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.

THE FORMULAE FOR PARAMETERS OF THE SECONDARY ELECTRON YIELD OF INSULATORS FROM 10 keV TO 30 keV

2013 ◽  
Vol 27 (32) ◽  
pp. 1350238 ◽  
Author(s):  
AI-GEN XIE ◽  
QING-FANG LI ◽  
YUN-YUN CHEN ◽  
HONG-YAN WU
Keyword(s):  
Energy Band ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Average Energy ◽  
Surface Barrier ◽  
Secondary Electrons ◽  
Secondary Electron Yield ◽  
Electron Yield ◽  
Mean Escape Depth ◽  
Primary Electrons

Based on the formula for the average energy required to produce an internal secondary electron (ε) in emitter, the energy band of insulator and the assumption that the maximum exit energy of secondary electron in insulator is reverse to the width of forbidden band, the formula for ε in insulator is deduced. On the basis of the formula for the number of internal secondary electrons produced in the direction of the velocity of primary electrons per unit path length, the energy band of insulator and the characteristic of secondary electron emission, the formula for the probability of secondary electrons passing over the surface barrier of insulator into the vacuum (B) is also deduced. According to some relationship between the parameters of secondary electron yield from insulator, the formula for the mean escape depth (1/α) is successfully deduced. The formulae for ε and 1/α are experimentally proven, respectively, and thereafter the formula for B is indirectly proven to be true by the experimental results. It is concluded that the formulae for ε, B and 1/α are universal to estimate ε, B and 1/α under the condition that primary electrons from 10 keV to 30 keV hit on an insulator, respectively.

FORMULA FOR MAXIMUM SECONDARY ELECTRON YIELD FROM METALS

2015 ◽  
Vol 22 (02) ◽  
pp. 1550019 ◽  
Author(s):  
AI-GEN XIE ◽  
LING WANG ◽  
LIU-HUA MU
Keyword(s):  
Alkali Metals ◽  
Secondary Electron ◽  
Empirical Relation ◽  
Secondary Electron Emission ◽  
Mean Value ◽  
Primary Electron ◽  
Electron Model ◽  
Secondary Electrons ◽  
Secondary Electron Yield ◽  
Electron Yield

Based on free-electron model, the calculated inelastic mean escape depth of secondary electrons, experimental one, the energy band of metal, the characteristics and processes of secondary electron emission, maximum number of secondary electrons released per primary electron δ(Φ,EF)PEm as a function of parameter Km, work function Φ and Fermi energy EF was deduced, where Km is a constant for a given metal in the energy range 100–800 eV. According to the relationship between maximum secondary electron yield from metal δ(Φ,EF)m and δ(Φ,EF)PEm, the formula for δ(Φ,EF)m as a function of atomic number Z, parameter Km, Φ and EF was deduced. Using the deduced formula for δ(Φ,EF)m, Z, experimental δ(Φ,EF)m, Φ and EF, Km relative to alkali metals, Km relative to earth-alkali metals and the mean value of Km were computed, respectively. And the formulae for maximum secondary electron yield from alkali metals, earth-alkali metals and metals were obtained and proved to be true, respectively. On the basis of the deduced formula for δ(Φ,EF)m and the empirical relation that high Φ are connected with high EF, it can be concluded that high δ(Φ,EF)m are connected with high Φ and vice versa.

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.

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.

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.

MAXIMUM SECONDARY ELECTRON YIELDS FROM SEMICONDUCTORS AND INSULATORS

2016 ◽  
Vol 24 (04) ◽  
pp. 1750045 ◽  
Author(s):  
A. G. XIE ◽  
Z. H. LIU ◽  
Y. Q. XIA ◽  
M. M. ZHU
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Maximum Yield ◽  
Secondary Electron Emission ◽  
High Energy ◽  
Secondary Electrons ◽  
Backscattered Electrons ◽  
Universal Formula ◽  
Yield Formula ◽  
Primary Electrons

Based on the processes and characteristics of secondary electron emission and the formula for the yield due to primary electrons hitting on semiconductors and insulators, the universal formula for maximum yield [Formula: see text] due to primary electrons hitting on semiconductors and insulators was deduced, where [Formula: see text] is the maximum ratio of the number of secondary electrons produced by primary electrons to the number of primary electrons. On the basis of the formulae for primary range in different energy ranges of [Formula: see text], characteristics of secondary electron emission and the deduced universal formula for [Formula: see text], the formulae for [Formula: see text] in different energy ranges of [Formula: see text] were deduced, where [Formula: see text] is the primary incident energy at which secondary electron yields from semiconductors and insulators, [Formula: see text], are maximized to maximum secondary electron yields from semiconductors and insulators, [Formula: see text]; and [Formula: see text] is the maximum ratio of the number of total secondary electrons produced by primary electrons and backscattered electrons to the number of primary electrons. According to the deduced formulae for [Formula: see text], the relationship among [Formula: see text], [Formula: see text] and high-energy back-scattering coefficient [Formula: see text], the formulae for parameters of [Formula: see text] and the experimental data as well as the formulae for [Formula: see text] in different energy ranges of [Formula: see text] as a function of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] were deduced, where [Formula: see text] and [Formula: see text] are the original electron affinity and the width of forbidden band, respectively. The scattering of [Formula: see text] was analyzed, and calculated [Formula: see text] values were compared with the values measured experimentally. It was concluded that the deduced formulae for [Formula: see text] were found to be universal for [Formula: see text].

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