Abstract
Three-dimensional nanocomposite networks consisting of percolated Si nanowires in a SiO matrix, Si:SiO, were studied. The structures were obtained by reactive ion beam sputter deposition of (x ≈ 0.6) thin films at 450 C and subsequent crystallization using conventional oven, as well as millisecond line focus laser treatment. Rutherford backscattering spectrometry, Raman spectroscopy, X-ray diffraction, cross-sectional and energy-filtered transmission electron microscopy were applied for sample characterization. While oven treatment resulted in a mean Si wire diameter of 10 nm and a crystallinity of 72% within the Si volume, almost single-domain Si structures of 30 nm in diameter and almost free of amorphous Si were obtained by millisecond laser application. The structural differences are attributed to the different crystallization processes: conventional oven tempering proceeds via solid state and millisecond laser application via liquid phase crystallization of Si. The five orders of magnitude larger diffusion constant in the liquid phase is responsible for the three-times larger Si nanostructure diameter. In conclusion, laser treatment offers not only significantly shorter process times, but moreover, a superior structural order of nano-Si compared to conventional heating.
Highlights
Since the introduction of the first transistor [1,2,3], silicon-based technology has determined the technological progress in the world significantly, and it has changed the way of life of our society in many areas
Three-dimensional, percolated Si:SiO2 networks were obtained by reactive ion beam deposition of thin films with a measured stoichiometry of SiO0.64±0.06
In contrast to predictions and previous studies on percolated Si:SiO2 networks [7,8,18], phase separation into amorphous silicon and silica occurred during the deposition of SiO0.6 layers
Summary
Since the introduction of the first transistor [1,2,3], silicon-based technology has determined the technological progress in the world significantly, and it has changed the way of life of our society in many areas. Despite great progress and expectations raised by other materials, silicon is still the material of choice for the further development of key technologies like nanoelectronics, photovoltaics, light emitting or energy storage [4,5]. Silicon nanostructures can be based on spherical/dot-like or cylindrical/wire-like geometries. Wire-like nanostructures, on the other hand, are usually not supported by an additional matrix [4]. When they are in direct contact with air, oxidation leads to a few nm-thin native oxide layer, and additional near-surface defects are formed, lowering the electrical performance of these structures
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