ray diffraction and Raman spectroscopy, together with dedicated simulations, allows unveiling the structural characteristics of the alloys. A consistent evaluation of the structural disorder characterizing the material is drawn as well as the presence of both Sb2 and Sb4 slabs is detected. A strong link exists among structural and TE properties, the latter having implications also in phase change SLs. A further improvement of the TE performances may be achieved by accurately engineering the intrinsic disorder. The possibility to tune the strain in designed Sb2+xTe3/GeTe SLs by controlling at the nanoscale the 2D character of the Sb2+xTe3 alloys is envisioned. 相似文献
200.
Wenhao Huang Lei Yin Feng Wang Ruiqing Cheng Zhenxing Wang Marshet Getaye Sendeku Junjun Wang Ningning Li Yuyu Yao Xiaoguang Yang Chongxin Shan Tao Yang Jun He 《Advanced functional materials》2019,29(36)
Nonvolatile memories based on van der Waals heterostructures have been proved to be promising candidates for next‐generation data storage devices. However, little attention has been focused on the structure with separated floating and control gates (the floating gates and control gates distribute at the different side of the channels), which were recently predicted to be capable of further improving device performance. Here, nonvolatile multibit optoelectronic memories are demonstrated using MoS2, hexagonal boron nitride (h‐BN), and graphene in a top‐floating‐gated structure. With separated top graphene floating gate, the devices show a large memory window (≈95 V) via sweeping gate voltage from 80 to ?80 V, a high on/off ratio (≈106) with an ultralow dark current (≈10?14 A), as well as excellent retention characteristic (≈104 s) and cyclic endurance. In addition, these devices can also be erased by a laser illumination with broadband spectrum after being electrically programmed. For the multilevel storage property, 7/6 stages controlled by different electrical operations, and 13/6/3 stages by different laser pulse illuminations are gained. The obtained results show a promising performance for nonvolatile optoelectronic memory using a top‐floating‐gated structure. 相似文献