Method for growing III-V group branched nanowires and III-V group branched nanowires

Abstract

The present invention discloses a method for growing III-V branched nanowires, wherein main branched nanowires are grown on a substrate, and the method comprises: depositing new III-V metal catalyst droplets on the surface of the main branched nanowires, driving the catalyst liquid to transfer from a high energy direction to a lower surface energy direction on the surface of the main branched nanowires, and controlling the growth environment so that the branched nanowires grow along a lower energy direction. A III-V branched nanowire is also provided, which is obtained by the above-mentioned method for growing III-V branched nanowires. Branched nanowires can be obtained without introducing stress and defects, which not only solves the problem of carrier loss caused by introducing defects during the growth of branched nanowires, but also can accurately control the position and density of secondary nanowire growth by controlling the growth conditions. In addition, the grown nanowires have regular shapes, which are convenient for connecting with other branched nanowires to form a three-dimensional structure.

Description

Technical Field

[0001] The present application relates to the technical field of branched nanowire preparation, and in particular to a method for growing group III-V branched nanowires and group III-V branched nanowires. Background Art

[0002] III-V semiconductor materials refer to compounds composed of Group IIIA elements in the periodic table, such as B, Al, Ga, In, Ta, and Group VA elements, such as N, P, As, Sb, etc. Group III-V materials usually have the advantages of direct band gap, high electron mobility, and high photoelectric conversion efficiency, and are therefore very suitable for use in optical communications, energy conversion, detectors, etc.

[0003] Branched or tree-like nanowires refer to the epitaxial growth of one or more secondary nanowires from the main nanowire trunk. The secondary nanowires can be connected to each other, so branched nanowires can naturally form higher-dimensional structures. By controlling the switching and transport of carriers in the three-dimensional structure, nanowires can have complex logical functions. The formation of three-dimensional nanostructures opens the door to designing more complex three-dimensional building blocks and utilizing their unique properties.

[0004] Three-dimensional nanostructures can have novel physical properties such as quantum effects, size effects and surface effects given by nanomaterials and structures, and can also achieve coordinated modulation of physical properties such as electron-phonon transport and coupling, spin polarization, exciton behavior, and wavefront regulation through three-dimensional geometric structures, thereby obtaining functions that planar devices do not have. Branched nanowires can achieve nanoscale integration of different functional materials, greatly enhanced junctions and surface areas, and can achieve three-dimensional structural interconnection, so they have unique optical, electronic and catalytic properties. The nano-integration of two or more materials allows branched nanowires to be used to prepare heterojunctions, thereby combining the advantages of different materials; due to their high surface / volume ratio, high light absorption and low reflectivity, branched nanowires can be used to make optoelectronic devices; the unique three-dimensional structure makes branched nanowires have great application potential in many fields such as supercapacitors, batteries and photochemical cells.

[0005] At present, it has been reported that the synthesis methods of branched nanowires include chemical vapor deposition, molecular beam epitaxy, hydrothermal method, etc., and GaN, GaP, and various heterojunctions such as InP / Zn3P2, Mg / Zn3P2, Zn3P2 / ZnSe, ITO / Zn3P2 and other branched nanowires have been synthesized. The length, diameter, chemical composition, etc. of the trunk of the branched nanowire and its branches can be controlled by the above preparation method. However, so far, most of the branched nanowires are catalyzed by metal droplets, which is very unfavorable for CMOS technology and will lead to the formation of deep energy level defects inside the Si material. In addition, the morphology, position on the trunk nanowire, and distribution density of the existing branched nanowires cannot be well controlled, which is not conducive to the formation of regular, stable, and large-scale high-dimensional structures of branched nanowires. Nanowires cannot be well aligned and connected to form higher-dimensional structures, which is unfavorable for the practical application of branched nanowires. In addition, in existing reports, defects are formed on nanowires by controlling stress as nucleation sites for branched nanowires, which is unfavorable for the transmission of carriers and will cause carrier loss. Summary of the invention

[0006] In view of this, the embodiments of the present application provide a method for growing group III-V branched nanowires and group III-V branched nanowires to solve the problems existing in the background technology.

[0007] According to a first aspect of an embodiment of the present application, a method for growing III-V branched nanowires is provided, wherein a main branch nanowire is grown on a substrate, and the method comprises:

[0008] The surface energy of the main branch of the nanowire is changed, and the branched nanowire grows along the direction of low surface energy by controlling the growth environment. The low surface energy is the defect-free nanowire surface. Newly deposited III-group metal catalyst droplets are attached to the surface of the main branch nanowire, and the catalyst liquid is driven to transfer from the direction of high energy to the direction of lower surface energy on the surface of the main branch nanowire. By controlling the growth environment, the branched nanowire grows along the direction of lower energy.

[0009] Preferably, the driving method is to change the surface energy of the surface of the main branch of the nanowire, because the position and direction of the branch nanowire are determined by the surface energy of the main branch nanowire. For example, by changing the ratio of III / V sources or changing the atomic density in the environment, changing the epitaxial temperature, introducing spasms / defects, changing the atomic structure of the main branch component, changing the contact direction between the droplet and the trunk, changing the droplet size, and introducing a third component in the droplet.

[0010] Preferably, the III-V group nanowires are selected from As-based nanowires, such as GaAs nanowires and InGaAs nanowires; N-based nanowires, such as InGaN, GaN nanowires, InN nanowires, AlInN nanowires, AlN nanowires, AlGaN nanowires, and AlInGaN nanowires; and P-based nanowires, such as InP nanowires.

[0011] Preferably, the method comprises:

[0012] S1: growing main branch nanowires on the substrate;

[0013] S2: Open the baffles of the catalyst source and the substrate, pre-deposit catalytic droplets as catalysts required for the growth of secondary nanowires; then open the growth source of the branch nanowires to start nucleation;

[0014] S3: Raise the substrate temperature and then turn on the growth source of the branch nanowires to start growth.

[0015] According to a second aspect of an embodiment of the present application, a III-V group branched nanowire is provided, which is obtained by the method for growing a III-V group branched nanowire described in the first aspect.

[0016] Preferably, the branched nanowire is a heterojunction, that is, the primary trunk and the secondary branches are made of two different materials, or the tertiary branches are made of different materials from the secondary branches, or the same elements but in different proportions.

[0017] Preferably, the branched nanowires are an array composed of branched nanowires.

[0018] Preferably, the branched nanowires are prepared on a silicon substrate, sapphire or a III-V group material substrate. Specifically, the branched nanowires are prepared on silicon, single crystal silicon thin film on insulator, sapphire, silicon carbide, flexible material or compound substrate, and glass, metal, organic material and other substrates with surface modification treatment; the compound substrates include GaN, GaAs, GaP, InP, GaSb, InGaN, InAs, InN, AlN, etc.; or a substrate composed of the above materials / structures; the substrate is prepared on a crystal plane family including {100}, {110}, {111}.

[0019] Preferably, the branched nanowires have a multi-branched structure, including a secondary or tertiary branched structure, which is obtained through multiple growths.

[0020] Preferably, the branched nanowires are prepared by hydrothermal method, CVD, MBE or the like.

[0021] Preferably, the secondary branches of the branched nanowires are non-uniformly distributed on the trunk, and their positions and densities are adjustable.

[0022] Preferably, the adjustable position and density are achieved by: introducing defects by changing the ratio of III / V sources or changing the epitaxial temperature, changing the main branch atomic composition, changing the main branch nanowire growth direction; or changing the surface energy of the droplet.

[0023] Preferably, the branched nanowire trunk and the secondary branches have different doping concentrations, or different optical absorption properties, or different catalytic properties, and possess different functions.

[0024] Preferably, the main trunk of the branched nanowire forms a predetermined angle with the secondary branches.

[0025] By adopting the metal-free catalytic molecular beam epitaxy method, the morphology, position, density, etc. of the branch structure of the branched nanowire can be precisely controlled, thereby exploring the realization of controllable nanoscale three-dimensional interconnected devices. By precisely controlling the element flux in the MBE device during the growth of the III-V branched nanowires, the catalytic droplets can be attached to the already grown nanowires. When the growth of the previous level of nanowires is completed, new III-group metal catalytic droplets are deposited and attached to the surface of the already grown nanowires, and then the V / III flux and substrate temperature are controlled to continue growing secondary nanowires.

[0026] By using this method, branched nanowires can be obtained without introducing stress and defects. This not only solves the problem of carrier loss caused by defects during the growth of branched nanowires, but also allows the position and density of secondary nanowire growth to be precisely controlled by controlling the growth conditions. In addition, the grown nanowires have regular shapes, which are convenient for connecting with other branched nanowires to form a three-dimensional structure.

[0027] The present invention is achieved by controlling surface energy. On the surface of defect-free branch nanowires, droplets tend to deposit and converge at low surface energy, which is conducive to the nucleation and growth of branch nanowires. The growth direction of branch nanowires is also controlled by surface energy. The growth direction of branch nanowires is also controlled by surface energy, and the droplets are transferred from the direction of high energy to the direction of lower surface energy through the movement of droplets on the main branches of the nanowires. Therefore, we can control the growth of main branch nanowires on substrates in different directions and obtain the surface of a certain main branch nanowire by controlling the growth environment. If the surface energy of the main branch surface is low, the catalytic droplets deposited for the second time will tend to stay and converge on this surface. Then, by controlling the growth environment, the branch nanowires grow along the direction with lower energy. Therefore, the surface of the main branch nanowire determines whether the catalytic droplets can adhere there. The properties of the branch nanowires themselves determine the dominant growth direction of the branch nanowires.

[0028] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] Figure 1 Schematic diagram of branched nanowires obtained by depositing catalytic droplets on defective main branches according to the prior art [1].

[0031] Figure 2 This is a schematic diagram of branched nanowires obtained by depositing catalytic droplets on defect-free nanowire main branches according to an embodiment of the present application.

[0032] Figure 3 The prior art [2] is to grow irregular branched nanowires on defective main branches.

[0033] Figure 4 Schematic diagram of growing regular and vertical GaAs homojunction branch nanowires on defect-free nanowire main branches according to an embodiment of the present application.

[0034] Prior art [1] and prior art [2] are as follows:

[0035] [1]Crystallographically driven Au catalyst movement during growth ofInAs / GaAs axial nanowire heterostructures. Journal of Applied Physics 105,073503 (2009); doi: 10.1063 / 1.3103265;

[0036] [2]Flux Engineering for Indium Tin Oxide Nanotree Crystal Alignment and Height-Dependent Branch Orientation. Cryst. Growth Des. 2013, 13, 1, 212–219. DETAILED DESCRIPTION

[0037] Here, exemplary embodiments will be described in detail. Example 1

[0038] An embodiment of the present invention provides a method for growing III-V group branched nanowires, wherein main branch nanowires are grown on a substrate, and the method comprises: depositing new III group metal catalyst droplets on the surface of the main branch nanowires, driving the catalyst liquid to transfer from a high energy direction to a lower surface energy direction on the surface of the main branch nanowires, and controlling the growth environment so that the branch nanowires grow along a lower energy direction, and the low surface energy area is a defect-free nanowire surface.

[0039] The driving method here is to change the surface energy of the main branch of the nanowire, because the position and direction of the branch nanowire are determined by the surface energy of the main branch nanowire. For example, by changing the ratio of III / V sources or changing the epitaxial temperature to introduce defects, change the atomic composition of the main branch, change the growth direction of the main branch nanowire; or change the surface energy of the droplet, such as introducing a third component into the droplet.

[0040] By adopting the metal-free catalytic molecular beam epitaxy method, the morphology, position, density, etc. of the branch structure of the branched nanowire can be precisely controlled, thereby exploring the realization of controllable nanoscale three-dimensional interconnected devices. By precisely controlling the element flux in the MBE device during the growth of the III-V branched nanowires, the catalytic droplets can be attached to the already grown nanowires. When the growth of the previous level of nanowires is completed, new III-group metal catalytic droplets are deposited and attached to the surface of the already grown nanowires, and then the V / III flux and substrate temperature are controlled to continue growing secondary nanowires.

[0041] By using this method, branched nanowires can be obtained without introducing stress and defects. This not only solves the problem of carrier loss caused by defects during the growth of branched nanowires, but also allows the position and density of secondary nanowire growth to be precisely controlled by controlling the growth conditions. In addition, the grown nanowires have regular shapes, which are convenient for connecting with other branched nanowires to form a three-dimensional structure.

[0042] The present invention is achieved by controlling surface energy. On the surface of defect-free branch nanowires, droplets tend to deposit and converge at low surface energy, which is conducive to the nucleation and growth of branch nanowires. The growth direction of branch nanowires is also controlled by surface energy. The growth direction of branch nanowires is also controlled by surface energy, and the droplets are transferred from the direction of high energy to the direction of lower surface energy through the movement of droplets on the main branches of the nanowires. Therefore, we can control the growth of main branch nanowires on substrates in different directions and obtain the surface of a certain main branch nanowire by controlling the growth environment. If the surface energy of the main branch surface is low, the catalytic droplets deposited for the second time will tend to stay and converge on this surface. Then, by controlling the growth environment, the branch nanowires grow along the direction with lower energy. Therefore, the surface of the main branch nanowire determines whether the catalytic droplets can adhere there. The properties of the branch nanowires themselves determine the dominant growth direction of the branch nanowires. Example 2

[0043] The III-V group nanowires are selected from GaAs nanowires, InGaAs nanowires, InGaN, GaN nanowires, and InN nanowires. The method of the present invention is described in detail below by taking GaAs nanowires as an example of the III-V group nanowires.

[0044] An embodiment of the present invention provides a method for growing III-V group branched nanowires, wherein main branch nanowires are grown on a substrate, and the method comprises:

[0045] S1: growing main branch nanowires on the substrate; this step may include the following sub-steps:

[0046] S11: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -6 Torr, Al beam current at 5× 10 -6 Torr, As beam current is 5×10 -6 Torr, so that the V / III beam current ratio is 20;

[0047] S12: First, the baffles of the Ga source and the substrate are opened for 30 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously;

[0048] S13: High-temperature growth of GaAs nanowires: After closing the baffles, raise the substrate temperature to 640°C within 10 minutes, and open the Ga source, As source and the baffles of the substrate at the same time to start the high-temperature growth of the nanowires; after 25 minutes of growth, close all the baffles to end the growth of the main branch nanowires.

[0049] S2: Open the baffles of the catalyst source and the substrate, pre-deposit catalytic droplets as catalysts required for the growth of secondary nanowires; then open the growth source of the branch nanowires to start nucleation; this step may include the following sub-steps:

[0050] S21: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -6 Torr, Al beam current at 5× 10 -6 Torr, As beam current is 5×10 -6 Torr, so that the V / III beam current ratio is 30;

[0051] S22: First, the baffles of the Ga source and the substrate are opened for 30 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously;

[0052] S3: Raise the substrate temperature, then turn on the growth source of the branch nanowires to start growth; this step includes:

[0053] S31: High-temperature growth of GaAs nanowires: After closing the baffles, raise the substrate temperature to 660°C within 10 minutes, and open the Ga source, As source and the baffles of the substrate at the same time to start the high-temperature growth of the nanowires; after 25 to 30 minutes of growth, close all the baffles to end the growth of the branched nanowires.

[0054] The III-V group nanowires are selected from InGaAs nanowires, InGaN, GaN nanowires, and InN nanowires, which will not be elaborated here.

[0055] Figure 1 This is a schematic diagram of a branched nanowire obtained by depositing a catalytic droplet on a defective main branch in the prior art [1]. It can be seen from the figure that there are a large number of defects on the main branch nanowire where the catalytic droplet is located.

[0056] Figure 2 This is a schematic diagram of a branched nanowire obtained by depositing a catalytic droplet on a defect-free nanowire main branch according to an embodiment of the present application. From this figure, it can be seen that there are no obvious defects on the main branch nanowire where the catalytic droplet is located.

[0057] contrast Figure 1 and Figure 2 It can be seen that the embodiment of the present application continues to deposit catalytic droplets on defect-free main branch nanowires, and the deposited droplets do not need to rely on defects, but the droplets will spontaneously converge at a lower surface energy, which is significantly different from previous reports by others.

[0058] Figure 3The prior art [2] shows that irregular branched nanowires are grown on defective main branches. As can be seen from the figure, the angle and direction of the branched nanowires are not controlled and they are twisted.

[0059] Figure 4 The schematic diagram of the embodiment of the present application is a schematic diagram of growing a regular and vertical GaAs homojunction branch nanowire on a defect-free nanowire main branch. From the figure, it can be seen that the morphology of the branch nanowire in the embodiment of the present application is controllable, and the growth direction is perpendicular to the main branch nanowire.

[0060] contrast Figure 3 and Figure 4 It can be seen that the embodiment of the present application can provide a method for effectively controlling the morphology and growth of branched nanowires. Through this method, the sidewalls of the nanowires are smooth and have a regular shape, and the growth direction can be controlled by the material properties, and the diameter of the growing nanowires can be controlled by the growth environment. Example 3

[0061] The III-V group nanowires are selected from GaAs nanowires, InGaAs nanowires, InGaN, GaN nanowires, and InN nanowires. The method of the present invention is described in detail below by taking GaAs nanowires as an example of the III-V group nanowires.

[0062] An embodiment of the present invention provides a method for growing III-V group branched nanowires, wherein main branch nanowires are grown on a substrate, and the method comprises:

[0063] S1: growing main branch nanowires on a substrate; this step may include the following sub-steps:

[0064] S11: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -7 Torr, Al beam current at 5× 10 -7 Torr, As beam current is 5×10 -7 Torr, so that the V / III beam current ratio is 50;

[0065] S12: First, the baffles of the Ga source and the substrate are opened for 120 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously;

[0066] S13: High-temperature growth of GaAs nanowires: After closing the baffles, raise the substrate temperature to 660°C within 15 minutes, and open the Ga source, As source and the baffles of the substrate at the same time to start the high-temperature growth of the nanowires; after 30 minutes of growth, close all the baffles to end the growth of the main branch nanowires.

[0067] S2: Open the baffles of the catalyst source and the substrate, pre-deposit catalytic droplets as catalysts required for the growth of secondary nanowires; then open the growth source of the branch nanowires to start nucleation; this step may include the following sub-steps:

[0068] S21: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -7 Torr, Al beam current at 5× 10 -7 Torr, As beam current is 5×10 -7 Torr, so that the V / III beam current ratio is 50;

[0069] S22: First, the baffles of the Ga source and the substrate are opened for 120 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously;

[0070] S3: Raise the substrate temperature, then turn on the growth source of the branch nanowires to start growth; this step includes:

[0071] S31: High-temperature growth of GaAs nanowires: After closing the baffles, raise the substrate temperature to 660°C within 15 minutes, and open the Ga source, As source and the baffles of the substrate at the same time to start the high-temperature growth of the nanowires; after 30 minutes of growth, close all the baffles to end the growth of the branched nanowires.

[0072] The III-V group nanowires are selected from InGaAs nanowires, InGaN, GaN nanowires, and InN nanowires, which will not be elaborated here. Example 4

[0073] The embodiment of the present invention further provides a III-V branched nanowire, which is obtained by the method for growing a III-V branched nanowire on a silicon substrate described in Embodiment 1, Embodiment 2 or Embodiment 3. Example 5

[0074] The branched nanowire is a heterojunction, that is, the primary trunk and the secondary branches are made of two different materials, or the tertiary branches are made of different materials from the secondary branches, or the same element types but different proportions. The main branch nanowire is made of GaAs material, and the branch nanowire is made of InGaAs material. Example 6

[0075] The branched nanowires have multiple branch structures, including secondary or tertiary branch structures, which are obtained through multiple growths.

[0076] The second level branches are grown on the basis of the first level branches, wherein the first level branches are perpendicular to the main branch nanowires, and the second level branches are parallel to the first level branches, so that the second level branches are parallel to the first level branches.

[0077] Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0078] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for growing III-V branched nanowires, characterized in that: The method includes: S1: growing main branch nanowires on the substrate; this step includes the following sub-steps: S11: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -6 Torr, Al beam current at 5× 10 -6 Torr, As beam current is 5×10 -6 Torr, so that the V / III beam current ratio is 20; S12: First, the baffles of the Ga source and the substrate are opened for 30 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously; S13: High-temperature growth of GaAs nanowires: After closing the baffles, the substrate temperature is raised to 640°C within 10 minutes, and the Ga source, As source and substrate baffles are opened at the same time to start the high-temperature growth of the nanowires; after 25 minutes of growth, all baffles are closed to end the growth of the main branch nanowires; S2: Open the baffles of the catalyst source and the substrate, pre-deposit catalytic droplets as catalysts required for the growth of secondary nanowires; then open the growth source of the branch nanowires to start nucleation; this step includes the following sub-steps: S21: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -6 Torr, Al beam current at 5× 10 -6 Torr, As beam current is 5×10 -6 Torr, so that the V / III beam current ratio is 30; S22: First, the baffles of the Ga source and the substrate are opened for 30 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously; S3: Raise the substrate temperature, then turn on the growth source of the branch nanowires to start growth; this step includes: S31: High-temperature growth of GaAs nanowires: After closing the baffles, raise the substrate temperature to 660°C within 10 minutes, and open the Ga source, As source and the baffles of the substrate at the same time to start the high-temperature growth of the nanowires; after 25 to 30 minutes of growth, close all the baffles to end the growth of the branched nanowires.

2. A method for growing III-V branched nanowires, characterized in that: The method includes: S1: growing main branch nanowires on a substrate; this step includes the following sub-steps: S11: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -7 Torr, Al beam current at 5× 10 -7 Torr, As beam current is 5×10 -7 Torr, so that the V / III beam current ratio is 50; S12: First, the baffles of the Ga source and the substrate are opened for 120 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously; S13: High-temperature growth of GaAs nanowires: After closing the baffles, the substrate temperature is raised to 660°C within 15 minutes, and the Ga source, As source and substrate baffles are opened at the same time to start the high-temperature growth of nanowires; after 30 minutes of growth, all baffles are closed to end the growth of the main branch nanowires; S2: Open the baffles of the catalyst source and the substrate, pre-deposit catalytic droplets as catalysts required for the growth of secondary nanowires; then open the growth source of the branch nanowires to start nucleation; this step includes the following sub-steps: S21: Low-temperature nucleation of GaAs nanowires: Set the substrate temperature at 630°C and adjust the Ga beam current at 5× 10 -7 Torr, Al beam current at 5× 10 -7 Torr, As beam current is 5×10 -7 Torr, so that the V / III beam current ratio is 50; S22: First, the baffles of the Ga source and the substrate are opened for 120 seconds to pre-deposit Ga droplets as a catalyst for the VLS growth of nanowires; then the baffle of the As source is opened to start the nucleation of GaAs nanowires, and after 10 minutes of growth, the Ga source, Al source, As source and the baffle of the substrate are closed simultaneously; S3: Raise the substrate temperature, then turn on the growth source of the branch nanowires to start growth; this step includes: S31: High-temperature growth of GaAs nanowires: After closing the baffles, raise the substrate temperature to 660°C within 15 minutes, and open the Ga source, As source and the baffles of the substrate at the same time to start the high-temperature growth of the nanowires; after 30 minutes of growth, close all the baffles to end the growth of the branched nanowires.

3. A III-V branched nanowire, characterized in that: Obtained by the method for growing III-V group branched nanowires as described in claim 1 or 2.

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