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Pulsed-laser assisted nanopatterning of metallic layers on silicon substrates under an atomic force microscope (AFM) tip has been investigated. A 532 nm Nd:YAG pulsed laser with a pulse duration of 7 ns was used. Boron doped silicon tips were used in contact mode. This technique enables processing of structures with a lateral resolution down to 10 nm on the copper layers. Nanopatterns such as pit array and multilines with lateral dimensions between 10 and 60 nm and depths between 1.5 and 7.0 nm have been created. The experimental results and mechanism of the nanostructure formation are discussed. The created features were characterized by AFM, scanning electron microscope and Auger electron spectroscopy. The apparent depth of the created pit has been studied as a function of laser intensity or laser pulse numbers. Dependence of nanoprocessing on the geometry parameters of the tip and on the optical and thermal properties of the processed sample has also been investigated. Thermal expansion of the tip, the field enhancement factor underneath the tip, and the sample surface heating were estimated. It is proposed that field-enhancement mechanism is the dominant reason for this nanoprocessing. [ABSTRACT FROM AUTHOR]

Pulsed UV laser ablation is applied to fabricate super-hydrophobic surfaces on metal substrates. The spike shape micro-structure arrays achieved by the laser ablation on the brass substrates increase the surface roughness (Ra) from ∼ 400 nm to ∼ 5 μm. Meanwhile, plenty of nano-structures (200 ∼ 600 nm) are also formed and scattered on the surface of the micro-structures. It is found that the water contact angle of the brass substrate increases from 110° to 161°. Super-hydrophobic property of the metal surfaces with both the micro- & nano-roughness is explained by water repellent model for double roughness structures. High speed camera imaging is used to analyze water droplet dynamics during its rolling down along the slanted super-hydrophobic brass surface. It shows that the pulsed laser ablation is a versatile approach to create large area super-hydrophobic surfaces for industrial applications. [ABSTRACT FROM AUTHOR]

The effect of laser energy fluence and substrate heating on the annealing of boron-implanted silicon-germanium epitaxial layers on silicon was investigated. By making use of the difference in the melting points of silicon-germanium and silicon, a process window in the laser energy fluence can be found such that the meltdepth was confined within the silicon-germanium. Pre-heating of the substrate to 300°C was done to reduce the laser fluence required and improve the surface morphology. Cross-sectional transmission electron microscopy showed that there were no end-of-range defects due to ion implantation at the silicon-germanium/silicon interface after the laser annealing. [ABSTRACT FROM AUTHOR]

Parallel nanostructuring of a GeSbTe film may significantly improve the recording performance in data storage. In this paper, a method that permits direct and massively parallel nanopatterning of the substrate surface by laser irradiation is investigated. Polystyrene spherical particles were deposited on the surface in a monolayer array by self-assembly. The array was then irradiated with a 248-nm KrF laser. A sub-micron nanodent array can be obtained after single-pulse irradiation. These nanodents change their shapes at different laser energies. The optical near-field distribution around the particles was calculated according to the exact solution of the light-scattering problem. The influence of the presence of the substrate on the optical near field was also studied. The mechanisms for the generation of the nanodent structures are discussed. [ABSTRACT FROM AUTHOR]

By using fluence-dependent transmission measurement with nanosecond laser pulses, we have studied optical limiting (OL) properties of new carbon nanocomposites as well as amorphous SixNy or amorphous SiC coated carbon nanotubes suspended in distilled water. The observed nonlinearity at 532 nm contributed to OL performance of the carbon nanocomposites or carbon nanoballs (CNBs) is suggested to have its origin in the optically induced heating or scattering effects. It is found that when the linear transmittance of the CNBs is less than or equal to 70%, the intensity-dependent transmission of the CNBs is comparable to that of C60. While at 80% linear transmittance, CNBs possess better OL behavior than that of C60. These findings strongly support a potential application of CNBs for all laser protection devices. We have also observed OL effects in the amorphous silicon nitride (a-SixNy) and amorphous silicon carbide (a-SiC) coated multi-walled carbon nanotubes (MWNTs) at wavelengths of 532 and 1064 nm, and found that their OL performances are slightly poorer than that of their parent MWNTs. The possible sources of thickness-dependent OL effects of a-SixNy and a-SiC coated MWNTs are discussed. [ABSTRACT FROM AUTHOR]