Fe-catalyzed growth of one-dimensional α-Si3N4 nanostructures and their cathodoluminescence properties

Abstract

Preparation of nanomaterials with various morphologies and exploiting their novel physical properties are of vital importance in nanoscientific field. Similarly to the III-N compound semiconductors, Si3N4 nanostructures also could be potentially used for making optoelectronic devices. In this paper, we report on an improved Fe-catalyzed chemical vapour deposition method for synthesizing ultra-long α-Si3N4 nanobelts along with a few nanowires and nanobranches on a carbon felt substrate. The ultra-long α-Si3N4 nanobelts grew via a combined VLS-base and nanobranches via a combined double-stage VLS-base and VS-tip mechanism, as well as nanowires via VLS-tip mechanism. The three individual nanostructures showed variant optical properties as revealed by a cathodoluminescence spectroscopy. A single α-Si3N4 nanobelt or nanobranch gave a strong UV-blue emission band as well as a broad red emission, whereas a single α-Si3N4 nanowire exhibited only a broad UV-blue emission. The results reported would be useful in developing new photoelectric nanodevices with tailorable or tunable properties.

Fe(NO3)3-assisted large-scale synthesis of Si3N4 nanobelts from quartz and graphite by carbothermal reduction–nitridation and their photoluminescence properties

“…The result is slightly different than the stoichiometric ratio in Si 3 N 4 (0.750:1), and various factors such as the scanning time, energy of X-ray, and amount and density of materials may be responsible for the accuracy of EDS spectrum25. The results of this and previous studies1521 indicate that the VLS base growth and VS tip growth contribute to the growth of Si 3 N 4 nanobelts. This process is described in detail as follows:…”

Novel, low-cost solid-liquid-solid process for the synthesis of α-Si3N4 nanowires at lower temperatures and their luminescence properties

“…This may have caused a different dominant luminescence mechanism between PL and CL measurements. The CL emission of the α-Si 3 N 4 nanowires centred at approximately 368 nm (3.37 eV) should arise from a recombination between the Si-Si σ * level and the N 2 0 level47. The peak at approximately 567 nm (2.19 eV) was ascribed to the recombination process at the silicon dangling bond46.…”

“…They considered the 305 nm peak as being due to recombination, either from the conduction band to the N 2 0 level, or from the valance band to the N 4 + level: the 540 nm peak is attributed to a recombination process at the silicon dangling bond, and the 735 nm peak is caused by recombination between the N 4 + and N 2 0 levels46. Huang et al 47 synthesised α-Si 3 N 4 nanobelts, nanowires, and nanobranches and compared the CL properties of these three nanostructures. They propose that the UV-blue emissions of their α-Si 3 N 4 nanobelt, nanowire, and nanobranch centred with a band from 3.05 eV to 3.34 eV should arise from a recombination between the Si-Si σ * level and the N 2 0 , and N 2 0 , levels, or between the N 4 + and intrinsic valence band edge47.…”

“…Huang et al 47 synthesised α-Si 3 N 4 nanobelts, nanowires, and nanobranches and compared the CL properties of these three nanostructures. They propose that the UV-blue emissions of their α-Si 3 N 4 nanobelt, nanowire, and nanobranch centred with a band from 3.05 eV to 3.34 eV should arise from a recombination between the Si-Si σ * level and the N 2 0 , and N 2 0 , levels, or between the N 4 + and intrinsic valence band edge47.…”

Synthesis of one-dimensional α-Fe2O3/Bi2MoO6 heterostructures by electrospinning process with enhanced photocatalytic activity

“…The photocatalytic activity of semiconductor photocatalysts often goes hand in hand with their morphologies, structures and specific surface areas. Onedimensional (1D) nanomaterials are suitable for applying to the photocatalysis due to possessing the large specific surface area, distinctive geometric structure and unique optical properties [5]. As is known to all, the electrospinning technique is capable of fabricating the 1D nanomaterials which have been employed in many applications [6].…”