JP3834646B2 - Method for producing silicon dioxide nanowire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a method for producing silicon dioxide nanowires. More specifically, the invention of this application relates to a method for producing highly oriented silicon dioxide nanowires having a stable composition, which is expected to be applied to blue light emitting materials, optical heads, optical devices and the like.
[0002]
[Prior art]
Silicon dioxide (SiO ₂ ) has been widely studied as a material exhibiting photoluminescence, and bulk or film-like silicon dioxide is known to have an emission peak at a wavelength of 652 to 288 nm.
[0003]
In recent years, nanometer-sized silicon dioxide nanowires have been synthesized by various methods, and have been found to emit blue light when miniaturized to nanometer size (for example, Non-Patent Documents 1 and 2). In addition, a method for producing oriented silicon dioxide nanowires using a liquid gallium catalyst is also known (for example, Non-Patent Documents 4 and 5).
[0004]
[Non-Patent Document 1]
DP Yu, QL Hang and Y. Ding et al. “Amorphous silica nanowires: Intensive blue light emitters”, Applied Physics Letters, Vol. 73, No. 21, p.3076-3078, 1998 [Non-Patent Document 2]
XC Wu, WH Song and KY Wang et al., “Preparation and photoluminescence properties of amorphous silica nanowires”, Chemical Physics Letters, 336, p.53-56, 2001 [Non-patent Document 3]
ZQ Liu, SS Xie, and LF Sun et al., “Synthesis of α-SiO ₂ nanowires using Au nanoparticle catalysts on a silicon substrate”, Journal of Materials Research, Vol. 16, No. 3, p.683-686, 2001 Patent Document 4]
Pan. ZW, Dai. ZR and Ma. C. Wang et al., “Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires” Journal American Chemical Society, Vol. 124, No. 8, pp. 1817-1822, 2002 [Non-Patent Document 5]
B. Zheng, Y. Wu and P. Yang et al., “Synthesis of Ultra-Long and Highly Oriented Silicon Oxide Nanowires from Liquid Alloys”, Advanced Materials, Vol. 14, No. 2, p.122-124, 2002 [0005]
[Problems to be solved by the invention]
However, the conventional methods for producing silicon dioxide nanowires use a small amount of oxygen remaining under reduced pressure and moisture contained in a carrier gas as an oxygen source necessary for producing silicon dioxide nanowires. Therefore, there has been a problem that it is difficult to obtain a product having a constant and stable composition.
[0006]
Accordingly, the invention of this application has been made in view of the circumstances as described above, and solves the problems of the prior art, and provides a method for producing highly oriented silicon dioxide nanowires with a stable composition. Is an issue.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of this application firstly, a silicon substrate to which nickel nanoparticles are adhered and an indium oxide powder are mixed in an infrared irradiation heating furnace and mixed with nitrogen gas and ammonia gas. The silicon substrate to which nickel nanoparticles are attached is heated to 900 ° C. or higher and 1000 ° C. or lower by infra-red irradiation heating, and the indium oxide powder is heated to 650 ° C. or higher and 680 ° C. or lower. A method for producing silicon dioxide nanowires is provided.
[0008]
Secondly, in the first invention, there is provided a method for producing silicon dioxide nanowires, wherein the flow rate of nitrogen gas is 200 ml / min or more and 1000 ml / min or less.
[0009]
Thirdly, in the first or second invention, there is provided a method for producing silicon dioxide nanowires, characterized in that the flow rate of ammonia gas is 100 ml / min or more and 400 ml / min or less.
[0010]
Fourth, in any one of the first to third inventions, the heating time of the silicon substrate to which nickel nanoparticles are adhered and the indium oxide powder is 30 minutes or more and 60 minutes or less. A method is also provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The invention of this application has the features as described above, and an embodiment thereof will be described below.
[0012]
In the method for producing silicon dioxide nanowires of the invention of this application, the silicon substrate to which nickel nanoparticles are adhered and the indium oxide powder are arranged separately in an infrared irradiation heating furnace and in a mixed gas stream of nitrogen gas and ammonia gas. The present invention is characterized by heating the silicon substrate to which nickel nanoparticles are adhered to 900 ° C. or higher and 1000 ° C. or lower and heating the indium oxide powder to 650 ° C. or higher and 680 ° C. or lower by infrared irradiation heating. By performing the silicon dioxide nanowire manufacturing method, a silicon dioxide nanowire with a stable composition and highly oriented can be obtained.
[0013]
Further, according to the method for producing silicon dioxide nanowires of the invention of this application, oxygen necessary for forming silicon dioxide nanowires can be provided in a controlled state, and a small amount of oxygen remaining under the conventional reduced pressure. The silicon dioxide nanowires having an extremely stable composition can be formed without causing the composition of the product to become unstable as in the method of using moisture contained in the carrier gas.
[0014]
The reason for heating the silicon substrate to which the nickel nanoparticles are adhered to 900 ° C. or more and 1000 ° C. or less is that even if it is heated to a temperature higher than 1000 ° C., further improvement in the effect cannot be expected, and the temperature is set too high. This is because the silicon substrate is thermally damaged, and when heated to a temperature lower than 900 ° C., the growth rate of silicon dioxide nanowires becomes slow, and infrared rays are applied to the silicon substrate using an infrared irradiation heating furnace. And indium oxide is disposed at a position opposite to the infrared irradiation surface of the silicon substrate to which the nickel nanoparticles are adhered and separated from the silicon substrate, so that the temperature of indium oxide becomes lower than 650 ° C. and sublimation occurs. This is because it becomes insufficient.
[0015]
Further, heating indium oxide to 650 ° C. or more and 680 ° C. or less cannot be expected to improve the effect even if it is heated to a temperature higher than 680 ° C. If the temperature is lower than 650 ° C., indium oxide sublimation is not expected. This is because it does not proceed sufficiently or the decomposition reaction of the produced indium nitride does not proceed.
[0016]
Then, the silicon substrate and the indium oxide powder to which the nickel nanoparticles are attached can be easily and rapidly heated to an appropriate temperature by arranging them in an appropriate position in an infrared irradiation heating furnace.
[0017]
At this time, the heating time of the silicon substrate to which the nickel nanoparticles are adhered and the indium oxide powder is preferably 30 minutes or more and 60 minutes or less. If the heating time is longer than 60 minutes, the silicon substrate is damaged and shorter than 30 minutes. When heated for a period of time, the amount of silicon dioxide nanowires produced is reduced.
[0018]
Moreover, it is preferable that the flow rate of nitrogen gas is 200 ml / min or more and 1000 ml / min or less, and the flow rate of ammonia gas is 100 ml / min or more and 400 ml / min or less. This is because even if the flow rate of nitrogen gas is more than 1000 ml / min, the effect is not improved, and when the flow rate of nitrogen gas is less than 200 ml / min, the nitrogen gas sufficiently plays the role of carrier gas. If the flow rate of ammonia is more than 400 ml / min, the effect is not improved, and if the flow rate of ammonia is less than 100 ml / min, the reaction with indium oxide is not effective. It will be enough.
[0019]
Next, an example of a specific method for producing the silicon dioxide nanowire of the invention of this application will be shown.
[0020]
A dispersion of nickel nanoparticles sonicated in acetone (particle diameter 20 nm) is dropped onto a silicon wafer as a mirror-polished silicon substrate used as a deposition substrate to form a thin film of nickel nanoparticles. The surface of the silicon wafer to which the nickel nanoparticles are attached is faced down and attached to a boron nitride holder in an infrared irradiation heating furnace.
[0021]
Next, the indium oxide powder is placed on a boron nitride holder below the silicon wafer, 2 to 3 mm away from the silicon wafer, and the inside of the infrared irradiation heating furnace is reduced to 5 Pa or less in nitrogen gas and ammonia gas. Is introduced. The flow rate of nitrogen gas is preferably 200 ml / min or more and 1000 ml / min or less, and the flow rate of ammonia gas is preferably 100 ml / min or more and 400 ml / min or less.
[0022]
The silicon wafer to which the nickel nanoparticles are adhered is heated from the upper part of the infrared irradiation heating furnace, heated to 900 ° C. or higher and 1000 ° C. or lower, and the indium oxide powder disposed below is heated to 650 ° C. or higher and 680 ° C. or lower, The heating time is from 30 minutes to 60 minutes.
[0023]
After the heating reaction is completed, by cooling the inside of the heating furnace to room temperature, silicon dioxide nanowire products that are black-gray are deposited on the surface of the silicon wafer, and the silicon dioxide nanowire with a stable composition and highly oriented Can be obtained.
[0024]
Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail.
[0025]
【Example】
<Example 1>
Mirror-polished n-type silicon wafer (20 × 20 × 1 mm ³ ) (silicon substrate) manufactured by Mitsubishi Materials Corp., a dispersion of nickel nanoparticles (Nilaco, particle size of about 20 nm) ultrasonically treated in acetone ) To form a nickel thin film.
[0026]
The silicon wafer was attached to a boron nitride holder in an infrared irradiation heating furnace with the nickel nanoparticle adhering side facing down. Next, 200 mg of indium oxide powder (purity 99.9%) manufactured by Wako Pure Chemical Industries, Ltd. was placed below the silicon wafer and separated from the silicon wafer by 2 to 3 mm.
[0027]
Reduce the pressure in the heating furnace to 5 Pa or less, introduce nitrogen gas (flow rate 500 ml / min) and ammonia gas (flow rate 300 ml / min), irradiate infrared rays from the top of the heating furnace, and rapidly heat the silicon wafer to about 900 ° C. Heated. By this heating operation, the powder of indium oxide located below the silicon wafer became about 650 ° C. Then, after heating was continued for 45 minutes, the inside of the infrared irradiation heating furnace was cooled to room temperature, thereby depositing a blackish gray product on the silicon surface.
[0028]
The result of having observed the surface of the silicon wafer after a heating with the scanning electron microscope (SEM) is shown to Fig.1 (a). FIG. 1A shows that many spherical particles (particle diameter of 50 nm or more and 20 μm or less) exist on the surface of the silicon wafer, and the silicon wafer showed some etched holes. FIG. 1 (b) shows a detailed scanning electron microscope image in the hole of the silicon wafer, and it was confirmed that a large amount of nanowires were grown and the structure was closely packed and highly oriented. The nanowire has a uniform diameter (10-20 nm) and a length of 5-20 μm.
[0029]
FIG. 2A shows a transmission electron microscope image of the nanowire. It was found that the nanowire was sufficiently oriented in the same manner as the image observed with the scanning electron microscope. Further, the measurement result of the X-ray energy diffusion spectrum of this part is shown in FIG. 2 (b). It is an amorphous silicon dioxide nanowire having a chemical composition of silicon and oxygen and having an atomic ratio of 1: 2. It was confirmed that there was. The peak of copper (Cu) in FIG. 2B is derived from the copper grid that holds the sample.
[0030]
Next, referring to spherical particles, there are two types of large and small particles. As shown in FIG. 1 (a), the small particles have a diameter of 50 nm or more and 200 nm or less. ) Shows its X-ray energy diffusion spectrum, and its chemical composition is metallic indium. The carbon peak in FIG. 3A is derived from the carbon film coated on the copper grid.
[0031]
The other large particle has a diameter of 1 to 20 μm, and its X-ray energy diffusion spectrum is shown in FIG. 3 (b), but its chemical composition was found to be an alloy of indium and nickel. The ratio of indium and nickel in this alloy has various values.
[0032]
On the other hand, when a silicon wafer to which nickel nanoparticles are not attached is used as a substrate, highly oriented silicon dioxide nanowires cannot be obtained, so nickel acts as a catalyst for producing silicon dioxide nanowires. It was inferred that
[0033]
【The invention's effect】
As described above in detail, the invention of this application makes it possible to produce highly oriented silicon dioxide nanowires with a stable composition, so that future blue light-emitting materials, optical heads, optical devices, etc. Application is expected.
[Brief description of the drawings]
FIG. 1A is a photograph illustrating a scanning electron microscope image of particles deposited on a silicon wafer, obtained by an embodiment of the invention of this application.
(B) It is the photograph which illustrated the scanning electron microscope image of the silicon dioxide nanowire which was obtained by one Embodiment of this application and was closely packed and orientated.
FIG. 2 (a) is a photograph illustrating a transmission electron microscope image of silicon dioxide nanowires obtained by an embodiment of the invention of this application.
(B) It is a graph of the X-ray energy diffusion spectrum of the silicon dioxide nanowire obtained by one Embodiment of this invention.
FIG. 3A is a graph of an X-ray energy diffusion spectrum of indium particles having a particle diameter of 50 to 200 nm formed according to an embodiment of the invention of this application.
(B) It is a graph of the X-ray energy-diffusion spectrum of the indium-nickel alloy particle | grains with a particle diameter of 1-20 micrometers formed by one Embodiment of this application.

Claims (4)

Silicon substrate with nickel nanoparticles attached and indium oxide powder are placed in an infrared irradiation heating furnace and separated in a mixed gas stream of nitrogen gas and ammonia gas, and silicon with nickel nanoparticles attached by infrared irradiation heating A method for producing silicon dioxide nanowires, wherein the substrate is heated to 900 ° C. or higher and 1000 ° C. or lower, and the indium oxide powder is heated to 650 ° C. or higher and 680 ° C. or lower. The method for producing silicon dioxide nanowires according to claim 1, wherein the flow rate of nitrogen gas is 200 ml / min or more and 1000 ml / min or less. The method for producing silicon dioxide nanowires according to claim 1, wherein the flow rate of the ammonia gas is 100 ml / min or more and 400 ml / min or less. The method for producing silicon dioxide nanowires according to any one of claims 1 to 3, wherein the heating time of the silicon substrate to which the nickel nanoparticles are adhered and the indium oxide powder is 30 minutes or more and 60 minutes or less.

Images