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.

Characterization of Secondary Electron Emission from Materials with Low or Negative Electron Affinity

1998 ◽  
Vol 509 ◽  
Author(s):  
J.E. Yater ◽  
A. Shih
Keyword(s):  
Energy Distribution ◽  
Surface Properties ◽  
Electron Affinity ◽  
Electron Emission ◽  
Secondary Electron ◽  
Surface Composition ◽  
Secondary Electron Emission ◽  
Emission Characteristics ◽  
Negative Electron Affinity ◽  
Diamond Surfaces

AbstractSecondary electron emission spectroscopy is used to examine the emission characteristics of diamond films as a function of the bulk and surface properties. We find significant variation in the secondary electron yields measured from diamond surfaces even when energy distribution measurements indicate that a low or negative electron affinity is present. In particular, we observe that the material properties, such as bulk and surface uniformity, surface composition, and impurity and defect concentrations, have a strong affect on the secondary electron yield measurements. Furthermore, the energy distribution of the emitted electrons is found to vary with adsorbate species. In certain cases, the energy distribution changes with adsorbate coverage even though the measured electron intensity remains unchanged. From an analysis of the data, we identify bulk and surface properties needed to optimize the emission characteristics.

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.

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.

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