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Positronium emission from semiconductors
https://repo.qst.go.jp/records/83287
https://repo.qst.go.jp/records/83287919ca04b-775e-4880-9c25-b9621d4cddae
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2021-09-04 | |||||
| タイトル | ||||||
| タイトル | Positronium emission from semiconductors | |||||
| 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_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Atsuo, Kawasuso
× Atsuo, Kawasuso× 河裾, 厚男× Atsumi, Miyashita× 宮下, 敦巳× Masaki, Maekawa× 前川, 雅樹× 和田, 健× 石田, 明× 長嶋, 泰之× Atsuo, Kawasuso× Atsumi, Miyashita× Masaki, Maekawa |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Positronium is spontaneously emitted from solids, when the formation potential or the work function is negative. So far, positronium emission from solids have been investigated mainly with metals and insulators. The number research on semiconductors is rather limited. It is intriguing to study positronium emission from semiconductors, because semiconductor has intermediate features between metal and insulator, for instance, the band gap and free carrier density. In this presentation, we will report our research about positronium emission from Si, SiC and GaN(0001) surfaces mainly through the positronium time-of-flight spectroscopy. The theoretical positronium formation potentials were also obtained by first-principles calculation. The positronium energy spectra for Al(111) and W(001) rise around the calculated positronium formation potentials. This means that positrons pick up electrons from the top of the occupied state (the Fermi level) as assumed in the calculation of formation potential. Contrarily, the positronium energy spectra for SiC(0001) and Si(111) rise significantly above the calculated positronium formation potentials. Moreover, the spectrum shapes are different from those for Al(111) and W(001). In the calculation of formation potential, the electrons at the top of the valence band are assumed to be picked up by positrons. Therefore, the above experimental results imply that electrons located sufficiently above the valence band top are picked up by positrons. The maximum energies observed for SiC(0001) and Si(111) are separated from their positronium formation potentials approximately by the band gap energies (3.2 eV for SiC, 1.1 eV for Si). Thus, we propose that the conduction electrons also participate in the positronium formation in SiC and Si. In the presentation, we also report the results on GaN and more thorough analyses of positronium energy spectra based on the Monte Carlo simulation. | |||||
| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 12.5th International Workshop on Positron and Positronium Chemistry (PPC 12.5) | |||||
| 発表年月日 | ||||||
| 日付 | 2021-09-03 | |||||
| 日付タイプ | Issued | |||||
