Cathode fall model and current-voltage characteristics of field emission driven direct current microplasmas

2013 ◽  
Vol 20 (11) ◽  
pp. 113505 ◽  
Author(s):  
Ayyaswamy Venkattraman
Keyword(s):  
Field Emission ◽  
Direct Current ◽  
Cathode Fall ◽  
Current Voltage ◽  
Current Voltage Characteristics

ELECTRONIC STRUCTURE AND CONDUCTIVITY OF HYDROCARBON FILMS OBTAINED IN PLASMA DISCHARGES OF TOKAMAK T-10

1970 ◽  
Vol 61 (11) ◽  
Author(s):  
Galina A. Sokolina ◽  
Igor I. Arkhipov ◽  
Nikolay Yu. Svechnikov ◽  
Sergey A. Grashin
Keyword(s):  
Activation Energy ◽  
Electronic Structure ◽  
Temperature Dependence ◽  
Direct Current ◽  
Plasma Discharges ◽  
X Ray ◽  
Hydrocarbon Films ◽  
Direct Current Conductivity ◽  
Current Voltage ◽  
Current Voltage Characteristics

Amorphous hydrocarbon films on silicon substrates obtained in the chamber of tokamak T-10 with space-bounded deuterium plasma by carbon diaphragms were studied. Using the methods of spectrophotometry, ellipsometry, X-ray photoemission spectroscopy and X-ray excited Auger electron spectroscopy, it was established that the refraction and absorption coefficients of films, as well as the parameters of the electronic structure such as the magnitude of the band gap, the fraction of sp2-hybridized carbon and the chemical composition of impurities depend on the characteristics of the discharge in the tokamak. It is shown that the deposited films refer to high-resistance dielectrics, and they can be classified by optical properties as hard or soft amorphous hydrocarbon films, depending on the type of the plasma discharge (pulse working discharge or long-term low-energy cleaning discharge). Wherein, the conductivity of hard films is less than that of soft films, which corresponds to a smaller fraction of sp2-states of carbon in these films and to a higher value of the band gap. The current-voltage characteristics and the temperature dependence of the direct current conductivity of hard and soft films were measured. It was shown that in the temperature range of 293–550 K, the conductivity is determined by the hopping conductivity mechanism over localized states near the Fermi level and the boundaries of the allowed bands. The hopping conductivity mechanism is also indicated by the power law obtained at room temperature at alternating current with a value of a power exponent close to 0.8. The measurement of the current-voltage characteristics and the temperature dependence of the conductivity of hard and soft films showed a significant difference in the activation energy of conductivity and the conductivity at an elevated temperature. The established dependences of the direct current conductivity and the activation energy value of the films on the discharge parameters can be used as diagnostic benchmarks of different types of plasma discharges in a tokamak. Data on the electrical conductivity of the films are analyzed within the framework of the concept of the electronic structure of amorphous non-crystalline materials.  

Field Emission Energy Distribution and Current-Voltage Characteristics Using Single Tip Gated Diodes

1999 ◽  
Vol 558 ◽  
Author(s):  
John M Bernhard ◽  
Ambrosio A. Rouse ◽  
Edward D. Sosa ◽  
Bruce E. Gnade ◽  
David E. Golden ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Data Acquisition ◽  
Work Function ◽  
Field Emission ◽  
Low Cost ◽  
Energy Analyzer ◽  
Flat Surfaces ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Camac Crate

ABSTRACTField emission current-voltage characteristics and simultaneous field emission electron energy distributions have been measured using single tip gate diodes. An energy distribution is generated at each step of a current-voltage characteristic using a compact low-cost simulated hemispherical energy analyzer. A PC programmed with graphics-based data acquisition software is used for data acquisition and control. The PC is connected to a CAMAC crate and a picoammeter through a GPIB interface. The picoammeter measures the current leaving the tip and the field emission electrons are energy analyzed, detected and processed in the CAMAC crate. The CAMAC crate also sends control voltages. to the gate anode and the energy analyzer. This apparatus was used to measure tip work functions and Fowler-Nordheim tip shape parameters for Mo and IrO2 field emission tips. Work function measurements from field emission tips are compared to photoelectric work function measurements from flat surfaces.

Superfast Drift Step Recovery Diodes (DSRDs) and Vacuum Field Emission Diodes Based on 4H-SiC

2013 ◽  
Vol 740-742 ◽  
pp. 1010-1013 ◽  
Author(s):  
Alexey V. Afanasyev ◽  
Boris V. Ivanov ◽  
Vladimir A. Ilyin ◽  
Alexey F. Kardo-Sysoev ◽  
Maria A. Kuznetsova ◽  
...  
Keyword(s):  
Field Emission ◽  
Wide Bandgap ◽  
Voltage Characteristic ◽  
Vacuum Field ◽  
Current Voltage ◽  
Capacitor Voltage ◽  
Current Densities ◽  
Current Voltage Characteristics ◽  
Manufacturing Methods ◽  
Diode Current

This paper presents the results of research and development of two types diode structures based on wide bandgap 4H-SiC: drift step recovery diodes (DSRDs) and field emission diodes (FED). Diodes’ structure and manufacturing methods are reviewed. Diode’s characteristics were obtained (static current-voltage characteristics and capacitor-voltage characteristic, switching properties’ characteristics for DSRDs). Field emission 4H-SiC structures illustrated high (≥102 А/сm2) current densities at electric field intensity of approximately 10V/um. 4H-SiC DSRDs in the generator structure with a single oscillating contour allowed to form sub nanosecond impulses at a load 50 Ohm and 1,5-2kV amplitude for a single diode (current density at V=2kV J= 4•103 А/сm2),what is significantly higher than similar DSRD’s parameters obtained for silicon.

scholarly journals Проверка применимости закона полевой эмиссии к исследованию многоострийных полевых эмиттеров методом анализа степени предэкспоненциального множителя напряжения

2019 ◽  
Vol 45 (18) ◽  
pp. 13
Author(s):  
Е.О. Попов ◽  
А.Г. Колосько ◽  
С.В. Филиппов
Keyword(s):  
Experimental Data ◽  
Carbon Nanotubes ◽  
Statistical Analysis ◽  
Field Emission ◽  
Power Law ◽  
Constant Voltage ◽  
Current Voltage ◽  
Power Law Exponent ◽  
Emission Mode ◽  
Current Voltage Characteristics

A method for testing the compliance of experimental current-voltage characteristics with a cold field emission mode is described. The method is based on the variation of voltage power-law exponent in the semilogarithmic coordinates ln (I/U^k) vs1/U, as well as the statistical analysis of experimental data fluctuations. It is shown that the current-voltage characteristics obtained using the high-voltage fast-scanning technique have a better fit to the field emission law than the characteristics given by a slow scanning with a constant voltage. A multi-tip nanocomposite emitter based on carbon nanotubes was taken as a sample. For processing experimental data, it was proposed to use modified Fowler-Nordheim coordinates with a voltage power-law exponent of 1.24.

Structure and emission properties of structures based on carbon walls and aluminum nitride

2021 ◽  
Author(s):  
S.A. Bagdasaryan ◽  
S.A. Nalimov
Keyword(s):  
Field Emission ◽  
Hexagonal Lattice ◽  
Opal Matrix ◽  
Emission Properties ◽  
Graphene Layers ◽  
Composition And Structure ◽  
Current Voltage ◽  
Aln Film ◽  
Current Voltage Characteristics ◽  
Field Emission Cathodes

To create field emission cathodes (autocathodes) used in the manufacture of displays and other devices, carbon nanowalls (CNW) are promising. The CNW layers are a porous material consisting of curved plates formed by graphene layers. The industrial use of CNW autocathodes is impeded by the heterogeneity and instability of the magnitude and density of the cathode current. To improve the characteristics of autocathodes, an AlN film is formed on the surface of the emitting substance, which also has the property of field emission. CNW was obtained from a gas mixture of H2 and CH4 activated by a dc glow discharge. The CNW layers were deposited on silicon substrates and substrates representing a layered structure made by forming an opal matrix (OM) layer on a Si substrate. AlN films with controlled composition and structure were prepared by RF magnetron reactive sputtering. CNW layers with a thickness of > 4 μm were obtained by successive growth of two CNW layers (Si/CNW/CNW structure). An additional CNW layer was also grown on the surface of the first layer coated with Ni (Si/CNW/Ni/CNW structure). AlN films were grown on a CNW layer (Si/CNW/AlN and Si/OM/Ni/CNW/AlN structures). It is shown that CNW plates are formed from graphene layers partially connected by atomic bonds (up to 30 layers) packed in a hexagonal lattice, and AlN films consisted of amorphous and axially textured crystalline phases. The current-voltage characteristics of the autocathodes were measured in a pulsed mode at a pressure of ~10−3 Pa. The Si/CNW/CNW structures are characterized by a threshold of autoemission of ≤ 3.6 V/μm and a high density of centers of emission. The current-voltage characteristics of the layered structures Si/CNW/AlN, Si/OM/Ni/CNW and Si/OM/Ni/CNW /AlN showed better emission properties compared to the Si/CNW structure. The current-voltage characteristics considered make it possible to predict the structure and composition of the emitting layer to improve the operational characteristics of multilayer autocathodes.

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