Grazing Incidence Small Angle X-ray Scattering Analysis Research Articles

Photoinduced Resist-free Imprinting (PRI) in fullerene thin films as revealed by Grazing Incidence Small-angle X-ray scattering

In this article we explore the potential of synchrotron Grazing Incidence Small Angle X-ray Scattering (GISAXS) to evaluate the extension of a Photoinduced Resist-free Imprinting (PRI) effect for grating-like Laser Induced Periodic Surface Structures (LIPSS) on spin-coated thin films of the fullerene derivative [6,6]-phenyl C71-butyric acid methyl ester (PC71BM). Valuable information about the nature of both the original fullerene LIPSS and of the remaining resist-free nanostructure in terms of geometry, size distribution, lattice periodicity and degree of order can be achieved by simulations of the GISAXS patterns. One of the most interesting features provided by the GISAXS analysis is the estimation of the paracrystalline distortion factor, which can be useful to evaluate the level of order in the nanostructure. Data revealed that LIPSS in PC71BM films can be described as one-dimensional paracrystalline lattices with levels of order in accordance with those typically observed in LIPSS of other materials. The PRI effect leaves a qualitatively similar nanostructure but about two times more disordered than the original LIPSS one. Our results show that GISAXS is a powerful tool to characterize Resist-free Imprinting procedures of potential relevance in nanotechnology.

GISAXS study of Si nanostructures in SiO2 matrix for solar cell applications

AbstractWe explore the process of Si nanoparticles formation in SiO2 matrix suitable for advanced solar cells application. To this purpose a superstructure consisting of alternating 5 nm thick SiOx and SiO2 layers was deposited by high vacuum evaporation from solid sources. After high temperature annealing of such structures in high vacuum, the SiOx decomposed and Si nanoparticles aggregated at their former position forming therefore a superstructure of Si nanoparticles embedded in dielectric SiO2 matrix. To explore such process of nanoobjects formation in different matrix, grazing incidence small‐angle X‐ray scattering (GISAXS) seems to be as relatively easy non‐destructive technique; a logical choice. Despite the fact that due to the rather small difference in electron density between Si and SiO2. GISAXS contrast is very small, by performing GISAXS with intense synchrotron light and subtracting the dominant surface contribution to the overall signal we managed to retrieve information on the structural changes within the layers. The conclusions from the GISAXS analysis were confirmed by photoluminescence measurements.

Surface dependent thermal evolution of the nanostructures in ultra-thin copper(ii) phthalocyanine films

The thermal evolution of the nano-grain structure and surface of ultra thin copper(II) phthalocyanine (CuPc) films was investigated by real time grazing incidence small angle X-ray scattering (GI-SAXS) and X-ray reflectivity measurements. The evolution was strongly affected by the substrate surface energy. On hydrophilic Si, CuPc film consisted of disk shaped nano-grains of two different sizes. The larger grains showed lateral crystal growth and planarization by thermal annealing, while the smaller grains did not increase in size. The grains formed clusters at high temperature. On hydrophobic Si, CuPc nano-grains are more randomly distributed. The crystal size did not increase in size upon thermal annealing. Thermal annealing induced a more random distribution of nano-grains with an increase in roughness, and large islands formed by the coalescence of small grains. The different thermal evolution models of CuPc films based on GI-SAXS analysis are consistent with the different temperature behavior of the hole mobilities of organic field-effect transistor (OFET) devices fabricated on both surfaces.

A grazing incidence small-angle x-ray scattering analysis on capped Ge nanodots in layerstructures

The grazing incidence small-angle x-ray scattering (GISAXS) intensity from buried Genanodots is examined both by GISAXS/reflectivity measurements and by simulations withdistorted wave Born approximation (DWBA). The validity and the condition of using theBorn approximation (BA) are discussed using simulations based on the layer structuresmodeled from a reflectivity analysis. As expected in the previous kinematic analysis, use ofthe BA is reasonable in determining the size and the shape of very small or thinnanodots. Several effects of layer structures on the GISAXS analysis are discussed.

Morphology and size distribution of gold nanoclusters ina−C:Hfilms studied by grazing incidence small-angle x-ray scattering

We present a morphological study of gold-containing amorphous hydrogenated carbon films $(a\ensuremath{-}\mathrm{C}:\mathrm{H}/\mathrm{A}\mathrm{u})$ grown by a combined physical vapor deposition/plasma-assisted chemical vapor deposition process. By using grazing incidence small-angle x-ray scattering (GISAXS) we show that isolated Au nanoclusters are regularly distributed within the $a\ensuremath{-}\mathrm{C}:\mathrm{H}$ matrix. From the GISAXS analysis, which we based on the local monodisperse approximation, the shape, size, and correlation distance of the nanoclusters as well as the size distribution both in the film plane and in the film growth direction are determined. We show that the nanocomposite films consist of an assembly of prolate and oblate ellipsoids (spherical on average, however) having a broader size distribution in the film plane than in the perpendicular direction.