MATERIAL SCIENCE

A Coat of Silicon

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Science  02 Nov 2007:
Vol. 318, Issue 5851, pp. 717
DOI: 10.1126/science.318.5851.717c

Silicon materials with nanometer-scale morphologies have a wide range of possible photonic applications, spanning waveguide amplifiers, light-emitting diodes, and laser media. Existing methods for making silicon nanocrystals embedded in a silicon dioxide matrix (nc-Si/SiO2) generally involve nucleation from a silicon oxide film and may require subsequent patterning using a resist and etching technique. Hessel et al. show that nc-Si/SiO2 can instead be prepared as a thin-film material through the deposition of solutions of hydrogen silsesquioxane (HSQ) followed by thermal processing at 1100oC. By crosslinking the HSQ using an electron beam, the authors could generate stable patterns at sub-10 nm resolution, without the need for etching or oxidation steps. The main advantage of this method, though, was the capacity to create smooth conformal coatings on thin glass fibers. When pumped with a blue laser source or ultraviolet lamp, the coated fibers emitted a red/orange glow. Adding erbium chloride to the HSQ stock solution gave rise to a second photoluminescent band at wavelengths relevant for optical communications.— MSL

Adv. Mater. 19 10.1002/adma.200700731 (2007).

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