Variable-energy Positron Study of Nanopore Structure in Hydrocarbon–Siliconoxide Hybrid PECVD Films

AbstractNanopore formation upon heat treatment of hydrocarbon-siliconoxide hybrid films was investigated by means of the variable-energy positron annihilation γ-ray and lifetime techniques. The films were prepared using plasma enhanced chemicalvapor deposition (PECVD),and nanoscopic poresinthe films weredeveloped throughthe decom positionofasacrificialhydrocarbonous porogenbyannealingthe filmsat temperaturesupto600°C.Asaresultofthe positron annihilation γ-ray measurements, the line-shape S parameter increases with increasing annealing temperature from 150°C to 400°C, while it reduces with further increasing temperature. This suggests that more positronium annihilate with carbonous elements remaining on the wall of pores formed at temperatures up to 400°C. The lifetime measurements revealed the nanopore sizes in the range from 0.2 nm3 to 2.0 nm3. With increasing the pore size the film refractive index reduced from 1.44 to 1.29. The variable-energy positron techniques were demonstrated to be useful to examine the nanoporosity evolution for porous PECVD films

Tuning the polarization states of optical spots at the nanoscale on the poincar´e sphere using a plasmonic nanoantenna

It is shown that the polarization states of optical spots at the nanoscale can be manipulated to various points on the Poincar´e sphere using a plasmonic nanoantenna. Linearly, circularly, and elliptically polarized near-field optical spots at the nanoscale are achieved with various polarization states on the Poincar´e sphere using a plasmonic nanoantenna. A novel plasmonic nanoantenna is illuminated with diffraction-limited linearly polarized light. It is demonstrated that the plasmonic resonances of perpendicular and longitudinal components of the nanoantenna and the angle of incident polarization can be tuned to obtain optical spots beyond the diffraction limit with a desired polarization and handedness

Formation of micrometer-order-thick poly-Si films on textured glass substrates by flash lamp annealing of a-Si films prepared by catalytic chemical vapor deposition

We investigate the microstructures of polycrystalline silicon (poly-Si) films formed by flash lamp annealing (FLA) of 4.5-μm-thick precursor a-Si films prepared by catalytic chemical vapor deposition (Cat-CVD) on Cr-coated textured glass substrates. Crystallization of a-Si is performed, keeping the dome-shaped structure formed during deposition of a-Si. The poly-Si film consists of densely-packed fine grains with sizes on the order of 10 nm. The grain size tends to increase approaching the Si/Cr interface, which can be understood as the result of solid-phase nucleation and following crystallization. Minority carrier lifetimes of the poly-Si films are worse than those formed on flat substrates. This degradation might be due to gaps in the Si layer formed during a-Si deposition or FLA