Secondary electron emission studies on MgO films

Ushio, Yoshijiro; Banno, Taisuke; Matuda, Namio; Saitō, Yoshio; Baba, Shigeru; Kinbara, Akira

doi:10.1016/0040-6090(88)90507-x

Cited by 45 publications

(12 citation statements)

References 20 publications

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“…Our results are in fair agreement with previous results concerning: the shift of E pmax between massive and supported layers samples, from 500 to 400 eV for SiO 2 9 and from 1 keV to 600 eV for MgO; 10 and the different trapping rates that exist between MgO and SiO 2 oxides, linked to the defect concentration.…”

Section: Test Conditionssupporting

confidence: 95%

Charge trapping characterization in the thin oxide layer/non‐conductive substrate system

Liebault

Moya-Siesse

Bernardini

et al. 2002

Surface & Interface Analysis

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The Trapping properties of a thin oxide layer deposited on a non-conductive substrate are investigated. This study is based on the charge trapping behaviour of defects, depending on their nature and their distribution.The injection of charges is made by means of the electron beam of a scanning electron microscope that exhibits a primary electron energy in the range 300-40 000 eV. Charge trapping characteristics are obtained by using the induced current method, which consists of measuring the evolution of the absorbed current induced by trapped charges in the metallic sample holder during the injection of charges. This method gives not only a quantitative determination of the amount of trapped charges but also the kinetics of charging.In order to characterize the role of the interface (thin oxide /substrate), several tests are performed with various primary energies allowing the oxide, the interface and the substrate to be explored successively, because an increasing primary electron energy corresponds to an increasing penetration depth. As an example, MgO/glass and MgO/enamel systems are investigated. Comparison between these different charging kinetics leads to a better understanding of the effect of the interface on the trapping properties of such systems.

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Section: Test Conditionssupporting

confidence: 95%

Charge trapping characterization in the thin oxide layer/non‐conductive substrate system

Liebault

Moya-Siesse

Bernardini

et al. 2002

Surface & Interface Analysis

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“…on the yield curves. As it has been also pointed out for MgO [10], the excellent agreement between the experiments and a very naive theory is very surprising. A priori, the use of a spatial attenuation function of the form:…”

Section: Resultsmentioning

confidence: 90%

About the Secondary Electron Emission Yield, δ, from e−-Irradiated Insulators

Cazaux

2000

Mikrochim Acta

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To account for the published yield curves, f (E 0 ), of some insulators such as diamond, an elementary theory of secondary electron emission (s.e.e) is used. This theory permits the estimation of the effective attenuation lengths of the emitted electrons during their transport and to explain the signi®-cant differences between the s.e.e. from metals and that from insulators. Some practical consequences related for instance to the lack of topographic contrast in LVSEM and to charging mechanisms in electron beam techniques are then deduced.The secondary electron emission yield is an important parameter of electron/solid interactions. In contrast to the metal case, its maximum value for insulators is far larger than the unity but it is a function of the crystalline state of the specimen, of its bias and of the irradiation conditions. Based on the use of a very simple semi-empirical equation, this paper is an attempt to account for the role of the various parameters involved in the s.e.e. yield of insulators. Practical consequences on the contrast of images in SEM and on charging mechanisms in e À irradiated insulators are also deduced. The One-Dimensional Constant-Loss Theory of s.e.e. This elementary theory, developed by Salow [1], Bruining [2] Dione [3] and many others [4 ± 6], is based on the fact that the average number of secondaries, n(z, E 0 ), produced per incident primary in a layer of thickness dz at the depth z below the surface is given by:where E(e.h) is the energy required to excite one secondary electron inside the solid (electron/hole pair generation) and R is the range of the incident electron of primary energy E 0 . The last identity in Eq. (1) is the result of approximating the stopping power to the ratio of the incident electron energy E 0 and the electron range. Assuming a one dimensional exponential attenuation for the transport of the secondaries towards the surface, f a 1/2 exp Àz/!, the equation obtained for , is:where B is the escape probability (into the vacuum); ! is an effective attenuation length and the geometrical factor 1/2, represents the fraction of the generated secondaries moving towards the surface. Next, the range could be approximated by a power law of the form:R C E n 0 3 with n 1.35 (for the energy range of interest, here) and with the material constant C given by 2.6Á10 2 (A/&Z ) where R is in mm E 0 in keV and & in g/cm 3 , A and Z are the mean atomic mass and atomic number respect [3 ± 5]. Finally, it is easy to compare the experimental results obtained from the use of short pulse excitations (to prevent charging effects) and the above simple Mikrochim. Acta 132, 173±177 (2000)

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“…For ionic insulators, of large ionization energy I (sum of bandgap E g and electron affinity A), Auger neutralization cannot occur for incident ions like Na + that have a neutralization energy E n < 2I + ε, where ε is the interaction energy between the final two holes in the valence band. Surprisingly, the yield of electrons from these ionic solids induced by slow ions has been found to be larger than for metals, [2][3][4][5] even though in metals less energy is required to remove an electron (the work function). In addition, electron emission from ionic insulators has been observed at impact energies below 100 eV, [4][5][6][7][8] in contrast to electron emission from metals, which is strongly reduced for impact energies below 0.5 -2 keV.…”

Section: Introductionmentioning

confidence: 99%