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The thermal decomposition on silicon carbide (SiC) is one of the most used growth techniques for fabrication of epitaxial graphene. However, it significantly diminishes graphene's otherwise exceptional carrier mobility. Reduction of the substrate influence is therefore essential for keeping conductivity at high levels. Here we present a novel technique where a sample with epitaxial graphene grown on SiC was exposed to intense 21.2 nm radiation. A sub-nanosecond pulse at low fluence in an interval 0.4–0.7 J/cm2 was used to break covalent sp3 bonds between the SiC substrate and buffer (the first graphene layer) which remains, except for release of its intrinsic strain, almost unaffected. A detailed analysis of the irradiated area examined by several microscopic and spectroscopic methods such as white-light interferometry and micro-Raman spectroscopy shows a clear evidence of a graphene layer detached from the substrate. Higher fluences induce damage to SiC substrate which expands due to the amorphization process. Damage thresholds were obtained by an advanced method of ablative imprints and compared with those calculated by the hybrid code XTANT. Image 1 [ABSTRACT FROM AUTHOR]

Silicon crystalline samples were exposed to intense single pulses of XUV radiation (λ=13.5nm) what lead to melting and ablation of the surface material. The deformation field around craters along the whole thickness of silicon wafers was observed by means of the synchrotron transmission section topography using the beam perpendicular to the surface of the sample. The geometrical shape and depth extension around craters was evaluated based on numerous, dense series of section topographs spaced by 10µm. In the topographs we observed the direct image connected with the boundary of the crater associated with some deformation of the Kato fringes. The evaluated depth extension, different for individual craters, was in the range of 30–100µm. The depth values were confirmed also by evaluations based on the Bragg case section topographs. It was possible to reproduce the contrast of the craters in transmission section topographs by numerical simulation based on integration of the Takagi–Taupin equations. The damage of the crystal defects connected with craters was approximated as droplet-like inclusions. [ABSTRACT FROM AUTHOR]

Abstract: An important problem in the experiments performed with the intense fourth generation X-ray sources is the damages of the examined samples caused by the high energy impact. The effect introduced by the beam from the FLASH source in crystalline silicon samples was studied through synchrotron white beam projection and section topography, enabling the evaluation of the strain field associated with the damages. The topographs indicated the existence of deformed field of cylindrical symmetry providing the dark contrast. It was also shown that some of the Bragg-case section images of spots in silicon correspond well to the simulated images of rod-like inclusions. [Copyright &y& Elsevier]

Abstract: The article presents preliminary investigation results on the near-surface damage produced by single pulses of XUV free-electron laser in the amorphous α-SiO2, the monocrystalline silicon and the epitaxial films of gold. The irradiation was delivered with single pulses of only 25fs at a wavelength of 32.5nm and of energy up to 10μJ. Structural modifications induced by irradiation were characterized by X-ray microdiffraction, as well as by the AFM and optical microscopy. Ablation craters of well-defined edges with smooth interiors and outer embankments surrounding the crater edges were found in the materials. Polycrystalline phases were revealed in Si and Au film samples, in the embankments and in central parts of some craters. In α-SiO2, a diffraction pattern typical of an amorphous material was observed without any traces of irradiation-initiated crystallization. A step-like, complete removal of gold film was evidenced inside craters, with only small gold residues in central part of craters exposed to higher fluences. [Copyright &y& Elsevier]