JP2010095407A - Noble metal single crystal nanowire having directionality, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noble metal nanowire having directionality toward the surface of a single crystal substrate by using a noble metal oxide, a noble metal, or a noble metal halide as a precursor and to provide a method for producing the same. <P>SOLUTION: There are provided a noble metal single crystal nanowire vertically or horizontally grown to the surface of a single crystal substrate, which nanowire is produced by heat-treating a precursor placed at the front end of a reaction furnace and a semiconductor or nonconductor single crystal substrate placed at the rear end of the reaction furnace in an atmosphere of a flowing inert gas and a method for producing the same. According to the present invention, the noble metal nanowire can be produced by using a noncatalytic vapor-phase transfer method, the process is therefore simple and reproducible and has a merit of suitability for mass production. The produced nanowire is a high-purity and high-quality noble metal nanowire in a perfect single crystal state free from defects and impurities. The noble metal nanowire has a specified directionality toward the surface of the single crystal substrate and is controllable in relation to its directionality and arrangement. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a noble metal nanowire having directivity with respect to the surface of a single crystal substrate using a noble metal oxide, a noble metal or a halogenated noble metal as a precursor and utilizing a gas phase transport method, and a method for producing the same.

  In general, noble metal single crystal nanowires have high chemical stability and high thermal conductivity and electrical conductivity, and thus have high utility value for electric, magnetic, optical elements and sensors.

  For example, Au has high electrical and thermal conductivity, and exhibits high SERS (surface enhanced Raman scattering) efficiency in the visible light region due to the optical properties of Au. When such Au is manufactured in the form of nanowires, it can be expected to develop many application fields from microelectronic devices to optical sensors. In particular, in the case of SERS, the size of the signal depends largely on the precise morphology of the Au nanostructures, so the technology to produce nanowires with clean surfaces is the most important for producing accurate chemical or biosensors. It is.

  In general, metal nanostructures can adsorb molecules on the surface using SAM (Self-Assembled Monolayer). Therefore, molecules adsorbed uniformly on the surface of Au nanostructures using this. A layer can be formed. By observing the SERS phenomenon of molecules using Au single crystal nanowires and SAMs and using the molecules forming SAMs as linkers, selective biomolecular analysis and utilization to optical devices are expected.

  Further, for example, in the case of Pd, attention is focused on utilization for sensors.

  However, the development of various and precise gas sensors is still a serious issue in the work field where high precision is required with the development of science and technology.

  The development of sensors with excellent sensing ability is at a low level not only in Japan but also in advanced countries. In particular, along with the development of fuel cells, the development of highly sensitive fuel cell hydrogen gas sensors that can detect hydrogen leaks that are expected to occur when they are commercialized is used as next-generation clean energy. It is also an issue that must be paralleled with research on fuel cells.

  In addition, the development of substances used as sensor materials is as important as the development of hydrogen sensors. Among them, one of the materials that has received the most attention is Pd metal, which has a strong adsorptive power to hydrogen and incorporates Pd, which is a metal capable of absorbing hydrogen of about 900 times its own volume, into a nanowire. Various researches on application to high-sensitivity sensors are underway.

  As described above, the use value of noble metal nanowires for electric, magnetic or optical elements, sensors, etc. is very high, but there is no report that noble metal nanowires were synthesized in a gas phase without using a catalyst. Most of the existing methods for synthesizing noble metal nanowires are liquid phase chemical synthesis methods using molds, surfactants, and capping agents, and the results of producing noble metal nanowires in the gas phase without a catalyst are as follows. It has never been reported to date.

  In addition, the liquid phase chemical synthesis method has problems that it is difficult to control the shape of the noble metal nanowire, the purity of the produced noble metal nanowire is inferior, the nanowire has defects, or is synthesized into a polycrystalline nanowire. is there. Furthermore, since the production method is more complicated than the vapor phase synthesis method, there is a problem that is not suitable for mass production.

  In particular, the technical challenge of improving device performance by reducing device size raises the need for basic research on nanowire synthesis and properties. Such a nanowire is usually produced by a bottom-up synthesis method. However, due to the characteristics of such a synthesis method, the nanowire grows in a position and a direction without constant order. The nanowires grown randomly in this way act as obstacles to the substantial application of nanowires, so that it is possible to precisely control the position and orientation of nanowires in order to realize large-area devices. Process must be preceded.

  In order to solve the conventional problems as described above, the present invention uses a gas phase transport method that does not use a catalyst, and has a high purity and high quality noble metal single crystal nanowire having directionality to a substrate and its manufacture It aims to provide a method.

  Another object of the present invention is to provide a device or sensor provided with the noble metal single crystal nanowire of the present invention.

  The present inventor has proposed a method for producing high-quality, high-purity noble metal nanowires that is suitable for mass production, and further developed this method to control the position and direction of nanowires through precise control over the growth of noble metal nanowires. It came to discover the manufacturing method which can be adjusted. Accordingly, it is possible to provide a basis on which a three-dimensional element can be realized through noble metal nanowires with controlled directivity aligned on a substrate.

  Further, it is known that when a noble metal nanowire grown vertically is doped with a small amount of a transition metal such as Co, Fe, or Mn, it exhibits ferromagnetic properties. Therefore, the vertical growth synthesis method of the present invention provides a very important basic technology in the production of a three-dimensional memory.

  The noble metal single-crystal nanowire of the present invention is a semiconductor or non-conductor (insulating) single layer produced under a non-catalytic condition using a precursor containing a noble metal oxide, a noble metal or a noble metal halide. It is characterized by having directionality with respect to the surface of the crystal substrate.

  The directionality refers to the direction between the surface of the substrate and the major axis of the nanowires manufactured on the top of the substrate, and characteristically has a direction perpendicular or horizontal to the surface of the substrate.

  The noble metal single crystal nanowire is obtained by heat-treating the precursor disposed at the front end of the reaction furnace and the single crystal substrate disposed at the rear end of the reaction furnace at a constant pressure in an atmosphere in which an inert gas flows. Manufactured. Here, the directionality is controlled by the type of the precursor, the type of the single crystal substrate, the surface direction of the single crystal substrate, the temperature of the heat treatment, the flow rate of the inert gas, the pressure, or the adjustment thereof. Is done.

  The noble metal nanowire having a specific orientation with respect to the substrate preferably has a precursor maintained at 1000 to 1200 ° C., and the single crystal substrate is maintained at 800 to 1100 ° C., and the front end of the reactor It is manufactured by flowing the inert gas at 50 to 200 sccm from the (precursor) toward the rear end (single crystal substrate) of the reactor, and performing the heat treatment at a pressure of 3 to 20 torr.

At this time, as the precursor, a noble metal oxide, a noble metal or a halogenated noble metal can be used, and a noble metal single crystal nanowire can be manufactured using the precursor. As the noble metal oxide, gold oxide, silver oxide, palladium oxide, platinum oxide, iridium oxide, osmium oxide, rhodium oxide, or ruthenium oxide can be used. Gold, silver, palladium, platinum, iridium, osmium, rhodium, or ruthenium single crystal nanowires can be manufactured using the noble metal oxide. The noble metal may be gold, silver, palladium, platinum, iridium, osmium, rhodium, or ruthenium, and the halogenated noble metal is selected from a fluorinated noble metal, a noble metal chloride, a noble metal bromide, or a noble metal iodide. More preferably, it can be selected from noble metal chloride, noble metal bromide or noble metal iodide, most preferably noble metal chloride. The noble metal of the halogenated noble metal can be selected from gold, silver, palladium, platinum, iridium, osmium, rhodium or ruthenium, and the halogenated noble metal includes a halogenated noble metal hydrate.
The precursor is preferably a noble metal oxide or a noble metal.

  Preferably, the noble metal oxide is selected from gold oxide or palladium oxide, the noble metal is selected from gold or palladium, and the halogenated noble metal is selected from gold halide or palladium halide.

  The noble metal single crystal nanowire is characterized by having the same crystal structure as the noble metal bulk, has high purity and high crystallinity, and is characterized in that a large number of noble metal nanowires are formed on the substrate in a specific arrangement that is not random. is there.

  In addition, the noble metal single crystal nanowire is characterized by having a vertical direction that grows perpendicular to the surface of the single crystal substrate.

  The noble metal single crystal nanowire having the vertical direction has the same crystal structure as the noble metal bulk, and has a feature of facet shape. At this time, the facet surface shape means that the surface is not formed on all the surfaces constituting the crystal, and the inclination of the tangent is not on the outer periphery of the specific cross section including the short axis or long axis of the noble metal nanowire. It means to change continuously.

  The vertically grown noble metal single crystal nanowire is an Au single crystal nanowire, and the Au single crystal nanowire has a feature of a face centered cubic structure. In addition, the Au single crystal nanowire is characterized by a facet shape, and the tangential slope changes discontinuously on the outer circumference of the long-axis cross section of the Au single crystal nanowire. The growth direction of the Au single crystal nanowire is <110>, and thus, the Au single crystal nanowire <110> is perpendicular to the surface of the substrate. Preferably, the <110> direction of the Au single crystal nanowire is perpendicular to the {0001} surface of the sapphire single crystal substrate.

  The vertically grown noble metal single crystal nanowire is a Pd single crystal nanowire, and the Pd single crystal nanowire has a face-centered cubic structure. The Pd single crystal nanowire is characterized by a facet shape, and the tangential slope changes discontinuously on the outer circumference of the long-axis cross section of the Pd single crystal nanowire. The growth direction of the Pd single crystal nanowire is <110>. Preferably, the <110> direction of the Pd single crystal nanowire is perpendicular to the {0001} surface of the sapphire single crystal substrate.

  In the noble metal nanowire having a perpendicular direction to the substrate surface, the precursor is maintained at 1000 to 1200 ° C., the single crystal substrate is maintained at 850 to 1100 ° C., and the pressure is 3 to 8 torr. It is preferable to carry out under the condition that the inert gas flows from 50 to 200 sccm from the front end of the reactor toward the rear end of the reactor.

  The noble metal single crystal nanowire is characterized by having a horizontal direction that grows horizontally parallel to the surface of the single crystal substrate.

  The noble metal single crystal nanowire grown horizontally parallel to the surface of the single crystal substrate is an Au single crystal nanowire, and the Au single crystal nanowire has a face-centered cubic structure. And the {110} or {111} plane of the Au single crystal nanowire is characterized by being parallel.

  Preferably, the single crystal substrate is a sapphire substrate having a {0001} surface, and the {110} plane of the Au single crystal nanowire is parallel to the {0001} plane of the single crystal substrate.

  Preferably, the single crystal substrate is a sapphire substrate having a {11-20} surface, and a directionality in which the {111} plane of the Au single crystal nanowire is parallel to the {11-20} plane of the single crystal substrate. Have

  The noble metal single crystal nanowire grown horizontally in parallel with the surface of the single crystal substrate is a Pd single crystal nanowire, and the Pd single crystal nanowire has a face-centered cubic structure. At this time, the single crystal substrate on which the Pd single crystal nanowire is manufactured is preferably a {0001} surface sapphire substrate.

  In the noble metal nanowire having a horizontal orientation with respect to the substrate surface, the precursor is maintained at 1000 to 1200 ° C., the single crystal substrate is maintained at 800 to 950 ° C., and under a pressure of 15 to 20 torr. It is preferable that the reaction is performed under a condition where the inert gas flows at 50 to 200 sccm from the front end of the reaction furnace toward the rear end of the reaction furnace.

  The single crystal substrate in the present invention is a group 4 single crystal substrate, a group 3-5 single crystal substrate, a group 2-6 single crystal substrate, a group 4-6 single crystal substrate, a sapphire single crystal substrate, a silicon oxide single crystal substrate, And a laminated substrate thereof, preferably a sapphire single crystal substrate.

  A method for producing a noble metal single crystal nanowire according to the present invention comprises a precursor containing a noble metal oxide, noble metal or halogenated noble metal disposed at the front end of a reactor, and a semiconductor or non-conductor single conductor disposed at the rear end of the reactor. A feature is that a noble metal single crystal nanowire having directionality with respect to the surface of the single crystal substrate is manufactured by heat-treating the crystal substrate at a constant pressure in an atmosphere where an inert gas flows.

  The directionality means the direction between the surface of the substrate and the major axis of the nanowire manufactured on the top of the substrate, and the major axis of the noble metal single crystal nanowire is perpendicular to the surface of the single crystal substrate. Or, there is a feature having a horizontal directionality.

  In the manufacturing method according to the present invention, the directionality includes the type of the precursor, the type of the single crystal substrate, the surface direction of the single crystal substrate, the condition of the heat treatment, the flow rate of the inert gas, the pressure, or these There are features that are adjusted by the combination.

At this time, a noble metal oxide, a noble metal, or a noble metal halide can be used as the precursor, and a noble metal single crystal nanowire can be produced using the precursor. As the noble metal oxide, gold oxide, silver oxide, palladium oxide, platinum oxide, iridium oxide, osmium oxide, rhodium oxide, or ruthenium oxide can be used, and gold, silver, Palladium, platinum, iridium, osmium, rhodium or ruthenium single crystal nanowires can be produced. The noble metal may be gold, silver, palladium, platinum, iridium, osmium, rhodium or ruthenium, and the halogenated noble metal is selected from a fluorinated noble metal, a noble metal chloride, a noble metal bromide, or a noble metal iodide. More preferably, it is preferably selected from noble metal chloride, noble metal bromide, or noble metal iodide, and most preferably noble metal chloride. The noble metal of the halogenated noble metal is selected from gold, silver, palladium, platinum, iridium, osmium, rhodium, or ruthenium, and the halogenated noble metal includes a halogenated noble metal hydrate.
The precursor is preferably a noble metal oxide or a noble metal.

  Preferably, the noble metal oxide is selected from gold oxide or palladium oxide, the noble metal is selected from gold or palladium, and the halogenated noble metal is selected from gold halide or palladium halide.

  The single crystal substrate includes a group 4 single crystal substrate, a group 3-5 single crystal substrate, a group 2-6 single crystal substrate, a group 4-6 single crystal substrate, a sapphire single crystal substrate, a silicon oxide single crystal substrate, and a laminate thereof. It is one of the substrates, and a sapphire single crystal substrate is preferable.

  In the manufacturing method according to the present invention, the noble metal single crystal nanowires are grown perpendicular to the surface of the single crystal substrate. At this time, the precursor is maintained at 1000 to 1200 ° C., and the single crystal The substrate is preferably maintained at 850 to 1100 ° C., and it is preferable that an inert gas is allowed to flow at 50 to 200 sccm from the front end of the reactor toward the rear end of the reactor. Is preferably performed under a pressure of 3 to 8 torr. The single crystal substrate on which the vertically grown noble metal single crystal nanowire is manufactured is preferably a {0001} plane sapphire single crystal substrate.

  The precursor is gold oxide or gold, and the vertically grown noble metal single crystal nanowire is an Au single crystal nanowire.

  The precursor is palladium oxide or palladium, and the vertically grown noble metal single crystal nanowire is a Pd single crystal nanowire.

  The manufacturing method according to the present invention is characterized in that the noble metal single crystal nanowires grow horizontally in parallel to the surface of the single crystal substrate, wherein the precursor is maintained at 1000 to 1200 ° C. The crystal substrate is preferably maintained at 800 to 950 ° C., preferably under the condition that the inert gas flows from 50 to 200 sccm from the front end of the reactor toward the rear end of the reactor, The heat treatment is preferably performed under a pressure of 15 to 20 torr.

  The single crystal substrate on which the horizontally grown noble metal single crystal nanowire is manufactured is preferably a sapphire single crystal, and the surface of the sapphire single crystal substrate is a {0001} plane or a {11-20} plane. And

The precursor is gold oxide or gold, and the horizontally grown noble metal single crystal nanowire is an Au single crystal nanowire.
The precursor may be palladium oxide or palladium, and the horizontally grown noble metal single crystal nanowire may be a Pd single crystal nanowire.

The noble metal single crystal nanowire manufactured by the manufacturing method of the present invention is characterized by being included in an electric element, an optical element, a magnetic element, a memory element, or a MEMS structure.
The noble metal single crystal nanowire of the present invention is provided in an electric element, an optical element, a magnetic element, a memory element, a MEMS structure, or the like.

  In one embodiment of the production method of the present invention, noble metal nanowires can be produced using a gas phase transport method that does not use a catalyst, so that the process is simple and reproducible, and is advantageous for mass production. The manufactured noble metal nanowire is a highly crystalline, solid phase, noble metal nanowire having a high purity single crystal state, and the single crystal substrate and the manufactured noble metal nanowire are in a specific direction. There are characteristics that have sex.

  In addition, the noble metal nanowires can be controlled and reproduced so as to have a specific direction with respect to the substrate, and the physical properties of the noble metal nanowires themselves by mass production using a simple manufacturing process, Highly pure and high quality Au single crystal nanowires and Pd single crystals that have the opportunity to study optical and electromagnetic properties, and have good electrical and thermal conductivity among metals, and are chemically stable. By providing a nanowire, a method for utilizing a highly sensitive and highly efficient electric element, optical element, or magnetic element using the nanowire is provided, and in particular, a noble metal nanowire having directionality with respect to a substrate surface is provided. It can be effectively used in the field of three-dimensional MEMS structures or three-dimensional memory devices.

  Hereinafter, a noble metal single crystal nanowire of the present invention and a method for manufacturing the same will be described in detail with reference to the accompanying drawings. The accompanying drawings are provided to explain the idea of the present invention to those skilled in the art with preferred examples for carrying out the present invention. Accordingly, the present invention is not limited to the accompanying drawings, and may be embodied in other forms. The same reference numerals denote the same components throughout the specification.

  Unless otherwise defined, technical terms used have the meaning normally understood by those having ordinary knowledge in the technical field to which the present invention belongs, and the present invention is described in the following description and accompanying drawings. Descriptions of known functions and configurations that may be confused with the gist of are omitted.

  The method for producing noble metal nanowires having directionality with respect to the substrate of the present invention includes a precursor containing noble metal oxide, noble metal or halogenated noble metal disposed at the front end of the reaction furnace, and a rear end of the reaction furnace. The noble metal single crystal nanowire having directionality is formed on the surface of the single crystal substrate by heat-treating the semiconductor or non-conductor single crystal substrate at a constant pressure in an atmosphere where an inert gas flows.

  More specifically, the precursor vaporized by the heat treatment is transported by the flow of the inert gas to cause nucleation and nucleation of a noble metal on the surface of the single crystal substrate, and thereby the surface of the single crystal substrate. It has the feature of producing noble metal single crystal nanowires having a vertical or horizontal orientation.

  The production method of the present invention is a method of forming a noble metal nanowire on a single crystal substrate by using a noble metal oxide, noble metal or halogenated noble metal as a precursor without using a catalyst, and using the catalyst. Since noble metal single crystal nanowires are manufactured through a gas phase mass transfer route without any problems, the process is simple and reproducible, and there is an advantage that high purity nanowires without impurities can be manufactured.

  In addition, the nucleation and nucleation growth conditions are controlled to have a vertical or horizontal orientation with respect to the surface of the substrate, and are arranged in a uniform and specific direction independently of each other without contacting each other. Precious metal single crystal nanowires can be manufactured.

  The long axis of the noble metal single crystal nanowire generated by nucleation and growth on the single crystal substrate maintains a vertical or horizontal relationship with respect to the surface of the single crystal substrate, and such vertical or horizontal orientation Can be controlled by adjusting the type of the precursor, the type of the single crystal substrate, the surface direction of the single crystal substrate, the heat treatment conditions, the flow rate of the inert gas, the pressure, or these conditions.

  More specifically, the temperatures of the front end portion (precursor) of the reactor and the rear end portion (single crystal substrate) of the reactor are respectively adjusted to adjust the flow rate of the inert gas and the heat treatment tube used during the heat treatment. The surface phase and each surface energy of the target noble metal single crystal are adjusted by adjusting the pressure of the noble metal, and finally the nucleation driving force, nucleation growth driving force, nucleation rate and nucleation growth of the noble metal on the upper part of the single crystal substrate. A noble metal nanowire having a specific orientation with respect to a single crystal substrate can be produced by nucleation and growth of the noble metal while adjusting the speed.

  At this time, the single crystal substrate is a surface of a non-conductor or semiconductor single crystal in which nucleation of a target noble metal single crystal, particularly two-dimensional nucleation easily occurs, and elastic stress induced by lattice mismatch (Elastic stress or elastic strain) and line defects must be selected appropriately.

  Easiness of nucleation of noble metal single crystal includes the target noble metal single crystal nanowire material, the atomic structure such as the target noble metal single crystal nanowire low index plane, the single crystal substrate material, the surface of the single crystal substrate It is determined by adjusting the direction, or these factors.

  Furthermore, when the target noble metal single crystal nanowire material is the same, by adjusting the material of the single crystal substrate, the surface direction of the single crystal substrate, or these conditions, nucleation of the noble metal single crystal nanowire and Each of the nuclei grows differently, and finally the directionality of the noble metal single crystal nanowire with respect to the substrate is controlled.

  As described above, the non-conductor or semiconductor single crystal substrate is a semiconductor or non-conductor that is easily chemically / thermally stable under the conditions of the heat treatment, and easily nucleates the target noble metal single crystal nanowire. If there is, it can be used without any particular limitation. Specifically, a group 4 single crystal selected from a silicon single crystal, a germanium single crystal, or a silicon germanium single crystal, a gallium arsenide single crystal, an indium phosphide single crystal, or a gallium phosphide single crystal. , A group 2-6 single crystal, a group 4-6 single crystal, a sapphire single crystal, a silicon oxide single crystal, and a laminated substrate thereof can be selected.

  For example, when the target noble metal single crystal nanowire is a single crystal nanowire of Au or Pd, it is easy to purchase at a low cost, and nucleation of the noble metal occurs on a low index surface that is a thermodynamically stable surface. It is substantial and preferred to use an easily occurring sapphire single crystal substrate.

  As described above, in order to manufacture a noble metal nanowire having directivity with respect to the surface of the single crystal substrate, it is necessary to control the initial nucleation and nucleation stages of the noble metal. The core conditions in this control are the pressure in the heat treatment piping, the heat treatment temperature at the front end of the reactor (precursor) and the rear end of the reactor (substrate), and the flow rate of the inert gas.

  Through theoretical and experimental results, it is known that all materials having crystallinity undergo a single-round phase transformation in which the atomic structure of the surface changes due to temperature, pressure, atmosphere, impurities, etc. that affect the surface energy. It has been. Temperature can be cited as an element having the greatest influence on the phase transformation, but the shape of a single crystal that is thermodynamically stable at a high temperature is a round shape that is not angular, and the surface atoms are It has an atomically irregular structure. At low temperatures, the influence of broken bond energy due to the crystal orientation of the single crystal is greater than the entropy energy, resulting in an angular shape. Each surface constituting the angular shape is a surface in a crystal direction with a small surface energy, and at this time, the surface is known to have an atomically flat structure.

  Such a phase transformation of the thermodynamic surface has a great influence on the nucleation and growth of particles, but when the atomic structure of the surface is an irregular structure, nucleation and nucleation occur. However, if the surface structure is an atomically flat structure, 2-D nucleation and lateral growth will occur.

  The method for producing noble metal nanowires aligned to have a specific orientation with respect to the surface of the single crystal substrate of the present invention utilizes the thermodynamically stable surface phase of the noble metal by utilizing the temperature and pressure of the heat treatment. And adjusting the flow rate of the inert gas to adjust the nucleation and nucleation growth driving force transmitted to the surface of the single crystal substrate to obtain the aligned direction as described above. .

  In order to adjust the above-described conditions affecting nucleation and growth, the precursor is preferably maintained at 1000 to 1200 ° C. and the single crystal substrate is maintained at 800 to 1100 ° C. Preferably, the inert gas is allowed to flow from 50 to 200 sccm from the front end (precursor) of the reactor toward the rear end (single crystal substrate) of the reactor, and the heat treatment is performed at 3 to 20 torr. It is preferable to carry out under pressure.

  When deviating from the ranges such as the preferable temperature, pressure and flow rate of the inert gas described above, the directionality with respect to the surface of the single crystal substrate is lost, or a rod or particle-shaped noble metal not in the form of nanowires is obtained, and the single crystal Instead, nanowires composed of polycrystalline materials are generated.

  In order to manufacture noble metal nanowires aligned to have a direction perpendicular to the surface of the single crystal substrate, the precursor is maintained at 1000 to 1200 ° C., and the single crystal substrate is Preferably, the temperature is maintained at 1100 ° C., and it is preferable that the inert gas flow at 50 to 200 sccm from the front end portion (precursor) of the reaction furnace to the rear end portion (single crystal substrate) of the reaction furnace, The heat treatment is preferably performed under a pressure of 3 to 8 torr.

  In order to manufacture noble metal nanowires aligned in a horizontal direction with respect to the surface of the single crystal substrate, the precursor is maintained at 1000 to 1200 ° C., and the single crystal substrate is 800 to 950. Preferably, the inert gas is allowed to flow at 50 to 200 sccm from the front end (precursor) of the reactor to the rear end (single crystal substrate) of the reactor. Is preferably performed under a pressure of 15 to 20 torr.

  The heat treatment time must be optimized according to the temperature, the flow of the inert gas, and the pressure conditions during the heat treatment, but the heat treatment is preferably performed for 30 minutes to 2 hours. During the heat treatment time, the precursor vaporized by the inert gas moves to the single crystal substrate to be used for nucleation and growth, but at the same time, it is already formed on the single crystal substrate. The movement of the noble metal through the gas phase and the substrate surface occurs between the formed noble metals, and particle growth occurs.

  Accordingly, after the heat treatment, the heat treatment is further performed in a state where the precursor is removed from the single crystal substrate on which the noble metal nanowires are formed, and the density of the noble metal nanowires aligned with respect to the single crystal substrate is determined. You can also adjust the size.

Precursors that can be used in the production method of the present invention include noble metal oxides, noble metals, and noble metal halides, and these can be used to produce noble metal single crystal nanowires. As the noble metal oxide, gold oxide, silver oxide, palladium oxide, platinum oxide, iridium oxide, osmium oxide, rhodium oxide or ruthenium oxide can be used, and gold, silver, Palladium, platinum, iridium, osmium, rhodium or ruthenium single crystal nanowires can be produced. The noble metal may be gold, silver, palladium, platinum, iridium, osmium, rhodium, or ruthenium, and the halogenated noble metal is selected from a fluorinated noble metal, a noble metal chloride, a noble metal bromide, or a noble metal iodide. More preferably, it is selected from noble metal chloride, noble metal bromide or noble metal iodide, and most preferably noble metal chloride. The noble metal of the halogenated noble metal is selected from gold, silver, palladium, platinum, iridium, osmium, rhodium or ruthenium, and the halogenated noble metal includes a halogenated noble metal hydrate.
The precursor is preferably a noble metal oxide or a noble metal.

  In addition, in order to adjust the magnetic characteristics of the noble metal nanowire, the precursor may further encapsulate a transition metal material. The transition metal material may be Co, Fe, Mg, Mn, Cr, Zr, Cu, Zn, V, Ti, Nb, Y or a mixture thereof.

  Using the oxide as a precursor, gold oxide, gold or gold halide, preferably gold oxide or gold, to produce aligned Au single crystal nanowires having directionality with respect to the surface of the single crystal substrate. And producing aligned Pd single crystal nanowires having directionality with respect to the surface of the single crystal substrate using palladium oxide, palladium or palladium halide, preferably palladium oxide or palladium as the precursor. Can do.

  In this case, the gold halide is preferably selected from gold fluoride, gold chloride, gold bromide or gold iodide, and the palladium halide is palladium fluoride, palladium chloride, palladium bromide or iodide. Preferably it is selected from palladium.

In order to experimentally prove the superiority of the manufacturing method of the present invention, according to the manufacturing method of the present invention, Au ₂ O ₃ , PdO, Au or Pd is used as a precursor, and an Au single layer having directionality with respect to the substrate is used. Crystal nanowires and Pd single crystal nanowires were respectively produced. Hereinafter, Examples 1 to 5 will be described in detail.

Example 1
Au single crystal nanowires oriented perpendicularly to the substrate were manufactured using a vapor phase transport method in a reaction furnace.
The reactor is divided into a front end portion and a rear end portion, and is independently provided with a heating body and a temperature control device. The piping in the reaction furnace was made of quartz material having a diameter of 1 inch and a length of 60 cm.

First, a boat-type container made of a high-purity alumina material charged with 0.02 g of Au ₂ O ₃ (Sigma-Aldrich, 334057) as a precursor was placed at the center of the front end of the reactor. In addition, a sapphire single crystal having a (0001) plane on the surface of the single crystal substrate was disposed at the center of the rear end of the reactor.
Next, argon gas was introduced from the front end of the reaction furnace and exhausted to the rear end of the reaction furnace. At this time, a vacuum pump is attached to the rear end portion of the reactor, and the pressure in the quartz pipe is maintained at 5 torr by the vacuum pump, and an argon gas of 100 sccm is utilized using an MFC (Mass Flow Controller). To flow.

  The temperature of the front end of the reactor (alumina boat type vessel (hereinafter abbreviated as precursor) in which precursors are charged) is maintained at 1100 ° C., and the temperature of the rear end of the reactor (silicon substrate) Were heat-treated for 30 minutes in a state maintained at 900 ° C. to produce Au single crystal nanowires.

(Example 2)
Pd single crystal nanowires oriented perpendicularly to the substrate were manufactured using a vapor transport method in a reaction furnace.
A Pd single crystal nanowire was manufactured using the same conditions and apparatus as in Example 1 except for the temperature of the heat treatment, the precursor, the flow rate of the inert gas, the pressure, and the like.

  As a precursor, 0.05 g of PdO (Sigma-Aldrich, 203971) was used, and the pressure in the quartz pipe was maintained at 6 torr using a vacuum pump.

  While maintaining the state where argon gas flows at 140 sccm, the temperature of the front end (precursor) of the reactor is maintained at 1100 ° C., and the temperature of the rear end (sapphire substrate) of the reactor is maintained at 900 ° C. Pd single crystal nanowires were manufactured by heat treatment for minutes.

(Example 3)
Au single crystal nanowires oriented horizontally with respect to the substrate were manufactured using a vapor phase transport method in a reaction furnace.
Au single-crystal nanowires were manufactured using the same conditions and apparatus as in Example 1 except for the heat treatment temperature, pressure, and inert gas flow rate.

  While maintaining the pressure in the quartz pipe at 17 torr using a vacuum pump, the temperature of the front end (precursor) of the reactor is maintained at 1100 ° C. while argon gas flows at 80 sccm, and the rear end of the reactor The part (sapphire substrate) was heat-treated for 30 minutes while maintaining the temperature at 850 ° C. to produce Au single crystal nanowires.

Example 4
Au single crystal nanowires oriented horizontally with respect to the substrate were manufactured using a vapor phase transport method in a reaction furnace.
An Au single crystal nanowire was manufactured using the same conditions and apparatus as in Example 3 except that a sapphire single crystal substrate having a (11-20) plane was used.

(Example 5)
Pd single crystal nanowires oriented horizontally with respect to the substrate were manufactured using a vapor phase transport method in a reaction furnace.
Pd single crystal nanowires were manufactured using the same conditions and apparatus as in Example 2 except for the heat treatment temperature, pressure, and inert gas flow rate.

  While maintaining the pressure in the quartz pipe by a vacuum pump at 20 torr, the temperature of the front end (precursor) of the reactor is maintained at 1100 ° C. while argon gas flows at 100 sccm, and the rear end of the reactor (sapphire) The substrate was maintained at 850 ° C. for 30 minutes to produce Pd single crystal nanowires.

(Example 6)
Using Au precursors, Au single crystal nanowires oriented perpendicular to the substrate were produced. Au single crystal nanowires were manufactured under the same conditions as in Example 1 except that 0.02 g of Au was used as the precursor.

(Example 7)
Using a Pd precursor, Pd single crystal nanowires oriented perpendicular to the substrate were fabricated. A Pd single crystal nanowire was manufactured under the same conditions as in Example 2 except that 0.05 g of Pd was used as the precursor.

(Example 8)
Using Au precursors, Au single crystal nanowires oriented horizontally with respect to the substrate were produced. Au single crystal nanowires were manufactured under the same conditions as in Example 3 except that Au was used as the precursor.

Example 9
Using a Pd precursor, Pd single crystal nanowires oriented horizontally with respect to the substrate were produced. A Pd single crystal nanowire was manufactured under the same conditions as in Example 5 except that Pd was used as the precursor.

  The physical characteristics of the nanowires manufactured in Example 1 are similar to the nanowires manufactured in Example 6, and the physical characteristics of the nanowires manufactured in Example 2 are manufactured in Example 7. The physical characteristics of the nanowire manufactured in Example 3 are similar to those of the nanowire manufactured in Example 8, and the physical characteristics of the nanowire manufactured in Example 5 are It was similar to the nanowire produced in Example 9. Therefore, the characteristics of the single crystal nanowire in the following analysis will be described based on Examples 1 to 5.

  That is, the noble metal single crystal nanowires manufactured according to Examples 1 to 5 are analyzed to analyze the quality, shape, purity, and the like of the noble metal single crystal nanowires having directionality with respect to the substrate, and the results are shown in the accompanying drawings. The description will be given with reference.

  1 to 4 show the results of measurement analysis on the Au single crystal nanowire manufactured by Example 1. FIG.

  First, FIG. 1A is an SEM photograph of Au single crystal nanowires manufactured on a sapphire single crystal substrate. As can be seen from FIG. 1, the Au single crystal nanowire of Example 1 of the present invention shows the characteristics of being grown and arranged perpendicular to the surface of the single crystal substrate. In addition, a large amount of single crystal nanowires are manufactured, and Au single crystal nanowires having a shape in which the nanowires are straightly extended in the long axis direction and individually separated without contacting each other are manufactured. .

  Further, the facet surface shape of the Au single crystal nanowire is shown macroscopically by the high-percentage SEM photograph of FIG.

FIG. 2 shows the result of structural diffraction by XRD of Au single crystal nanowire.
As can be seen from the diffraction result of FIG. 2, the face-centered cubic structure (FCC Structure) of the manufactured Au single crystal nanowire is shown, which is in good agreement with the bulk Au diffraction result without the peak shift of diffraction. ing.
The structure and shape of the Au single crystal nanowire manufactured as described above were observed in detail using TEM.

  As can be seen from the results of FIGS. 3A to 3C, it can be confirmed that the manufactured Au single-crystal nanowire has a facet shape while having a smooth surface.

Through the SAED (Selected Area Electron Diffraction) pattern of FIG. 3A, it can be confirmed that the manufactured Au single crystal nanowire is a single crystal composed of a single crystal.
3A and 3B, it can be confirmed that the growth direction (long axis) of the Au single crystal nanowire is the <110> direction. Moreover, it can confirm that a nanowire is a perfect single crystal body from the result of FIG.3 (c).

  According to the results of FIGS. 1 to 3C, the cross section perpendicular to the growth direction of the Au single crystal nanowire has a facet surface shape in which the slope value of the tangent on the outer periphery of the cross section changes discontinuously. It can be confirmed that each surface forming the facet surface shape of the nanowire having the facet surface shape is a low index surface such as {111} {110} {100}.

  FIG. 4 shows the result of analyzing the components of the Au single crystal nanowire using EDS (Energy Dispersive Spectroscopy) attached to the TEM equipment. As can be seen from the results of FIG. 4, it is confirmed that the manufactured nanowire is made only of Au, except for the secondary measured material due to the characteristics of the measurement equipment such as the grid. be able to.

  5 to 8 show the results of measurement analysis for the Pd single crystal nanowire manufactured by Example 2. FIG.

  FIG. 5A is an SEM photograph of a Pd single crystal nanowire manufactured on a sapphire single crystal substrate. As can be seen from the figure, it can be confirmed that a large number of nanowires having a diameter of 50 to 150 nm and a length of 5 to 10 μm are grown and arranged perpendicular to the surface of the single crystal substrate. In addition, it can be confirmed that the nanowires have a shape extending straight in the long axis direction, and Pd single crystal nanowires are manufactured in which the nanowires are individually separated without contacting each other. Furthermore, it can be confirmed that the facet surface shape of the Pd single crystal nanowire is shown macroscopically from the high-rate SEM photograph of FIG.

FIG. 6 is a result of structural diffraction by XRD of a Pd single crystal nanowire.
As can be seen from the diffraction results of FIG. 6, it can be confirmed that the manufactured Pd single crystal nanowires coincide with the bulk Pd diffraction results and show a face-centered cubic structure.

  The structure and shape of the Pd single crystal nanowire manufactured as described above were observed in detail using TEM.

  As can be seen from the results of FIGS. 7A to 7C, it can be confirmed that the manufactured Pd single crystal nanowire has a facet shape while having a smooth surface.

  It can be confirmed that the Pd single crystal nanowire manufactured through the SAED pattern of FIG. 7A is a single crystal composed of a single crystal, and the growth direction (long axis) of the Pd single crystal nanowire is < 110> direction can be confirmed. Further, it can be confirmed that each surface forming the surface of the facet-shaped nanowire is a low index surface such as {111} {110} {100}. Furthermore, it can be confirmed through the HRTEM image of FIG. 7C that the manufactured single crystal nanowire has high crystallinity without defects.

FIG. 8 shows a result of analyzing the components of the Pd single crystal nanowire using the EDS mounted on the TEM equipment.
FIG. 13 is an SEM photograph of Pd single crystal nanowire.
As can be seen from the results of FIG. 8 and FIG. 13, it is confirmed that the manufactured nanowire is made only of Pd, excluding the substances measured secondary due to the characteristics of the measurement equipment such as the grid. Can do.

  As described above, as a result of analyzing the noble metal nanowires manufactured according to Example 1 and Example 2 of the present invention, the noble metal nanowires of the present invention are commonly formed on the surface of the single crystal substrate regardless of the type of the material. On the other hand, it was confirmed that the nanowires were characterized by being vertically grown and arranged, were high-quality single crystals, and were high-purity nanowires that did not contain impurities. In addition, a large amount of nanowires were formed on the substrate, and it was confirmed that the nanowires were individually separated without contacting each other. As a crystallographic feature, the noble metal single crystal nanowire of the present invention has the same crystal structure as the noble metal bulk, the growth direction (long axis) of the single crystal nanowire is the <100> direction, and the facet shape It can be confirmed.

  9 and 10 show the results of measurement analysis for the Au single crystal nanowire manufactured in Example 3. FIG.

FIG. 9 is a SEM photograph of Au single crystal nanowires manufactured with a sapphire single crystal substrate.
As can be seen from FIG. 9, it can be confirmed that a large amount of nanowires grown and arranged in the horizontal direction with respect to the surface of the single crystal substrate are manufactured.

  FIG. 10 is a high-resolution TEM photograph at the interface between the manufactured Au single crystal nanowire and the sapphire substrate. As can be seen from the electron diffraction pattern on the upper right side of FIG. 10, the manufactured Au single crystal nanowire is pure. It can be confirmed that it consists of a single crystal and has the same face-centered cubic structure as bulk Au. Further, as a result of detailed observation of the crystallographic relationship between the manufactured Au single crystal nanowire and the single crystal substrate using TEM, as can be seen from the results of FIG. 110) plane and the (0001) plane which is the sapphire single crystal surface can be confirmed to be epitaxially grown.

  The Au single crystal nanowire epitaxially grown on the surface of the sapphire single crystal can have a growth direction of <110>, and the long axis <110> of the Au single crystal nanowire has a <11-20> direction on the surface of the sapphire single crystal. It can be confirmed that they are parallel. As a result, it is confirmed that a large amount of Au single crystal nanowire grown horizontally as shown in FIG. 9 has a structure arranged in a triangle or hexagon in six directions that are crystallographically identical to <11-20>. be able to.

  11 to 12 show the results of measurement analysis for the Au single crystal nanowire manufactured through Example 4. FIG.

  FIG. 11 is an SEM photograph of Au single crystal nanowires manufactured on an a-plane sapphire single crystal substrate. As in Example 3, it can be confirmed that a large amount of nanowires that are grown and arranged horizontally with respect to the surface of the single crystal substrate are manufactured. However, unlike Example 3 in which the long axis <110> of the Au single crystal nanowire is arranged in six directions that are crystallographically identical to <11-20> of the single crystal substrate, a single direction It is shown that Au single crystal nanowires arranged in the above are manufactured.

  FIG. 12 is a high-rate TEM photograph of the interface between the produced Au single crystal nanowire and the sapphire substrate. As can be seen from the electron diffraction pattern on the upper right side of FIG. 12, it is confirmed that the manufactured Au single crystal nanowire is made of pure single crystal and has the same face-centered cubic structure as bulk Au. be able to. Further, as a result of detailed observation of the crystallographic relationship between the manufactured Au single crystal nanowire and the single crystal substrate using TEM, the growth direction of <110> in the Au single crystal nanowire is similar to the result of Example 3. Can be confirmed. The (11-1) plane of the manufactured Au single crystal nanowire and the (11-20) plane which is the surface of the sapphire single crystal are epitaxially grown, and the long axis direction of the Au single crystal nanowire is <110>. It can be confirmed that the direction and the <0001> direction of the a-plane sapphire single crystal substrate are parallel. Thus, it can be recognized that a large amount of Au single crystal nanowires grown horizontally as shown in FIG. 11 are arranged in a single direction of <0001>.

  In addition, as a result of component analysis of the Au single crystal nanowires manufactured in Example 3 and Example 4 using the EDS mounted on the TEM equipment, as in the case of Example 1, the characteristics of the measurement equipment such as the grit are secondary. Excluding the substances measured next, it was confirmed that the manufactured nanowires were pure Au single crystal nanowires made of only Au.

  FIG. 13 is a SEM photograph of the Pd single crystal nanowire manufactured in Example 5. Using TEM indicating that Pd single crystal nanowires grown parallel to the substrate are manufactured like Au single crystal nanowires grown parallel to the substrate in Example 3 and Example 4. As a result of analyzing the crystal structure, a single-crystal Pd single-crystal nanowire was produced in the same manner as in Example 2. As a result of component analysis using EDS mounted on the TEM equipment, pure Pd alone was obtained. Pd single crystal nanowire was confirmed.

  Through Examples 1 to 5, a pure single crystal produced under a non-catalytic condition using a precursor containing a noble metal oxide, noble metal or halogenated noble metal, and high quality with few internal defects In addition, it can be confirmed that the high-purity noble metal nanowires have a certain direction and are formed on the top of the substrate. Such orientation may be controlled by the type of the precursor, the type of the single crystal substrate, the surface direction of the single crystal substrate, the temperature of the heat treatment, the flow rate of the inert gas, the pressure, or adjustment thereof. I was able to confirm that I could do it.

  As described above, the noble metal nanowire manufacturing method of the present invention and the noble metal nanowire manufactured by this manufacturing method can control the orientation with respect to the surface of the substrate and the size and shape of the nanowire, and can be reproduced through a simple manufacturing process. By mass-producing high-purity and high-quality nanowires, it provides a foundation for studying physical, optical, and electromagnetic properties of noble metal nanowires themselves. Also, among metals, electrical conductivity and thermal conductivity are good, and chemically stable noble metal nanowires can be used to improve the characteristics of electrical, optical and magnetic elements, and reduce their size be able to.

  In particular, it is used in a spectroscopic device that utilizes the surface characteristics of noble metal nanowires, a biological information detection device (biosensor), or a sensor device that detects light, electricity, magnetism, heat or vibration, or a combination thereof. The detection characteristics can be adjusted to improve the sensitivity, accuracy, and reproducibility of the sensor.

  In addition, it can be used to manufacture a MEMS structure, a three-dimensional memory element, and the like by using a vertical arrangement with respect to the surface of the single crystal substrate.

  In the description of the embodiments and drawings described above, the specific precursor and the specific single crystal substrate have been described in a limited manner, but this is for a general understanding of the present invention. The present invention is not limited to the above-described embodiments and the like, and various modifications and variations can be made from such description by those who have ordinary knowledge in the field to which the present invention belongs.

It is a SEM photograph figure of Au single crystal nanowire manufactured by Example 1 of the present invention. 1 is an XRD diagram of an Au single crystal nanowire manufactured according to Example 1 of the present invention. FIG. FIG. 2 is a TEM diagram of an Au single crystal nanowire manufactured according to Example 1 of the present invention, in which (a) is a limited field diffraction diagram of the Au single crystal nanowire of (b), and (b) is an Au single crystal nanowire of FIG. (C) is a high-resolution TEM photograph of (b). 1 is an EDS diagram of an Au single crystal nanowire manufactured according to Example 1 of the present invention. FIG. It is a SEM photograph of Pd single crystal nanowire manufactured by Example 2 of the present invention. It is a XRD figure of the Pd single crystal nanowire manufactured by Example 2 of this invention. FIG. 3 is a TEM diagram of a Pd single crystal nanowire manufactured according to Example 2 of the present invention, in which (a) is a limited field diffraction diagram of (b) a Pd single crystal nanowire, and (b) is a Pd single crystal nanowire of FIG. It is a dark field image, (c) is a high-resolution TEM photograph. It is an EDS figure of the Pd single crystal nanowire manufactured by Example 2 of the present invention. It is a SEM photograph of Au single crystal nanowire manufactured by Example 3 of the present invention. 4 is a high-resolution TEM photograph of an interface between an Au single crystal nanowire and a substrate manufactured according to Example 3 of the present invention. It is a SEM photograph of Au single crystal nanowire manufactured by Example 4 of the present invention. 6 is a high-resolution TEM photograph of an interface between an Au single crystal nanowire and a substrate manufactured according to Example 4 of the present invention. It is a SEM photograph figure of Pd single crystal nanowire manufactured by Example 5 of the present invention.

Claims (34)

  A noble metal single crystal nanowire having directionality with respect to the surface of a semiconductor or non-conductor single crystal substrate produced under a non-catalytic condition using a precursor containing a noble metal oxide, noble metal or halogenated noble metal.   The noble metal single crystal nanowire according to claim 1, wherein the directivity is a vertical or horizontal directivity.   3. The noble metal oxide is selected from gold oxide or palladium oxide, the noble metal is selected from gold or palladium, and the halogenated noble metal is selected from gold halide or palladium halide. Noble metal single crystal nanowire.   The noble metal single crystal nanowire according to claim 2 or 3, wherein the noble metal single crystal nanowire is grown perpendicularly to a surface of the single crystal substrate.   The noble metal single crystal nanowire according to claim 4, wherein the precursor is gold oxide or gold, and the vertically grown noble metal single crystal nanowire is an Au single crystal nanowire.   6. The noble metal single crystal nanowire according to claim 5, wherein the Au single crystal nanowire has a face-centered cubic structure and a major axis direction is <110>.   The noble metal single crystal nanowire according to claim 4, wherein the precursor is palladium oxide or palladium, and the vertically grown noble metal single crystal nanowire is a Pd single crystal nanowire.   The noble metal single crystal nanowire according to claim 7, wherein the Pd single crystal nanowire has a face-centered cubic structure, and a major axis direction of the Pd single crystal nanowire is <110>.   The noble metal single crystal nanowire according to claim 4, wherein the noble metal single crystal nanowire has the same crystal structure as a noble metal bulk and has a faceted surface shape.   The precursor is maintained at 1000 to 1200 ° C., and the single crystal substrate is maintained at 850 to 1100 ° C. from the front end of the reactor toward the rear end of the reactor under a pressure of 3 to 8 torr. The noble metal single crystal nanowire according to claim 4, wherein the noble metal single crystal nanowire is grown vertically to the surface of the single crystal substrate by flowing an inert gas at 50 to 200 sccm.   The noble metal single crystal nanowire according to claim 2, wherein the noble metal single crystal nanowire is horizontally grown parallel to the surface of the single crystal substrate.   The noble metal single crystal nanowire according to claim 11, wherein the precursor is gold oxide or gold, and the noble metal single crystal nanowire that grows horizontally in parallel with the surface of the single crystal substrate is an Au single crystal nanowire.   The single crystal substrate is a {0001} plane sapphire substrate, and the {0001} plane of the single crystal substrate and the face-centered cubic {110} plane of the Au single crystal nanowire are parallel to each other. Noble metal single crystal nanowire.   The single crystal substrate is a {11-20} sapphire substrate, and the {11-20} plane of the single crystal substrate and the face-centered cubic {111} plane of the Au single crystal nanowire are parallel to each other. 12. A noble metal single crystal nanowire according to 12.   12. The noble metal single crystal nanowire according to claim 11, wherein the precursor is palladium oxide or palladium, and the noble metal single crystal nanowire that is horizontally grown parallel to the surface of the single crystal substrate is a Pd single crystal nanowire.   The noble metal single crystal nanowire according to claim 15, wherein the Pd single crystal nanowire has a face-centered cubic structure.   The noble metal single crystal nanowire according to claim 15, wherein the single crystal substrate is a sapphire substrate having a {0001} plane.   The precursor is maintained at 1000 to 1200 ° C., the single crystal substrate is maintained at 800 to 950 ° C., and from the front end of the reactor to the rear end of the reactor under a pressure of 15 to 20 torr. 12. The noble metal single crystal nanowire according to claim 11, wherein the noble metal single crystal nanowire is grown horizontally in parallel with the surface of the single crystal substrate by flowing an inert gas at 50 to 200 sccm.   The noble metal single crystal nanowire according to claim 1, wherein the single crystal substrate is a sapphire single crystal substrate.   Precursor containing noble metal oxide, noble metal or halogenated noble metal disposed at the front end of the reaction furnace, and a semiconductor or non-conductor single crystal substrate disposed at the rear end of the reaction furnace in an atmosphere where an inert gas flows, A method for producing a noble metal single crystal nanowire, characterized in that a noble metal single crystal nanowire having a directivity with respect to the surface of the single crystal substrate is formed by heat treatment at a constant pressure.   21. The method for producing a noble metal single crystal nanowire according to claim 20, wherein a major axis of the noble metal single crystal nanowire has a vertical or horizontal orientation with respect to a surface of the single crystal substrate.   The directionality is adjusted by the type of the precursor, the type of the single crystal substrate, the surface direction of the single crystal substrate, the conditions of the heat treatment, the flow rate of the inert gas, the pressure, or a combination thereof. The manufacturing method of the noble metal single-crystal nanowire as described in 1 ..   21. The method of manufacturing a noble metal single crystal nanowire according to claim 20, wherein the noble metal single crystal nanowire is vertically grown with respect to a surface of the single crystal substrate.   The method for producing noble metal single crystal nanowires according to claim 23, wherein the precursor is maintained at 1000 to 1200 ° C, and the single crystal substrate is maintained at 850 to 1100 ° C.   25. The method for producing a noble metal single crystal nanowire according to claim 24, wherein the inert gas is allowed to flow from 50 to 200 sccm from the front end of the reactor toward the rear end of the reactor.   26. The method for producing a noble metal single crystal nanowire according to claim 25, wherein the heat treatment is performed under a pressure of 3 to 8 torr.   21. The method of manufacturing a noble metal single crystal nanowire according to claim 20, wherein the noble metal single crystal nanowire is horizontally grown parallel to the surface of the single crystal substrate.   28. The method of manufacturing a noble metal single crystal nanowire according to claim 27, wherein the precursor is maintained at 1000 to 1200 [deg.] C., and the single crystal substrate is maintained at 800 to 950 [deg.] C.   29. The method for producing a noble metal single crystal nanowire according to claim 28, wherein the inert gas is allowed to flow from 50 to 200 sccm from the front end of the reactor toward the rear end of the reactor.   30. The method of producing a noble metal single crystal nanowire according to claim 29, wherein the heat treatment is performed under a pressure of 15 to 20 torr.   21. The noble metal according to claim 20, wherein the noble metal oxide is selected from gold oxide or palladium oxide, the noble metal is selected from gold or palladium, and the halogenated noble metal is selected from gold halide or palladium halide. A method for producing a single crystal nanowire.   The single crystal substrate includes a group 4 single crystal substrate, a group 3-5 single crystal substrate, a group 2-6 single crystal substrate, a group 4-6 single crystal substrate, a sapphire single crystal substrate, a silicon oxide single crystal substrate, and a laminate thereof. 21. The method for producing a noble metal single crystal nanowire according to claim 20, which is any one of the substrates.   33. An element including an electric element, an optical element, a magnetic element, a memory element, or a MEMS structure provided with the noble metal single crystal nanowire manufactured by the manufacturing method according to any one of claims 20 to 32.   An element including an electric element, an optical element, a magnetic element, a memory element, or a MEMS structure provided with the noble metal single crystal nanowire according to any one of claims 1 to 19.

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