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 […]
Tag Archives: Silicon
Physicists discover a new optical property that measures the twist in tiny helicesÂ
Phys.org June 17, 2024 Biomimetic nanotechnology and self-assembly advances need chirality. There is a need to develop general methods to characterize chiral building blocks at the nanoscale in liquids such as water. An international team of researchers (UK, Italy, USA – University of Nebraska, Pennsylvania State University) observed chiroptical second-harmonic Tyndall scattering effect in high-refractive-index dielectric nanomaterial Si nanohelices. They provided a theoretical analysis that explained the origin of the effect and its direction dependence, resulting from different specific contributions of “electric dipole–magnetic dipole” and “electric dipole–electric quadrupole” coupling tensors. They narrowed down the number of such terms to 8 […]
Research team discovers new property of light
Phys.org May 7, 2024 The nature of enhanced photoemission in disordered and amorphous solids is an intriguing question. An international team of researchers (Russia, USA – UC Irvine) studied 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. The model system showed 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, their experiments suggested these could be understood through electronic Raman scattering. They attributed […]
Surprisingly strong and deformable silicon
EurekAlert June 10, 2020 Silicon is very brittle which can become a problem when trying to make MEMS from silicon, such as the acceleration sensors in smartphones. Researchers in Switzerland have demonstrated that Si processed by modern lithography procedures exhibits an ultrahigh elastic strain limit, near ideal strength (shear strength ~4 GPa) and plastic deformation at the micron-scale, one order of magnitude larger than samples made using focused ion beams, due to superior surface quality. This extended elastic regime enables enhanced functional properties by allowing higher elastic strains to modify the band structure. Further, the micron-scale plasticity of Si allows the investigation […]