Synthesis, growth mechanism, and light-emission properties of twisted SiO2 nanobelts and nanosprings.

Amorphous twisted SiO(2) nanobelts have been synthesized on Si wafers using facile thermal evaporation. These nanobelts are produced together with SiO(2) nanowires and a small quantity of SiO(2) nanosprings. Spectral and microstructural analyses suggest that the twisted SiO(2) nanobelts and nanosprings form via a polar surface driven process. Spontaneous polarization on the very thin polar crystalline SiO(2) layers on the amorphous SiO(2) nanobelt and nanospring surfaces makes the nuclei rearrange orderly and causes the nanobelt and nanowire to roll up at a certain twisty angle. The cathodoluminescence spectrum acquired from these SiO(2) nanostructures reveals three emission bands at 4.4, 3.7, and 2.7 eV originating from oxygen-related defect centers. The polar surface driven mechanism can adequately explain the growth of these novel twisty nanobelts and nanosprings which have potential applications in sensors, transducers, resonators, and photonics.