Electron penetration and energy transfer in solid targets

Fitting, H.‐J.; Glaefeke, H.; Wild, Walter J.

doi:10.1002/pssa.2210430119

Cited by 107 publications

(49 citation statements)

References 11 publications

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“…18 -20 based on empirical results of the electron penetration into and through thin films, see "film-bulk method" in Ref. 30. By means of this method the resulting PE current in dependence on the target depth x and the PE initial energie E 0 was found: …”

Section: A Primary Electron (Pe) Scatteringmentioning

confidence: 99%

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Electron beam charging of insulators: A self-consistent flight-drift model

Touzin

Gœuriot

Guerret‐Piécourt

et al. 2006

Journal of Applied Physics

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106

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Electron beam irradiation and the self-consistent charge transport in bulk insulating samples are described by means of a new flight-drift model and an iterative computer simulation. Ballistic secondary electron and hole transport is followed by electron and hole drifts, their possible recombination and/or trapping in shallow and deep traps. The trap capture cross sections are the Poole-Frenkel-type temperature and field dependent. As a main result the spatial distributions of currents j(x,t), charges ρ(x,t), the field F(x,t), and the potential slope V(x,t) are obtained in a self-consistent procedure as well as the time-dependent secondary electron emission rate σ(t) and the surface potential V0(t). For bulk insulating samples the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and σ=1. Especially for low electron beam energies E0<4keV the incorporation of mainly positive charges can be controlled by the potential VG of a vacuum grid in front of the target surface. For high beam energies E0=10, 20, and 30keV high negative surface potentials V0=−4, −14, and −24kV are obtained, respectively. Besides open nonconductive samples also positive ion-covered samples and targets with a conducting and grounded layer (metal or carbon) on the surface have been considered as used in environmental scanning electron microscopy and common SEM in order to prevent charging. Indeed, the potential distributions V(x) are considerably small in magnitude and do not affect the incident electron beam neither by retarding field effects in front of the surface nor within the bulk insulating sample. Thus the spatial scattering and excitation distributions are almost not affected.

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Section: A Primary Electron (Pe) Scatteringmentioning

confidence: 99%

“…(7) and an empirical expressions for dE/dx from Ref. 30, we may write the SE generation rate g SE in SiO 2 and Al 2 O 3 targets in the form of a semi-empirical equation…”

Section: A Primary Electron (Pe) Scatteringmentioning

confidence: 99%

Electron beam charging of insulators: A self-consistent flight-drift model

Touzin

Gœuriot

Guerret‐Piécourt

et al. 2006

Journal of Applied Physics

Self Cite

106

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“…E¼const is nonmonotonic because of the mass thickness-dependent variation of the ratio of the nanoparticle size and the penetration depth L and depth of energy dissipation maximum l of primary electrons (see [17]). It is seen from comparison of Tables 1 and 2 that at the energy E = 25 keV, maximum penetration depth L for films of all mass thicknesses exceeds the average size (diameter) of nanoparticles a that is the whole volume of nanoparticles and i/i 0 > 1 gets excited.…”

Section: Excitation By Fast Electronsmentioning

confidence: 99%

Emission Properties of Metal Nanoparticles

Nepijko¹,

Elmers²,

Schönhense³

2015

Handbook of Nanoparticles

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Nanoparticles emit electrons and photons when they are excited by electron injection via electric current; electromagnetic radiation via microwave fields; laser radiation in infrared, visible and synchrotron (X-ray) ranges; and electron and ion bombardment. In each case, the emission mechanism depends on characteristic length scales of the nanoparticle. If the particle size is commensurate with it or is smaller, a size dependence of emission is observed [1][2][3]. Also, it is interesting that nanoparticles may demonstrate properties absent in bulk material. Electron Emission from Metal Nanoparticles Excitation by Electron InjectionExcitation by electron injection into nanoparticles via electron tunneling (electric current flow through an ensemble of tunnel-coupled metal nanoparticles on a dielectric substrate) is accompanied by electron emission [1][2][3][4]. Electron emission is observed as soon as the conductivity deviates from an ohmic behavior. Corresponding experiments are realized "in situ", e. g., when an ensemble of gold nanoparticles is deposited onto an insulating substrate directly in the column of a transmission electron microscope [5]. The main discussion in the literature concerning the mechanism of electron emission is connected with field emission [6] and electron gas heating [7]. In the first case, it is supposed that an electric field is strongly enhanced near nanoparticles and thus sufficient for field emission because of the small radius of curvature of nanoparticles. In the second case, the electron gas heating results from an attenuation of the electron-phonon interaction in nanoparticles. If the size is much smaller than the electron mean free path, the electrons execute a periodic motion within the particle without volume scattering and are reflected specularly from the boundaries. This oscillation has the frequency o ¼ ). The larger the frequency difference for electron and phonon subsystems, the less they exchange energy with one another. Experimental studies show that the electron-phonon interaction constant observed in ten nanometer-sized gold particles is several orders of magnitude lower than in the case of bulk material [8]. The energy fed into a nanoparticle under current excitation is absorbed by its electron subsystem. If the electron-phonon interaction is sufficiently attenuated, the electron subsystem temperature increases and electrons become heated, whereas the lattice remains relatively cold. The electron emission takes place under such conditions. Electron emission provoked by electron transport has been visualized using emission electron microscopy (EEM) [9][10][11]. Figure 1a-d shows a series of EEM images of a silver nanoparticle film (caesium was used to reduce the work function). The images have been acquired at different voltages applied between the contacts U f = 0 (a), 8 (b), 10 (c), and 11 V (d). The gap with a silver nanoparticle film between the silver contacts is 5 mm. Nanoparticle emissivity considerably differs because of the spread of the particle

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“…More details about the calculation of the normalization constants A and B can be found in Ref. 39 and in our earlier work. 25 In the continuous irradiation mode we consider two additional modifications of the source functions.…”

Section: Charge Injectionmentioning

confidence: 99%

“…Many semi-empirical expressions have been proposed for R with the following general form R(ρ, E 0 ) = CE Γ 0 , where the values for C and Γ vary from study to study. 39,40 The constant C depends on the material and the exponent Γ has been mostly assumed to have a certain material-independent value, although, in some studies Γ has also been considered material-dependent. 41 The exponential expression for R emanates from Bethe's theory for the stopping power of charged particles in matter.…”

Section: -10mentioning

confidence: 99%

A modified and calibrated drift-diffusion-reaction model for time-domain analysis of charging phenomena in electron-beam irradiated insulators

2018

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This paper presents a modified self-consistent drift-diffusion-reaction model suitable for the analysis of electron-beam irradiated insulators at both short and long time scales. A novel boundary condition is employed that takes into account the reverse electron current and a fully dynamic trap-assisted generation-recombination mechanism is implemented. Sensitivity of the model with respect to material parameters is investigated and a calibration procedure is developed that reproduces experimental yield-energy curves for uncharged insulators. Long-time charging and yield variations are analyzed for stationary defocused and focused beams as well as moving beams dynamically scanning composite insulators.

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Electron penetration and energy transfer in solid targets

Cited by 107 publications

References 11 publications

Electron beam charging of insulators: A self-consistent flight-drift model

Electron beam charging of insulators: A self-consistent flight-drift model

Emission Properties of Metal Nanoparticles

A modified and calibrated drift-diffusion-reaction model for time-domain analysis of charging phenomena in electron-beam irradiated insulators

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