Broadband photo- and electroluminescence from silicon via momentum-expanded photonic states

Abstract: Silicon's indirect bandgap has long been seen as a limitation, fundamentally restricting its ability to emit light and hindering the development of silicon-based light sources. Here, we present a conceptually new solution to this persistent challenge. We demonstrate ultrabroadband photo- and electroluminescence from silicon, enabled by a novel radiative pathway mediated by momentum-expanded Heisenberg photonic states that bypass phonon-assisted transitions. This mechanism, previously demonstrated using metallic nanoparticles as photon confiners, is now realized in an all-silicon material using embedded sub-1.5 nm silicon nanoparticles to create confined photonic states. The results show excellent agreement with prior studies, confirming that the confinement size, rather than the specific confining material, is the main factor for activating radiative transitions in a momentum-forbidden system. Consistent with the photonic momentum expansion concept, both photo- and electro-driven emissions span the visible and near-infrared spectral ranges, with electroluminescence visible to the naked eye even under ambient daylight conditions. The simplicity and material-agnostic nature of this approach promise compatibility with standard fabrication processes, offering a practical and transformative route toward high-performance, all-silicon light-emitting diodes and laser sources. More generally, these findings reveal the emergence of a new hybrid light-matter regime, photonic Heisenberg matter, where extreme photon confinement directly reshapes the electronic transition landscape.