Showing papers on "Field electron emission published in 2020"
TL;DR: In this article, a series of Bi3+/Eu3+-activated GdNbO4 phosphors were used for non-contact temperature measurement and field emission display.
164 citations
60 citations
07 Feb 2020
58 citations
TL;DR: To overcome the problem that Bi3+-activated phosphors suffer from, it is an urgent need to realize narrow-band light emission of bi3+ activated phosphors, which not only improves their luminescence, but also improves their performance.
Abstract: To overcome the problem that Bi3+-activated phosphors suffer from, it is an urgent need to realize narrow-band light emission of Bi3+-activated phosphors, which not only improves their luminescence...
47 citations
TL;DR: An exponential increase of the nanotube resistivity with tensile strain is demonstrated up to a recorded elongation of 12%, thereby making WS2 NTs suitable for piezoresistive strain sensor applications.
Abstract: This study reports the electrical transport and the field emission properties of individual multi-walled tungsten disulphide (WS2 ) nanotubes (NTs) under electron beam irradiation and mechanical stress. Electron beam irradiation is used to reduce the nanotube-electrode contact resistance by one-order of magnitude. The field emission capability of single WS2 NTs is investigated, and a field emission current density as high as 600 kA cm-2 is attained with a turn-on field of ≈100 V μm-1 and field-enhancement factor ≈50. Moreover, the electrical behavior of individual WS2 NTs is studied under the application of longitudinal tensile stress. An exponential increase of the nanotube resistivity with tensile strain is demonstrated up to a recorded elongation of 12%, thereby making WS2 NTs suitable for piezoresistive strain sensor applications.
37 citations
TL;DR: In this article, the authors focus on generalizing field emission-driven microscale gas breakdown to consider the contribution of other forms of electron emission, specifically thermionic and space-charge limited.
Abstract: This Perspective outlines theoretical, simulation, and experimental studies linking electron emission and gas breakdown. Many studies have investigated field emission-driven microscale gas breakdown, including recent reviews [Garner et al., IEEE Trans. Plasma Sci. 48, 808–824 (2020); Fu et al., Plasma Res. Express 2, 013001 (2020)]. This Perspective focuses on generalizing field emission-driven microscale gas breakdown to consider the contribution of other forms of electron emission, specifically thermionic and space-charge limited. Recent theoretical studies have unified thermionic, field, and space-charge limited emission with and without collisions to derive “nexuses” where the individual solutions match, indicating transitions in the mechanisms. Reducing device size to nanoscale at atmospheric pressure leads to a transition from field emission to space-charge limited emission for nitrogen at ∼250 nm. This Perspective summarizes the derivation of these nexuses and future extensions. We next describe simulation and theoretical studies for field emission-driven microscale gas breakdown and highlight how the nexus theory may be integrated to account for temperature, space-charge, and pulse parameters. Finally, we summarize the development of optical techniques to assess microscale gas breakdown and recent nanoscale experiments at atmospheric pressure that suggest that space-charge may begin to contribute to field emission prior to gas breakdown. We highlight the combination of theory, simulation, and experiment to link electron emission and gas breakdown mechanisms across length, pressure, and temperature scales for applications that include vacuum electronics, pulsed power, and medicine.
36 citations
TL;DR: This Letter demonstrates a record low mean transverse energy of 5 meV from the cryo-cooled surface of copper using near-threshold photoemission and shows that the electron energy spread obtained from such a surface is less than 11.5 MeV, making it the smallest energy spread electron source known to date.
Abstract: Achieving a low mean transverse energy or temperature of electrons emitted from the photocathode-based electron sources is critical to the development of next-generation and compact x-ray free electron lasers and ultrafast electron diffraction, spectroscopy, and microscopy experiments. In this Letter, we demonstrate a record low mean transverse energy of 5 meV from the cryo-cooled (100) surface of copper using near-threshold photoemission. Further, we also show that the electron energy spread obtained from such a surface is less than 11.5 meV, making it the smallest energy spread electron source known to date: more than an order of magnitude smaller than any existing photoemission, field emission, or thermionic emission based electron source. Our measurements also shed light on the physics of electron emission and show how the energy spread at few meV scale energies is limited by both the temperature and the vacuum density of states.
34 citations
24 Jul 2020
TL;DR: In this article, the authors present a theory of field emission and thermionic emission, including the subsequent transition to the space-charge limited emission regime, and develop a new tool to identify transitions within a diode's geometric and electric parameter spaces.
Abstract: This paper presents a theory of field emission and thermionic emission, including the subsequent transition to the space-charge limited emission regime. Since transitions between mechanisms can influence the full solution even orders of magnitude distant in voltage or current density, the paper develops a new tool to identify transitions within a diode's geometric and electric parameter spaces.
33 citations
TL;DR: In this paper, the electrical transport in back-gate field effect transistors with ultrathin palladium diselenide (PdSe2) channel was studied, and the authors demonstrated field emission from few-layer Pse2 nanosheets with current up to the uA and turn-on field below 100 V/um.
Abstract: We study the electrical transport in back-gate field-effect transistors with ultrathin palladium diselenide (PdSe2) channel. The devices are normally-on and exhibit dominant n-type conduction at low pressure. The electron conduction, combined with the sharp edge and the workfunction decreasing with the number of layers, opens the way to applications of PdSe2 nanosheets in vacuum electronics. In this work, we demonstrate field emission from few-layer PdSe2 nanosheets with current up to the uA and turn-on field below 100 V/um, thus extending the plethora of applications of this recently isolated pentagonal layered material.
31 citations
TL;DR: In this article, one step co-precipitation method of synthesis of ZnO and Cu-doped nanostructures with distinct amount (1, 3 and 5 mol %) of copper was reported.
30 citations
TL;DR: A facile approach based on piezoelectric-driven nanotips inside a scanning electron microscope to contact and electrically characterize ultrathin MoS2 (molybdenum disulfide) flakes on a SiO2/Si (silicon dioxide/silicon) substrate is reported.
Abstract: We report a facile approach based on piezoelectric-driven nanotips inside a scanning electron microscope to contact and electrically characterize ultrathin MoS2 (molybdenum disulfide) flakes on a SiO2/Si (silicon dioxide/silicon) substrate. We apply such a method to analyze the electric transport and field emission properties of chemical vapor deposition-synthesized monolayer MoS2, used as the channel of back-gate field effect transistors. We study the effects of the gate-voltage range and sweeping time on the channel current and on its hysteretic behavior. We observe that the conduction of the MoS2 channel is affected by trap states. Moreover, we report a gate-controlled field emission current from the edge part of the MoS2 flake, evidencing a field enhancement factor of approximately 200 and a turn-on field of approximately 40 V / μ m at a cathode–anode separation distance of 900 nm .
TL;DR: A series of novel and efficient Sr2GdNbO6 (SGNO):Mn4+ red phosphors were synthesized by traditional high-temperature solid-state method as discussed by the authors.
TL;DR: In this article, the authors employed an Au layer to coat CNT cathodes with capability to precisely control the coated film thickness and systematically investigated the film thickness effect on field emission properties of the CNT composite field-emission devices.
TL;DR: The results indicate that FEG-based ultrafast electron sources may enable high-performance analytical UTEM and use a nanosecond laser to show that the laser-driven FEG can support high-quality TEM imaging and electron holography when using a stroboscopic configuration.
TL;DR: In this article, the field emission properties of 3-nm and 10-nm decorated vertically aligned carbon nanotubes (VACNTs) grown on Si substrate before and after oxidation are investigated.
TL;DR: In this article, NiO-SnO2 nano-ceramic matrix was synthesized via a solgel auto-combustion technique with a perspective to investigate its noteworthy electric field emission and temperature-induced conduction anomaly.
Abstract: Microstructural NiO–SnO2 nano-ceramic matrix was synthesized via a solgel auto-combustion technique with a perspective to investigate its noteworthy electric field emission and temperature-induced conduction anomaly. Exceptional field emission performance of nickel-tin oxide composites was discovered with a low turn-on field of 3.9 V/μm and a threshold field of 5.30 V/μm with a good field emission current density of 110.44 μA/cm2 and current stability. Density functional theory was employed to estimate its local work function (Φ) 3.365 eV, and the field enhancement factor (β) was obtained as 1570 by Fowler–Nordheim plot. The anomalies in conductivity spectra at 523 K were detected by a number of physical properties measurement including impedance, conductivity, dielectric, and differential scanning calorimetry with thermal expansion. These phenomena can be rationalized in terms strain-dependent thermal hysteresis effects and localized/delocalized e g electron with a transition from inferior conductive linkage [Ni2+–O2−–Ni2+] and [Sn2+/Sn4+–O2−–Sn2+/Sn4+] to higher conductive linkage [Ni2+–Ni3+] and [Sn2+–Sn4+] of coupled NiO–SnO2 matrix. The temperature dependence frequency exponent (n), ln τ, Rg, Rgb, Cg, and Cgb support additionally the conduction anomaly behavior, and the variation of dielectric constant (ɛr) and loss (tan δ) with temperature around 523 K has been explained in terms of the reduction of space charge layers due to reversal movement of delocalized e g electrons from the grain boundary limit. The frequency dispersing impedance, conductivity, and dielectric spectra with elevated temperature were also demonstrated to comprehend its conduction mechanism with theoretical correlation.
Posted Content•
TL;DR: In this article, the field emission measurements from the edges of the MoS$_2$ nanosheets were performed in high vacuum using a tip-shaped anode.
Abstract: Monolayer molybdenum disulfide (MoS$_2$) nanosheets, obtained via chemical vapor deposition onto SiO$_2$/Si substrates, are exploited to fabricate field-effect transistors with n-type conduction, high on/off ratio, steep subthreshold slope and good mobility. The transistor channel conductance increases with the reducing air pressure due to oxygen and water desorption. Local field emission measurements from the edges of the MoS$_2$ nanosheets are performed in high vacuum using a tip-shaped anode. It is demonstrated that the voltage applied to the Si substrate back-gate modulates the field emission current. Such a finding, that we attribute to gate-bias lowering of the MoS$_2$ electron affinity, enables a new field-effect transistor based on field emission.
TL;DR: In this article, ZnO nanorods were synthesized by hydrothermal method and characterized in terms of morphological and structural properties by means of field emission scanning electron micr...
Abstract: In this research, first, ZnO nanorods were synthesized by hydrothermal method and characterized in terms of morphological and structural properties by means of field emission scanning electron micr...
TL;DR: In this article, a nano-manipulated tungsten probe-tip as anode inside the vacuum chamber of a scanning electron microscope was used to investigate the field emission properties of InSb nanowires.
Abstract: InSb nanowire arrays with different geometrical parameters, diameter and pitch, are fabricated by top-down etching process on Si(100) substrates. Field emission properties of InSb nanowires are investigated by using a nano-manipulated tungsten probe-tip as anode inside the vacuum chamber of a scanning electron microscope. Stable field emission current is reported, with a maximum intensity extracted from a single nanowire of about 1$\mu A$, corresponding to a current density as high as 10$^4$ A/cm$^2$. Stability and robustness of nanowire is probed by monitoring field emission current for about three hours. By tuning the cathode-anode separation distance in the range 500nm - 1300nm, the field enhancement factor and the turn-on field exhibit a non-monotonic dependence, with a maximum enhancement $\beta \simeq $ 78 and a minimum turn-on field $E_{ON} \simeq$ 0.033 V/nm for a separation d =900nm. The reduction of spatial separation between nanowires and the increase of diameter cause the reduction of the field emission performance, with reduced field enhancement ($\beta <$ 60) and increased turn-on field ($E_{ON} \simeq $ 0.050 V/nm). Finally, finite element simulation of the electric field distribution in the system demonstrates that emission is limited to an effective area near the border of the nanowire top surface, with annular shape and maximum width of 10 nm.
TL;DR: A hierarchical NiO]-CdO]2 nanocomposite has been synthesized by a sol-gel auto-combustion route and characterized with a view to studying the electric field emission and conduction mechanism therein this paper.
TL;DR: In this article, a reduced graphene oxide- cerium oxide (rGO-CeO2) nanocomposite is prepared by simple hydrothermal method for enhanced charge storage supercapacitor performance.
TL;DR: In this paper, carbon nanotubes (CNTs) were directly grown on copper and nickel foams by chemical vapor deposition (CVD) process, followed by the deposition of reduced graphene oxide (rGO) through dip-coating method.
TL;DR: The results demonstrate that a miniscule leakage current between the gate and the constriction of devices perfectly follows the Fowler-Nordheim model of electron field emission from a metal electrode and injects quasiparticles with energies sufficient to weaken or even suppress superconductivity.
Abstract: In semiconductor electronics, the field-effect refers to the control of electrical conductivity in nanoscale devices, which underpins the field-effect transistor, one of the cornerstones of present-day semiconductor technology. The effect is enabled by the penetration of the electric field far into a weakly doped semiconductor, whose charge density is not sufficient to screen the field. On the contrary, the charge density in metals and superconductors is so large that the field decays exponentially from the surface and can penetrate only a short distance into the material. Hence, the field-effect should not exist in such materials. Nonetheless, recent publications have reported observation of the field-effect in superconductors and proximised normal metal nanodevices. The effect was discovered in gated nanoscale superconducting constrictions as a suppression of the critical current under the application of intense electric field and interpreted in terms of an electric-field induced perturbation propagating inside the superconducting film. Here we show that ours, and previously reported observations, governed by the overheating of the constriction, without recourse to novel physics. The origin of the overheating is a leakage current between the gate and the constriction, which perfectly follows the Fowler-Nordheim model of electron field emission from a metal electrode.c`
04 Nov 2020
TL;DR: In this paper, the authors proposed a transistors based on field emission for the vacuum channel transistors. But the transistors are not suitable for solid-state electro-electromechanical systems.
Abstract: Nanoscale vacuum channel transistors based on field emission have gained attention recently, and device demonstrations using various material systems have been reported. Whereas solid-state electro...
TL;DR: In this paper, the influence of synthesis duration and growth ambient on the surface morphology, crystal structure and band gap of the grown films by using field emission electron microscope (FESEM), high resolution X-ray diffraction (HR-XRD) and ultraviolet-visible spectrophotometer (UV-vis).
TL;DR: In this paper, a comprehensive analytical electron emission model is developed and its implementation in the particle-in-cell 2D3V code SPICE2 is discussed, where the properties of emissive sheaths of present tokamaks, where thermionic emission is strongly suppressed by space-charge effects and by prompt re-deposition, are reviewed for arbitrary magnetic field inclination angles.
Abstract: The accurate description of the emitted current that escapes from hot tungsten surfaces is essential for reliable predictions of the macroscopic deformation due to melt motion induced by fast transient events. A comprehensive analytical electron emission model is developed and its implementation in the particle-in-cell 2D3V code SPICE2 is discussed. The properties of emissive sheaths of present tokamaks, where thermionic emission is strongly suppressed by space-charge effects and by prompt re-deposition, are reviewed for arbitrary magnetic field inclination angles. The unique characteristics of emissive sheaths that emerge during ITER ELMs, where weakly impeded thermionic emission is coupled with field emission and competes with electron-induced emission, are revealed. The first ITER simulations are reported for normal inclinations.
TL;DR: In this paper, an efficient algorithm is described to calculate the spatial dependence of the temperature distribution along a carbon nanotube (CNT) during field emission (FE) by considering the effects of Joule heating and radiative losses from the CNT sidewall and tip.
Abstract: An efficient algorithm is described to calculate the spatial dependence of the temperature distribution along a carbon nanotube (CNT) during field emission (FE). The algorithm considers the effects of Joule heating in the CNT and radiative losses from the CNT sidewall and tip. The CNT emission current density and the rate of heat exchange per unit area at the CNT tip due to either Henderson-cooling or Nottingham-heating effects are calculated using recent analytical expressions derived by Jensen [J. Appl. Phys. 126, 065302 (2019)]. The latter are valid in the thermionic and field emission regimes and in the transition region between these two extremes. The temperature dependence of the electrical resistivity ρ ( T ) and the thermal conductivity κ ( T ) of the CNT is also included in the model. It is shown that replacing ρ ( T ) and κ ( T ) by their spatial averages over the length of the CNT can lead to an overestimate of the value of the external electric field threshold at which thermal runaway of the CNT occurs. These results should be considered when calculating the field emission characteristics of CNT arrays such as from a carbon nanotube fiber whose FE properties are primarily determined by the FE properties of the array of CNTs at the tip of the fiber. Using the new algorithm, the simulation times to calculate the CNT FE characteristics and the spatial temperature distribution are found to be nearly two orders of magnitude faster compared to those required when both the current and energy exchange at the CNT tip are calculated numerically.
TL;DR: This work examined the effect of the acceleration voltage and the use of different detectors on the contrast formation in several types of specimens, focusing on materials formed mainly of carbon and oxygen, with low inherent contrast in the SEM.
TL;DR: This work demonstrates the feasibility of MXene as cold electron source, establishing a preliminary foundation for its applications in field emission-based devices.
Abstract: As a novel class of two-dimensional materials, MXene has provoked tremendous progress for various applications in functional devices. Here, we pioneer a preliminary understanding on the field emission behavior of MXene for the first time. Ti3C2 paper is fabricated by using facile filtration method, and multiple vertical sheets appear on the surface of MXene paper with high electrical conductivity (2.93 × 105 S m-1) and low work function (3.77 eV). The field electron emission performance and electric field distribution on MXene emitters are measured and simulated under planar and standing conditions. Both emitter conditions exhibit stable, uniform electron emission pattern, and the standing emitter achieves high emission current density of 59 mA cm-2 under 7.5 V μm-1. This work demonstrates the feasibility of MXene as cold electron source, establishing a preliminary foundation for its applications in field emission-based devices.