Controlled Fabrication Of SiC Nanoarrays And Their Field Emission Properties

SiC low dimensional nanomaterials have been considered as one of the most promising candidates to be used as field emission (FE) cathodes. The key point is to realize the controlled fabrication of SiC nanoarrays. During the past decades, many efforts have been devoted to the investigation of SiC low-dimensional nanostrutures. However, for the application of SiC nanostructures, a systematically study is still highly required for the foundamental exploration related to the synthesis and properties characterization of SiC nanostructures.In present work, directed by the exploration of SiC nanostructures with excellent FE properties, SiC nanoarrays have been fabricated successfully via pyrolysis of polymeric precursors. By tailoring the two key parameters such as substrates and catalysts for the growth of SiC nanostructures, the controlled fabrication of SiC nanoarrays has been achieved. Meanwhile, the FE properties of SiC nanoarrays have been characterized over the range of room-temperature (RT) to 500℃. The detailed work is shown as bellow:Single-crystal 3C-SiC nanoneedles have been synthesized via pyrolysis polymeric precursors on carbon papers. The nanoneedles grow along [111] direction with the lengthes and diameters of up to tens of microns and about several hundred nanometers, respectively. FE measurements show that SiC nanoneedles possess very low turn-on fields of 1.30-0.66V/μm in the range of RT to 500℃). The electron field emission of SiC nanoneedles follows the traditional F-N theory.It is found that controlled fabrication of SiC nanoarrays can be accomplished by tailoring the used substrates. The single-crystal SiC substrates with different indices of crystallographic plane have a profound effect on the growth of SiC nanoarrays. The densities and yields of SiC nanoarrays on the single-cryatalline SiC substrates can be significantly enhanced by hot-erosion treatment of the substrates. We have improved the density of SiC nanoarrays for at least 20 times and area up to 4 mm2 with a density if 2.4×107 mm-2 by hot-erosion. The FE properties of SiC nanoarrays, which was synthesized……, implies that SiC nanoarrays obey the traditional F-N field emission theory from RT to 300℃. However, at 400 and 500℃, the electron emission is dominant by the typical thermal emission. The electron emission behavior at 350℃possess both of the two types as mentioned above. The turn-on fields and work functions of SiC nanoarrays are reduced with the increase of work temperatures. The controlled growth of SiC nanoarrays can also be achieved by optimization of the catalysts with various types and concentrations. It is found that the SiC nanoarrays can only grow with a certain concentration of catalyst, in which a higher catalyst concentration favors a higher density of the nanoarrays. The nanoarrays can not grow without catalysts or with a very low catalyst concentration. As for the types of catalysts, the Co-and Au-based catalysts favor the growth of SiC nanoarrays on the single-crystal SiC substrates. However, the Fe-based (e.g. FeCl2 and Fe(NO3)3) catalysts are not suitable for the fabrication of SiC nanoarrays.Current work might direct the controlled growth of SiC nanoarrays with a certain foundamental data and techniques. Meanwhile, the obtained results exhibit academic significance and potential applications as for evaluation of the work ability of SiC nanostructures to be used as the FE cathodes, investigation of direct thermal electric conversion, and obtaining a high emission current densities required for many unique applications.