scholarly journals Structural and Secondary Electron Yield Properties of Titanium–Palladium Films with Laser-Treated Copper Substrate for Application in Neutron Generators

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1222
Author(s):  
Yong Gao ◽  
Sheng Wang ◽  
Jie Wang ◽  
Zhiming You ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Substrate Surface ◽  
Secondary Electron Emission ◽  
Copper Substrate ◽  
Film Surface ◽  
Incident Electron Energy ◽  
Secondary Electron Yield ◽  
Electron Yield ◽  
Neutron Generators

Secondary electron emission (SEE) of the oxygen-free high-conductivity copper (OFHC) target surface in neutron generators limits the stability and improvement of the neutron yield. A novel-type target of titanium–palladium films coated on laser-treated OFHC target substrate was proposed and explored in this work to obtain low secondary electron yield (SEY) without introducing any components. The combination of Ti–Pd films and laser-treated OFHC substrate can effectively suppress secondary electron emission and enhance the adsorption ability to hydrogen isotopes with the existence of Pd film. The surface morphologies, surface chemical states, and SEYs of Ti–Pd films with laser-treated OFHC substrate were studied systematically for the first time. The XPS results showed that the laser-treated OFHC substrate surface was basically covered by Pd film. However, the Pd film surface was partially oxidized, with percentages of 21.31 and 10.02% for PdO and PdO2, respectively. The SEYs of Ti–Pd films with laser-treated OFHC substrate were all below 1 within the investigated primary energy range of 100–3000 eV, which would be sufficient for application in neutron generators. Specifically, the maximum SEY (δmax) of laser-treated OFHC substrate coated by Ti–Pd films was 0.87 with corresponding incident electron energy of 400 eV.

Secondary Electron Emission Studies of Diamond Surfaces

1995 ◽  
Vol 416 ◽  
Author(s):  
A. Shih ◽  
J. Yater ◽  
P. Pehrsson ◽  
J. Butler ◽  
C. Hor ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Mean Free Path ◽  
Incident Electron Energy ◽  
Sample Treatment ◽  
High Electron ◽  
Total Electron ◽  
Electron Yield

ABSTRACTDiamond exhibits high secondary-electron yields which vary strongly with sample preparation and sample treatment. In this study, we identify some of the factors that govern the secondary-electron emission yield of diamond. Comparative studies are made with polycrystalline diamond films having different dopants (boron or nitrogen), dopant concentrations and surface conditions (hydrogen-terminated or oxidized). In these studies, the total electron yield as a function of the incident-electron energy and the energy distribution of the secondary emitted electrons are measured. The results show that both electrical conductivity and hydrogen-termination play essential roles in the secondary-electron emission process. For hydrogen-terminated samples, the energy distribution shows a large and narrow peak at the onset of electron emission. The long mean-free path of the secondary electrons and the low or negative electron affinity are essential to the exceedingly high electron yield of diamond.

Secondary Electron Yield Curve for Liquid Water

1999 ◽  
Vol 5 (S2) ◽  
pp. 282-283
Author(s):  
B.L. Thiel ◽  
D.J. Stokes ◽  
D. Phifer
Keyword(s):  
Liquid Water ◽  
Secondary Electron ◽  
Yield Curve ◽  
Secondary Electron Emission ◽  
Biological Tissues ◽  
Incident Electron Energy ◽  
Secondary Electron Yield ◽  
Electron Yield ◽  
Secondary Electron Emission Coefficient ◽  
Environmental Sem

We have measured the secondary electron yield curve for liquid water using an Environmental SEM. The secondary electron emission coefficient, measured as a function of incident electron energy, is important for interpreting contrast in hydrated biological and inorganic specimens. This information is even more critical for water than other materials, as it is a factor of prime importance in understanding radiation damage in biological tissues.[1]These measurements were taken using a Philips XL-30 field emission ,ESEM, and repeated on an Electroscan E3 ESEM, equipped with a CeB6 filament. A specially designed Faraday cup was fashioned from brass and fitted with a removable graphite cup having an inset for a platinum aperture. This assembly was placed into an electrically floating Peltier cooling stage, and connected to a KE Instruments probe current meter.

THEORETICAL RESEARCH OF SECONDARY ELECTRON EMISSION FROM NEGATIVE ELECTRON AFFINITY SEMICONDUCTORS

2019 ◽  
Vol 26 (04) ◽  
pp. 1850181 ◽  
Author(s):  
AI-GEN XIE ◽  
YANG YU ◽  
YA-YI CHEN ◽  
YU-QING XIA ◽  
HAO-YU LIU
Keyword(s):  
Electron Affinity ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Primary Electron ◽  
Theoretical Research ◽  
Negative Electron Affinity ◽  
Secondary Electron Yield ◽  
Electron Yield ◽  
Yield Formula

Based on primary range [Formula: see text], relationships among parameters of secondary electron yield [Formula: see text] and the processes and characteristics of secondary electron emission (SEE) from negative electron affinity (NEA) semiconductors, the universal formulas for [Formula: see text] at [Formula: see text] and at [Formula: see text] for NEA semiconductors were deduced, respectively; where [Formula: see text] is incident energy of primary electron. According to the characteristics of SEE from NEA semiconductors with [Formula: see text], [Formula: see text], deduced universal formulas for [Formula: see text] at [Formula: see text] and at [Formula: see text] for NEA semiconductors and experimental data, special formulas for [Formula: see text] at 0.5[Formula: see text] of several NEA semiconductors with [Formula: see text] were deduced and proved to be true experimentally, respectively; where [Formula: see text] is the [Formula: see text] at which [Formula: see text] reaches maximum secondary electron yield. It can be concluded that the formula for [Formula: see text] of NEA semiconductors with [Formula: see text] was deduced and could be used to calculate [Formula: see text], and that the method of calculating the 1/[Formula: see text] of NEA semiconductors with [Formula: see text] is plausible; where [Formula: see text] is the probability that an internal secondary electron escapes into vacuum upon reaching the surface of emitter, and 1/[Formula: see text] is mean escape depth of secondary electron.

MAXIMUM SECONDARY ELECTRON YIELD AND PARAMETERS OF SECONDARY ELECTRON YIELD OF METALS

2016 ◽  
Vol 23 (05) ◽  
pp. 1650039 ◽  
Author(s):  
AI-GEN XIE ◽  
HAN-SUP UHM ◽  
YUN-YUN CHEN ◽  
EUN-HA CHOI
Keyword(s):  
Energy Range ◽  
Electron Emission ◽  
Energy Band ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Average Energy ◽  
Surface Barrier ◽  
Secondary Electrons ◽  
Secondary Electron Yield ◽  
Electron Yield

On the basis of the free-electron model, the energy range of internal secondary electrons, the energy band of a metal, the formula for inelastic mean escape depth, the processes and characteristics of secondary electron emission, the probability of internal secondary electrons reaching surface and passing over the surface barrier into vacuum B as a function of original work function [Formula: see text] and the distance from Fermi energy to the bottom of the conduction band [Formula: see text] was deduced. According to the characteristics of creation of an excited electron, the definition of average energy required to produce an internal secondary electron [Formula: see text], the energy range of excited electrons and internal secondary electrons and the energy band of a metal, the formula for expressing [Formula: see text] using the number of valence electron of the atom V, [Formula: see text] and atomic number Z was obtained. Based on the processes and characteristics of secondary electron emission, several relationships among the parameters of the secondary electron emission and the deduced formulae for B and [Formula: see text], the formula for expressing maximum secondary electron yield of metals [Formula: see text] using Z, V, back-scattering coefficient r, incident energy of primary electron at which secondary electron yield reaches [Formula: see text], [Formula: see text] and [Formula: see text] was deduced and demonstrated to be true. According to the deduced formula for [Formula: see text] and the relationships among [Formula: see text] and several parameters of secondary electron emitter, it can be concluded that high [Formula: see text] values are linked to high V, Z and [Formula: see text] values, and vice versa. Based on the processes and characteristics of secondary electron emission and the deduced formulae for the B, [Formula: see text] and [Formula: see text], the influences of surface properties on [Formula: see text] were discussed.

Formulae for low-energy secondary electron yield from different kinds of emitters as a function of measurable variables

2017 ◽  
Vol 31 (10) ◽  
pp. 1750105 ◽  
Author(s):  
Ai-Gen Xie ◽  
Kun Zhon ◽  
De-Lin Zhao ◽  
Yu-Qing Xia
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Primary Electron ◽  
Low Energy ◽  
Secondary Electron Yield ◽  
Universal Formula ◽  
Electron Yield ◽  
Energy Formula ◽  
Yield Formula

Based on the characteristics of secondary electron emission and the relationships among parameters of secondary electron yield [Formula: see text] in the low-energy range of [Formula: see text] eV (low-energy [Formula: see text]), the universal formula for low-energy [Formula: see text] as a function of [Formula: see text], [Formula: see text] and maximum [Formula: see text] was deduced, where [Formula: see text] and [Formula: see text] are the incident energies of primary electron and of [Formula: see text], respectively. From the deduced universal formula and experimental low-energy [Formula: see text] from metals, semiconductors and insulators, special formula for low-energy [Formula: see text] from metals as a function of [Formula: see text], [Formula: see text] and [Formula: see text] and that for low-energy [Formula: see text] from semiconductors and insulators as a function of [Formula: see text], [Formula: see text] and [Formula: see text] were deduced, respectively. The results were analyzed, it can be concluded that the two deduced special formulae can be used to calculate low-energy [Formula: see text] from metals, semiconductors and insulators, respectively.

Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

1990 ◽  
Vol 48 (1) ◽  
pp. 422-423
Author(s):  
John C. Russ
Keyword(s):  
Monte Carlo ◽  
Energy Loss ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Analytical Calculation ◽  
Mean Free Path ◽  
Single Scattering ◽  
High Energy ◽  
Secondary Electron Yield ◽  
Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

Effect of TiO2 Addition on the Secondary Electron Emission and Discharge Properties of MgO Protective Layer

2000 ◽  
Vol 621 ◽  
Author(s):  
Younghyun Kim ◽  
Rakhwan Kim ◽  
Hee Jae Kim ◽  
Hyeongtag Jeon ◽  
Jong-Wan Park
Keyword(s):  
Band Structure ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Film Surface ◽  
Protective Layer ◽  
Discharge Voltage ◽  
Plasma Display Panel ◽  
Plasma Display ◽  
Deposited Films

ABSTRACTSecondary electron emission from a cathode material in AC PDP (Plasma Display Panel) is dominated by potential emission mechanism, which is sensitive to band structure of a protective layer. Therefore, the secondary electron emission property can be modified by a change in the energy band structure of the protective layer. Mg2-2xTixO2 films were prepared by e-beam evaporation method to be used as possible substitutes for the conventional MgO protective layer. The oxygen content in the films and in turn, the ratio of metal to oxygen gradually increased with the increasing TiO2 content in the starting materials. The pure MgO films exhibited the crystallinity with strong (111) orientation. The Mg2-2xTixO2 films, however, had the crystallinity with (311) preferred orientation. The stress relaxation, when the [TiO2/(MgO+TiO2)] ratio in the evaporation starting materials was 0.15, seems to be related to inhomogeneous film surface due to an excessive addition of TiO2 to MgO. When the [TiO2/(MgO+TiO2)] ratios of 0.1 and 0.15 were used, the deposited films exhibited the secondary electron emission yields improved by 50% compared to that of the conventional MgO protective layer, which resulted in reduction in discharge voltage by 12%.

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