Phys.org September 20, 2024
Photons do not carry sufficient momentum to induce indirect optical transitions in semiconducting materials, such as silicon, necessitating the assistance of lattice phonons to conserve momentum. Therefore, silicon is a less attractive material for a wide variety of optoelectronic applications. An international team of ranchers (Russia, Israel, USA – UC Irvine) introduced an alternative strategy to fulfill the momentum-matching requirement in indirect optical transitions. They demonstrated that when confined to scales below ∼3 nm, photons acquired sufficient momentum to allow electronic transitions at the band edge of Si without the assistance of a phonon. Confined photons allowed simultaneous energy and momentum conservation in two-body photon-electron scattering converting silicon into a direct bandgap semiconductor. According to the researchers their work leads to a marked increase in the absorptivity of Si from the UV to the near-IR providing opportunities for more efficient use of indirect semiconductors in photovoltaics, energy conversion, light detection, and emission… read more. TECHNICAL ARTICLE
Graphical abstract. Credit: ACS Nano, XXXX, XXX, XXX-XXX, 22 August 2024