scholarly journals The Design of the Emission Layer for Electron Multipliers

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yuman Wang ◽  
Baojun Yan ◽  
Kaile Wen ◽  
Shulin Liu ◽  
Ming Qi ◽  
...  
Keyword(s):  
Secondary Electron Emission ◽  
Protective Layer ◽  
Atomic Layer ◽  
Low Energy ◽  
Main Body ◽  
Empirical Formulas ◽  
Emission Layer ◽  
Spherical System ◽  
Electron Multiplier ◽  
Separate Electron

AbstractThe electron multipliers gain is closely related to the secondary electron emission coefficient (SEE) of the emission layer materials. The SEE is closely related to the thickness of the emission layer. If the emission layer is thin, the low SEE causes the low gain of electron multipliers. If the emission layer is thick, the conductive layer can't timely supplement charge to the emission layer, the electronic amplifier gain is low too. The electron multipliers usually choose Al2O3 and MgO film as the emission layer because of the high SEE level. MgO easy deliquescence into Mg(OH)2 Mg2(OH)2CO3 and MgCO3 resulting in the lower SEE level. The SEE level of Al2O3 is lower than MgO, but Al2O3 is stable. We designed a spherical system for testing the SEE level of materials, and proposed to use low-energy secondary electrons instead of low-energy electron beam for neutralization to measuring the SEE level of Al2O3, MgO, MgO/Al2O3, Al2O3/MgO, and precisely control the film thickness by using atomic layer deposition. We propose to compare the SEE under the adjacent incident electrons energy to partition the SEE value of the material, and obtain four empirical formulas for the relationship between SEE and thickness. Since the main materials that cause the decrease in SEE are Mg2(OH)2CO3 and MgCO3, we use the C element atomic concentration measured by XPS to study the deliquescent depth of the material. We propose to use the concept of transition layer for SEE interpretation of multilayer materials. Through experiments and calculations, we put forward a new emission layer for electron multipliers, including 2–3 nm Al2O3 buffer layer, 5–9 nm MgO main-body layer, 1 nm Al2O3 protective layer or 0.3 nm Al2O3 enhancement layer. We prepared this emission layer to microchannel plate (MCP), which significantly improved the gain of MCP. We can also apply this new emission layer to channel electron multiplier and separate electron multiplier.

scholarly journals The Design of the Emission Layer for Electron Multipliers

2021 ◽  
Author(s):  
Yuman Wang ◽  
Baojun Yan ◽  
Kaile Wen ◽  
Shulin Liu ◽  
Ming Qi ◽  
...  
Keyword(s):  
Secondary Electron Emission ◽  
Protective Layer ◽  
Atomic Layer ◽  
Main Body ◽  
Emission Layer ◽  
Spherical System ◽  
Electron Multiplier ◽  
Secondary Electron Emission Coefficient ◽  
Separate Electron ◽  
Amplifier Gain

Abstract The electron multipliers gain is closely related to the secondary electron emission coefficient (SEE) of the emission layer materials. The SEE is closely related to the thickness of the emission layer. If the emission layer is thin, the low SEE causes the low gain of electron multipliers. If the emission layer is thick, the conductive layer can't timely supplement charge to the emission layer, the electronic amplifier gain is low too. The electron multipliers usually choose Al2O3 and MgO film as the emission layer because of the high SEE level. MgO easy deliquescence into Mg(OH)2 resulting in the lower SEE level. The SEE level of Al2O3 is lower than MgO, but Al2O3 is stable. We designed a spherical system for testing the SEE level of materials, and proposed to use lowenergy secondary electrons instead of low-energy electron beam for neutralization to measuring the SEE level of Al2O3, MgO, MgO/Al2O3, Al2O3/MgO, and precisely control the film thickness by using atomic layer deposition (ALD). We propose to compare the SEE under the adjacent incident electrons energy to partition the SEE value of the material, and obtain four empirical formula for the relationship between SEE and thickness. Through experiments and calculations, we put forward a new emission layer for electron multipliers, including 2~3 nm Al2O3 buffer layer, 9nm MgO main-body layer, 1nm protective layer or 0.3nm enhancement layer. We can apply this new emission layer to channel electron multiplier (CEM), microchannel plate (MCP), separate electron multiplier.

scholarly journals Evolvement Investigation of Secondary Electron Emission for Ultrathin MgO Coatings Prepared by Atomic Layer Deposition

2021 ◽  
Vol 11 (11) ◽  
pp. 4801
Author(s):  
Xiangping Zhu ◽  
Junjiang Guo ◽  
Xiangxin Li ◽  
Rundong Zhou ◽  
Dan Wang ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Coating Thickness ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Atomic Layer ◽  
Emission Layer ◽  
Layer Deposition ◽  
20 Nm ◽  
Semi Empirical

MgO is a kind of high secondary electron yield (SEY) material with important applications in electron multipliers. MgO coatings can be used as the electron emission layer for multiplier dynode to improve the electron gain significantly. However, the SEY investigation on ultrathin MgO coatings is not complete and needed to be supplemented urgently. In this work, a series of MgO coatings with increasing thickness were prepared by atomic layer deposition. SEY properties and energy spectra were characterized, and the effect of coating thickness on SEY was systematically analyzed. Experimental results show that SEY of MgO/Si samples rises as the coating thickness increases. Merely, SEY almost does not change with the coating thickness when the thickness exceeds 30 nm. Then, a SEY semi-empirical theory was employed to interpret the SEY regularities of MgO coatings by regarding the coating samples as ideal double-layer structures. Theoretical calculation quantitatively explained the SEY variation observed during the experiments, and further quantified the SEY contribution level of top coating and bottom substrate for the 1 nm and 20 nm MgO coatings. The work is of great significance for comprehending the SEY of ultrathin MgO coatings and expanding the applications of nanoscale coatings with high SEY.

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

1978 ◽  
Vol 36 (1) ◽  
pp. 524-525
Author(s):  
T. Koshikawa ◽  
Y. Fujii ◽  
E. Sugata ◽  
F. Kanematsu
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Life Time ◽  
Activation Process ◽  
Beam Diameter ◽  
Activation Temperature ◽  
Electron Multiplier ◽  
Activation Condition ◽  
Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

scholarly journals Secondary electron emission characteristics of Al2O3 coatings prepared by atomic layer deposition

AIP Advances ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 095303 ◽  
Author(s):  
Junjiang Guo ◽  
Dan Wang ◽  
Yantao Xu ◽  
Xiangping Zhu ◽  
Kaile Wen ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Atomic Layer ◽  
Emission Characteristics ◽  
Layer Deposition

Atomic Layer Deposition of a Nanometer-Thick Li3PO4 Protective Layer on LiNi0.5Mn1.5O4 Films: Dream or Reality for Long-Term Cycling?

2021 ◽  
Vol 13 (13) ◽  
pp. 15761-15773
Author(s):  
Maxime Hallot ◽  
Borja Caja-Munoz ◽  
Clement Leviel ◽  
Oleg I. Lebedev ◽  
Richard Retoux ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Protective Layer ◽  
Atomic Layer ◽  
Layer Deposition

CHEMICAL RECONSTRUCTION OF THE TiAl(010) SURFACE

1995 ◽  
Vol 02 (02) ◽  
pp. 183-189 ◽  
Author(s):  
C.P. WANG ◽  
S.K. KIM ◽  
F. JONA ◽  
D.R. STRONGIN ◽  
B.-R. SHEU ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Atomic Structure ◽  
Atomic Layer ◽  
Interlayer Spacing ◽  
Low Energy ◽  
Intensity Analysis ◽  
Low Energy Electron Diffraction ◽  
Surface Phases ◽  
Low Energy Electron ◽  
Bulk Structure

The atomic structure of a clean (010) surface of the ordered binary alloy TiAl (with tetragonal bulk structure of the CuAu I type) is studied with quantitative low-energy electron diffraction (QLEED). Two different surface phases are found depending on the preparation procedure. After a cleaning step in vacuo by means of Ar-ion bombardments, anneals at 750−850°C produce a 2×1 surface and anneals at about 900° C produce a 1×1 surface. A QLEED intensity analysis of the 1×1 structure reveals the occurrence of chemical reconstruction, whereby the Ti atoms in the first layer exchange places with the Al atoms in the second layer. Thus, while any bulk (010) plane contains 50% Al and 50% Ti , the top atomic layer of a (010) surface contains 100% Al and the second atomic layer contains 100% Ti . Both layers are slightly buckled and the first interlayer distance is compressed about 7.1% while the second interlayer spacing is expanded about 7.4% with respect to the bulk value.

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%.

Sign in / Sign up

Export Citation Format

Share Document