Abstract
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 ∼355
nm, blue emission at ∼464
nm and a green emission at ∼520
nm. A plausible growth mechanism has also been proposed for the formation of donut-shaped SnO
2 structures.