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.

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.

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.

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.

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.

scholarly journals Contribution from recoiling atoms in secondary electron emission induced by slow highly charged ions from tungsten surface

2012 ◽  
Vol 30 (4) ◽  
pp. 707-711 ◽  
Author(s):  
Lixia Zeng ◽  
Zhongfeng Xu ◽  
Yongtao Zhao ◽  
Yuyu Wang ◽  
Jianguo Wang ◽  
...  
Keyword(s):  
Electron Emission ◽  
Secondary Electron Emission ◽  
Projectile Energy ◽  
Total Electron Yield ◽  
Projectile Velocity ◽  
Total Electron ◽  
Electron Yield ◽  
Emission Yield ◽  
Tungsten Surface ◽  
Charged Ions

AbstractThe electron emission yield γ induced by Ne2+ and O2+ impacting on a clean tungsten surface has been measured. The range of projectile energy is from 3 keV/u to 14 keV/u. The total electron yield gradually increases with the projectile velocity. It is found simultaneously that the total electron yield for O2+ is larger than the total electron yield for Ne2+, which is opposite to the results for higher projectile velocity. After considering the contribution from recoiling atoms to the energy distribution and electron emission yield, we find that recoiling atoms are of crucial importance in electron emission in our energy range. Thus, the unexpected results in our experiment can be explained successfully.

scholarly journals Charge effect in secondary electron emission from silicon surface induced by slow neon ions

2012 ◽  
Vol 30 (2) ◽  
pp. 319-324 ◽  
Author(s):  
Zhongfeng Xu ◽  
Lixia Zeng ◽  
Yongtao Zhao ◽  
Jianguo Wang ◽  
Yuyu Wang ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Charge State ◽  
Electron Emission ◽  
Secondary Electron Emission ◽  
Normal Incidence ◽  
Total Electron Yield ◽  
Total Electron ◽  
Electron Yield ◽  
Emission Yield ◽  
First Time

AbstractTotal electron emission yield for impact of slow Neq+(q = 2, 4, 6, 8) ions with various kinetic energy under normal incidence on n-type Si has been measured. It is shown that for the same charge state, the total electron yield γ increases linearly as the kinetic energy of projectile at impact increases, up to velocities corresponding to the “classical” threshold. Separation of kinetic electron yield γKE and potential electron yield γPE shows that γPE is proportional to the ion charge state and γKE increases linearly with projectile velocity. Finally, based on “single hole without hopping” hypothesis, the expression of the “CRF” F(q) is given, and the relation between γKE and q is obtained successfully for the first time, which is also a basis for judging whether the “trampoline effect” exists.

AES Investigation of Inhomogenous Metal-Insulator Samples

2005 ◽  
Vol 11 (6) ◽  
pp. 567-571 ◽  
Author(s):  
Gábor Dobos ◽  
György Vida ◽  
Zoltán Tóth ◽  
Katalin Josepovits
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Surface Coverage ◽  
Secondary Electron Emission ◽  
Oxide Thickness ◽  
Primary Electron ◽  
Metal Insulator ◽  
Total Electron ◽  
Emission Yield ◽  
Effect Of Surface

In this article, the secondary electron-emission properties of both vertically and laterally inhomogeneous samples are discussed. To study the effect of surface coverage, the total electron-emission yield of tungsten and niobium samples was measured as a function of primary electron energy and oxide thickness. A method is suggested to avoid charging difficulties during AES measurements of samples that consist of both metal and various insulator parts.

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