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) van der Waals Heterojunctions
摘要： Van der Waals heterojunctions (vdWHs) have gained extensive attention because they can integrate the excellent characteristics of the stacked materials and most vdWHs exhibit type-II band alignment. However, type-III vdWHs with broken gaps are still very rare, which limits the development and application of two-dimensional (2D) materials in the fields of tunnel FETs (TFETs). Here, we theoretically demonstrate that 2D phosphorene/SnS2 (SnSe2) vdWHs possess type-III (broken-gap) band alignment, and their I-V curves present negative differential resistance (NDR) effects. The BTBT transport mechanism and its applications in TFETs are analyzed. Interestingly, a positive electric field can enlarge the tunnelling window and a negative electric field can realize multiple-band-alignment transformation (type I, type II, and type III). Thus, this work presents the intrinsic physics mechanism and electric field tunable multiple-band alignments in 2D type-III vdWHs and related electronic devices.
关键词： tunnel FETs,SnS2,phosphorene,type-III band alignment,Van der Waals heterojunctions,electric field,SnSe2
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC) - Budapest, Hungary (2018.8.26-2018.8.30)] 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC) - Design Considerations of GaN Transistor Based Capacitive Wireless Power Transfer System
摘要： The paper discusses and evaluates design of capacitive wireless power transfer (WPT) system. The capacitive WPT can replace a conventional inductive WPT for example in applications where metallic objects are placed close to receiver or transceiver. Main limitation for wider application of the capacitive WPT is due to small coupling capacitance between two surfaces in limited space. Therefore, to utilize capacitive WPT system the switching frequency should be as high as possible. Challenges associated with design of capacitive WPT system operating in MHz range are discussed in this paper. In the paper it is described WPT system that consists of two copper plates to transfer power from the primary side to the secondary side. Some calculation considerations of resonant network is given in the paper. The high switching of inverter transistors requires high performance transistors with optimized driver circuit. The design of GaN transistor based inverter and driver circuit is discussed and experimental results are shown.
关键词： wireless power transfer,capacitance,electric field,high frequency inverter
更新于2025-09-09 09:28:46
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Study on the Application of Electric Field to Giant Vesicles Comprised of 1,2-Dilauroyl-Sn-Glycero-3-Phosphatidylcholine Using Optical Fluorescence Microscopy
摘要： The influence of alternating electric field (AC) in the structure and dynamics of giant unilamellar vesicles (GUVs) comprised of 1,2-dilauroyl-sn-glycero-3-phosphatidylcholine (DLPC) is reported. The investigations were conducted by using optical fluorescence microscopy as the method of analysis. The lipid membrane of the DLPC GUVs at the fluid phase can be deformed and they migrate towards the electrodes under AC electric field. Nevertheless, membrane disruption or vesicle fusion was never noticed. The addition of concentrated glucose solution influences the osmotic pressure of the system leading to the formation of filaments at the outer region of the GUVs. These long flexible cylinders do not retract spontaneously. However, the application of AC electric field (20 V/mm, 20 Hz) enables the filaments to be retracted back to the GUVs membrane at a calculated speed of 0.18 μm.s-1
关键词： Electric field,GUVs,Fluorescence microscopy,DLPC
更新于2025-09-09 09:28:46
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European Microscopy Congress 2016: Proceedings || Atom-Resolved STEM Imaging Using a Segmented Detector
摘要： In scanning transmission electron microscopy (STEM), the imaging of atomic columns with a segmented detector has been developed to visualize the local electric field in a crystal. The imaging technique is based on the differential phase contrast (DPC) method, which detects the deflection of the electron beam due to the electric field. The DPC method has been applied to various materials, including semiconductors, metals, and insulators. In this study, we demonstrate the imaging of atomic columns in a SrTiO3 crystal using a segmented detector. The atomic columns are clearly resolved, and the local electric field is visualized. The results show that the DPC method is a powerful tool for studying the electric field in materials at the atomic scale.
关键词： atomic columns,electric field,segmented detector,scanning transmission electron microscopy,differential phase contrast
更新于2025-09-09 09:28:46
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Evolution of ferroelectric and piezoelectric response by heat treatment in pseudocubic BiFeO3–BaTiO3 ceramics
摘要： Heat treatment of ceramics is an important process to tailor the fine electromechanical properties. To explore the criteria for optimized heat treatment in a perovskite structure of (1–x)Bi1.05FeO3–xBaTiO3 (BF–BT100x) system, the structural phase relation, ferroelectric and piezoelectric response of BF–BT36 and BF–BT40 ceramics prepared by furnace cooling (FC) and quenching process were investigated. The X-ray diffraction examination showed single pseudocubic perovskite structure for all the ceramics. The homogenous microstructure was obtained for all ceramics with relatively large grain size in the furnace cooled samples. Well saturated ferroelectric hysteresis loops and enhanced piezoelectric constant (d33 = 97 pC/N) were achieved by quenching process. Dielectric curve of BF–BT36 showed large dielectric constant at its Curie temperature, however, BF–BT40 showed diffused relaxor-like dielectric anomalies. Quenched BF–BT36 samples showed typical butterfly like field induced strain curves, however negative strain decreased in BF–BT40 ceramics. From these investigated study, it is observed that BF–BT ceramics are very sensitive to the heat treatment process (furnace cooling and quenching) on the dielectric, electromechanical properties.
关键词： Quenching process,Electric field induced strain,Dielectric relaxation,BF–BT
更新于2025-09-09 09:28:46
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Modulation of the electronic properties of two-dimensional MoTe2/WSe2 heterostructure by electrical field
摘要： The structure and electronic properties of two-dimensional MoTe2/WSe2 van der Waals heterostructure under external electric field have been investigated by first-principles calculation. The interlayer distance between MoTe2 and WSe2 is 3.613? and the binding energy per unit is ?0.183eV, which indicated that MoTe2 is bound to WSe2 via van der Waals interaction. The interlayer distance can be modified by external electric field and the band gap of MoTe2/WSe2 heterostructure continuously decreases with increasing external electric field, eventually a transition from semiconductor to metal is observed, particularly, the band alignment of the MoTe2/WSe2 heterostructure can be effectively tuned from intrinsic type-II to type-I. Applying external electric field along +z direction and ?z direction has different effects on the band gap due to the intrinsic spontaneous polarization in MoTe2/WSe2 heterostructure. Our study indicates that the external electric field can significantly tune the band offsets and modify the band alignment between MoTe2 and WSe2. The present study would be helpful for application of such transition-metal dichalcogenides heterostructures in nano- and optoelectronics.
关键词： band gap,MoTe2/WSe2 heterostructure,external electric field,Density of States
更新于2025-09-09 09:28:46
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Controllable magnetization and resistivity jumps of manganite thin films on BaTiO <sub/>3</sub> substrate
摘要： Manganites thin films grown on ferroelectric BaTiO3 (BTO) exhibit dramatic jumps for both magnetization and resistivity upon cooling in accordance with the temperature-dependent structural transitions of the BTO substrate. Both upward and downward jumps have been reported at the same temperature point where BTO undergoes a structural transition from monoclinic to rhombohedral. Using La5/8Ca3/8MnO3/BaTiO3 as protype system, we solve the puzzle by showing that the direction of the jumps can be controlled by applying an electric field during post growth cooling which determines the orientation of the c-axis of the BTO substrate at room temperature. This offers a convenient way to control the magnetic and transport behavior of manganites films using electric field.
关键词： manganite thin films,resistivity jumps,electric field control,magnetization,BaTiO3 substrate
更新于2025-09-09 09:28:46
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One-particle density matrix polarization susceptibility tensors
摘要： The electric field-induced change in the one-electron density has been expressed as a series of the one-particle density matrix susceptibilities interacting with the spatial distribution of the electric field. The analytic approximate expressions are derived at the Hartree-Fock theory, which serves as a basis for the construction of the generalized model that is designed for an arbitrary form of wavefunction and any type of one-particle density matrix. It is shown that it is possible to accurately predict the changes in the one-electron ground-state density of water molecule in a spatially uniform electric field, as well as in spatially non-uniform electric field distribution generated by point charges. When both linear and quadratic terms with respect to the electric field are accounted for, the electric field-induced polarization energies, dipole moments, and quadrupole moments are quantitatively described by the present theory in electric fields ranging from weak to very strong (0.001–0.07 a.u.). It is believed that the proposed model could open new routes in quantum chemistry for fast and efficient calculations of molecular properties in condensed phases.
关键词： polarization susceptibility tensors,one-particle density matrix,quantum chemistry,Hartree-Fock theory,electric field-induced polarization
更新于2025-09-09 09:28:46
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[IEEE 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Erlagol (Altai Republic), Russia (2018.6.29-2018.7.3)] 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Analysis of the Technological Parameters Influence on the Reproducibility of the Active Dielectrics Properties
摘要： An analytical description of the process parameters and various industry sorts of external factors influence (heat, electrical, magnetic, mechanical) on active dielectrics properties (relative permittivity, polarization) that govern the materials use in functional electronics elements is presented. The article proves expediency of x-rays use to improve the reproducibility of dielectric properties of hydrogen-containing ferroelectrics (for example, triglycine sulfate). Higher reproducibility of parameters is due to the presence of flat areas in dependence of the relative permittivity on the electric field (cid:304)(E) during (cid:534)-radiation exposure, and therefore the additional errors of dialectic properties measurement are reduced significantly due to the impossibility of fixing the exact values of process parameters. For example, when the radiation dose D = 50 kR extra measurement error (cid:304) is reduced not less than 2.5 times.
关键词： properties reproducibility,radiation,Active dielectric,dielectric permeability,electric field strength
更新于2025-09-09 09:28:46
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Computational design of GeSe/graphene heterojunction based on density functional theory
摘要： Based on density functional theory, we computational designed the hetero junction composed by decreasing the interlayer distance in G/g hetero structure. The height of Schottky barrier can be demonstrated that both the intrinsic electric properties of the GeSe monolayer and graphene are well preserved in G/g hetero structure. It is found that an energy gap of 0.17 eV in graphene is opened by GeSe monolayer and graphene. The effects of interlayer coupling, strains and electric fields on the electronic structures of the designed GeSe/graphene (G/g) hetero structure are explored. We found that applying in-plane strains and the electric fields perpendicular to the G/g hetero structure can control the Schottky barriers at the G/g interface. Our results predict that the ultra-thin G/g hetero structure can be used as two-dimensional semiconductor-based optoelectronic devices.
关键词： density functional,heterostructure,GeSe monolayer,strain,electric field
更新于2025-09-09 09:28:46