Multi-wavelength enhancement of silicon Raman scattering by nanoscale laser surface ablation

Abstract

International audienceIn this paper, we produce nanoholes on a silicon surface by laser ablation. Those nanoholes lead to a yield enhancement of light-matter interaction. Performing Raman spectroscopy on silicon, an enhancement of its main Raman mode is observed: it is twice higher with the nanoholes compared to a flat surface. Such a feature appears whatever the excitation wavelength (488, 514.5 and 632.8 nm) and the laser power, revealing a broad band light-matter interaction enhancement. In addition, no change in the position and shape of the main Raman mode of silicon is observed, suggesting that no structural damages are induced by laser ablation. These results clearly demonstrate the potentiality of such nanostructures for the further development of silicon photonics. (C) 2013 Elsevier B. V. All rights reserved

Ultra-high ordered, centimeter scale preparation of microsphere Langmuir films

“…The substrates exhibit in average $84% monolayer coverage ratio, due to large number of clusters ($16% of total discontinuities). This is still higher than the previously reported 60% ratio when using the standard LB technique [34,35]. The reduction in coverage of monolayer could be attributed to the nature of particles (size, density, degree of functionalization) but is worth reminding here that similar results were obtained for both PS and silica spheres with the same size (1 lm) and the same functionalization (C18).…”

“…In recent work, we have shown that such monolayers are compatible with photonic applications [34,35], and in this paper we present results and discuss on monolayer quality improvement. An important point in this paper is to highlight the utility of such monolayers with ease preparation and high coverage ratio, over large area and with high stability, reliable for the final laser engineered photonic structures and throughout the overall fabrication process.…”

“…The LB technique provides one of the few methods of preparing organized assemblies of monolayers, which are prerequisite in various applications where high-accuracy spatially resolved methods are needed [33]. Such monolayers made with transparent microspheres find applications in the structuration of bulk substrates, resulting in either nanohole or nanobump arrays [34][35][36][37][38][39], but have also been explored in the literature in the context of electronics, optics, microlithography, chemical sensors, and biosensors [32][33][34][35][36][37][38][39][40][41]. It has been demonstrated that properly coated nanoparticles can be organized at the air-water interface by using the same procedure.…”

“…In our earlier works [34,35], we adopted the standard protocol of LB film preparation and the obtained monolayers exhibit nearly 60% coverage ratio, at a surface pressure of 15 mN/m and 10 mm/min compression rate as the substrates were evidently not completely void free. The best results obtained by the standard protocol reveal the limit on what can be achieved for the preparation of microsphere monolayers when the operation a LB system relies only on surface tension measurements.…”

Co-mediated nucleation of erbium/silicon nanoclusters in fused silica

“…The intensity of phonon peaks can be directly related to the density of chemical bonds associated with the respective vibrations, as we do not observe a measurable increase in surface roughness of silica substrate upon implantation which has been reported to affect the Raman intensity. 17 When Er is present in the SiO 2 matrix in addition to the excess Si, the spectral increase observed in zone 2 indicates that more Si-Si bonding occurs in this sample. In other words, this indicates that the presence of Er promotes the nucleation of Si-nc.…”