Showing papers on "Field electron emission published in 2011"
TL;DR: In this paper, a sulfur-graphene (S-GNS) composites have been synthesized by heating a mixture of graphene nanosheets and elemental sulfur.
375 citations
TL;DR: In this paper, the morphology-dependent field emission properties of graphdiyne arrays were measured and display high performance field emissions properties, and the turn-on field and threshold field of GDNTs annealed decreased to 4.20 and 8.83 V/μm, respectively.
Abstract: Graphdiyne nanotube (GDNT) arrays were prepared through an anodic aluminum oxide template catalyzed by Cu foil. The as-grown nanotubes have a smooth surface with a wall thickness of about 40 nm; after annealing, the GDNTs are about 15 nm. The morphology-dependent field emission properties of graphdiyne arrays were measured and display high performance field emission properties. The turn-on field and threshold field of GDNTs annealed decreased to 4.20 and 8.83 V/μm, respectively.
282 citations
TL;DR: The temperature dependence of resistivity of silver thin film, determined in the temperature range of 100-300 K, exhibit semiconducting behavior of the sample, and the sample shows the activated variable range hopping in the localized states near the Fermi level.
Abstract: This work reports the preparation and characterization of silver nanoparticles synthesized through wet chemical solution method and of silver films deposited by dip-coating method X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared silver nanoparticles and thin film The morphology and crystal structure of silver nanoparticles have been determined by FESEM, HRTEM, and FETEM The average grain size of silver nanoparticles is found to be 175 nm The peaks in XRD pattern are in good agreement with that of face-centered-cubic form of metallic silver TGA/DTA results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water The temperature dependence of resistivity of silver thin film, determined in the temperature range of 100-300 K, exhibit semiconducting behavior of the sample The sample shows the activated variable range hopping in the localized states near the Fermi level
264 citations
TL;DR: In this article, a composite MoS2/carbon nanotubes (CNT) material has been produced by hydrothermal decomposition of a mixture of multiwall CNTs and a water solution of ammonium molybdate and thiourea and X-ray photoelectron spectroscopy revealed a downshift of C 1s peak of the composite as compared to the pristine CNT sample that was related to charge transfer between the components.
Abstract: Composite MoS2/carbon nanotube material has been produced by hydrothermal decomposition of a mixture of multiwall carbon nanotubes (CNTs) and a water solution of ammonium molybdate and thiourea. Transmission electron microscopy and Raman spectroscopy showed formation of MoS2 layers on the CNT surface and MoS2 flakes. X-ray photoelectron spectroscopy revealed a downshift of C 1s peak of the composite as compared to the pristine CNT sample that was related to charge transfer between the components. This fact was confirmed by near-edge X-ray absorption fine structure spectroscopy which detected a decrease of intensity of π* resonance in the C K-edge spectrum after the MoS2 deposition. Quantum-chemical calculations of a CNT@MoS2 model showed a positive charging of the CNT surface. Comparison of field emission characteristics of CNTs and the composite indicated lowering of the voltage threshold in the latter sample.
254 citations
TL;DR: In this paper, a transparent and flexible optoelectronic material composed of vertically aligned ZnO NWs grown on reduced graphene/PDMS substrates was presented, which showed a typical metal-semiconductor ohmic contact without a contact barrier.
Abstract: We present a transparent and flexible optoelectronic material composed of vertically aligned ZnO NWs grown on reduced graphene/PDMS substrates. Large-area reduced graphene films were prepared on PDMS substrates by chemical exfoliation from natural graphitevia oxidative aqueous dispersion and subsequent thermal reduction. ZnO NWs were hydrothermally grown on the reduced graphene film substrate and maintained their structural uniformity even in highly deformed states. The electrical contact between semiconducting ZnO NWs and the metallic graphene film was straightforwardly measured by electric force microscopy (EFM). It shows a typical metal–semiconductor ohmic contact without a contact barrier. Owing to the mechanical flexibility, transparency, and low contact barrier, the ZnO NWs/graphene hybrids show excellent field emission properties. Low turn-on field values of 2.0 V μm−1, 2.4 V μm−1, and 2.8 V μm−1 were measured for convex, flat, and concave deformations, respectively. Such variation of field emission properties were attributed to the modification of ZnO NWs emitter density upon mechanical deformation.
237 citations
TL;DR: In situ nitrogen (N2) plasma treatment was carried out using electron cyclotron resonance plasma, resulting in various nitrogen functionalities being grafted to the FLG surface as mentioned in this paper.
Abstract: Vertically aligned few-layered graphene (FLG) nanoflakes were synthesized on bare silicon (Si) substrates by a microwave plasma enhanced chemical vapor deposition method. In situ nitrogen (N2) plasma treatment was carried out using electron cyclotron resonance plasma, resulting in various nitrogen functionalities being grafted to the FLG surface. Compared with pristine FLGs, the N2 plasma-treated FLGs showed significant improvement in field emission characteristics by lowering the turn-on field (defined at 10 μA/cm2) from 1.94 to 1.0 V/μm. Accordingly, the field emission current increased from 17 μA/cm2 at 2.16 V/μm for pristine FLGs to about 103 μA/cm2 at 1.45 V/μm for N-doped FLGs. Furthermore, N-doped FLG samples retained 94% of the starting current over a period of 10 000 s, during which the fluctuations were of the order of ±10.7% only. The field emission behavior of pristine and N2 plasma-treated FLGs is explained in terms of change in the effective microstructure as well as a reduction in the work ...
155 citations
TL;DR: In this article, low threshold field < 0.1 V/μm emission of multiple electron beams from atomically thin edges of reduced graphene oxide (rGO) was reported.
Abstract: Point sources exhibit low threshold electron emission due to local field enhancement at the tip. The development and implementation of tip emitters have been hampered by the need to position them sufficiently apart to achieve field enhancement, limiting the number of emission sites and therefore the overall current. Here we report low threshold field (< 0.1 V/μm) emission of multiple electron beams from atomically thin edges of reduced graphene oxide (rGO). Field emission microscopy measurements show evidence for interference from emission sites that are separated by a few nanometers, suggesting that the emitted electron beams are coherent. On the basis of our high-resolution transmission electron microscopy, infrared spectroscopy, and simulation results, field emission from the rGO edge is attributed to a stable and unique aggregation of oxygen groups in the form of cyclic edge ethers. Such closely spaced electron beams from rGO offer prospects for novel applications and understanding the physics of line...
132 citations
TL;DR: Ultraviolet-visible (UV-vis) absorption spectra, (13)C nuclear magnetic resonance (NMR), and powder X-ray diffraction (PXRD) characterizations demonstrated that crystalline and amorphous compound 1 possess different molecular packing.
Abstract: A trifluoromethyl-substituted benzothiadiazole-cored phenylene vinylene fluorophore (1) was synthesized and displayed piezo- and vapochromism and thermo-induced fluorescence variation in solid phase. Grinding could disrupt the crystalline compound 1 with orange emission into amorphous compound 1 with green emission, and heating treatment could change the amorphous compound 1 into crystalline compound 1. Ultraviolet-visible (UV-vis) absorption spectra, (13)C nuclear magnetic resonance (NMR), and powder X-ray diffraction (PXRD) characterizations demonstrated that crystalline and amorphous compound 1 possess different molecular packing. A differential scanning calorimetry (DSC) measurement revealed that the emission switching was due to the exchange between the thermodynamic-stable crystalline and metastable amorphous states. The ground sample exhibited vapochromic fluorescence property. Furthermore, compound 1 showed interesting supramolecular assembly characteristics in solution. Slowly cooling the hot N,N-dimethylformamide (DMF) solution of compound 1 resulted in the formation of orange fluorescent fibers, whereas sonication treatment of the cooling solution led to the generation of organic molecular gel. The field emission scanning electronic microscope (FESEM) and fluorescent microscopy images revealed smooth nano- or microfiber and network morphology properties. The PXRD spectra confirmed that these nano- or microstructures had a similar molecular-packing model with the crystalline state of compound 1. Slow evaporation of the toluene solution of compound 1 could produce green emissive microrods, which exhibited interesting thermo-induced fluorescence variation.
129 citations
Posted Content•
TL;DR: In this article, the authors reported low threshold field emission of multiple electron beams from atomically thin edges of reduced graphene oxide (rGO) point sources by using high-resolution transmission electron microscopy, infrared spectroscopy and simulation results.
Abstract: Point sources exhibit low threshold electron emission due to local field enhancement at the tip. The development and implementation of tip emitters have been hampered by the need to position them sufficiently apart to achieve field enhancement, limiting the number of emission sites and therefore the overall current. Here we report low threshold field (< 0.1V/um) emission of multiple electron beams from atomically thin edges of reduced graphene oxide (rGO). Field emission microscopy (FEM) measurements show evidence for interference from emission sites that are separated by a few nanometers, suggesting that the emitted electron beams may be coherent. Based on our high-resolution transmission electron microscopy, infrared spectroscopy and simulation results, field emission from the rGO edge is attributed to a stable and unique aggregation of oxygen groups in the form of cyclic edge ethers. Such closely spaced electron beams from rGO offer prospects for novel applications and understanding the physics of linear electron sources.
119 citations
TL;DR: In this paper, an Ag-Al2O3 nanocermet spectrally selective solar absorber coatings were prepared at different Ag contents on copper, silicon and glass substrates using unbalanced magnetron sputtering technique.
118 citations
TL;DR: In this paper, a kind of conductive pen was designed, prepared with nano-silver colloid as the conductive ink and gel-ink pen as the writing implement, and used to draw conductive patterns on paper substrate by direct-writing for flexible electronics.
Abstract: A kind of conductive pen was designed, prepared with nano-silver colloid as the conductive ink and gel-ink pen as the writing implement, and used to draw conductive patterns on paper substrate by direct-writing for flexible electronics. Silver nanoink (20 wt%) was characterized using field emission transmission electron microscopy (FETEM), size distribution analyser (SDA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and selected-area electron diffraction (SAED). Paper-based conductive patterns were investigated by a surface profilometer, a 4-point probe, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. It can be found that silver nanoparticles have a small size, about 2.1 ± 0.5 nm in diameter with monodispersity, and the melting point sharply decreased to 105 °C. A conductive line drawn on weighing paper not only had good mechanical/electrical fatigue properties, but also low resistivity. Especially, when the sintering condition is 200 °C for 60 min, the resistivity can be down to 6.8 μΩ cm, 4.25 times the bulk resistivity. In addition, the reparation of conductive patterns and application in a practical circuit were also studied.
TL;DR: The outstanding flexible field emission properties of carbon hybrid films made of vertically aligned N-doped carbon nanotubes grown on mechanically compliant reduced graphene films are demonstrated and this high-performance flexible carbon field emitter is potentially useful for diverse, flexibleField emission devices.
Abstract: The outstanding flexible field emission properties of carbon hybrid films made of vertically aligned N-doped carbon nanotubes grown on mechanically compliant reduced graphene films are demonstrated. The bottom-reduced graphene film substrate enables the conformal coating of the hybrid film on flexible device geometry and ensures robust mechanical and electrical contact even in a highly deformed state. The field emission properties are precisely examined in terms of the control of the bending radius, the N-doping level, and the length or wall-number of the carbon nanotubes and analyzed with electric field simulations. This high-performance flexible carbon field emitter is potentially useful for diverse, flexible field emission devices.
TL;DR: Graphene-polyaniline composites have been synthesized using simple chemical procedure in two different ways (i) by mixing of the pre-synthesized graphene and polyanILine nanofibers and (ii) by in situ polymerization in presence of graphite oxide followed by further reduction.
TL;DR: Energy distribution curves of laser-induced electron pulses from a tungsten tip have been measured as a function of tip voltage and laser power, allowing direct insight into the involved electron dynamics and revealing the temporal tunability of electron emission via the two experimental parameters.
Abstract: Energy distribution curves of laser-induced electron pulses from a tungsten tip have been measured as a function of tip voltage and laser power Electron emission via tunneling through and/or excitation over the surface barrier from photoexcited nonequilibrium electron distributions are clearly observed The spectral shapes largely vary with the emission processes and are strongly affected by electron dynamics Simulations successfully reproduce the spectra, thus allowing direct insight into the involved electron dynamics and revealing the temporal tunability of electron emission via the two experimental parameters These results should be useful to optimize the pulse characteristics for many applications based on ultrafast laser-induced electron emission
TL;DR: In this article, the authors report the observation and characterization of field emission current from individual single and few-layer graphene flakes laid on a flat SiO2/Si substrate, and demonstrate that the emission process is stable over a period of several hours.
Abstract: We report the observation and characterization of field emission current from individual single- and few-layer graphene flakes laid on a flat SiO2/Si substrate. Measurements were performed in a scanning electron microscope chamber equipped with nanoprobes which allowed local measurement of the field emission current. We achieved field emission currents up to 1 μA from the flat part of graphene flakes at applied fields of few hundred volt per micrometer. We found that the emission process is stable over a period of several hours and that it is well described by a Fowler–Nordheim model for currents over five orders of magnitude.
TL;DR: In this paper, the performance of Sn-doped ZnO nanorods was characterized by X-ray diffraction, field emission scanning electron microscope, UV-vis spectroscopy, Raman spectra, solid-state nuclear magnetic resonance (NMR) spectra and room temperature photoluminescence spectra.
TL;DR: In this paper, a method for the patterned growth of ZnO nanowires (NWs) is presented, which combines the direct patterning of NPs via microcontact printing and subsequent low-temperature hydrothermal growth.
Abstract: We present a novel and simple method for the patterned growth of ZnO nanowires (NWs) that combines (1) the direct patterning of ZnO nanoparticle (NP) seeds via microcontact printing and (2) subsequent low-temperature hydrothermal growth. The ZnO NPs can be patterned as seed layers for ZnO NW growth on various substrates including flexible polymer films. The NW geometry and configuration can be controlled by varying the printing conditions (time and pressure) and the hydrothermal reaction time. The “needleleaf-like” sharp-tipped ZnO NWs with a radially grown structure were examined at the pattern edges. To assess the possibility of high-performance electronic applications of the patterned ZnO NWs, their field emission characteristics were examined by fabricating a high-performance field emission device with a patterned ZnO NW array. The remarkable enhancement of the field emission properties is attributed to the minimized field emission screening that results from the radial ZnO NW structures and micropatt...
TL;DR: In this article, the maximum growth rate of carbon nanosheets using acetylene as a feedstock gas was found to be 16μm/h or ∼8 times that of previously reported methane nanoshes.
TL;DR: In this article, a well-aligned graphene field emission arrays were fabricated on copper foils via simple photolithography and wet etching techniques, showing a turn-on field of 7.2 V/μm at 100 nA/cm2 and good emission current stability.
Abstract: Well-aligned graphene field emission arrays were fabricated on copper foils via simple photolithography and wet etching techniques. The method offered high-ordered micro sized graphene pattern in the array elements. Field emission measurement revealed a turn-on field of 7.2 V/μm at 100 nA/cm2 and a good emission current stability. Exposed graphene edges were produced on each array element edge and found to be the significant contributors to the emission current. Owing to the obvious advantages of low cost and easy for scale-up production, this method demonstrates the feasibility of utilizing such graphene field emission array configurations in display applications.
TL;DR: It is expected that Zn(2)GeO(4):Mn( 2+) phosphors exhibit more saturated green emission than the commercial FEDs phosphor ZnO:Zn, and it isexpected that these phosphors are promising for application in field-emission displays.
Abstract: (Zn1−x−yMgy)2GeO4: xMn2+ (y = 0–0.30; x = 0–0.035) phosphors with uniform submicrorod morphology were synthesized through a facile hydrothermal process. X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the samples. SEM and TEM images indicate that Zn2GeO4:Mn2+ samples consist of submicrorods with lengths around 1–2 μm and diameters around 200–250 nm, respectively. The possible formation mechanism for Zn2GeO4 submicrorods has been presented. PL and CL spectroscopic characterizations show that pure Zn2GeO4 sample shows a blue emission due to defects, while Zn2GeO4:Mn2+ phosphors exhibit a green emission corresponding to the characteristic transition of Mn2+ (4T1→6A1) under the excitation of UV and low-voltage electron beam. Compared with Zn2GeO4:Mn2+ sample prepared by solid-state reaction, Zn2GeO4:Mn2+ phosphors obtained by hydrothermal process followed by high temperature annealing show better luminescence properties. In addition, codoping Mg2+ ions into the lattice to substitute for Zn2+ ions can enhance both the PL and CL intensity of Zn2GeO4:Mn2+ phosphors. Furthermore, Zn2GeO4:Mn2+ phosphors exhibit more saturated green emission than the commercial FEDs phosphor ZnO:Zn, and it is expected that these phosphors are promising for application in field-emission displays.
TL;DR: In this paper, the fabrication of a flexible field-emission device (FED) using single-walled carbon nanotube (SWNT) network films as conducting electrodes (anode and cathode) and thin multiwalled CNT/TEOS hybrid films as the emitters is reported.
Abstract: The fabrication of a flexible field-emission device (FED) using single-walled carbon nanotube (SWNT) network films as the conducting electrodes (anode and cathode) and thin multi-walled CNT/TEOS hybrid films as the emitters is reported. P-type doping with gold ions and passivation with tetraethylorthosilicate (TEOS) made the SWNT network film highly conductive and environmentally stable, and hence a good alternative to conventional indium tin oxide electrodes. CNT/TEOS hybrid emitters showed high current density, low turn-on field, and long-term emission stability, compared with CNT emitters; these characteristics can be attributed to the TEOS sol, acting both as a protective layer surrounding the nanotube tip, and as an adhesive layer enhancing the nanotube adhesion to the substrate. All-CNT-based flexible FEDs fabricated by this approach showed high flexibility in field emission characteristics and extremely bright electron emission patterns.
TL;DR: In this paper, superhydrophobic surfaces based on ZnO-PDMS nanocomposite coatings are demonstrated by a simple, facilitile, time-saving, wet chemical route.
TL;DR: In this article, single crystalline NiO nanoplatelets were successfully synthesized by new facile method at 200°C and the morphology and microstructure were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM).
TL;DR: The photoluminescence spectra of doped NWs having a blue-shift in the UV region show a prominent tuning in the optical band gap, without any significant peak relating to intrinsic defects.
Abstract: Vertically oriented well-aligned Indium doped ZnO nanowires (NWs) have been successfully synthesized on Au-coated Zn substrate by controlled thermal evaporation. The effect of indium dopant on the optical and field-emission properties of these well-aligned ZnO NWs is investigated. The doped NWs are found to be single crystals grown along the c-axis. The composition of the doped NWs is confirmed by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and X-ray photospectroscopy (XPS). The photoluminescence (PL) spectra of doped NWs having a blue-shift in the UV region show a prominent tuning in the optical band gap, without any significant peak relating to intrinsic defects. The turn-on field of the field emission is found to be ∼2.4 V μm−1 and an emission current density of 1.13 mA cm−2 under the field of 5.9 V μm−1. The field enhancement factor β is estimated to be 9490 ± 2, which is much higher than that of any previous report. Furthermore, the doped NWs exhibit good emission current stability...
TL;DR: In this paper, a ternary Fe3O4-SnO2-graphene nanocomposite was firstly synthesized by using a gas-liquid interfacial synthesis approach.
TL;DR: In this article, the electron transport properties of n-decylamine-functionalized Si nanosheets (NSs) were characterized using atomic force microscopy with a conductive cantilever under vacuum conditions at room temperature.
Abstract: We have characterized the electron transport properties of n-decylamine-functionalized Si nanosheets (NSs) using atomic force microscopy with a conductive cantilever under vacuum conditions at room temperature. Electrons are transported from the cantilever to the substrate through Si NSs. The Si NSs exhibit nonresonant tunneling; the transport mechanisms are based on direct tunneling at low bias voltages and Fowler–Nordheim tunneling at high bias voltages.
TL;DR: In this paper, a modified polymeric precursor method was used to synthesize SrTiO 3 nanoparticles for the first time via a modified polymer precursor method, which were characterized by thermogravimetry, X-ray diffraction (XRD), BET surface area, micro-Raman spectroscopy, field emission scanning and transmission electron microscopy (FE-SEM and FE-STEM), high-resolution transmission electron microscope (HRTEM) and photoluminescence measurements.
Patent•
06 May 2011
TL;DR: In this paper, a light-emitting device of a field electron emission type, a cathode electrode having an electron emission source, and an anode electrode with a phosphor that emits light by excitation by an electron field emitted from the electron emission sources are provided.
Abstract: PROBLEM TO BE SOLVED: To provide a light-emitting device which is suitable for both-face light emission SOLUTION: In the light-emitting device of a field electron emission type, a cathode electrode having an electron emission source, and an anode electrode having a phosphor that emits light by excitation by an electron field emitted from the electron emission source are provided In the cathode electrode in which in a multi-layered substrate having a lamination structure of a surface layer, a catalyst layer, and a rear face layer, a through-hole penetrating the surface layer, the catalyst layer, and the rear face layer is installed, and the electron emission source is formed on the surface of the catalyst layer exposed by the through-hole In the light-emitting device, in the anode electrode in which a first anode electrode and a second anode electrode are arranged to oppose each other via the through-hole of the cathode electrode COPYRIGHT: (C)2011,JPO&INPIT
TL;DR: The quality of silver tips fabricated not only offers atomically resolved STM imaging, but more importantly, also allows us to perform challenging "color" photon mapping with emission spectra taken at each pixel simultaneously during the STM scan under relatively small tunnel currents and relatively short exposure time.
Abstract: We describe a reliable fabrication procedure of silver tips for scanning tunneling microscope (STM) induced luminescence experiments. The tip was first etched electrochemically to yield a sharp cone shape using selected electrolyte solutions and then sputter cleaned in ultrahigh vacuum to remove surface oxidation. The tip status, in particular the tip induced plasmon mode and its emission intensity, can be further tuned through field emission and voltage pulse. The quality of silver tips thus fabricated not only offers atomically resolved STM imaging, but more importantly, also allows us to perform challenging “color” photon mapping with emission spectra taken at each pixel simultaneously during the STM scan under relatively small tunnel currents and relatively short exposure time.
TL;DR: The developed multipixel x-ray array source has 50 individually controllable pixels and it has several distinct advantages over other irradiation source including high-temporal resolution (millisecond level), the ability to electronically shape the form, and intensity distribution of the radiation fields.
Abstract: The authors report a carbon nanotube (CNT) field emission multipixel x-ray array source for microradiotherapy for cancer research. The developed multipixel x-ray array source has 50 individually controllable pixels and it has several distinct advantages over other irradiation source including high-temporal resolution (millisecond level), the ability to electronically shape the form, and intensity distribution of the radiation fields. The x-ray array was generated by a CNT cathode array (5×10) chip with electron field emission. A dose rate on the order of >1.2 Gy∕min per x-ray pixel beam is achieved at the center of the irradiated volume. The measured dose rate is in good agreement with the Monte Carlo simulation result.