Design and synthesis of amorphous SiOx structures generated by Sn quantum dots: Growth mechanism and luminescent origin

초록

SiO<inf>x</inf> structures with different diameters of a few hundreds of nanometers and/or a few micrometers are prepared using applied thermal evaporation. Subsequently, Sn quantum dot-based SiO<inf>x</inf> architectures are synthesized via the continuous steps of the carbothermal reduction of SnO<inf>2</inf>, substitution of Sn4+ for In3+, thermal oxidation of Si, Sn sublimation, interfacial reaction, and diffusion reaction consistent with corresponding phase equilibriums. Several crystalline and spherical-shaped Sn quantum dots with diameters between 2 and 7 nm are observed in the amorphous SiO<inf>x</inf> structures. The morphological evolution, including hollow Sn (or SnO<inf>x</inf>) sphere and wire-like, worm-like, tube-like, and flower-like SiO<inf>x</inf>, occurs stepwise on the Si substrate upon increasing the given process energies. The optical characteristics based on confocal measurements reveal the as-synthesized SiO<inf>x</inf> structures, irrespective of whether crystallinity is formed, which all have visible-range emissions originating from the numerous different-sized and -shaped Sn quantum dots permeating into the SiO<inf>x</inf> matrix. In addition, photoluminescence emissions ranging between ultraviolet and red regions are in agreement with confocal measurements. The origins of the morphology- and luminescence-controlled amorphous SiO<inf>x</inf> with Sn quantum dots are also discussed. © 2016 IOP Publishing Ltd.

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