Synthesis of donut-like SnO_2 structures composed of small nanocrystals on silicon substrate: Growth mechanism, structural and optical properties

摘要

Donut-shaped crystalline SnO_2 structures composed of small nanocrystals were grown on silicon substrate, for the first time, via non-catalytic simple thermal evaporation process by using tin powder in the presence of oxygen. The as-grown donut-like SnO_2 structures were characterized in detail in terms of their structural and optical properties by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS) and room-temperature photoluminescence (PL). The morphological observations by FESEM revealed that the grown structures are donut-like which are made by the random accumulation of hundreds of small SnO_2 nanocrystals. The optical property of as-grown donut-shape structures was observed by room-temperature PL spectrum which exhibit three bands, i.e. UV emission at approx 355nm, blue emission at approx 464nm and a green emission at approx 520nm. A plausible growth mechanism has also been proposed for the formation of donut-shaped SnO_2 structures.