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Secondary charged particle emissions induced by low-energy ion impact on non-metallic surfaces
https://ir.soken.ac.jp/records/467
https://ir.soken.ac.jp/records/4670d09d1a2-4490-46c6-b249-0fc780c1092d
| 名前 / ファイル | ライセンス | アクション |
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要旨・審査要旨 / Abstract, Screening Result (331.6 kB)
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本文 (8.1 MB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||
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| 公開日 | 2010-02-22 | |||||
| タイトル | ||||||
| タイトル | Secondary charged particle emissions induced by low-energy ion impact on non-metallic surfaces | |||||
| タイトル | ||||||
| タイトル | Secondary charged particle emissions induced by low-energy ion impact on non-metallic surfaces | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_46ec | |||||
| 資源タイプ | thesis | |||||
| 著者名 |
保坂, 一元
× 保坂, 一元 |
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| フリガナ |
ホサカ, カズモト
× ホサカ, カズモト |
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| 著者 |
HOSAKA, Kazumoto
× HOSAKA, Kazumoto |
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| 学位授与機関 | ||||||
| 学位授与機関名 | 総合研究大学院大学 | |||||
| 学位名 | ||||||
| 学位名 | 博士（理学） | |||||
| 学位記番号 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 総研大甲第325号 | |||||
| 研究科 | ||||||
| 値 | 数物科学研究科 | |||||
| 専攻 | ||||||
| 値 | 10 核融合科学専攻 | |||||
| 学位授与年月日 | ||||||
| 学位授与年月日 | 1998-03-24 | |||||
| 学位授与年度 | ||||||
| 値 | 1997 | |||||
| 要旨 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | It is well known that the interactions of energetic particles with solid surfaces lead to the emission of particles such as electrons and target atoms from the target surface. This is usually referred to as the secondary particle emissions. One of the fundamental observations of this phenomenon is the measurement of the secondary particle emission yield, γ, defined as the average number of particles emitted per the incoming particle. There are a lot of experimental as well as theoretical studies on the secondary electron emission yields induced by ion impact on the metal surfaces. Therefore, the relevant mechanisms have been understood reasonably well. However, investigations on the secondary ton emission yields have still been limited.<br /> Furthermore, only a few attempts have been made so far in understanding phenomena under ton impact on the non-metallic surfaces though alkali-halides have been investigated in some details. Therefore, we do not have sufficient understanding in the interaction mechanisms between ions and non-metallic surfaces.<br /> The purpose of the present study is to reveal any difference in the interactions of tons with metal and non-metallic surfaces. Such studies are of great importance not only in basic physics but also in applied fields such as very-large-scale-integrated-circuits (VLSI) technology, fusion plasmas, surface analysis etc.<br /> In the present study, the secondary electron emission yields, γ-, and the secondary positive ion emission yields, γ+, from some non-metallic surfaces induced by low energy ton (0.3〜100 keV H+, 2.5 keV H2+ and 2.5〜150 keV Ar+) impact have been measured using a cylindrical double-wall cup under an ultra high vacuum chamber (〜10-11 Torr) pumped down with the combination of a turbo molecular pump, an ion pump and a titanium sublimation pump with a liquid nitrogen trap. In order to clean the target surfaces they were sputtered with argon ions and also heated with a ceramic heater placed behind the target. An Auger electron spectrometer has been used in order to check the surface cleanness.<br /> It has been found that the observed γ- from the non-metallic surfaces is proportional to the electronic stopping power over the collision energy range investigated. It is noted that similar relations are well known in metal targets. However, the proportional coefficients in γ- are 2-3 times larger than those for metal targets. These results also agree with tendencies for oxygen-covered metal surfaces observed in the present experiment which show that γ- increases as the oxygen coverage increases. We have also observed, for the first time, an interesting phenomenon where the observed γ- strongly depends on the incident ion beam flux and becomes zero above a critical ion flux for SrCeO3 target.<br /> Similarly, we have found that the observed γ+, which has been found to be independent of the incident ion flux investigated, is larger than the results calculated with the TRIM code. It has been found from TRIM code calculations, however, that a significant part of the observed γ+ in proton and hydrogen molecular ion impact are due to the secondary electrons emitted from the wall of the inner cup under impact of the neutral primary particles backscattered from the target surfaces. Nevertheless the observed γ+ from non-metallic targets under argon ion impact is far large, compared with the calculated results. Then it has been found that γ+ induced by argon ion impact on SrCeO3 is proportional not to the nuclear stopping power, but to the electronic stopping power. This result shows that a greater part of these secondary tons are not emitted by physical sputtering. The observed γ+ in 2.5 keV argon ion impact seems to be in reasonable agreement with that extrapolated from the data available which is believed to be due to the Coulomb explosion on the non-metallic surfaces.<br /> Furthermore, in order to identify the mass and energy of the secondary positive ions emitted from targets, two different techniques have been used: One was a collector method using graphite and beryllium sheets which were analyzed with Rutherford backscattering technique using 1.8 MeV helium ions. Another was the mass and energy analysis with a quadrupole mass spectrometer attached with four meshes, to which the retarding voltage was applied for kinetic energy selection.<br /> Both experiments confirm that target elements are emitted as tons (as well as neutrals) by the incident ion impact. Furthermore, the second experiment shows that these emitted tons have large kinetic energy, comparable to the incident ton energy. Such large kinetic energy can be qualitatively understood to be provided probably by the electrostatic potential caused by local charge-accumulation of the incident ions on the non-metallic surfaces due to their high resistivities. This phenomenon can also explain how the observed γ- depends on the incident ion beam fluxes because some fractions of the electrons produced in the target are not able to overcome the Coulomb barrier generated by accumulation of the incident ion charge and cannot be liberated into vacuum.<br /> It is concluded from the present work that the key mechanisms responsible in the secondary particle emissions from the non-metallic surfaces are very different from those in metal targets induced by the energetic ton impact. | |||||
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| 値 | 有 | |||||
