Molecular Simulation of Covalent Bond Dynamics in Liquid Silicon

Observation of plasmon excitation in liquid silicon by inelastic x-ray scattering

Inelastic x-ray scattering (IXS) measurements were performed for observing the excitation of bulk plasmons in metallic liquid silicon (Si). The peak due to plasmon excitation was observed within the energy loss around 17 eV. Combined with IXS data of crystalline Si measured at several elevated temperatures, it was found that temperature dependence of the excitation energy in the crystalline solid state is explained by the electron gas including the band gap effect, whereas in the metallic liquid state near the melting point, it exhibits a departure from the electron gas; the plasmon energy takes a lower value than that of the electron gas. Such lowering of plasmon energies is reasonably explained by a model incorporating semiconducting component to the electron gas. Non-simple metallic nature in liquid silicon is highlighted by the observation of electron collective dynamics.

Approximately 30 nm Nanogroove Formation on Single Crystalline Silicon Surface under Pulsed Nanosecond Laser Irradiation

Nanogrooves with a minimum feature size down to 30 nm (λ/26) can be formed directly on silicon surface by irradiation from two orthogonal polarized 1064 nm/10 ns fiber laser beams. The creation of such small nanogrooves is attributed to surface thermal stress during resolidification and supercooling with the double laser beams' irradiation. By varying the pulse number and laser fluence, the feature size of narrow grooves on silicon surface can be tuned. The experimental results and numerical calculation of surface thermal behaviors indicated that the high repetition rate of the nanosecond laser leads to the incubation effect and different silicon optical and thermal properties during laser irradiation. Resolution on this scale should be attractive in nanolithography, particularly considering that this method is available in far field and in ambient air.