Photoluminescence of Porous Silicon

Gelloz, Bernard

doi:10.1007/978-3-319-04508-5_32-1

Cited by 1 publication

(1 citation statement)

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“…3 An important challenge in photonics is to forge direct absorption and emission channels in Si throughout the visible and near-infrared range. 4,5 Tunable visible photoluminescence (PL) in porous silicon (p-Si) emerged in the early 1990s and presented exciting prospects for light-emitting silicon devices. 6−10 Nonetheless, despite impressive advances ever since, the origin of PL in Si remains a subject of debate.…”

Section: Introductionmentioning

confidence: 99%

Photon-Momentum-Enabled Electronic Raman Scattering in Silicon Glass

Kharintsev,

Battalova,

Noskov

et al. 2024

ACS Nano

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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.

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Section: Introductionmentioning

confidence: 99%