CN111969056A - Core-shell structure AlGaN/GaN heterojunction nanowire-based transistor and preparation method thereof - Google Patents

Abstract

The invention provides an AlGaN/GaN heterojunction nanowire-based transistor with a core-shell structure and a preparation method thereof, belonging to the technical field of microelectronics. In the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the invention, the GaN nanowire, the AlN layer and the AlGaN layer form the AlGaN/GaN heterojunction nanowire with the core-shell structure, and the AlGaN/GaN heterojunction nanowire with the structure can form the wrapping type source electrode, the drain electrode and the gate electrode, so that two-dimensional electron gas is generated on the inner interface of the whole core-shell structure, namely the two-dimensional electron gas is generated on any side surface of the AlGaN/GaN heterojunction nanowire.

Description

A core-shell structure AlGaN/GaN heterojunction nanowire-based transistor and its preparation method

technical field

The invention relates to the technical field of microelectronics, in particular to a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor and a preparation method thereof.

Background technique

As a representative of the third-generation semiconductor material, GaN material has more prominent advantages: large forbidden band width (3.4eV), high temperature resistance, radiation resistance, stable physical and chemical properties, etc. In all kinds of III-nitride heterojunctions, AlGaN/GaN will form two-dimensional electron gas (2DEG) on the inner surface of the heterojunction due to the large spontaneous polarization effect, which is widely used in the preparation of high Electron Mobility Transistors. Today, GaN-based high electron mobility transistor devices (HEMTs) have been widely used in power amplifiers, switches, oscillators and integrated circuits such as low-noise, high-power, broadband traveling waves; The development of Internet technology represented by 5G technology and 5G technology will also have good application prospects in the fields of communication, radar, electronics, aerospace, nuclear industry, national defense and military.

One-dimensional nanowires, due to their size advantages, not only have the excellent properties of semiconductor materials, but also have good mechanical flexibility, high specific surface area and unique electrical properties, etc., making them a hot research topic at present. The future microelectronic integration field has good application prospects.

AlGaN/GaN heterojunction nanowire-based HEMT electronic devices not only have excellent characteristics such as high frequency and high voltage, but also combine with the basic properties of nanowires, which are instructive for the production of integrated electronic devices of high temperature, high frequency and high power. significance. However, the traditional AlGaN/GaN heterojunction nanowire-based HEMT electronic device is similar to a sandwich structure, with AlN and AlGaN on the GaN layer respectively, and a two-dimensional electron gas between GaN and AlN is formed on the inner side of GaN, and only in it A GaN surface forms a two-dimensional electron gas, resulting in a limited total number of electrons in the two-dimensional electron gas. As the voltage increases, its current increases first and then remains unchanged, which limits the further improvement of the electron mobility of electronic devices.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor and a preparation method thereof. The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor has high electron mobility.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The present invention provides a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor, comprising a substrate and GaN nanowires supported on the surface of the substrate, wherein the GaN nanowires are in the shape of a hexagonal prism and are arranged along the In the length direction of the GaN nanowire, the outer periphery of the GaN nanowire is sequentially wrapped with an AlN layer and an AlGaN layer, and the GaN nanowire, the AlN layer and the AlGaN layer form an AlGaN/GaN heterojunction nanowire with a core-shell structure; All sides of the core-shell structure AlGaN/GaN heterojunction nanowires generate two-dimensional electron gas;

Also includes a source electrode and a drain electrode respectively disposed at both ends of the AlGaN/GaN heterojunction nanowire;

Also includes a gate electrode disposed between the source electrode and the drain electrode;

Also includes a gate dielectric layer disposed on the back side of the gate electrode, the gate dielectric layer being in contact with the AlGaN/GaN heterojunction nanowires;

The source electrode, the drain electrode and the gate electrode are all wrapped in form, and the source electrode, the drain electrode and the gate electrode all form a closed loop and are wrapped on the AlGaN/GaN heterojunction nanowire.

Preferably, the side length of the top hexagon of the GaN nanowire is 0.5-10 μm, and the height of the GaN nanowire is 130-180 μm.

Preferably, the thickness of the AlN layer is 1-3 nm.

Preferably, the ratio of the total atomic number of Al to metal elements in the AlGaN layer is (0.1-0.3): 1; the thickness of the AlGaN layer is 10-30 nm.

Preferably, the material of the source electrode and the drain electrode is independently stacked Ti/Al/Ni/Au or stacked Ti/Al/Ti/Au; the distance between the source electrode and the drain electrode is 50-80 μm.

Preferably, the material of the gate dielectric layer is HfO ₂ or Al ₂ O ₃ , and the thickness of the gate dielectric layer is 100-200 nm.

Preferably, the material of the gate electrode is stacked Ni/Au, and in the stacked Ni/Au, the thickness of the Ni layer is 20-40 nm, and the thickness of the Au layer is 150-450 nm.

The present invention provides the preparation method of the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to the above technical solution, comprising the following steps:

The Si ₃ N ₄ seed crystal layer was grown on the sapphire substrate by metal organic chemical vapor deposition method;

growing GaN nanowires vertically on the Si ₃ N ₄ seed layer;

An AlN layer and an AlGaN layer are sequentially epitaxially grown around the outer side of the GaN nanowires, and after ultrasonic treatment, the sapphire substrate is removed to obtain a solution of AlGaN/GaN heterojunction nanowires containing a core-shell structure;

The solution containing the core-shell structure AlGaN/GaN heterojunction nanowires is coated on the substrate, and after drying, a source electrode is prepared at one end of the obtained core-shell structure AlGaN/GaN heterojunction nanowires. A drain electrode is prepared at the other end of the AlGaN/GaN heterojunction nanowire with the core-shell structure to form a wrapped source electrode and a wrapped drain electrode;

A gate dielectric layer is prepared between the source electrode and the drain electrode, a gate electrode is prepared on the gate dielectric layer to form a wrapped gate electrode, and after annealing, a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor is obtained .

Preferably, the method for preparing the source electrode or the drain electrode is independently a magnetron sputtering method or an electron beam evaporation method.

Preferably, the method for preparing the gate dielectric layer and the gate electrode is a magnetron sputtering method.

The present invention provides a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor, comprising a substrate and GaN nanowires supported on the surface of the substrate, wherein the GaN nanowires are in the shape of a hexagonal prism and are arranged along the In the length direction of the GaN nanowire, the outer periphery of the GaN nanowire is sequentially wrapped with an AlN layer and an AlGaN layer, and the GaN nanowire, the AlN layer and the AlGaN layer form an AlGaN/GaN heterojunction nanowire with a core-shell structure; All sides of the AlGaN/GaN heterojunction nanowire of the core-shell structure generate two-dimensional electron gas; it also includes a source electrode and a drain electrode respectively disposed at both ends of the AlGaN/GaN heterojunction nanowire; a gate electrode between the source electrode and the drain electrode; further comprising a gate dielectric layer disposed on the back side of the gate electrode, the gate dielectric layer being in contact with the AlGaN/GaN heterojunction nanowires; the source electrode, The forms of the drain electrode and the gate electrode are all wrapped, and the source electrode, the drain electrode and the gate electrode all form a closed loop and are wrapped on the AlGaN/GaN heterojunction nanowire.

In the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention, the GaN nanowire, the AlN layer and the AlGaN layer form the core-shell structure AlGaN/GaN heterojunction nanowire, and the AlGaN/GaN heterojunction of this structure Junction nanowires can form wrapped drain electrodes, source electrodes, and gate electrodes, so that two-dimensional electron gas can be generated at the inner interface of the entire core-shell structure, that is, there are two-dimensional electrons on any side of the AlGaN/GaN heterojunction nanowires. Compared with the traditional HEMT electronic device (nanowire level, and only one face has two-dimensional electrons), the gas increases the conduction current of the device and effectively improves the electrical performance of the HEMT electronic device.

In the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention, the source electrode, the drain electrode and the gate electrode are all wrapped in the form, that is, the source electrode, the drain electrode and the gate electrode combine the core-shell structure AlGaN/GaN Heterojunction nanowire wrapping can make the two-dimensional electron gas better transport, improve the contact between metal and semiconductor, and then improve the electrical conductivity of the device; while in the existing HEMT device, the source electrode, drain electrode and gate electrode are generally Covering the electrodes, that is, covering the GaN nanowires, cannot generate a two-dimensional electron gas on either side of the nanowires.

The present invention provides a method for preparing the above-mentioned core-shell structure AlGaN/GaN heterojunction nanowire-based transistor. The present invention uses the MOCVD method to epitaxially grow the core-shell structure AlGaN/GaN heterojunction nanowire, and can control the growth conditions of MOCVD so that the The length, width and height of the AlGaN/GaN heterojunction nanowire are controllable, thereby effectively improving the growth controllability of the AlGaN/GaN heterojunction nanowire-based HEMT device.

The preparation method of the invention combines MOCVD epitaxial growth, magnetron sputtering, rapid thermal annealing and other technologies to realize the preparation of the core-shell structure AlGaN/GaN heterojunction nanowire-based HEMT electronic device. The method is simple and has high repeatability. It is more conducive to practical application in the field of semiconductor devices.

Description of drawings

1 is a schematic structural diagram of a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention;

2 is a schematic diagram of a core-shell structure AlGaN/GaN heterojunction nanowire in the present invention;

3 is a schematic flowchart of a method for preparing a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to the present invention;

4 is a current-voltage transfer curve diagram of the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor prepared in Example 1 under different gate voltages.

Detailed ways

As shown in FIG. 1 , the present invention provides a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor, comprising a substrate and a GaN nanowire supported on the surface of the substrate, and the GaN nanowire has a shape of A hexagonal prism shape, along the length direction of the GaN nanowire, the outer periphery of the GaN nanowire is sequentially wrapped with an AlN layer and an AlGaN layer, and the GaN nanowire, the AlN layer and the AlGaN layer form a core-shell structure AlGaN/GaN Heterojunction nanowires; all sides of the core-shell structure AlGaN/GaN heterojunction nanowires generate two-dimensional electron gas;

Also includes a source electrode and a drain electrode respectively disposed at both ends of the AlGaN/GaN heterojunction nanowire;

Also includes a gate electrode disposed between the source electrode and the drain electrode;

Also includes a gate dielectric layer disposed on the back side of the gate electrode, the gate dielectric layer being in contact with the AlGaN/GaN heterojunction nanowires;

The source electrode, the drain electrode and the gate electrode are all wrapped in form, and the source electrode, the drain electrode and the gate electrode all form a closed loop and are wrapped on the AlGaN/GaN heterojunction nanowire.

In the present invention, unless otherwise specified, the required materials are all commercially available products well known to those skilled in the art.

The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the invention includes a substrate. In the present invention, the substrate is preferably sapphire or high-resistance silicon, and the present invention has no special limitation on the sapphire or high-resistance silicon, and a commercially available commodity well-known in the art can be selected. In the present invention, before the substrate is used, it is preferred to use acetone, isopropanol and deionized water to perform ultrasonic cleaning in sequence, and dry it with nitrogen. The present invention does not have a special limitation on the processes of ultrasonic cleaning and nitrogen drying, and can be carried out according to well-known processes in the art.

The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention includes GaN nanowires supported on the surface of the substrate, and the GaN nanowires are in the shape of a hexagonal prism; along the length of the GaN nanowires The outer side of the GaN nanowire is wrapped with an AlN layer and an AlGaN layer in turn, and the GaN nanowire, the AlN layer and the AlGaN layer form an AlGaN/GaN heterojunction nanowire with a core-shell structure (as shown in Figure 2) , all sides of the core-shell structure AlGaN/GaN heterojunction nanowires generate two-dimensional electron gas. In the present invention, the side length of the top hexagon of the GaN nanowire is preferably 0.5-10 μm, more preferably 2-8 μm, still more preferably 5-6 μm, and the height of the GaN nanowire is preferably 130-180 μm , more preferably 150 to 160 μm. The present invention does not have a special limitation on the quantity and arrangement of the GaN nanowires, and can be set according to the quantity and manner well known in the art.

In the present invention, the thickness of the AlN layer is preferably 1 to 3 nm, more preferably 1.5 to 2.5 nm.

In the present invention, the ratio of the total number of atoms of Al to metal elements in the AlGaN layer is preferably (0.1-0.3): 1, more preferably 0.2: 1, that is, Al _x Ga _1-x N, wherein x is preferably 0.1-0.3, more preferably 0.2; the thickness of the AlGaN layer is preferably 10-30 nm, more preferably 15-25 nm.

In the present invention, the GaN nanowires, the AlN layer and the AlGaN layer form AlGaN/GaN heterojunction nanowires with a core-shell structure; in the AlGaN/GaN heterojunction nanowires with a core-shell structure, the AlN layer and the AlGaN layer The layer is only wrapped around the outer side of the GaN nanowire along the length direction, and at both ends of the GaN nanowire, the AlN layer and the AlGaN layer are not wrapped.

The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention further includes a source electrode and a drain electrode respectively disposed at both ends of the AlGaN/GaN heterojunction nanowire. In the present invention, the distance between the source electrode and the drain electrode is preferably 50 to 80 μm, and more preferably 60 to 70 μm. The present invention does not specifically limit the specific positions of the two ends, as long as the above-mentioned distance is satisfied. In the present invention, the material of the source electrode and the drain electrode is independently preferably stacked Ti/Al/Ni/Au or stacked Ti/Al/Ti/Au; wherein, the Ti layer and AlGaN/GaN heterojunction The nanowires are in contact, and the Au layer is the outermost layer; in the materials of the source electrode and the drain electrode, the thickness of the Ti layer is preferably 10-30 nm, more preferably 15-25 nm, and the thickness of the Al layer is independently preferably 90-120 nm The thickness of the Ni layer is preferably 5 to 15 nm, more preferably 8 to 12 nm, and the thickness of the Au layer is independently preferably 80 to 150 nm, more preferably 100 to 120 nm.

The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention further includes a gate electrode disposed between the source electrode and the drain electrode. In the present invention, the material of the gate electrode is preferably stacked Ni/Au, wherein the Ni layer is in contact with the gate dielectric layer, and in the stacked Ni/Au, the thickness of the Ni layer is preferably 20-40 nm, more preferably 30 nm, the thickness of the Au layer is preferably 150 to 450 nm, and more preferably 300 nm. In the present invention, the thickness of the gate electrode is preferably 170 to 490 nm, more preferably 360 nm.

The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor provided by the present invention further includes a gate dielectric layer disposed on the inner side of the gate electrode, and the gate dielectric layer is in contact with the AlGaN/GaN heterojunction nanowire. The present invention does not specifically limit the specific position of the gate dielectric layer on the inner side of the gate electrode, which can be understood according to the positions well known in the art. In the present invention, the material of the gate dielectric layer is preferably HfO ₂ or Al ₂ O ₃ , and the thickness of the gate dielectric layer is preferably 100-200 nm, more preferably 120-180 nm, and even more preferably 150-160 nm.

In the present invention, the source electrode, the drain electrode and the gate electrode are all wrapped in the form of wrapping, which means that each electrode forms a closed loop, wrapped on each surface of the AlGaN/GaN heterojunction nanowire superior.

The present invention provides the preparation method of the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to the above technical solution, comprising the following steps:

The Si ₃ N ₄ seed crystal layer was grown on the sapphire substrate by metal organic chemical vapor deposition method;

growing GaN nanowires vertically on the Si ₃ N ₄ seed layer;

An AlN layer and an AlGaN layer are sequentially epitaxially grown around the outer side of the GaN nanowires, and after ultrasonic treatment, the sapphire substrate is removed to obtain a solution of AlGaN/GaN heterojunction nanowires containing a core-shell structure;

The solution containing the core-shell structure AlGaN/GaN heterojunction nanowires is coated on the substrate, and after drying, a source electrode is prepared at one end of the obtained core-shell structure AlGaN/GaN heterojunction nanowires. A drain electrode is prepared at the other end of the AlGaN/GaN heterojunction nanowire with the core-shell structure to form a wrapped source electrode and a wrapped drain electrode;

A gate dielectric layer is prepared between the source electrode and the drain electrode, a gate electrode is prepared on the gate dielectric layer to form a wrapped gate electrode, and after annealing, a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor is obtained .

The invention adopts the metal organic chemical vapor deposition method to grow the Si ₃ N ₄ seed crystal layer on the sapphire substrate. The Si ₃ N ₄ seed crystal layer of the present invention is discretely grown on the surface of the sapphire substrate. In the present invention, the thickness of the Si ₃ N ₄ seed crystal layer is not particularly limited, and the thickness well-known in the art may be selected. In the present invention, the discrete distribution of the Si ₃ N ₄ seed crystal layer on the surface of the substrate means that the Si ₃ N ₄ seed crystal is discontinuous, thereby ensuring that the subsequent growth of gallium nitride on the seed crystal can form a columnar shape . The present invention utilizes the Si ₃ N ₄ seed crystal layer to provide seeds for the growth of GaN, and the dispersion (discontinuity) of the seed crystal ensures the dispersion of the subsequently grown gallium nitride, thereby ensuring that vertical structure GaN nanowires are obtained.

In the present invention, the raw materials for growing the Si ₃ N ₄ seed crystal layer are preferably SiH ₄ and NH ₃ , and the present invention does not limit the dosage ratio of the SiH ₄ and NH ₃ , and can grow discrete Si ₃ The N ₄ seed layer is sufficient. The present invention has no particular limitation on the specific process of the metal organic chemical vapor deposition (MOCVD) method, and the process is performed according to a well-known process in the art, and a Si ₃ N ₄ seed crystal layer can be grown on the substrate. In the embodiment of the present invention, the temperature of the MOCVD reaction chamber used for the MOCVD is 800°C.

After growing the Si ₃ N ₄ seed crystal layer, the present invention vertically grows GaN nanowires on the Si ₃ N ₄ seed crystal layer, and sequentially epitaxially grows an AlN layer and an AlGaN layer around the outer side of the GaN nanowires. After ultrasonic treatment , removing the sapphire substrate to obtain a solution of AlGaN/GaN heterojunction nanowires with a core-shell structure. In the present invention, the metal organic chemical vapor deposition method is preferably used to grow the GaN nanowires, the AlN layer and the AlGaN layer. The present invention has no particular limitation on the specific process of the metal organic chemical vapor deposition method (MOCVD), and can be performed according to a process well known in the art. In the present invention, the raw materials for growing the GaN nanowires are preferably TMGa and NH ₃ , the raw materials for growing the AlN layer are preferably TMAl and NH ₃ , and the raw materials for growing the AlGaN layer are preferably TMGa, TMAl and NH ₃ . The present invention does not specifically limit the ratio of the raw materials used for growing the GaN nanowire, the AlN layer and the AlGaN layer, and the ratio well known in the art can be selected.

In the present invention, the ultrasonic treatment is preferably performed by mixing the products after epitaxial growth of the AlN layer and the AlGaN layer with a solvent, and performing ultrasonication. In the present invention, the solvent is preferably water, alcohol or isopropanol; the present invention does not limit the amount of the solvent, as long as the product after epitaxial growth of AlN layer and AlGaN layer can be completely infiltrated. In the present invention, the ultrasonic time is preferably 15-30 min, more preferably 20-250 min. The present invention has no special limitation on the ultrasonic equipment, and an ultrasonic equipment well-known in the art can be selected. In the invention, the GaN nanowires are broken by ultrasonic treatment, and the GaN nanowires are separated from the sapphire substrate, and a single nanowire is obtained by peeling off the epitaxial wafer after epitaxial growth of the AlN layer and the AlGaN layer to prepare a transistor device. The outer layers are AlN and AlGaN sequentially, forming AlGaN/GaN heterojunction nanowires with core-shell structure.

After obtaining the solution of the AlGaN/GaN heterojunction nanowires containing the core-shell structure, the present invention coats the solution of the AlGaN/GaN heterojunction nanowires containing the core-shell structure on the substrate, and after drying, the obtained solution is obtained. A source electrode is prepared at one end of the core-shell structure AlGaN/GaN heterojunction nanowire, and a drain electrode is prepared at the other end of the core-shell structure AlGaN/GaN heterojunction nanowire to form a wrapped source electrode and a wrapped drain electrode . In the present invention, the concentration of the solution of the core-shell structure-containing AlGaN/GaN heterojunction nanowire is not particularly limited, and the concentration may correspond to the amount of the above-mentioned solvent. In the present invention, the solvent is volatilized by drying to obtain AlGaN/GaN heterojunction nanowires with a core-shell structure. The present invention does not have a special limitation on the coating and drying processes, and can be performed according to well-known processes in the art. In the present invention, the substrate is used to transfer and support the AlGaN/GaN heterojunction nanowire of the core-shell structure, so as to facilitate the subsequent preparation of the source electrode, the drain electrode and the gate electrode.

In the present invention, a patterned metal mask is preferably used to prepare the drain electrode or the source electrode. The present invention has no special limitation on the patterned metal mask, and any patterned metal mask known in the art can be used. In the present invention, the method for preparing the source electrode or the drain electrode is independently preferably a magnetron sputtering method or an electron beam evaporation method. The present invention has no particular limitation on the specific process of the magnetron sputtering method or the electron beam evaporation method, and the wrapped drain electrode and the wrapped source electrode of the above-mentioned thickness can be formed according to the process well known in the art.

After the source electrode and the drain electrode are formed, the present invention prepares a gate dielectric layer between the source electrode and the drain electrode, prepares a gate electrode on the gate dielectric layer to form a wrapped gate electrode, and obtains a core-shell structure after annealing AlGaN/GaN heterojunction nanowire-based transistors. In the present invention, the method for preparing the gate dielectric layer and the gate electrode is preferably a magnetron sputtering method. The specific process of the magnetron sputtering method is not particularly limited in the present invention, and the wrapped gate dielectric layer and the wrapped gate electrode can be formed according to the processes well known in the art. In the present invention, a patterned metal mask is preferably used to prepare the gate dielectric layer and the gate electrode. The present invention has no special limitation on the patterned metal mask, and any patterned metal mask known in the art can be used. The specific position of the gate electrode is not particularly limited in the present invention, and the gate electrode may be located between the source electrode and the drain electrode according to operations well known in the art.

In the present invention, the annealing is preferably performed in a rapid annealing furnace, the annealing is preferably performed in a N ₂ environment, the annealing temperature is preferably 850° C., and the time is preferably 30s; contact with the device and improve the conductivity of the electrodes.

3 is a schematic flow chart of a method for preparing a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to the present invention; as shown in the figure, the present invention first grows a Si 3 N 4 seed crystal layer on the substrate, and then grows the Si ₃ N ₄ seed crystal layer on the Si ₃ N ₄ GaN nanowires are vertically grown on the seed layer, and AlN layers and AlGaN layers are epitaxially grown on the outside of the GaN nanowires in turn. The obtained product is ultrasonicated, and the epitaxial wafer is peeled off to obtain a core-shell structure AlGaN/GaN heterojunction nanowires; then prepare a wrapped source electrode and a wrapped drain electrode at both ends of the core-shell structure AlGaN/GaN heterojunction nanowire, and then prepare a wrapped gate dielectric layer between the source electrode and the drain electrode, And a gate electrode is prepared on the gate dielectric layer to obtain a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

Use acetone, isopropanol and deionized water to ultrasonically clean the sapphire substrate in turn, dry it with nitrogen, and put it into the MOCVD chamber;

Using the MOCVD method, using SiH ₄ and NH ₃ as raw materials, setting the MOCVD reaction chamber temperature to 800 ° C, growing discrete Si ₃ N ₄ seed crystal layers on the sapphire substrate, using TMGa and NH ₃ as raw materials, in the Si 3 N 4 seed layer. _3N4 GaN nanowires are grown _on the seed layer, the side length of the hexagon in the nanowire hexagonal cylinder is 0.5 μm, and the height is 130 μm, and then an AlN layer (raw material) is sequentially epitaxially grown around the outer side of the GaN nanowires. are TMAl and NH ₃ ) and AlGaN layers (the raw materials are TMGa, TMAl and NH ₃ ), the thickness of the AlN layer is 1 nm, the atomic ratio of Al to the total metal elements in the AlGaN layer is 0.1:1, and the thickness of the AlGaN layer is 10nm;

The epitaxially grown sample was immersed in deionized water, immersed in water, and ultrasonicated for 15 min. The obtained solution containing AlGaN/GaN heterojunction nanowires was spin-coated on a sapphire substrate and dried to obtain a core-shell structure AlGaN/GaN Heterojunction nanowires;

Using a patterned metal mask and magnetron sputtering, a source electrode and a drain electrode are respectively prepared at both ends of the core-shell structure AlGaN/GaN heterojunction nanowire to form a wrapped source electrode and a wrapped leakage current. The distance between the source electrode and the drain electrode is 50 μm; wherein, the material of the source electrode and the drain electrode is Ti/Al/Ni/Au arranged in layers, and the thickness of each layer is 20nm/100nm/10nm/100nm; and Ti The layer is in contact with the AlGaN/GaN heterojunction nanowire, and the Au layer is the outermost layer;

Then another patterned metal mask is used between the source electrode and the drain electrode to prepare an Al ₂ O ₃ gate dielectric layer (with a thickness of 150 nm) by means of magnetron sputtering, and Ni is prepared on the gate dielectric layer. /Au gate electrode, the thickness of each layer is 30nm/300nm, and the Ni layer is in contact with the gate dielectric layer;

The product with source electrode, drain electrode and gate electrode was annealed in a rapid annealing furnace at 850° C. for 30s under N ₂ environment; a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor (CS-HEMT) was obtained.

Example 2

Use acetone, isopropanol and deionized water to ultrasonically clean the sapphire substrate in turn, dry it with nitrogen, and put it into the MOCVD chamber;

Using the MOCVD method, using SiH ₄ and NH ₃ as raw materials, setting the MOCVD reaction chamber temperature to 800 ° C, growing discrete Si ₃ N ₄ seed crystal layers on the sapphire substrate, using TMGa and NH ₃ as raw materials, in the Si 3 N 4 seed layer. _3N4 GaN nanowires are grown _on the seed layer, the side length of the hexagon in the nanowire hexagonal cylinder is 10 μm, and the height is 180 μm, and then an AlN layer is epitaxially grown around the outer side of the GaN nanowire (the raw material is TMAl and NH ₃ ) and AlGaN layers (the raw materials are TMGa, TMAl and NH ₃ ), the thickness of the AlN layer is 3nm, the atomic ratio of Al to total metal elements in the AlGaN layer is 0.3:1, and the thickness of the AlGaN layer is 30nm ;

The epitaxially grown sample was immersed in deionized water, immersed in water, and ultrasonicated for 15 min. The obtained solution containing AlGaN/GaN heterojunction nanowires was spin-coated on a sapphire substrate and dried to obtain a core-shell structure AlGaN/GaN Heterojunction nanowires;

Using a patterned metal mask and magnetron sputtering, a source electrode and a drain electrode are respectively prepared at both ends of the core-shell structure AlGaN/GaN heterojunction nanowire to form a wrapped source electrode and a wrapped leakage current. The distance between the source electrode and the drain electrode is 80 μm; wherein, the material of the source electrode and the drain electrode is Ti/Al/Ni/Au arranged in layers, and the thickness of each layer is 30nm/120nm/15nm/150nm; and Ti The layer is in contact with the AlGaN/GaN heterojunction nanowire, and the Au layer is the outermost layer;

Then another patterned metal mask is used between the source electrode and the drain electrode to prepare an Al ₂ O ₃ gate dielectric layer (with a thickness of 150 nm) by means of magnetron sputtering, and Ni is prepared on the gate dielectric layer. /Au gate electrode, the thickness of each layer is 30nm/300nm, and the Ni layer is in contact with the gate dielectric layer;

The product with source electrode, drain electrode and gate electrode was annealed in a rapid annealing furnace at 850° C. for 30s under N ₂ environment; a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor (CS-HEMT) was obtained.

Example 3

Use acetone, isopropanol and deionized water to ultrasonically clean the sapphire substrate in turn, dry it with nitrogen, and put it into the MOCVD chamber;

Using the MOCVD method, using SiH ₄ and NH ₃ as raw materials, setting the MOCVD reaction chamber temperature to 800 ° C, growing discrete Si ₃ N ₄ seed crystal layers on the sapphire substrate, using TMGa and NH ₃ as raw materials, in the Si 3 N 4 seed layer. _3N4 GaN nanowires are grown _on the seed layer, the side length of the hexagon in the nanowire hexagonal cylinder is 3 μm, and the height is 150 μm, and then the AlN layer is epitaxially grown around the outer side of the GaN nanowire (the raw material is TMAl and NH ₃ ) and AlGaN layers (the raw materials are TMGa, TMAl and NH ₃ ), the thickness of the AlN layer is 1.5 nm, the atomic ratio of Al to the total metal elements in the AlGaN layer is 0.15:1, and the thickness of the AlGaN layer is 15nm;

The epitaxially grown sample was immersed in deionized water, immersed in water, and ultrasonicated for 15 min. The obtained solution containing AlGaN/GaN heterojunction nanowires was spin-coated on a sapphire substrate and dried to obtain a core-shell structure AlGaN/GaN Heterojunction nanowires;

Using a patterned metal mask and magnetron sputtering, a source electrode and a drain electrode are respectively prepared at both ends of the core-shell structure AlGaN/GaN heterojunction nanowire to form a wrapped source electrode and a wrapped leakage current. The distance between the source electrode and the drain electrode is 65 μm; the material of the source electrode and the drain electrode is Ti/Al/Ni/Au laminated and arranged, and the thickness of each layer is 20nm/100nm/10nm/100nm respectively; and the Ti layer In contact with AlGaN/GaN heterojunction nanowires, the Au layer is the outermost layer;

Then another patterned metal mask is used between the source electrode and the drain electrode to prepare an Al ₂ O ₃ gate dielectric layer (with a thickness of 150 nm) by means of magnetron sputtering, and Ni is prepared on the gate dielectric layer. /Au gate electrode, the thickness of each layer is 30nm/300nm, and the Ni layer is in contact with the gate dielectric layer;

The product with source electrode, drain electrode and gate electrode was annealed in a rapid annealing furnace at 850° C. for 30s under N ₂ environment; a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor (CS-HEMT) was obtained.

Performance Testing

The electrical performance of the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor prepared in Example 1 was tested, and the current-voltage characteristics of the above transistor were measured using a source meter and a matching probe station. The results are shown in Figure 4, from Figure 4 It can be seen that with the increase of the gate voltage (VG), the maximum output voltage across the source and drain electrodes increases, indicating a better control capability of the gate (when the gate voltage is greater than -3V). When the gate voltage is fixed, the current between the source and drain electrodes first increases and then saturates with the increase of the voltage between the source and drain, which is in line with the characteristics of the transistor and indicates that the transistor provided by the present invention has better electrical performance.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A core-shell structure AlGaN/GaN heterojunction nanowire-based transistor, comprising a substrate and a GaN nanowire supported on the surface of the substrate, the GaN nanowire is in the shape of a hexagonal prism, and along the GaN nanowire In the length direction of the nanowire, an AlN layer and an AlGaN layer are sequentially wrapped around the outer side of the GaN nanowire, and the GaN nanowire, the AlN layer and the AlGaN layer form an AlGaN/GaN heterojunction nanowire with a core-shell structure; the All sides of the core-shell structure AlGaN/GaN heterojunction nanowires generate two-dimensional electron gas; Also includes a source electrode and a drain electrode respectively disposed at both ends of the AlGaN/GaN heterojunction nanowire; Also includes a gate electrode disposed between the source electrode and the drain electrode; Also includes a gate dielectric layer disposed on the back side of the gate electrode, the gate dielectric layer being in contact with the AlGaN/GaN heterojunction nanowires; The source electrode, the drain electrode and the gate electrode are all wrapped in form, and the source electrode, the drain electrode and the gate electrode all form a closed loop and are wrapped on the AlGaN/GaN heterojunction nanowire. 2 . The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to claim 1 , wherein the top hexagon of the GaN nanowire has a side length of 0.5-10 μm, and the GaN nanowire has a side length of 0.5-10 μm. 3 . The height of 130 ~ 180μm. 3 . The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to claim 1 , wherein the thickness of the AlN layer is 1-3 nm. 4 . 4 . The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to claim 1 , wherein the ratio of the total number of atoms of Al to metal elements in the AlGaN layer is (0.1-0.3):1 ; The thickness of the AlGaN layer is 10-30 nm. 5. The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to claim 1, wherein the material of the source electrode and the drain electrode is independently stacked Ti/Al/Ni/Au or stacked The provided Ti/Al/Ti/Au; the distance between the source electrode and the drain electrode is 50-80 μm. 6 . The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to claim 1 , wherein the material of the gate dielectric layer is HfO ₂ or Al ₂ O ₃ , and the thickness of the gate dielectric layer is HfO 2 or Al 2 O 3 . is 100 to 200 nm. 7 . The core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to claim 1 , wherein the gate electrode is made of stacked Ni/Au, and in the stacked Ni/Au, Ni The thickness of the layer is 20 to 40 nm, and the thickness of the Au layer is 150 to 450 nm. 8. The preparation method of the core-shell structure AlGaN/GaN heterojunction nanowire-based transistor according to any one of claims 1 to 7, characterized in that, comprising the following steps: The Si ₃ N ₄ seed crystal layer was grown on the sapphire substrate by metal organic chemical vapor deposition method; growing GaN nanowires vertically on the Si ₃ N ₄ seed layer; An AlN layer and an AlGaN layer are sequentially epitaxially grown around the outer side of the GaN nanowires, and after ultrasonic treatment, the sapphire substrate is removed to obtain a solution of AlGaN/GaN heterojunction nanowires containing a core-shell structure; The solution containing the core-shell structure AlGaN/GaN heterojunction nanowires is coated on the substrate, and after drying, a source electrode is prepared at one end of the obtained core-shell structure AlGaN/GaN heterojunction nanowires. A drain electrode is prepared at the other end of the AlGaN/GaN heterojunction nanowire with the core-shell structure to form a wrapped source electrode and a wrapped drain electrode; A gate dielectric layer is prepared between the source electrode and the drain electrode, a gate electrode is prepared on the gate dielectric layer to form a wrapped gate electrode, and after annealing, a core-shell structure AlGaN/GaN heterojunction nanowire-based transistor is obtained . 9 . The preparation method according to claim 8 , wherein the method for preparing the source electrode or the drain electrode is independently a magnetron sputtering method or an electron beam evaporation method. 10 . 10 . The preparation method according to claim 8 , wherein the method for preparing the gate dielectric layer and the gate electrode is a magnetron sputtering method. 11 .

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