THEORY OF SECONDARY ELECTRON EMISSION; THE MECHANISM OF EXCITATION OF SECONDARY ELECTRONS

1962 ◽  
pp. 78-96
Author(s):  
Dr. H. BRUINING
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Secondary Electrons

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].

scholarly journals The efficiency of secondary electron emission

1933 ◽  
Vol 139 (838) ◽  
pp. 436-447 ◽  
Keyword(s):  
Velocity Distribution ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Inelastic Collisions ◽  
Secondary Beam ◽  
X Rays ◽  
Secondary Electrons ◽  
The Third ◽  
Primary Electrons

The velocity distribution of the secondary electrons produced by bombarding a metallic face with a stream of primary electrons has been a matter of interest ever since the beginning of the study of secondary electron emission. As early as in 1908, Richardson and von Baeyer independently showed that slow moving electrons were copiously reflected from conducting faces. Farnsworth showed that for primary electrons having velocities less than 9 volts, most of the secondary electrons had velocities equal to the primary. As the primary potential was increased, the percentage of the reflected electrons decreased gradually but was appreciable at 110 volts. Davisson and Kunsman obtained reflected electrons even at primary potentials of 1000 and 1500 volts in the cases of some metal faces. At higher potentials we have also the electrons that undergo the Davisson and Germer scattering from the many crystal facets on the bombarded targets. As the potential is increased, the number of electrons with low velocities increases steadily and at large applied potentials, we have a large percentage of these in the secondary beam. These conclusions followed as a result of the work of Farnsworth who studied the distribution of velocities of the secondary electrons by the retarding potential method. He did not actually calculate the energy distribution from his curves but has drawn attention to the above conclusions. A careful investigation of the velocity distribution of the secondary electrons from various conducting faces was made by Rudberg at primary potentials ranging up to about 1000 volts. He adopted a magnetic deflection method similar to the one used in the analysis of the β rays and of the electrons excited by X-rays. The method had indeed been used by previous workers for the study of secondary emission, but Rudberg improved the technique considerably and obtained better focussing conditions. His results suggest that there are three groups of electrons in the secondary beam. The first group contains electrons returning with the same velocity as the primary. In the second group of electrons, we have those which undergo inelastic collisions with the orbital and structure electrons and hence are returned with some loss of energy. Richardson has drawn attention to the well-marked minimum between the two groups in Rudberg’s curves and infers that free electrons are not involved in the collisions. Finally there is the third group which contains the slow secondary electrons. The second and the third groups appear to be definitely connected with each other since they are both predominant at high primary potentials and become negligible at low primary potentials. Richardson suggests that the third group is the result of the excitation accompanying the inelastic collisions.

scholarly journals Total secondary electron emission from polycrystalline Nickel

1930 ◽  
Vol 128 (807) ◽  
pp. 41-56 ◽  
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Considerable Proportion ◽  
Secondary Beam ◽  
X Rays ◽  
Applied Potential ◽  
Polycrystalline Nickel ◽  
Low Velocity ◽  
Secondary Electrons

The importance of secondary electron emission in its relation to the excitation of soft X-rays has been pointed out in a recent paper by Prof. O. W. Richardson. He has shown that at every potential where there is an increased excitation of soft X-rays, there is correspondingly an increase in the emission of secondary electrons, and has discussed at some length the mechanism of the generation of secondary electrons. It was therefore felt that a much clearer idea of the phenomenon of soft X-ray excitation from metallic surfaces could be had by studying the secondary electron emission from polycrystalline and single crystal faces. As early as in 1908 Richardson showed that slowly moving electrons are reflected in considerable proportion from metallic plates. Davisson and Kunsman, in a series of papers commencing from 1921, showed that at low voltages up to about 9 volts most of the secondary electrons were purely reflected electrons with velocities the same as the incident electrons. The percentage of the reflected electrons fell rapidly as the applied potential was increased above 9 volts, while that of low velocity electrons increased steadily. Farnsworth, with improved apparatus, added much valuable information regarding the generation of secondary electrons and the conditions operating in such cases. These observers showed that the total emission of secondary electrons from a metal surface depended on the applied potential, the nature of the surface and the previous heat treatment of the metal. They also found that the ratio of the secondary beam to the primary increases with applied potential and becomes greater than 1 after a certain potential, depending on the nature of the bombarded metal, is reached.

Thickness Dependence in Secondary Electron Emission from Carbon

1975 ◽  
Vol 33 ◽  
pp. 100-101
Author(s):  
D. Voreades
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Secondary Emission ◽  
Secondary Electrons ◽  
Emission Process ◽  
Backscattered Electrons ◽  
Escape Depth ◽  
Mode Of Operation ◽  
Scanning Electron

Secondary electrons are used in making topographical pictures of specimens in the scanning electron microscope. A better understanding of the secondary emission process will contribute in improving the resolution in this mode of operation.Recent experiments have indicated first that the escape depth of secondary electrons is a few atomic layers at the surface of the solid and second that the backscattered electrons are much more efficient in producing secondaries than the incoming ones. The results vary considerably. However, any model that one makes, for example similar to that of Jonker, consistent with these recent experimental results, will have the thickness as an important parameter.

Surface effects in a capacitive argon discharge in the intermediate pressure regime

2021 ◽  
Author(s):  
Jon Tomas Gudmundsson ◽  
Janez Krek ◽  
De-Qi Wen ◽  
Emi Kawamura ◽  
Michael A Lieberman
Keyword(s):  
Excited States ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Plasma Sheath ◽  
Secondary Electrons ◽  
Particle In Cell ◽  
Argon Discharge ◽  
Discharge Operation ◽  
Ion Impact

Abstract One-dimensional particle-in-cell/Monte Carlo collisional (PIC/MCC) simulations are performed on a capacitive 2.54 cm gap, 1.6 Torr argon discharge driven by a sinusoidal rf current density amplitude of 50 A/m2 at 13.56 MHz. The excited argon states (metastable levels, resonance levels, and the 4p manifold) are modeled self-consistently with the particle dynamics as space- and time-varying fluids. Four cases are examined, including and neglecting excited states, and using either a fixed or energy-dependent secondary electron emission yield due to ion and/or neutral impact on the electrodes. The results for all cases show that most of the ionization occurs near the plasma-sheath interfaces, with little ionization within the plasma bulk region. Without excited states, secondary electrons emitted from the electrodes are found to play a strong role in the ionization process. When the excited states, secondary electron emission due to neutral and ion impact on the electrodes are included in the discharge model, the discharge operation transitions from α-mode to γ-mode, in which nearly all the ionization is due to secondary electrons. Excited states are very effective in producing secondary electrons, with approximately 14.7 times the contribution of ion bombardment. Electron impact of ground state argon atoms by secondary electrons contributes about 76 % of the total ionization; primary electrons, about 11 %; metastable Penning ionization, about 13 %; and multi-step ionization, about 0.3 %.

Study of Secondary Electron Emission Depended on Surface Charge of Space Insulator Materials

2014 ◽  
Vol 716-717 ◽  
pp. 137-141
Author(s):  
Na Feng ◽  
De Tian Li ◽  
Sheng Sheng Yang ◽  
Yi Feng Chen ◽  
Dao Tang Tang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Electron Irradiation ◽  
Electron Emission ◽  
Essential Role ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Dielectric Surface ◽  
Electron Bombardment ◽  
Secondary Electrons ◽  
Surface Charging

Secondary electron emission (SEE) processes play an essential role in spacecraft surface charging. It is difficult to study SEE of insulator whose surface cumulates charges by incident electron bombardment because of poor conductivity. This paper investigated the theoretical process of generation, transfer and escape of secondary electrons, and finally the paper presented a mathematical model to calculate the secondary electron emission. We also have improved measurement system to measure total SEE coefficient from dielectric with 1-5 keV electron irradiation which is perfectly fit to mathematical model, and the SEE coefficient with different surface charging is investigated. The results indicate the SEE coefficient decreases with positive charging and increase with negative charging of dielectric surface.

HIGH DENSITY DIAMOND WHISKER FABRICATION AND SUPPRESSION OF SECONDARY ELECTRON EMISSION BY WHISKERS

2002 ◽  
Vol 01 (05n06) ◽  
pp. 431-436
Author(s):  
D. JEON ◽  
S. W. LEE ◽  
Y. J. BAIK
Keyword(s):  
Electron Emission ◽  
Diamond Film ◽  
Secondary Electron ◽  
Metal Clusters ◽  
Secondary Electron Emission ◽  
Narrow Gap ◽  
Secondary Electrons ◽  
Parallel Direction ◽  
Emission Yield ◽  
Primary Electrons

Diamond whiskers were formed by etching diamond thin films using metal clusters as a shadow mask, which were deposited on the diamond film before or during etching. The whiskers were as thin as 100 nm and the density was as high as 1010/ cm 2. The secondary electron emission yield of the diamond whiskers was significantly reduced as compared to the initial diamond film. The decrease in the yield was more significant if the primary electrons were impinged in parallel direction with the whiskers. We suggest that absorption of the secondary electrons in the narrow gap between the whiskers was the reason for the decreased yield.

The interaction of atomic particles with solid surfaces at intermediate energies I. Secondary electron emission

1969 ◽  
Vol 314 (1516) ◽  
pp. 39-51 ◽  
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Molecular Ions ◽  
Solid Surfaces ◽  
Surface Layers ◽  
Secondary Electrons ◽  
Intermediate Energies ◽  
Positive Ions ◽  
The Individual

The electron emission from a number of metal and carbon targets bombarded by various positive ions is measured by a method employing a magnetic field to separate secondary electrons from scattered ions. Molecular ions are shown to produce emission approximately equal to that which would be produced by the individual atoms independently. Accurate measurements have been made of the energy distribution of secondary electrons. These are close to Gaussian. It is concluded that secondary electron emission is confined to the surface layers of the target atoms since no electrons possess energies close to zero.

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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