UCI主導の研究チームが光の新しい性質を発見(UC Irvine-led research team discovers new property of light)

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2024-05-06 カリフォルニア大学校アーバイン校(UCI)

カリフォルニア大学アーバイン校の化学者が率いる研究チームは、光と物質の相互作用の新たな方法を発見しました。この発見は、太陽光発電システム、発光ダイオード、半導体レーザーなどの技術進歩につながる可能性があります。最近「ACS Nano」誌に発表された論文で、科学者たちは、光子がシリコンのナノメートルスケールの空間に閉じ込められると、固体材料の電子と同様の大きな運動量を得ることができることを明らかにしました。この研究は、光と物質の相互作用に関する理解を深め、化学分析だけでなく構造研究への応用を広げる道を開きます。

<関連情報>

シリコンガラスにおける光子運動量を利用した電子ラマン散乱 Photon-Momentum-Enabled Electronic Raman Scattering in Silicon Glass

Sergey S. Kharintsev, Elina I. Battalova, Aleksey I. Noskov, Jovany Merham, Eric O. Potma, and Dmitry A. Fishman
ACS Nano  Published::March 4, 2024
DOI:https://doi.org/10.1021/acsnano.3c12666

Abstract

UCI主導の研究チームが光の新しい性質を発見(UC Irvine-led research team discovers new property of light)

The nature of enhanced photoemission in disordered and amorphous solids is an intriguing question. A point in case is light emission in porous and nanostructured silicon, a phenomenon that is still not fully understood. In this work, we study structural photoemission in heterogeneous cross-linked silicon glass, a material that represents an intermediate state between the amorphous and crystalline phases, characterized by a narrow distribution of structure sizes. This model system shows a clear dependence of photoemission on size and disorder across a broad range of energies. While phonon-assisted indirect optical transitions are insufficient to describe observable emissions, our experiments suggest these can be understood through electronic Raman scattering instead. This phenomenon, which is not commonly observed in crystalline semiconductors, is driven by structural disorder. We attribute photoemission in this disordered system to the presence of an excess electron density of states within the forbidden gap (Urbach bridge) where electrons occupy trapped states. Transitions from gap states to the conduction band are facilitated through electron–photon momentum matching, which resembles Compton scattering but is observed for visible light and driven by the enhanced momentum of a photon confined within the nanostructured domains. We interpret the light emission in structured silicon glass as resulting from electronic Raman scattering. These findings emphasize the role of photon momentum in the optical response of solids that display disorder on the nanoscale.

1700応用理学一般
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