JP4701451B2 - Zinc sulfide nanocable coated with silicon carbide film and method for producing the same - Google Patents

Description

  The present invention relates to a zinc sulfide nanocable coated with a silicon carbide film, which is expected to be applied to a high-temperature, high-power, high-frequency nanoelectronic device or nano-light-emitting device, and a method for producing the same.

  In recent years, nano-sized electronic devices have been actively researched and developed. Nano-cables having a nano-sized diameter are necessary for, for example, wiring and nano-sized coils that connect individual nano-electronic devices, and as a new functional device based on the nano-wire quantum wire structure, For example, application to nano light-emitting devices is also expected.

  Silicon carbide (SiC) is a group IV-IV semiconductor with a large band gap energy, and since electron mobility and thermal conductivity are high, application to high-temperature, high-power, and high-frequency nanoelectronic devices is expected Moreover, it is a material expected as a light emitting material based on the quantum wire structure of the nanocable.

For this reason, conventionally, various methods for producing nanowires and nanorods made of silicon carbide have been proposed. For example, there is a method of reacting carbon nanotubes and silicon monoxide in argon at 1400 ° C. (see Non-Patent Document 1). In addition, there is a method (see Non-Patent Document 2) of reducing a composite gel of tetraethoxysilane and saccharose at high temperature. There is also a method of chemical vapor deposition of a carbon, silicon, silicon dioxide powder mixture in a hydrogen stream (see Non-Patent Document 3). There is also a method of chemical vapor deposition of silicon powder and graphite powder in a hydrogen stream (see Non-Patent Document 4). There is also a method of reducing sodium tetrachloride and carbon tetrachloride with sodium in an autoclave (see Non-Patent Document 5). There is also a method of reducing silicon powder and carbon tetrachloride with sodium (see Non-Patent Document 6).
In addition, silicon carbide nanotubes having a hollow structure include a method of reacting carbon nanotubes with silicon monoxide (see Non-Patent Documents 7 and 8).
Furthermore, the structure which covered the surface of the zinc sulfide nanowire with silicon is also known (refer nonpatent literature 9).
Z. W. Pan, et al., Adv. Mater. 12: 1186, 2000 G. W. Meng, et al. Mater. Res. 13, 2533, 1998 X. T.A. Zhou, et al., Appl. Phys. Lett. 74, 3942, 1999 H. L. Lai, et al., Appl. Phys. Lett. 76, 294, 2000 Q. Y. Lu, et al., Appl. Phys. Lett. 75, 507, 1999 J. et al. Q. Hu, et al. Phys. Chem. B104, 5251, 2000 J. et al. M.M. Nhut, et al., Catalysis Today, 76, 11, pp. 2002 X. H. Sun, et al. Am. Chem. Soc. 124, 14464, 2002 J. et al. Q. Hu, et al., Angew. Chem. Int. Ed. 43, 63, 2004

  Thus, nano-cables using silicon carbide are suitable for high-temperature, high-power, high-frequency nano-electronic devices, and nano-light-emitting devices, so various structures and manufacturing methods are proposed. However, the present inventors have an object to provide a zinc sulfide nanocable covered with a silicon carbide film and a method for manufacturing the same, which are different from these conventional structures.

In order to achieve the above object, the following invention is provided.
The zinc sulfide nanocable of the invention 1 is characterized by comprising a zinc sulfide nanowire having a uniform diameter in the length direction and a silicon carbide film having a uniform thickness covering the surface of the nanowire.
Invention 2 is a preferred embodiment of the zinc sulfide nanocables invention 1, wherein the zinc sulfide nanowire has a diameter and wherein the area by der of 130 nm to 40 nm.
Invention 3 is a preferred embodiment of the zinc sulfide nanocables invention 1, wherein the silicon carbide film is characterized in that the thickness Saga 15 nm in the range of 50 nanometers.

Invention 4 is a method for producing a zinc sulfide nanocable according to any one of Inventions 1 to 3, wherein a mixed powder of zinc sulfide powder and silicon monoxide powder is heated in an inert gas stream to sublimate zinc sulfide. is allowed, a first step of forming the sublimed zinc sulfide nanowires by supplying zinc sulfide on a substrate held at a predetermined temperature, and the inert gas is subsequently heated by switching the methane, the methane gas together to produce a graphitic carbon by the decomposition, the silicon monoxide to form silicon by disproportionation reaction, where the resulting carbon and silicon of the zinc sulfide nanowires on a substrate maintained at the predetermined temperature is supplied to the surface is reacted, characterized in that comprising a second step of coating the surface of the zinc sulfide nanowire silicon carbide film.

Invention 5 is a preferred embodiment of the method for producing a zinc sulfide nanocable according to Invention 4, wherein the heating in the first step is performed in a temperature range of 1100 ° C. to 1200 ° C. for 0.5 hours to 1.5 hours. It is characterized by being performed by .
Invention 6 is a preferred embodiment of the method for producing a zinc sulfide nanocable according to Invention 4 or 5, wherein the heating in the second step is performed at a temperature range of 1250 ° C to 1500 ° C for 0.5 hour to 1. It is characterized by being performed in a range of 5 hours.
Invention 7 provides a preferred embodiment of the method of any of zinc sulfide nano cable from the invention 4 6, a predetermined temperature of the substrate is characterized by about 800 ° C. der Rukoto.

  According to this manufacturing method, zinc sulfide coated with a silicon carbide film comprising a zinc sulfide nanowire having a uniform diameter in the length direction and a silicon carbide film having a uniform thickness covering the surface of the nanowire. Nano cables can be manufactured. Moreover, the diameter of the zinc sulfide nanowire is distributed in the range of 40 nm to 130 nm, and the length is distributed in the range of several μm to several tens of μm. The thickness of the silicon carbide film is distributed in the range of 15 nm to 50 nm.

  Since the nanocable of the present invention is a zinc sulfide nanocable coated with a silicon carbide film, it is suitable for application to high-temperature, high-power, high-frequency nanoelectronic devices, and nanolight-emitting devices.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, an example of an apparatus used for the manufacturing method of the present invention will be described.
FIG. 1 is a schematic cross-sectional view of a vertical high-frequency heating furnace used in the production method of the present invention. The heating furnace 1 includes a crucible 2, a graphite cylinder 4 containing the crucible 2 and coated on the outside with a carbon fiber 3 as a heat insulating material, and a non-conductive container 5 such as fused quartz containing the graphite cylinder 4. And a high-frequency heating coil 6 disposed outside the container 5.

Next, the manufacturing method of the present invention using the heating furnace 1 will be described. The manufacturing method includes steps 1 and 2, and step 1 is as follows.
A mixed powder of zinc sulfide powder and silicon monoxide powder is put into a crucible 2 made of boron nitride, and the crucible 2 is attached to the center of the graphite cylinder 4. After depressurizing the inside of the heating furnace 1, the temperature of the crucible 2 is raised to 1100 to 1200 ° C. while flowing an inert gas, and held at this temperature for 0.5 to 1.5 hours. Under the present circumstances, the surface of the carbon fiber 3 of a heat insulating material is maintained at about 800 degreeC. By this step, zinc sulfide in the crucible 2 is sublimated, and nanowires made of zinc sulfide grow on the surface of the carbon fiber 3 of the heat insulating material.

Step 2 is as follows.
The inert gas is switched to methane gas, and then the temperature of the crucible 2 is raised to 1250 to 1500 ° C. and held at this temperature for 0.5 to 1.5 hours. Through this process, graphite-like carbon is generated by decomposition of methane gas, and silicon is generated by disproportionation reaction of silicon monoxide, and the generated carbon and silicon grow on the surface of carbon fiber 3 as a heat insulating material. The surface of the zinc sulfide nanowire reacts, and the surface of the zinc sulfide nanowire is coated with silicon carbide. After cooling the heating furnace 1 to room temperature, the zinc sulfide nanocable covered with silicon carbide formed on the surface of the carbon fiber 3 as a heat insulating material is taken out.

  In the above, the weight ratio of the zinc sulfide powder to the silicon monoxide powder is preferably in the range of 2.5: 1 to 1.5: 1. If the weight of the zinc sulfide powder is larger than this range, the zinc sulfide powder is unreacted. It remains as it is. Conversely, if the weight of the zinc sulfide powder is less than this range, the final product contains a large amount of silicon nanostructures. When argon is used as the inert gas, the flow rate is preferably in the range of 0.5 to 1.2 liters / minute, and if the flow rate is higher than 1.2 liters / minute, the zinc sulfide vapor is moved out of the furnace. It will be released. If the flow rate is less than 0.5 liter / minute, the growth location of the zinc sulfide nanowire is not stable.

  The heating temperature in step 1 is preferably in the range of 1100 to 1200 ° C., and if it exceeds 1200 ° C., zinc sulfide evaporates very quickly and dissipates out of the graphite cylinder, resulting in a decrease in yield. When the temperature is lower than 1100 ° C., the evaporation of zinc sulfide is very slow and the zinc sulfide powder remains and the reaction does not proceed. The heating time when heating to 1100 to 1200 ° C. is preferably in the range of 0.5 to 1.5 hours, and since the reaction proceeds sufficiently in 1.5 hours, it is not necessary to spend more time. If it is shorter than 0.5 hour, zinc sulfide powder remains.

  The heating temperature in step 2 is preferably in the range of 1250 to 1500 ° C., and the reaction proceeds sufficiently at 1500 ° C., so it is not necessary to set the temperature higher than this. Below 1250 ° C, the decomposition of silicon monoxide is significantly slowed down. The heating time in step 2 is preferably in the range of 0.5 to 1.5 hours, and the generated silicon carbide is partially oxidized when a time of 1.5 hours or longer is applied. If it is less than 0.5 hour, the yield decreases. The flow rate of methane gas is preferably in the range of 30 to 100 ml / min. If it exceeds 100 ml / min, amorphous carbon is mixed in the product. If the flow rate is less than 30 ml / min, the yield of the final product is reduced.

  By steps 1 and 2, a zinc sulfide nanocable covered with a silicon carbide film is obtained on the surface of the carbon fiber of the heat insulating material maintained at about 800 ° C. Moreover, the diameter of the zinc sulfide nanowire of each nanocable and the thickness of the silicon carbide film to be coated are uniform in the length direction. The silicon carbide film is distributed in a range of 15 to 50 nm. The length is distributed in the range of several to several tens of μm.

Next, the zinc sulfide nanocable covered with the silicon carbide film of the present invention produced by the above production method will be described based on the examples.
A mixed powder of 1 g of silicon monoxide powder (325 mesh) made by Sigma-Aldrich, as well as 2 g of zinc sulfide powder made by Sigma-Aldrich (purity 99.99%) was put in a crucible made of boron nitride. This crucible was attached to the center of a graphite cylinder covered with a carbon fiber as a heat insulating material, and this graphite cylinder was attached to the center of a vertical high frequency induction heating furnace. The pressure inside the heating furnace was reduced to about 27 Pa, and then heated at 1150 ° C. for 1 hour while flowing argon gas at a flow rate of 1.0 liter / min. Then, it heated at 1400 degreeC for 1 hour, making methane gas flow with the flow volume of 50 ml / min continuously. Several mg of black powder was deposited on the surface of the carbon fiber of the heat insulating material maintained at about 800 ° C.

  FIG. 2 is a diagram showing a transmission electron microscope image of the deposited black powder. The figure shows that the nanocable has a uniform diameter of about 100 nm. It can also be seen that the nanocable consists of a dark core at the center of the nanocable and a bright sheath around it. The length of the nano cable is several to several tens of μm.

3 and 4 are diagrams showing high-magnification transmission electron microscope images of nanocables.
It can be seen from FIG. 3 that this nanocable has a structure in which a dark core with a uniform diameter of about 130 nm is covered with a bright sheath with a uniform thickness of about 15 nm.
It can be seen from FIG. 4 that this nanocable has a structure in which a dark core with a uniform diameter of about 40 nm is covered with a bright sheath with a uniform thickness of about 40 nm.

FIG. 5 is a diagram showing the results of elemental analysis of nanocables using an energy dispersive X-ray analyzer, where the horizontal axis represents X-ray energy and the vertical axis represents X-ray intensity.
From the figure, it can be seen that the nanocable is composed of zinc, sulfur, silicon, and carbon. The copper signal is derived from the copper grid used when attaching the sample.

Next, nanotubes were formed by treating the nanocable with hydrochloric acid.
FIG. 6 is a view showing a transmission electron microscope image of the nanotube. From the figure, it can be seen that by treating with hydrochloric acid, the inner dark core is not dissolved, and a nanotube composed of an outer bright sheath is formed.

The nanotubes formed by this hydrochloric acid treatment were subjected to elemental analysis using an energy dispersive X-ray analyzer.
FIG. 7 is a diagram showing the results of elemental analysis of nanotubes using an energy dispersive X-ray analyzer, in which the horizontal axis represents X-ray energy and the vertical axis represents X-ray intensity. From the figure, it can be seen that the bright sheath is silicon carbide.

  5 and FIG. 7 collectively, it can be seen that the dark core portion of the nanocable is zinc sulfide and the bright sheath portion is silicon carbide. That is, it can be seen that the black powder produced by the production method of the present invention is a zinc sulfide nanocable covered with a silicon carbide film.

  According to the present invention, since it is a zinc sulfide nanocable coated with a silicon carbide film, it is suitable for application to high-temperature, high-power, high-frequency nanoelectronic devices and nanolight-emitting devices.

It is a cross-sectional schematic diagram of the vertical type high-frequency heating furnace used for the manufacturing method of this invention. It is a figure which shows the transmission electron microscope image of the zinc sulfide nano cable coat | covered with the silicon carbide film | membrane of this invention. It is a figure which shows the high magnification transmission electron microscope image of the zinc sulfide nano cable coat | covered with the silicon carbide film | membrane of this invention. It is a figure which shows the high magnification transmission electron microscope image of the zinc sulfide nano cable coat | covered with the silicon carbide film | membrane of this invention. It is a figure which shows the elemental analysis result of the zinc sulfide nanocable coat | covered with the silicon carbide film of this invention by the energy dispersive X-ray analyzer. It is a figure which shows the transmission electron microscope image of the silicon carbide nanotube formed by hydrochloric acid processing the zinc sulfide nano cable coat | covered with the silicon carbide film of this invention. It is a figure which shows the elemental-analysis result of the silicon carbide nanotube formed by the hydrochloric acid process of the zinc sulfide nano cable coat | covered with the silicon carbide film of this invention by the energy dispersive X-ray analyzer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Crucible 3 Carbon fiber of a heat insulating material 4 Graphite cylinder 5 Container 6 High frequency heating coil

Claims (4)

A zinc sulfide nanowire having a uniform diameter of 40 to 130 nm and a silicon carbide film having a uniform thickness of 15 to 50 nm covering the surface of the nanowire. A zinc sulfide nanocable coated with a silicon carbide film characterized by comprising: The mixed powder of vulcanization zinc powder and silicon monoxide powder by heating in an inert gas stream is sublimed zinc sulfide, zinc sulfide nanowires by supplying the sublimated zinc sulfide on a substrate held at a predetermined temperature The first gas forming step, and the inert gas is switched to methane gas and subsequently heated to generate graphite-like carbon by decomposition of the methane gas and to generate silicon by the disproportionation reaction of the silicon monoxide. The carbon and silicon produced here are supplied to and reacted with the surface of the zinc sulfide nanowire on the substrate maintained at the predetermined temperature, and the surface of the zinc sulfide nanowire is coated with a silicon carbide film. A process for producing a zinc sulfide nanocable characterized by comprising the steps of:   3. The method for producing a zinc sulfide nanocable according to claim 2, wherein the heating in the first step is performed in a temperature range of 1100 ° C. to 1200 ° C. for 0.5 hours to 1.5 hours. . 4. The zinc sulfide nanocable according to claim 2, wherein the heating in the second step is performed in a temperature range of 1250 ° C. to 1500 ° C. for 0.5 hours to 1.5 hours. Production method.