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Investigation of Disorder in Mixed Phase, <i>sp</i> <sup>2</sup> – <i>sp</i> <sup>3</sup> Bonded Graphene-Like Nanocarbon
摘要： Disorder in a mixed phase, sp2–sp3 bonded graphene-like nanocarbon (GNC) lattice has been extensively studied for its electronic and field emission properties. Morphological investigations are performed using scanning electron microscopy (SEM) which depicts microstructures comprising of atomically flat terraces (c-planes) with an abundance of edges (ab planes which are orthogonal to c-planes). Scanning tunneling microscopy (STM) is used to observe the atomic structure of basal planes whereas field emission microscopy (FEM) is found to be suitable for resolving nano-topography of edges. STM images revealed the hexagonal and non-hexagonal atomic arrangements in addition to a variety of defect structures. Scanning tunneling spectroscopy is carried out to study the effect of this short-range disorder on the local density of states. Current versus voltage (I–V) characteristics have been recorded at different defect sites and are compared with respect to the extent of the defect. As sharp edges of GNC are expected to be excellent field emitters, because of low work function and high electric field, enhancement in current is observed particularly when applied electric field is along basal planes. Therefore, it is worthwhile to investigate field emission from these samples. The FEM images show a cluster of bright spots at low voltages which later transformed into an array resembling ledges of ab-planes with increasing voltage. Reproducible I–V curves yield linear Fowler-Nordheim plots supporting field emission as the dominant mechanism of electron emission. Turn on field for 10 μA current is estimated to be ～3 V/μm.
关键词： Field Emission Microscopy,Graphene-Like Nanocarbon,Scanning Tunneling Spectroscopy,Scanning Tunneling Microscopy
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission current investigation of p-type and metallized silicon emitters in the frequency domain
摘要： We investigated two different field emitter arrays consisting of 10×10 p-type and 10×10 undoped Au-coated high aspect ratio silicon tips. The I-V characterization of the p-type sample showed a pronounced saturation for voltages higher than 500 V and a maximum emission current of 39 nA. The metallized sample revealed a FN-like emission up to several μA. The metallized and the p-type sample operating below the saturation region showed high current fluctuations of ±16%. Whereas, the metallized sample with current regulation and the p-type sample in the saturation yielded a current stability of ±0.4% and ±0.3%, respectively. Investigations in the frequency domain revealed the for field emission typical 1/f-noise. By operating in the saturation region (p-type sample) or using an emission current regulation (metallized sample) the noise level was reduced by at least 20 dB. Finally, the p-type sample was illuminated by a light emitting diode to increase and modulate the emission current in the saturation region. The emission current was increased by a factor of 3.7 to 145 nA. With this configuration we emulated an unstable emission behavior and evaluated the performance of our emission current regulation circuit.
关键词： field emitter array,current stability,current fluctuation,field emission noise,field emission,silicon tip
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Fluctuations of the emission characteristics of multi-tip field cathodes
摘要： Report presents a complex experimental study of the fluctuations in the emission characteristics of multi-tip field cathodes based on composites "disordered carbon nanotubes in a polymer matrix". The objects of the study: correlation of the glow patterns of the field emission projector with the level of the macroscopic emission current, emission sites activity, distribution of the current load on the emission sites, field enhancement factor of the individual emission sites, dependence of the current-voltage characteristics and effective emission parameters on the voltage and vacuum levels, formation of a calibration grid on the SK-diagram, modeling of the adsorption/desorption processes on the emitter surface.
关键词： emitter surface analysis,field emission images,current fluctuation,nanocomposite,field emission,carbon nanotubes,IVC
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Influence of adsorbates on the performance of a field emitter array in a high voltage triode setup
摘要： The influence of residual gas pressure on the characteristics of black-Silicon field emitter arrays in a high voltage triode setup is investigated. I-V-characteristics at different pressure levels show a decrease of emission current with rising pressure. This can be explained by an increase of the work function and charging of the emitter surface due to adsorbates. The initial characteristics can be restored by heating the FEA up to 110 °C during electron emission. This regeneration procedure enables an extension of the lifetime from about 20 h to 440 h at a residual gas pressure of 10-5 mbar.
关键词： silicon tips,emission current stability,semiconductor field emission,field emitter array
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Stable and low noise field emission from single p-type Si-tips
摘要： Single gated p-type Si-tips with two different tip radii were fabricated. An emission current of 2.40 μA was measured for the sharp-edged tip at a voltage of 170 V. In contrast, a stable and reproducible emission behavior was observed with an increased tip radius resulting in a pronounced saturation region between 90 V and 150 V, but merely an emission current of 0.55 μA at 150 V. More remarkable is the stable emission behavior with fluctuation of ± 4 % during a measurement period of 30 minutes. The integral emission current in a homogeneous tip array (16 emitters) showed nearly the same I-V characteristics compared to the single tip and is therefore, most dominated by only a stable single tip in the array.
关键词： gate-electrode,p-type Si-tips,low current fluctuations,emission stability,field emission
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission patterns from carbon nanotubes calculated by time-dependent density functional theory
摘要： We calculated the field emission patterns of various types of carbon nanotubes (CNTs). Regarding the near field regime, emission patterns of CNTs and hydrogen terminated CNTs (H-CNTs) well corresponds to the atoms located in the tube tip. We also found different focusing features; a focused-type and an unfocused-type. The beams from armchair (5,5) and (6,6) types are focused, while the beam from zigzag (9,0) types are unfocused.
关键词： field emission,carbon nanotubes,emission pattern,time dependent density functional theory,first principle calculation,ab initio calculation
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Structural evolution of polycrystalline tungsten tips with palladium oxide reservoirs
摘要： We present herein a method to prepare thermodynamically stable tungsten (W) nanopyramids. First, the sides of a W needle are coated with a collodion containing powdered palladium oxide. The W needle is subsequently annealed under ultrahigh vacuum to adsorb palladium (Pd) atoms onto the apex of the W needle via surface diffusion and thereby produce a W nanotip coated with a monolayer Pd film. Field ion microscopy reveals that {111} planes of the W nanotip are contracted by faceting the {211} planes surrounding the {111} plane. This structural change is analogous to the formation of three-sided W nanopyramids. The W nanopyramids appear generally the same as the existing nanopyramids. However, as opposed to the existing nanopyramids, the tip of the proposed nanopyramids does not comprise a single atom.
关键词： faceting,nanotip,palladium oxide,field emission,palladium,tungsten,field ion microscopy
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Discrepancies and universality in the fractional reduction of the apex-field enhancement factor considering small clusters of field emitters
摘要： Numerical simulations are important when assessing the many characteristics of field emission related phenomena. In this work, we analyze the fractional change of the apex-Field Enhancement Factor (FEF), ??, from a single emitter, with apex-FEF ??1, and a pair, with apex-FEF ??2. We show, based on finite element technique, that the functional dependence ??(??) (?? corresponding to the distance between the axis of the emitters) obeys a recently proposed power law decay [1], at sufficient large distances in the limit of infinite domain size, which is not observed by using a long time established exponential decay [2] or a more sophisticated fitting formula proposed recently by Harris et al. [3]. This inverse-third power law functional dependence is respected for various systems like infinity arrays and small clusters of emitters with different shapes. Thus, ??? ～ ?????, with ?? = 3, is suggested to be a universal signature of the charge-blunting (CB) effect in small clusters or arrays, at sufficient large distances between emitters with any shape. These results improve the physical understanding of the field electron emission theory to accurately characterize emitters in small clusters or arrays.
关键词： charge-blunting effect,power law decay,apex-Field Enhancement Factor,field emission,numerical simulations
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission from vertically-aligned graphene edges on graphitized pencil lead
摘要： We have already demonstrated that the graphitized mechanical pencil lead show superior field emission features in high emission current regime [1]. In this paper, we present the results of additional detailed analysis of field emission from completely graphitized pencil lead including Raman scattering, FIM/FEM images and energy distributions of emitted electrons as well as field emission characteristics also in low emission current regime. It is concluded again that the fully graphitized pencil lead is promising as low cost but superior field emitters
关键词： graphite,energy distribution,FIM,FEM,vertically-aligned graphene,field emission
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Evidence for single-electron tunneling in electron energy spectra of diamond tip field emitter
摘要： Field emission from microscale diamond tips was studied using electron energy spectroscopy. A processing at high emission currents was applied to modify the atomic surface structure of pristine diamond tips. Subsequently, staircase-like current-voltage characteristics were obtained which are typical for the single-electron tunneling occurring due to the Coulomb blockade effect in emitting carbon nanostructures formed on the surface of the diamond tips. Characteristic electron energy spectra consisted of several peaks, each corresponding to a certain charging state of the emitting nanostructure. The measured spectra were used to determine the parameters of the Coulomb blockade (e.g. charging energy) and reveal peculiar features of single-electron effects in field emission systems.
关键词： electron energy spectroscopy,Coulomb blockade,single-electron tunneling,field emission
更新于2025-09-23 15:21:21