Femtosecond Laser Induced Metallization in Silicon via Photon Momentum Mediated Band Transition
Abstract
Silicon-based technology has been at the forefront of electronic and photonic research since the dawn of the electronic revolution. However, silicon is fundamentally an indirect-bandgap semiconductor: the conduction band minimum and valence band maximum occur at different points in momentum space, so optical transitions require phonon assistance to conserve crystal momentum. This three-body electron-photon-phonon interaction renders silicon an inefficient material for light-absorbing applications such as solar cells and optoelectronic devices. In this work, we build on an established nanoscale photon-momentum confinement mechanism, which broadens the photon momentum distribution and enables phonon-free absorption in silicon, by subsequently applying a high-intensity femtosecond pulsed excitation that injects hot carriers beyond the Mott density, collapsing the bandgap and inducing a reversible semiconductor-to-metal transition. While nanoscale photon-momentum confinement itself has been previously established, the central contribution of this work is this subsequent, carrier density-driven stage, which drives the momentum-enhanced region into a reversible transient metallic phase. Our simulations report highly negative permittivity, enhanced optical power absorption, a large absorption coefficient, and low skin depth, with carrier densities reaching a notable value, far exceeding the Mott threshold. We have shown carrier driven metallization with stable operation below melting threshold of silicon. These results establish a general mechanism for dynamically inducing metallic states in silicon, offering a potential pathway toward monolithically integrated active photonic components and dynamically reconfigurable electro-optical devices within conventional CMOS platforms.
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BibTeX
@misc{haque2026femtosecond,
title = {{Femtosecond Laser Induced Metallization in Silicon via Photon Momentum Mediated Band Transition}},
author = {Ehatasham Haque and Sunjana Tarannum and Jannatul Shahrin Shoshi and Mahdy Rahman Chowdhury},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.21527},
eprint = {2608.21527},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.21527},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Femtosecond Laser Induced Metallization in Silicon via Photon Momentum Mediated Band Transition
AU - Ehatasham Haque
AU - Sunjana Tarannum
AU - Jannatul Shahrin Shoshi
AU - Mahdy Rahman Chowdhury
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2608.21527
UR - https://arxiv.org/abs/2608.21527
AB - Silicon-based technology has been at the forefront of electronic and photonic research since the dawn of the electronic revolution. However, silicon is fundamentally an indirect-bandgap semiconductor: the conduction band minimum and valence band maximum occur at different points in momentum space, so optical transitions require phonon assistance to conserve crystal momentum. This three-body electron-photon-phonon interaction renders silicon an inefficient material for light-absorbing applications such as solar cells and optoelectronic devices. In this work, we build on an established nanoscale photon-momentum confinement mechanism, which broadens the photon momentum distribution and enables phonon-free absorption in silicon, by subsequently applying a high-intensity femtosecond pulsed excitation that injects hot carriers beyond the Mott density, collapsing the bandgap and inducing a reversible semiconductor-to-metal transition. While nanoscale photon-momentum confinement itself has been previously established, the central contribution of this work is this subsequent, carrier density-driven stage, which drives the momentum-enhanced region into a reversible transient metallic phase. Our simulations report highly negative permittivity, enhanced optical power absorption, a large absorption coefficient, and low skin depth, with carrier densities reaching a notable value, far exceeding the Mott threshold. We have shown carrier driven metallization with stable operation below melting threshold of silicon. These results establish a general mechanism for dynamically inducing metallic states in silicon, offering a potential pathway toward monolithically integrated active photonic components and dynamically reconfigurable electro-optical devices within conventional CMOS platforms.
ER -