JP5144135B2 - Nanowire, device including nanowire, and method for manufacturing the same - Google Patents

Description

  The present invention relates to a nanowire in which fine particles are self-organized on the surface of a nanowire body.

  Research and development for miniaturizing transistors in large scale integrated circuits (LSIs) and thin film transistors (TFTs) in flat panel displays are being actively promoted. In the silicon semiconductor process, microfabrication of 0.1 μm or less is realized by shortening the wavelength of the light source for exposure in the photolithography process. However, there is a limit to miniaturization by the conventional lithography technique, and along with the progress of miniaturization, the costs of the exposure apparatus and the mask member are rapidly increasing.

  In recent years, carbon nanotubes (Non-patent Document 1) and nanowires (Patent Document 1) formed from materials exhibiting semiconductor properties have attracted attention. Carbon nanotubes and nanowires are fine structures having a diameter of about 1 nm to 1 μm, and can be formed in a self-organized manner. For this reason, there is a possibility of realizing a nanometer-sized high-performance electronic device without using advanced photolithography technology and etching technology. Such a fine structure is expected as a technology that enables a high-performance device to be produced at a low cost without using a complicated process technology.

  Hereinafter, a conventional nanowire structure will be described with reference to FIG.

  FIG. 20A shows a schematic structural diagram of a nanowire. The length of the nanowire is about 500 nm to 1 mm, and can be appropriately set according to the application purpose.

  FIG. 20B shows a nanowire (hereinafter referred to as “core-shell nanowire”) 201 in which the core portion 202 (inner side) and the shell portion 203 (outer side) are made of different materials (Patent Document 2). ).

  FIG. 20C shows a nanowire 204 (hetero nanowire) in which a first semiconductor nanowire 205 and a second semiconductor nanowire 206 are arranged in the length direction of the nanowire (Patent Document 2).

  In the hetero-growth technique based on the normal epitaxial growth technique, it is necessary to match the lattice constant at the hetero interface in order to reduce defects and dislocations, and there is a restriction in material selection. However, nanowires having a quasi-one-dimensional structure may be able to alleviate stress due to lattice constant mismatch, so that the degree of freedom in material selection can be improved.

  Nanowires that can realize microstructures and material engineering in a self-organizing manner are expected in the future.

Non-Patent Document 2 reports that by doping boron into silicon nanowires, the outer diameter of the nanowires increases and irregularities and gold-rich microparticles (nanoparticles) are generated on the surface thereof.
Special table 2004-535066 specification Special table 2004-532133 specification R. Martel, et al. , “Single-and multi-wall carbon nanotube field-effect transistors,” Appl. Phys. Lett. 73 pp. 2447, 1998 L. Pan, et al. , “Effect of diborane on the microstructure of boron-doped silicon nanowires” J. et al. Cryst. Growth. 277 pp. 428, 2005

  Nanowires are expected to be used in various applications and are being actively researched. However, since they are extremely fine structures, the surface of nanowires can be further processed to improve functionality. Is extremely difficult.

  Non-Patent Document 1 discloses that when the impurity is doped during the growth of the nanowire, irregular irregularities are formed on the surface of the nanowire, but the formation of the irregularities cannot be controlled and applied to an electronic device. It is difficult.

  Although it is known that a large number of fine particles are formed on the surface of the nanowire depending on the growth conditions of the nanowire, a technique for selectively forming such fine particles in a desired region of the nanowire is not known. If the formation and distribution of fine particles on the surface of nanowires can be controlled, nanowires with fine particles can be applied to various electronic devices, but unfortunately no such control technology has been developed. Is the current situation.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a nanowire in which fine particles are formed in a self-organized manner on the surface of a nanowire body, a device including the nanowire, and a manufacturing method thereof. It is in.

  The nanowire of the present invention is formed of a crystalline semiconductor nanowire main body formed of a first material and a second material partially including an element constituting the semiconductor, and at least a part of the surface of the nanowire main body. And the surface of the nanowire body is smooth.

  In a preferred embodiment, an oxide film is not substantially formed on at least a portion of the smooth surface of the nanowire body that is in contact with the plurality of fine particles.

  In a preferred embodiment, the nanowire has an average diameter of 1 nm or more and 1 μm or less.

  In a preferred embodiment, the plurality of fine particles are dispersed throughout the surface of the nanowire body.

  In a preferred embodiment, the surface of the nanowire body is divided into a first region in which the plurality of fine particles are dispersed and a second region in which the plurality of fine particles are not formed.

  In a preferred embodiment, the plurality of fine particles contain at least one metal element.

  In a preferred embodiment, the plurality of fine particles are formed of a metal or an alloy of a metal and the first material.

  In a preferred embodiment, the second material contains at least one metal selected from the group consisting of gold, silver, copper, and iridium.

  In a preferred embodiment, the average particle size of the plurality of fine particles is less than 20 nm.

  In a preferred embodiment, the nanowire body is a single crystal.

  In a preferred embodiment, the first material is formed of at least one material selected from the group consisting of silicon, germanium, and carbon.

  The field effect transistor of the present invention is a field effect transistor comprising any one of the above nanowires, a channel region formed in the nanowire, an electrode connected to the nanowire and functioning as a source region and a drain region, A gate electrode that controls conductivity in at least a part of the channel region; and a gate insulating film that electrically insulates the gate electrode from the channel region.

  In a preferred embodiment, at least some of the plurality of fine particles are present in a region in contact with the electrode on the surface of the nanowire.

  In a preferred embodiment, an impurity is doped in a portion of the nanowire that contacts the electrode.

  In a preferred embodiment, the fine particles are chemically modified with functional molecules.

  In a preferred embodiment, the functional molecule contains a —SH group at a binding site with the fine particle.

In a preferred embodiment, the functional _{molecule, X- (C n H m)} -SH (n, m are natural numbers) and _{X: -NH 2, -COOH, -C} x H y, -C a F b ( x, y, a, and b are natural numbers).

  The sensor of the present invention includes any one of the nanowires functioning as a sensing unit, and a first electrode and a second electrode connected to the nanowire.

  The electronic device of the present invention includes any one of the above nanowires in which a functional molecule is chemically modified in the fine particles, and a member chemically bonded to the nanowire via the functional molecule.

  The electronic device of the present invention includes any one of the above nanowires.

  In a preferred embodiment, the electronic device further includes an electrode in contact with the plurality of fine particles in the nanowire.

  The method of manufacturing a nanowire according to the present invention includes a step (A) of preparing a substrate having catalytic metal particles disposed on the surface, and a step (B) of growing a nanowire body formed of a first material on the substrate. In the step (B), a plurality of fine particles formed from the second material are grown on at least a part of the surface of the nanowire body.

  Since the nanowire of the present invention includes a plurality of fine particles located on the surface of the nanowire main body, various devices using the fine particles can be realized. In the present invention, metal particles can be formed in a self-organized manner on the surface of the nanowire body, and the manufacture thereof is easy. Therefore, to electronic devices such as transistors and memories, and electronic equipment using these electronic devices. The application of can be expected.

  In order to manufacture such a nanowire by the conventional technique, it is necessary to attach separately produced metal particles to the surface of the nanowire body. When formed by such a method, it becomes difficult to increase the bonding force between the metal particles and the nanowire and to accurately control the density and particle size of the metal particles.

  Further, it has been reported that gold fine particles can be formed during the growth of the nanowire, but irregular irregularities are formed on the surface of the nanowire body. When irregular irregularities are generated on the surface of the nanowire body made of a semiconductor, crystal defects and levels on the surface increase and the semiconductor characteristics are deteriorated. According to the present invention, since the surface of the nanowire main body is maintained smooth, excellent characteristics can be exhibited.

  First, a nanowire according to the present invention will be described with reference to FIG. 1A is a perspective view of a nanowire according to the present invention, and FIG. 1B is a cross-sectional view taken along line AA of FIG.

  The illustrated nanowire is a nanowire in which a plurality of fine particles are formed on the surface of a nanowire body (hereinafter referred to as “fine particle coated nanowire”). A fine particle-coated nanowire 101 shown in FIG. 1 has a structure in which a catalytic metal 102 is provided at one end of a nanowire main body, and a plurality of fine particles 103 are arranged on the surface of the nanowire main body 104. The catalyst metal 102 and the fine particles 103 contain the same metal. The catalytic metal 102 can be removed after the nanowire is formed, and the final particulate coated nanowire need not have the catalytic metal 102. For simplicity, illustration of the catalyst metal 102 is omitted in drawings other than FIG.

  The nanowire body 104 is made of a crystalline semiconductor (first material) having a smooth surface. For example, a group IV semiconductor such as Si, Ge, or SiGe, a group III-V semiconductor such as GaAs, InP, or InAs, or ZnS is used. , ZnSe, CdS, etc., can be formed from II-VI group semiconductors. Here, the “crystalline semiconductor” is preferably a single crystal, but may partially include a defect or may be polycrystalline.

  The catalytic metal 102 and the fine particles 103 are formed from, for example, a metal atom such as gold, silver, copper, nickel, cobalt, iron, titanium, or an alloy or a composite material of these metal atoms and a material constituting the nanowire body 104. Can be done.

  The fine particles 103 are formed of a second material that partially contains an element constituting the semiconductor of the nanowire body 104. The average particle diameter of the fine particles 103 is about 1 nm to 50 nm, and typically 20 nm or less. The cross section of the fine particles typically has a shape close to a circle or an ellipse, but may have various shapes including polygons. The length of the fine particle coated nanowire 101 is, for example, about 1 μm to 100 μm, and the diameter thereof is, for example, about 2 nm to 1 μm.

  In a preferred embodiment, an oxide film is not substantially formed on at least a portion of the smooth surface of the nanowire body 104 that is in contact with the plurality of fine particles 103. As will be described later, the metal contained in the plurality of fine particles 103 is derived from the catalyst metal 102, and the distribution of the plurality of fine particles 103 is that the fine particles 103 move on the smooth surface of the nanowire body 104 (migration). Has spread by. According to the inventors' experiments, this migration is unlikely to occur when the surface of the nanowire body 104 is oxidized. For this reason, it is preferable to cause formation and migration of the plurality of fine particles 103 in a situation where the surface of the nanowire body 104 is being oxidized. As a result, a configuration in which an oxide film is not substantially formed on at least a portion of the smooth surface of the nanowire body 104 that is in contact with the plurality of fine particles 103 is realized. After such migration is completed, portions that are not in contact with the plurality of fine particles 103 may be oxidized afterwards or may be covered with an oxide film.

  Next, an example of the method for producing the fine particle-coated nanowire according to the present invention will be described with reference to FIGS. 2 (a) to 2 (c) are process diagrams showing the nanowire manufacturing method of the present invention. Nanowires can be grown by a gas-liquid-solid (VLS) growth mechanism, which is a known method.

  First, as shown in FIG. 2A, the catalytic metal 102 is disposed on an arbitrary substrate 105. Examples of the arrangement method include a method in which a metal colloid solution is applied by a spin coating method and a method in which a metal thin film is deposited by a sputtering method or a vapor deposition method to form particles.

  Next, the substrate 105 on which the catalytic metal 102 is disposed is introduced into a chamber such as a CVD apparatus. As shown in FIG. 2B, a source gas 106 containing an element constituting the nanowire is introduced into the chamber and kept at a predetermined pressure. The substrate 105 is heated by a lamp, a heater, or the like to keep the substrate at an arbitrary temperature (however, the temperature is lower than the temperature at which the source gas 106 decomposes on the substrate 105). In such a situation, the source gas 106 is selectively decomposed only in the vicinity of the catalytic metal 102. The catalytic metal 102 reacts with the decomposed source gas to form an alloy 102a of the catalytic metal and the elements constituting the nanowire.

  Next, as shown in FIG. 2C, the elements constituting the nanowires generated by the decomposition of the source gas 106 are dissolved in the alloy 102a of the catalyst metal and the elements constituting the nanowires and become supersaturated. . The element constituting the nanowire is precipitated from the supersaturated alloy 102a of the catalyst metal and the element constituting the nanowire, and the precipitated element aggregates to grow a crystalline semiconductor (nanowire body).

In the present invention, fine particles are formed on the nanowire surface in a self-organizing manner during the heat treatment during or after the nanowire growth. In order to form such fine particles, the nanowire growth atmosphere can be controlled. For example, by growing nanowires under a low pressure (for example, atmospheric gas pressure: 10 ⁻³ Torr or less), impurities such as boron are concentrated at a high concentration. Even if it is not doped, a fine particle-coated nanowire can be formed. Detailed growth conditions will be described later.

  Hereinafter, preferred embodiments of the present invention will be described.

(Embodiment 1)
First, a first embodiment of a nanowire according to the present invention will be described with reference to FIGS. Since the nanowire of the present embodiment is a nanowire in which gold particles (gold dots) are formed on the Si nanowire body, it is hereinafter referred to as “gold dot-coated Si nanowire”.

  FIG. 3 is a photograph showing an example of a transmission electron microscope (TEM) image of the gold dot-coated Si nanowire 110 in the present embodiment. 4A is a graph showing the elemental analysis results in the POINT1 region in FIG. 3, and FIG. 4B is a graph showing the elemental analysis results in the POINT2 region in FIG. FIG. 5A is a cross-sectional TEM image of a plane perpendicular to the length direction of the gold dot-coated Si nanowire, and FIG. 5B is an enlarged view of a portion B in FIG. 5A. . 6A is a diagram showing the elemental analysis results in the POINT3 region of FIG. 5B, and FIG. 6B is a diagram showing the elemental analysis results in the POINT4 region of FIG. 5B.

  The gold dot-coated Si nanowire 110 shown in FIG. 3 has a structure in which a plurality of metal particles 112 are arranged on the surface of the Si nanowire body 111. From the results of the elemental analysis shown in FIG. 4, it can be seen that the particulate black spots shown in FIG. 3 are composed of gold and silicon elements, and the other regions are composed of silicon elements. Therefore, the gold dot-coated Si nanowire 110 has a structure in which a plurality of particles composed of gold and silicon elements having a particle diameter of about 2 nm to 5 nm are formed in a self-organized manner.

  The cross-sectional shape of the gold dot-coated Si nanowire 110 is typically a hexagon as shown in FIG. 5, and has a shape covered with a silicon oxide film 113 of about 2 nm to 3 nm outside the Si nanowire body 111. ing. The silicon oxide film 113 is a natural oxide film formed by reacting with oxygen in the atmosphere even in a normal bulk Si substrate or the like. The formation of the silicon oxide film 113 is performed after the metal particles 112 are formed on the surface of the Si nanowire body 111, and at least when the metal particles 112 are formed, the metal particles 112 are formed from the Si nanowire body 111. In contact with the semiconductor.

  From the results of elemental analysis shown in FIGS. 6A and 6B, the POINT3 region in FIG. 5B is composed of gold or silicon element, whereas the POINT4 region is composed of silicon element. I understand that. Therefore, it can be seen that the metal particles 112 shown in FIG. 3 are present on the surface of the Si nanowire body 111.

  Gold dot-coated Si nanowires in which fine particles of about 2 nm to 10 nm are formed on the surface of the nanowire body in a self-organized manner are expected to be widely applied to electronic devices such as transistors, memories, and sensors.

  Next, an example of a nanowire manufacturing method in the present embodiment will be described with reference to FIGS.

  First, as shown in FIG. 7A, a silicon substrate 115 that functions as a growth substrate is prepared, and catalytic metal particles 114 are formed on the silicon substrate 115. The growth substrate only needs to have heat resistance against the heat treatment temperature during nanowire growth. For example, a silicon oxide film or a silicon nitride film is deposited on a substrate made of another semiconductor material, an insulating material, a refractory metal material, or the like. It may be what was done. The plane orientation and resistivity of the growth substrate may be set arbitrarily.

  In this embodiment, gold is used as the catalyst metal particles 114. The catalytic metal particles 114 are excellent in promoting decomposition of the raw material gas, and are used to form a eutectic state with the elements constituting the nanowire and promote the growth of the nanowire. Since the size of the catalyst metal particle 114 is approximately equal to the diameter of the nanowire, it is set so that a nanowire having a desired diameter can be obtained. Usually, the catalyst metal particle 114 has a diameter of 1 nm to 10000 nm, preferably 5 nm to 100 nm.

  As a method of forming the catalytic metal particles 114 on the silicon substrate 115, a known method can be used. For example, a thin film of a catalytic metal is formed on the surface of the silicon substrate 115 using a known thin film forming apparatus such as a sputtering method or a vapor deposition method. Thereafter, the catalytic metal thin film may be self-aggregated by heat-treating the catalytic metal thin film.

  As a method for forming gold particles, for example, an EB vapor deposition method may be used to deposit a gold thin film of about 0.5 nm to 10 nm and heat treatment may be performed at 500 ° C. for about 30 minutes to 3 hours. Since the diameter of the gold particles depends on the film thickness of the gold thin film and the heat treatment conditions, the film thickness of the gold thin film is adjusted so as to obtain a desired gold particle diameter. In this embodiment, a gold thin film is deposited to a thickness of about 2 nm, and heat treatment is performed at 500 ° C. for 10 minutes in a vacuum.

  Next, the silicon substrate 115 on which the catalytic metal particles 114 are formed is inserted into a chamber such as a CVD apparatus. Then, as shown in FIG. 7B, a raw material gas 106 containing silicon element is introduced into the chamber and maintained at a predetermined pressure, and the silicon substrate 115 is heated at a temperature lower than the temperature at which the raw material gas 106 decomposes. Thereby, on the silicon substrate 115, the element constituting the nanowire in the source gas 106 decomposed on the surface of the catalytic metal particle 114 reacts with the catalytic metal particle 114 to form an alloy thereof.

As the source gas 106 for forming the silicon nanowire, SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiH ₂ Cl ₂ , SiCl ₄ or the like can be used. As an example of the growth conditions in this embodiment, an ultra-high vacuum CVD apparatus is used as the CVD apparatus, the substrate temperature is set between 350 ° C. and 500 ° C., Si ₂ H ₆ gas is used as the source gas, The Si ₂ H ₆ gas flow rate is adjusted in the range of 10 to 150 sccm so that the pressure becomes 10 ⁻⁵ Torr to 10 ⁻² Torr. For example, when the above conditions are used, growth can be performed at a rate of 50 nm / min to 300 nm / min.

  Next, as shown in FIG. 7C, silicon, which is an element constituting the nanowire, is precipitated by decomposition of the source gas 106, and the deposited silicon is aggregated to grow a crystalline semiconductor layer. Is formed. During the growth process, the catalytic metal particles 114 are in a eutectic state containing Si. Since the eutectic state of gold and Si is realized at about 360 ° C. or higher, the growth of the gold dot-coated nanowire 110 is performed at a temperature higher than 360 ° C.

In the gold dot-coated Si nanowire 110 of the present embodiment, for example, during the nanowire growth described above, gold particles (metal particles 112) are formed on the surface of the Si nanowire body 111 in a self-organized manner. In order to grow metal particles 112 made of gold or an alloy of gold and silicon on the surface of the Si nanowire body 111, the nanowire growth atmosphere may be controlled under a low pressure (for example, 10 ⁻³ Torr or less, preferably 10 ⁻⁴ (Torr or less).

  Non-Patent Document 2 reports that gold nanoparticles are formed on silicon nanowires when boron is doped at a high concentration in silicon nanowires. However, irregular irregularities are formed on the surface of the nanowire body disclosed in Non-Patent Document 2, and the smoothness is lost. Further, in the portion where the gold nanoparticles are formed, the diameter of the nanowire body is larger than that in the other portions.

  According to the manufacturing method of the present embodiment, the metal particles 112 can be generated in a self-organized manner even when impurities are not doped at a high concentration, and since the surface of the Si nanowire body 111 is smooth, crystal defects Etc. are difficult to form, and the characteristics of the semiconductor are improved. In the present specification, “smooth” means that there are only irregularities sufficiently smaller than the average particle diameter of the fine particles formed on the surface, and an irregularity step exceeding 5 nm is formed on the surface of the nanowire body. Preferably not.

  For example, the density of the metal particles 112 can be controlled by adjusting the nanowire growth atmosphere. For example, the density of the metal particles 112 can be increased as the pressure in the chamber during nanowire growth is reduced.

  Hereinafter, the formation mechanism of the metal particles 112 will be described in more detail.

  First, FIG. 21A to FIG. 22B will be referred to. 21A and 21B are photographs showing silicon nanowires grown at an atmospheric gas pressure of 0.2 Torr, and FIGS. 22A and 22B are photographs showing silicon nanowires grown at an atmospheric gas pressure of 0.01 Torr. FIGS. 21A and 22A, in which a large number of nanowires are shown, are photographs taken by SEM, and FIGS. 21B and 22B taken by enlarging one nanowire are photographs taken by TEM.

  In FIG. 21B, fine particles are not observed on the surface of the nanowire body, and in FIG. 22B, it can be seen that a large number of fine particles are distributed on the surface of the nanowire body.

  The nanowire growth rate in FIGS. 21A and 21B was about 1 μm / min, whereas the nanowire growth rate in FIGS. 22A and 22B was about 0.2 μm / min. Thus, the growth rate greatly changes depending on the pressure of the atmospheric gas during the growth process, and the growth rate of the nanowire decreases as the atmospheric gas pressure decreases.

The atmospheric gas contains the raw material gas at a predetermined partial pressure (for example, 10 ⁻³ to 10 ⁻⁶ Torr), and the difference in atmospheric gas pressure depends on the pressure of the carrier gas (typically H ₂ ). ing. When the atmospheric gas pressure is increased by increasing the pressure of the carrier gas, the mean free path of the source gas molecules is shortened, and the frequency of the source gas molecules colliding with the eutectic catalyst metal within a unit time is increased. For this reason, if the partial pressure of the source gas is constant, the higher the atmospheric gas pressure (carrier gas pressure), the higher the nanowire growth rate.

  The reason why fine particles are formed on the surface of the nanowire body when the atmospheric gas pressure is low is considered to be because the amount of Si supplied to the catalyst metal in the eutectic state during the nanowire growth process is reduced. For this reason, in a catalyst metal, Si concentration falls and gold becomes excessive. Excess gold is thought to leave the catalytic metal and migrate the surface of the nanowire body.

  Thus, the formation of fine particles can be controlled by adjusting the atmospheric gas pressure during the nanowire growth step. For example, when the atmospheric gas pressure is 0.1 Torr or less, the generation of fine particles can be promoted. However, when the pressure is increased beyond 0.1 Torr, the formation of fine particles is suppressed and the formation of fine particles is prevented. You can also. Further, when the atmospheric gas pressure is changed during the nanowire growth process, it is possible to selectively form fine particles in a specific portion of one nanowire. That is, it is possible to obtain a heterostructure nanowire in which a portion where fine particles are formed on the surface and a portion where fine particles are not formed on the surface are connected.

  FIG. 23A to FIG. 24B show the results of the subsequent heat treatment performed on the nanowires in which the fine particles were not formed immediately after the growth as shown in FIG. 21B. FIG. 23A and FIG. 23B are TEM photographs (dark field images) of samples subjected to heat treatment (anneal) at 450 ° C. for 10 minutes under high vacuum (UHV). On the other hand, FIG. 24A and FIG. 24B are TEM photographs (dark field images) of samples subjected to heat treatment at 450 ° C. for 10 minutes under a low vacuum (0.3 Torr).

  As shown in FIGS. 23B and 24B, the migration distance of the fine particles varies depending on the pressure difference of the atmospheric gas during the heat treatment. That is, the higher the atmospheric gas pressure during heat treatment, the longer the migration distance of the fine particles, and the fine particles can be distributed over a wide range on the surface of the nanowire body.

  The heat treatment is performed continuously with the growth process in the growth apparatus without exposing the grown nanowire body to the atmosphere. When the nanowire body after growth is exposed to the atmosphere, a natural oxide film is formed on the surface of the nanowire body, so that it is difficult to migrate the fine particles by heat treatment. FIG. 25A and FIG. 25B are TEM photographs (dark field images) of samples subjected to heat treatment at 450 ° C. for 10 minutes under atmospheric pressure (nitrogen atmosphere) after exposure to the atmosphere. As can be seen from FIG. 25A and FIG. 25B, even if the heat treatment is performed after exposure to the atmosphere, the distribution of fine particles does not spread and is only slightly present in the vicinity of the catalyst metal shown in FIG. 25A.

  For this reason, when forming microparticles after growth rather than during nanowire growth, it is preferable to take care not to oxidize the surface of the nanowire body.

  The heat treatment for forming fine particles after the nanowire growth needs to be performed at a temperature equal to or higher than the temperature at which the semiconductor and the catalyst metal constituting the nanowire body become eutectic. In the case of gold dot-coated nanowires, it is preferable to perform heat treatment at a temperature of 360 to 750 ° C. The reason why the upper limit of the heat treatment temperature is set to 750 ° C. is that the evaporation of gold starts when the theoretical temperature exceeds 750 ° C.

  In the present embodiment, the metal particles 112 made of gold are formed on the surface of the Si nanowire body 111 made of silicon. However, metal particles 112 other than gold may be formed on the surface of the Si nanowire body 111. Desired metal particles 112 can be formed by using a catalyst metal made of the same material as the material of the metal particles 112 to be formed on the surface of the Si nanowire body 111.

  By changing the source gas, the material constituting the nanowire body can be changed. For example, when growing germanium nanowires, germane gas may be used as a source gas.

  Thus, the particles attached to the surface of the nanowire body can be formed during the formation of the conventional nanowire without adding a special manufacturing process, and by changing the growth conditions of the nanowire, The particle density can be controlled. Fine metal particles can be formed on the surface of the nanowire body using a known nanowire growth apparatus, and the density can be controlled. Therefore, application to electronic devices such as transistors and memories is expected.

(Embodiment 2)
Next, a second embodiment of a nanowire according to the present invention will be described with reference to FIGS. The nanowire of this embodiment is a hetero metal particle coated nanowire.

  FIG. 8A is a perspective view showing a hetero metal particle coated nanowire structure, FIG. 8B is a perspective view showing a hetero metal particle coated nanowire structure in which metal particles are present at both ends, and FIG. FIG. 2 is a perspective view showing a hetero metal particle-coated nanowire structure having no metal particles at both ends. 9A is a hetero gold particle-coated Si nanowire TEM image, FIG. 9B is an X portion enlarged TEM image of FIG. 9A, and FIG. 9C is a Y portion enlarged TEM image of FIG. 9A. It is. FIG. 10A shows the results of elemental analysis in the POINT1 region of FIG. 9, FIG. 10B shows the results of POINT2 in FIG. 9, and FIG. 10C shows the results of elemental analysis in the POINT3 region of FIG.

  As shown in FIG. 8A, the hetero metal particle-coated nanowire of the present embodiment is divided into a region 120 where the metal particles 112 are present on the surface of the nanowire body 104 and a region 121 where the metal particles 112 are not present. . The region 121 where no metal particles are present has a structure similar to that of a conventional nanowire.

  The hetero metal particle-coated nanowire shown in FIG. 8 (b) is different from the nanowire of FIG. 8 (a) in that it has regions 120 where the metal particles 112 are present at both ends of the nanowire body 104. It is the same in other respects.

  The hetero metal particle-coated nanowire shown in FIG. 8C is different from the nanowire of FIG. 8A in that it has regions 121 where the metal particles 112 do not exist at both ends of the nanowire body 104.

  FIGS. 9A to 9C show TEM images of hetero gold-coated Si nanowires in which gold particles are formed on the surface of a silicon nanowire body. From FIG. 9, it can be seen that the hetero gold-coated Si nanowire has a region 123 where gold dots exist in the Y portion in the vicinity of the gold catalyst 122, and the X portion has a conventional nanowire structure.

  10A to 10C, the POINT1 region (gold catalyst 122) is composed of gold, the POINT2 region (metal particles 112) is composed of gold and silicon, and the POINT3 region (Si nanowire body 111) is composed of silicon element. You can see that The size of the gold particles is about 2 nm to 10 nm.

  In this manner, a region where fine metal particles of about 2 nm to 10 nm are formed in a self-organized manner on one nanowire body and a region where no metal particles are formed can be arranged. Such nanowires are also expected to be widely applied to electronic devices such as transistors, memories, and sensors.

  Next, the manufacturing method of the nanowire of this embodiment is demonstrated.

  The method of manufacturing the nanowire of this embodiment uses the manufacturing process of the gold dot-coated Si nanowire described in the first embodiment. Below, the manufacturing method of this embodiment is demonstrated.

First, gold particles are formed on a silicon substrate. As a formation method, the same method as in Embodiment 1 can be used. Next, this growth substrate is inserted into the chamber of the CVD apparatus. Gold dot-coated Si nanowires can be grown by introducing Si ₂ H ₆ gas as a source gas containing silicon element into the chamber, maintaining the pressure at about 10 ⁻⁴ Torr, and heating the substrate at 450 ° C. It grows to a desired length by adjusting the growth time. For example, when the above conditions are used, a growth rate of 50 nm / min to 300 nm / min can be realized.

Next, after growing gold dot-coated Si nanowires to a desired length, conventional Si nanowires are continuously grown. As a method of hetero-growth, the pressure in the chamber is kept at about 10 ⁻² Torr by increasing the flow rate of the source gas Si ₂ H ₆ or introducing H ₂ gas into the chamber. Si nanowires can be grown.

  In this embodiment, after forming the gold dot-coated Si nanowire from the growth substrate, the conventional Si nanowire is continuously grown, but this order can be changed by controlling the pressure in the chamber, It is also possible to form a plurality of gold dot coat regions in one nanowire.

  In this embodiment, silicon is used as the nanowire material and gold is used as the metal particle material. However, the material of the nanowire or the metal particles can be changed by changing the nanowire source gas and the catalyst metal.

  As described above, according to the present embodiment, the metal particle-coated nanowire in which fine metal particles of about 2 nm to 10 nm are formed on the surface of the nanowire body and the conventional nanowire in a single nanowire. It becomes possible to grow without adding a new process. Therefore, since a fine metal particle can be formed at an arbitrary position of the nanowire by self-formation by using a conventional nanowire growth process, application to an electronic device is expected.

(Embodiment 3)
Next, an embodiment of a field effect transistor according to the present invention will be described with reference to FIGS. This transistor includes a nanowire (hereinafter referred to as “contact-doped hetero metal particle-coated nanowire”) in which impurities are doped in a contact region in contact with an electrode and metal particles are formed.

  FIG. 11A is a perspective view showing the contact-doped hetero metal particle-coated nanowire 130 in this embodiment, and FIG. 11B is a cross-sectional view taken along the line BB of FIG. FIG. 12 is a perspective view of a transistor using the contact-doped hetero metal particle-coated nanowire 130 (hereinafter referred to as “nanowire transistor”). FIG. 13A is a top view of the nanowire transistor of FIG. 12, and FIG. 13B is a cross-sectional view taken along the line CC of FIG. 13A.

The contact doped hetero metal particle-coated nanowire 130 shown in FIG. 11 is coated with metal particles at both ends, similarly to the hetero metal particle-coated nanowire of FIG. The difference from the hetero metal particle coated nanowire of FIG. 8B is that both ends (metal particle coated region 131) are doped with impurities and can function as contact regions. For example, when the nanowire is formed of silicon, the metal particle coat region 131 is formed of a group III element such as boron or a group V element such as phosphorus or arsenic at 1 × 10 ¹⁸ atoms / cm ⁻³ to 1. × 10 ²⁰ atoms / cm ^{-3 is} doped. The metal particles 134 in the metal particle coating region 131 are preferably formed from an alloy of a nanowire material and a metal. For example, when the nanowire is made of silicon, the metal particles 134 are preferably made of an alloy such as nickel silicide or titanium silicide.

  FIGS. 12 and 13 show a transistor 140 using contact-doped hetero metal particle coated nanowires 130 as a channel. Hereinafter, the structure of the nanowire transistor 140 will be described.

  The nanowire transistor 140 includes a source electrode 144 and a drain electrode 145 that are in contact with the contact-doped hetero metal particle-coated nanowire 130, respectively, and a substrate 141 that supports them. In order to form a good electrical contact between the source electrode 144 and the drain electrode 145 and the contact-doped hetero metal particle nanowire 130, an electrical contact is formed via the impurity-doped metal particle region 131. Has been.

  On the main surface of the substrate 141, a gate electrode 142 and a gate insulating film 143 that electrically insulates between the gate electrode 142 and the contact-doped hetero metal particle coated nanowire 130 are formed. As described above, the transistor of this embodiment has a bottom gate type transistor structure in which the contact-doped hetero metal particle coated nanowire 130 is disposed on the gate insulating film 143.

  When a voltage is applied to the gate electrode 142, the conductivity of the channel region of the contact-doped hetero metal particle-coated nanowire 130 is controlled via the gate insulating film 143.

  As the substrate 141, a plastic substrate such as polyimide or aromatic ester, a glass substrate, a sapphire substrate, or the like may be used. As materials for the gate electrode 142, the source electrode 144, and the drain electrode 145, metals such as titanium, gold, aluminum, and nickel, conductive polymers, alloys of semiconductor materials such as polysilicon and titanium silicide, and metals are used. Use it.

  Note that although the transistor of this embodiment is a bottom gate type, the transistor of the present invention may have a top gate structure.

  In this embodiment, the impurity is doped in the contact portion with the source / drain electrode. However, even if the impurity is not doped, the contact resistance is reduced as compared with the case of using the conventional nanowire.

  In the nanowire transistor of this embodiment, since a plurality of metal or alloy particles of metal and nanowire material are formed at the contact portion between the nanowire and the source / drain electrode, the contact resistance is reduced on a substrate having low heat resistance. be able to. Therefore, by providing a region where fine metal particles of about 2 nm to 10 nm are formed in a single nanowire and a region where they are not formed, contact between the electrode and the semiconductor layer without adversely affecting the device. A transistor exhibiting a high current driving capability with improved characteristics can be realized.

  Next, the manufacturing method of the nanowire and nanowire transistor of this embodiment is demonstrated.

  FIG. 14A to FIG. 14C are diagrams illustrating an example of a method for manufacturing a nanowire transistor in the present embodiment.

  The basic method of the manufacturing method of the nanowire in the present embodiment is the same as the manufacturing method in the second embodiment. However, in this embodiment, metal particles are formed from an alloy of a nanowire material and a metal. In order to form alloy particles, the pressure in the chamber and the metal species of the catalyst may be optimized during the growth of the metal particle-coated nanowire, or the metal particle-coated nanowire may be grown and then heat-treated in an arbitrary atmosphere. .

  The nanowire transistor can be manufactured by a known method except that a metal particle-coated nanowire is used. Hereinafter, the manufacturing method of the nanowire transistor in this embodiment is demonstrated.

  First, as shown in FIG. 14A, the gate electrode 142 and the gate insulating film 143 are formed on the main surface of the substrate 141. The gate electrode 142 can be formed by, for example, depositing a gate metal using a known film forming apparatus such as a sputtering method or an evaporation method, and then patterning the gate metal by photolithography and etching techniques. The gate insulating film 143 can be formed by, for example, spin-coating a gate insulating film material precursor on the substrate 141 and then removing the solvent and performing heat treatment. In addition, the gate insulating film 143 may be deposited by a CVD method, a sputtering method, or an evaporation method.

  Next, as shown in FIG. 14B, the contact-doped hetero metal particle coated nanowire 130 is disposed on the gate insulating film 143 described above. Specifically, the contact-doped hetero metal particle-coated nanowire 130 is peeled from the growth substrate (not shown in FIG. 14) and dispersed in a solution. As a method of peeling the nanowire from the growth substrate, for example, a method of mechanically peeling the growth substrate by irradiating ultrasonic waves or a method of thinly etching the surface of the growth substrate may be used.

  The solvent used for the dispersion includes an aqueous solution, an organic solvent, or a mixture of water and an organic solvent. Examples of the organic solvent include alcohols such as ethanol, propanol, pentanol, hexanol and ethylene glycol, esters such as ethylene glycol monomethyl ether, ketones such as methyl ethyl ketone, alkanes such as hexane and octane, solvents such as tetrahydrofuran and chloroform. Should be used. As a mixed liquid of water and an organic solvent, a mixed liquid of water and alcohol, a mixed liquid of water and tetrahydrofuran, or the like can be used.

  Next, a mold having a groove having a desired shape on its surface is brought into close contact with the upper surface of the gate insulating film 143, and the above-described dispersion is caused to flow in this groove (flow method). When such a flow method is used, the position and shape of the nanowire can be controlled by the groove of the mold, and the nanowire direction can be oriented in the mold method by the flow of liquid. Note that the contact-doped hetero metal particle-coated nanowire 130 can be disposed at a desired position on the substrate 141 even by using a known method other than the flow method, for example, a transfer method.

  Next, as shown in FIG. 14C, a source electrode 144 and a drain electrode 145 are formed. Specifically, after the metal film is deposited, a lift-off method may be used in which the metal film may be patterned by photolithography and etching techniques.

  As described above, according to the present embodiment, the contact resistance can be reduced by using the metal particle-coated nanowire in which fine metal particles of about 2 nm to 10 nm are self-organized on the nanowire surface. In addition, since a process of heat-treating and alloying the electrode material and the semiconductor layer material is not necessary, a transistor with high performance and reduced variation can be realized over a substrate with low heat resistance.

  By providing the electrode that contacts the fine particles of the nanowire body as described above, various electronic devices having excellent contact characteristics can be manufactured. Such an electronic device is not limited to a transistor, and may be a sensor, a light emitting element, or a light receiving element.

(Embodiment 4)
Hereinafter, an embodiment of a sensor using nanowires according to the present invention (hereinafter referred to as “nanowire sensor”) will be described with reference to FIG.

  FIG. 15A is a schematic view of the surface structure of a nanowire (hereinafter referred to as “chemically modified nanowire”) 150 in which the surface of the metal particle-coated nanowire is chemically modified with a functional molecule, and FIG. ) Is a cross-sectional view showing the structure of a sensor using the nanowire 150. The chemically modified nanowire 150 in FIG. 15A includes a semiconductor nanowire body 153, a plurality of metal particles 152 formed on the surface thereof, and a functional molecule 151 used for the chemical modification. The metal particles 152 in the present embodiment are made of gold, but the same effect can be expected even if they are made of other metals (for example, noble metals such as silver, copper, iridium).

A feature of the nanowire 150 shown in FIG. 15A is that the metal particles 152 located on the surface of the semiconductor nanowire body 153 are chemically modified with the functional molecules 151. Examples of the functional molecule 151 that chemically modifies the metal particles 152 include NH ₂ (CH ₂ ) _n SH, COOH (CH) _n SH, CF ₃ (CF ₂ ) _n (C ₂ H ₄ ) _m SH (provided that n and m are natural numbers).

  The nanowire sensor shown in FIG. 15B is a sensor that uses the chemically modified nanowire 150 as a sensing unit. The nanowire sensor has the same structure as the nanowire transistor of the third embodiment. Although the nanowire sensor of this embodiment includes the gate electrode 142, the gate electrode 142 may not be included.

The nanowire sensor of this embodiment functions as a pH sensor. When the chemically modified nanowire 150 is obtained by chemically modifying NH ₂ (C ₆ H ₆ ) SH as a functional molecule, the amino in the functional molecule 151 on the surface of the nanowire 150 decreases when the pH in the solution is lowered. group is changed to -NH ₃ ^+. As a result, since the conductance between the source electrode 144 and the drain electrode 145 changes, the pH of the solution can be sensed according to the drain current flowing through the semiconductor nanowire body 153.

  This nanowire sensor can be manufactured by a method similar to the method of manufacturing the nanowire transistor of the third embodiment.

  Although the sensor of this embodiment functions as a pH sensor, it can operate as another sensor by appropriately selecting the functional molecule 151. Further, chemically modified nanowires can be used for electronic devices other than sensors. For example, if charge is taken in and out through the functional molecule 151, it can be operated as a memory.

  In the nanowire sensor of the present embodiment, sensing can be performed by chemically modifying a functional molecule on a self-organized metal particle and adsorbing or reacting a specimen with the functional molecule. When the nanowire of the present invention is used, the density of the metal particles can be controlled depending on the growth condition of the nanowire, so that a highly sensitive sensor can be realized.

(Embodiment 5)
Hereinafter, with reference to FIG. 16, an embodiment of a structure in which nanowires chemically modified to metal particles of the present invention are used and nanowires are arranged at arbitrary positions on an arbitrary substrate or electrode will be described.

  FIG. 16A is a schematic diagram showing chemically modified nanowires 160 and a substrate 161, and FIG. 16B shows a structure in which nanowires 160 are arranged at arbitrary positions on electrodes 164 provided on the substrate 161. FIG. Gold fine particles 162 are formed on the surface of the nanowire 160 of the present embodiment.

  The chemically modified nanowire 160 in FIG. 16A has the same configuration as the chemically modified nanowire 150 of the fourth embodiment. A characteristic point of this embodiment is that the chemically modified nanowire 160 is chemically bonded to a functional group on the substrate 161.

  The functional group X in the functional molecule chemically bonded to the nanowire 160 can be selected from the following combinations, for example.

If the surface of the substrate 161 is -OH, X is _{(CH 3 O) 3 Si -} , (C 2 H 5) 3 Si-, Cl 3 Si-, NCO- and the like, surface -NH ₂ substrate 161 , -NH-, X is HOOC-, NCO-, and the like.

  When the hetero metal particle-coated nanowire in the second embodiment is used, the metal particles are selectively formed in a specific portion of the semiconductor nanowire, so that a chemical bonding site can be formed at an arbitrary position in the nanowire.

  In the example of FIG. 16B, the chemically modified nanowire 160 does not form a chemical bond with the surface of the substrate 161, but forms a chemical bond with the electrode 164. As the nanowire 160 in this case, as shown in FIG. 8B, it is preferable to use a nanowire having both ends coated with metal particles.

In order to define the arrangement position of the nanowire 160, chemical modification may be performed at any position of the electrode 164 using a functional molecule such as HOOC— (CH ₂ ) _n —SH. If the nanowire 160 is chemically modified with a functional molecule 163 such as NH ₂ — (CH ₂ ) _n —SH, the position of the nanowire 160 is determined so as to form an amide bond between the functional molecules. Accordingly, the nanowire 160 can be disposed at an arbitrary position of the electrode 164.

  In the conventional method of arranging nanowires using chemical modification, it is difficult to accurately control the position and direction of the nanowires because the catalytic metal part necessary for the growth of the nanowires is bonded to the substrate. However, in the present embodiment, since chemical modification can be applied to a wide range in the axial direction of the nanowire, adhesion to an object such as a substrate or an electrode is improved. In addition, by selectively chemically modifying any part of the object, the position and orientation of the chemically modified nanowire 160 can be defined in a self-aligned manner with respect to the object.

(Embodiment 6)
Hereinafter, an embodiment of a memory (hereinafter referred to as “nanowire memory”) in which the metal particles of the present invention are embedded in an insulating film will be described with reference to FIG.

  FIG. 17A shows a cross-sectional structure of a nanowire 170 in which metal particles are embedded in an insulating film, and FIG. 17B shows a cross-sectional configuration example of a nanowire memory formed using the nanowire 170.

  A nanowire 170 shown in FIG. 17A has a nanowire 171 covered with an insulating film 173, and metal particles 172 are embedded in the insulating film 178. The insulating film 173 is preferably formed from, for example, silicon oxide, silicon nitride, hafnium oxide, or the like.

  The nanowire 170 is manufactured by, for example, forming an insulating film 173 around the above-described metal particle-coated nanowire by sputtering or laser ablation, and then performing heat treatment to diffuse the metal particles 172 into the insulating film 173. Can do.

  When gold dot-coated Si nanowires are used, nanowires in which gold particles are embedded in a silicon oxide film can be formed by oxidizing the nanowires in an oxygen atmosphere.

  The nanowire memory shown in FIG. 17B includes a nanowire 170 in which metal particles 172 are embedded in an insulating film 173, but basically has a structure similar to the structure of the nanowire transistor of the third embodiment. ing. In the memory operation, charges are injected from the nanowire 171 into the metal particle 172 by applying a bias voltage to the gate electrode 142. On the other hand, by applying a reverse bias voltage to the gate electrode 142, charges can be injected from the metal particles 172 into the nanowire 171.

  The nanowire memory of FIG. 17B can also be manufactured in the same manner as the manufacturing method of the nanowire transistor of the third embodiment.

  In the nanowire memory of this embodiment, a highly accurate memory can be formed by applying a nanowire in which the metal particles 172 formed in a self-organized manner according to the present invention are embedded in an insulating film 173 to the memory. In addition, when the nanowire of the present invention is used, the density of the metal particles 172 can be controlled by the growth conditions, so that variation in particle density can be reduced and a memory with improved accuracy can be realized.

(Embodiment 7)
Next, an embodiment of an electronic device according to the present invention will be described with reference to FIGS. The electronic device of the present embodiment is a display including an organic electroluminescence element (organic EL element).

  FIG. 18 schematically shows the configuration of the display. In the display of FIG. 18, a plurality of pixels 185 are arranged in a matrix on a substrate 180. Each pixel 185 is provided with an organic EL element, and the organic EL element is controlled by a circuit including a TFT arranged in the vicinity thereof. On the substrate 180, an X scan electrode 183, a Y scan electrode 184, an X driver 181 and a Y driver 182 for controlling the TFT are formed.

  FIG. 19 shows a circuit diagram in the vicinity of a pixel. The pixel 185 is controlled by a switching transistor 190 and a driver transistor 191. These transistors 190, 191 are transistors comprising nanowires according to the present invention.

  A voltage is applied from the Y driver 182 to the source electrode of the switching transistor 190 via the Y scanning electrode 184. The drain electrode of the switch transistor 190 and the gate electrode of the driver transistor 191 are electrically connected. The drain electrode of the driver transistor 191 is electrically connected to a pixel electrode (not shown) disposed under the pixel. In addition, a voltage for causing the pixel to emit light is applied to the source electrode of the driver transistor 191.

  On the other hand, an image signal voltage is applied to the gate electrode of the switching transistor 190 from the X driver 181 via the X scanning electrode 183. A voltage is applied to the gate electrode of the driver transistor 191 from the switching transistor to which the voltage of the image signal is applied. As a result, a voltage is applied from the driver transistor to the pixel electrode. Although not shown, a transparent electrode is disposed on the pixel. When a voltage is applied between the pixel electrode and the transparent electrode, the pixel portion emits light.

  The electronic device according to the present invention is not limited to the above-described display, and may be a liquid crystal display device or another electronic device. The nanowire according to the present invention can be used in various electronic devices.

  The nanowire according to the present invention can be manufactured by a simple manufacturing process, and can be applied to electronic devices such as transistors and memories, micro devices, and the like.

(A) is a side view which shows the nanowire of this invention, (b) is the AA sectional view taken on the line. (A)-(c) is process drawing which shows the manufacturing method of the nanowire of this invention. 2 is a photograph showing a nanowire TEM image of Embodiment 1. FIG. (A) And (b) is a graph which shows the nanowire elemental-analysis result of Embodiment 1. FIG. (A) is the photograph which shows the nanowire cross-section TEM image of Embodiment 1, (b) is the photograph which expanded the part. (A) And (b) is a graph which shows the nanowire elemental-analysis result of Embodiment 1. FIG. FIGS. 3A to 3C are process diagrams illustrating a method for producing a nanowire according to Embodiment 1. FIGS. (A) to (c) is a structural schematic diagram of the nanowire of Embodiment 2. FIG. (A) to (c) are photographs showing nanowire TEM images of Embodiment 2. (A)-(c) is a figure which shows the nanowire elemental-analysis result of Embodiment 2. FIG. (A) is the nanowire structure schematic diagram of Embodiment 3, (b) is the BB sectional drawing. It is a nanowire transistor structure perspective view of Embodiment 3. (A) is a top view of the nanowire transistor of Embodiment 3, (b) is the CC sectional view taken on the line. (A) to (c) are views showing a method of manufacturing the nanowire transistor of the third embodiment. (A) And (b) is the nanowire sensor structural drawing of Embodiment 4. FIG. (A) is a figure which shows the nanowire chemically modified, (b) is a figure which shows the nanowire of Embodiment 5 arrange | positioned in the arbitrary positions of a board | substrate. (A) is sectional drawing of the nanowire of Embodiment 6, (b) is sectional drawing of a memory element provided with the said nanowire. 10 is a schematic diagram of an organic EL display according to Embodiment 7. FIG. FIG. 10 is a circuit diagram of a pixel driving transistor of Embodiment 7. (A) to (c) is a schematic diagram of a conventional nanowire structure. It is a SEM photograph which shows the silicon nanowire grown by atmospheric gas pressure 0.2Torr. It is a cross-sectional TEM photograph which shows the silicon nanowire grown by atmospheric gas pressure 0.2Torr. It is a SEM photograph which shows the silicon nanowire grown by atmospheric gas pressure 0.01Torr. It is a cross-sectional TEM photograph which shows the silicon nanowire grown by atmospheric gas pressure 0.01Torr. It is a TEM photograph (high magnification) of the sample which performed the heat processing (Anneal) for 450 minutes at 450 degreeC under the high vacuum (UHV). It is a TEM photograph (low magnification) of the sample which performed the heat processing (Anneal) for 450 minutes at 450 degreeC under the high vacuum (UHV). It is the TEM photograph (high magnification) of the sample which performed the heat processing for 10 minutes at 450 degreeC under the low vacuum (0.3Torr). It is a TEM photograph (low magnification) of the sample which heat-processed for 450 minutes at 450 degreeC under the low vacuum (0.3 Torr). It is a TEM photograph (high magnification) of the sample which performed the heat processing for 450 minutes at 450 degreeC under atmospheric pressure (nitrogen atmosphere) after air exposure. It is a TEM photograph (low magnification) of the sample which heat-processed at 450 degreeC and 10 minutes under atmospheric pressure (nitrogen atmosphere) after exposure to air | atmosphere.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Fine particle coated nanowire 102 Catalytic metal 103 Fine particle 102a Alloy of catalytic metal and semiconductor material 104 Nanowire main body 105 Substrate 106 Source gas 110 Gold dot coat Si nanowire 111 Si nanowire main body 112 Metal particle 113 Silicon oxide film (natural oxide film)
114 Catalytic metal particles 115 Silicon substrate 116 Disilane gas 120 Metal particle present area 121 Metal particle absent area 122 Gold catalyst 123 Gold dot present area 124 Gold dot absent area 130 Contact doped hetero metal particle coated nanowire 131 Impurity-doped metal particle coated region 132 Semiconductor nanowire 133 Impurity-doped region 134 Semiconductor-metal alloy particle 140 Nanowire transistor 141 Substrate 142 Gate electrode 143 Gate insulation film 144 Source electrode 145 Drain electrode 150 Chemically modified nanowire 151 Functional molecule 152 Metal particle 153 Semiconductor nanowire body 160 Chemically modified nanowire 161 Substrate 162 Metal particle 163 Functional molecule 164 Electrode 165 Chemical bond 170 Nanowire embedded with metal particles in insulating film 171 Nanowire 172 Metal particle 173 Insulating film 180 Flexible substrate 181 X driver 182 Y driver 183 X scan electrode 184 Y scan electrode 185 Pixel 190 Switch transistor 191 Driver transistor DESCRIPTION OF SYMBOLS 200 Semiconductor nanowire 201 Core shell nanowire 202 Core part 203 Shell part 204 Hetero nanowire 205 1st semiconductor nanowire 206 2nd semiconductor nanowire

Claims (22)

A crystalline semiconductor nanowire body formed from a first material;
A plurality of fine particles formed from a second material partly including an element constituting the semiconductor and located on at least part of the surface of the nanowire body;
With
A nanowire having a smooth surface of the nanowire body.   2. The nanowire according to claim 1, wherein an oxide film is not substantially formed on at least a portion of the smooth surface of the nanowire body that is in contact with the plurality of fine particles.   The nanowire according to claim 1, wherein an average diameter of the nanowire is 1 nm or more and 1 µm or less.   The nanowire according to claim 1, wherein the plurality of fine particles are dispersed over the entire surface of the nanowire body.   The nanowire according to claim 1, wherein the surface of the nanowire body is divided into a first region in which the plurality of fine particles are dispersed and a second region in which the plurality of fine particles are not formed.   The nanowire according to any one of claims 1 to 5, wherein the plurality of fine particles contain at least one kind of metal element.   The nanowire according to claim 6, wherein the plurality of fine particles are formed of a metal or an alloy of the metal and the first material.   The nanowire according to claim 1, wherein the second material contains at least one metal selected from the group consisting of gold, silver, copper, and iridium.   The nanowire according to claim 1, wherein an average particle diameter of the plurality of fine particles is less than 20 nm.   The nanowire according to claim 1, wherein the nanowire body is a single crystal.   The nanowire according to claim 1, wherein the first material is formed of at least one material selected from the group consisting of silicon, germanium, and carbon. A field effect transistor comprising the nanowire according to claim 1,
A channel region formed in the nanowire;
An electrode connected to the nanowire and functioning as a source region and a drain region;
A gate electrode for controlling conductivity in at least a part of the channel region;
A gate insulating film for electrically insulating the gate electrode from the channel region;
A field effect transistor comprising:   13. The field effect transistor according to claim 12, wherein at least some of the plurality of fine particles are present in a region in contact with the electrode in the surface of the nanowire.   The field effect transistor according to claim 13, wherein a portion of the nanowire that contacts the electrode is doped with an impurity.   The nanowire according to claim 1, wherein a functional molecule is chemically modified on the fine particles.   The nanowire according to claim 15, wherein the functional molecule includes a —SH group at a binding site with the fine particle. The functional _{molecule, X- (C n H m)} -SH (n, m are natural numbers) and _{X: -NH 2, -COOH, -C} x H y, -C a F b (x, y, a , B is a natural number). The nanowire according to any one of claims 1 to 9, which functions as a sensing unit;
A first electrode and a second electrode connected to the nanowire;
With a sensor. A nanowire according to any of claims 15 to 17,
A member chemically bonded to the nanowire via the functional molecule;
An electronic device comprising:   An electronic device comprising the nanowire according to claim 1.   21. The electronic device according to claim 20, further comprising an electrode in contact with the plurality of fine particles in the nanowire. Preparing a substrate having catalytic metal particles disposed on the surface (A);
Growing a nanowire body formed from a first material on the substrate (B);
A method for producing nanowires, comprising:
In the step (B), a method for producing a nanowire, wherein a plurality of fine particles formed from a second material are grown on at least a part of the surface of the nanowire body.