CN104766910B - A kind of GaN nano wire and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of GaN nano wire and preparation method thereof, GaN nano wire preparation method step includes：By MOCVD in substrate Epitaxial growth III-nitride film, and preparation graphically shelters film on this epitaxial wafer, GaN hexagonal pyramid micro-structurals are grown on the patterned epitaxial wafer based on MOCVD selective areas growing method, then the method corroded by alkaline solution falls { 1 101 } side etch of GaN hexagonal pyramid micro-structurals, for { 1 100 } face, top surface is the GaN nano wire in (0001) face for the final side that is prepared into.The advantages of present invention has process is simple, the diameter of nano wire, height and controllable position, can be used to make high performance GaN nano-devices.

Description

A kind of GaN nanowire and its preparation method

technical field

The invention relates to the technical field of semiconductor devices, in particular to a GaN nanowire and a preparation method thereof, which can be used in nanowire microelectronics and optoelectronic devices.

Background technique

Because the properties of nanomaterials such as force, heat, electricity, light, and magnetism are very different from traditional bulk materials, their research has rich scientific content and important scientific value, so it is considered to be one of the three major science and technologies in the 21st century. one. Among them, semiconductor nanowires are considered to be the basic structure of future micro-nano devices due to their unique one-dimensional quantum structure. In recent years, the research work of semiconductor nanowires has made great progress, and its application fields include integrated circuits, transistors, lasers, light-emitting diodes, single-photon devices, and solar cells. Among them, among many semiconductor materials, GaN-based semiconductor materials have a wide direct band gap, and are widely used in high It has become the third-generation semiconductor material after the first-generation germanium and silicon semiconductor materials and the second-generation gallium arsenide and indium phosphide compound semiconductor materials. Therefore, the preparation of GaN nanowires has become a research hotspot.

Although GaN nanowires have very important application prospects, the practical and industrialization of GaN nanowire devices still needs to solve a series of problems. The key issue is how to realize the accurate control of the radius, height and position of GaN nanowires. Therefore, designing and developing a GaN nanowire preparation method whose radius, height and position can be adjusted is the motivation of the present invention.

Contents of the invention

In order to overcome the problem that the radius, height and growth position of GaN nanowires are difficult to control, the present invention first proposes a method for preparing GaN nanowires.

Another purpose of the present invention is to propose a GaN nanowire with practical and industrial value.

In order to achieve the above object, technical scheme of the present invention:

A method for preparing GaN nanowires, comprising the steps of:

Step 1: epitaxially growing a III-nitride film on the substrate by MOCVD;

Step 2: Depositing a dielectric layer on the above-mentioned III-nitride thin film, and preparing the dielectric layer into a patterned masking film;

Step 3: Epitaxial growth of a GaN hexagonal pyramid microstructure with {1-100} planes on the sides and (0001) planes on the top plane by MOCVD selective area growth technology on the above-mentioned patterned group-III nitride film;

Step 4: Etch the {1-101} plane of the GaN hexagonal pyramid microstructure by etching with an alkaline solution, and finally prepare a GaN nanowire with a {1-100} plane on the side and a (0001) plane on the top.

In this preparation method, the height of the GaN hexagonal pyramid microstructure and the size of the (0001) top surface can be changed by controlling the growth parameters of the epitaxially grown GaN hexagonal pyramid microstructure, thereby controlling the thickness of the GaN nanowires formed after being corroded by an alkaline solution. height and radius.

Preferably, the alkaline solution is KOH or NaOH solution, and the mass concentration range of the solution is 5%-80%.

Preferably, in the step 4, wet etching is used to etch the GaN hexagonal pyramid microstructure into GaN nanowires, and the temperature range of the solution during the etching process is 20 ^° C-100 ^° C.

Preferably, the material of the patterned masking film is SiO ₂ or SiN _x , the pattern structure of the opening is circular, and the diameter of the circular hole is in the range of 1 μm-20 μm.

Preferably, the substrate is Si, sapphire, SiC, GaN, AlN or ZnO substrate.

Preferably, the Group-III nitride thin film is an AlN thin film, a GaN thin film, or a composite layer composed of AlN and GaN thin films.

Preferably, by changing the specific pattern structure of the patterned masking film, the position and arrangement form of the GaN hexagonal pyramid structure grown by MOCVD epitaxial growth can be controlled, thereby controlling the position of the GaN nanowire or nanowire array formed after the final corrosion of the alkaline solution and array form.

Preferably, the height of the GaN nanowire is controlled by the height of the GaN hexagonal pyramid microstructure, and the radius of the GaN nanowire is controlled by the (0001) top surface of the GaN hexagonal pyramid microstructure.

A GaN nanowire is a GaN nanowire with a {1-100} plane on the side and a (0001) plane on the top. The bottom of the GaN nanowire is a patterned masking film, a group-III nitride film, and substrate.

Compared with the prior art, the beneficial effects of the present invention are: the present invention provides a GaN nanowire growth preparation process with low cost and strong operability, and the height, diameter and growth position of the GaN nanowire can be precisely control, and a single GaN nanowire or GaN nanowire array can be realized according to requirements.

Description of drawings

Fig. 1 is a flow chart of the basic preparation of GaN nanowires provided by the present invention.

FIG. 2A is an SEM image of the GaN hexagonal pyramid microstructure provided by Embodiment 1 of the present invention.

FIG. 2B is an SEM image of the GaN nanowire provided in Embodiment 1 of the present invention.

FIG. 3A is an SEM image of the GaN hexagonal pyramid microstructure provided by Embodiment 2 of the present invention.

FIG. 3B is an SEM image of the GaN nanowire provided in Embodiment 2 of the present invention.

FIG. 4 is a schematic structural diagram of a GaN nanowire array provided by Embodiment 3 of the present invention.

5 is a schematic cross-sectional structure diagram of a nanowire InGaN/GaN LED with a core/shell structure provided by Embodiment 4 of the present invention.

FIG. 6 is a schematic cross-sectional structure diagram of a rod-shaped nanowire InGaN/GaN LED provided in Embodiment 5 of the present invention.

detailed description

The specific examples described below further describe the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the following descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are Should be included within the protection scope of the present invention.

In the accompanying drawings, 1-substrate, 2-group III nitride film, 3-patterned masking film, 4-GaN hexagonal pyramid microstructure, 5-GaN nanowire, 6-InGaN/GaN active layer, 7-p -GaN capping layer, 8- _SiO2 capping layer.

Referring to Fig. 1, the basic preparation process of the GaN nanowire of the present invention is:

Step 1: epitaxially grow III-nitride films on the substrate by MOCVD;

The second step: depositing a dielectric layer on the above-mentioned III-nitride thin film, and preparing the dielectric layer into a patterned masking film;

Step 3: GaN hexagonal pyramid microstructures with {1-100} planes on the sides and (0001) planes on the top planes are epitaxially grown by MOCVD selective region growth technology on the above-mentioned patterned III-nitride films;

Step 4: Etch the {1-101} plane of the GaN hexagonal pyramid microstructure by etching with an alkaline solution, and finally prepare a GaN nanowire with a {1-100} plane on the side and a (0001) plane on the top.

The following examples are given based on the basic preparation process of the above-mentioned GaN nanowires:

Example 1

GaN nanowires with a diameter of less than 200 nm and a height of about 5 μm are prepared on a Si substrate. The material structure of this embodiment is, from bottom to top, Si substrate, AlN group III nitride film, and _SiO2 patterned masking film , GaN nanowires. That is, in this embodiment, the substrate 1 is a Si substrate, the III-nitride film 2 is an AlN III-nitride film, and the patterned masking film 3 is a _SiO2 patterned masking film.

Its preparation method comprises the following steps in turn:

Step 1: Put the Si substrate into the MOCVD reaction chamber, and epitaxially grow an AlN III-nitride film with a thickness of 300 nm on the Si substrate;

Step 2: Deposit a _SiO2 dielectric layer with a thickness of 100 nm on the above-mentioned AlN III-nitride film (the AlN film grown on the Si substrate is an epitaxial wafer) by PECVD, and use conventional photolithography and wet etching Method, the SiO ₂ dielectric layer is prepared into a patterned masking film with a periodic hole structure, and the pattern of the patterned masking film is a circle with a hole diameter of 3 μm;

Step 3: Put the above-mentioned epitaxial wafer with patterned masking film into the ^MOCVD reaction chamber, and pass 10000 sccm of ammonia gas (NH3) and 40 sccm of trimethylgallium ( TMGa) for 30 minutes, a GaN hexagonal pyramid microstructure is selectively grown. The side of the GaN hexagonal pyramid microstructure is a {1-101} plane, the top plane is a (0001) plane, the height is about 5 μm, and the diameter of the top plane is less than 200 nm. , its structure is shown in Figure 2A;

Step 4: Put the above-mentioned epitaxial wafer with the GaN hexagonal pyramid microstructure in a potassium hydroxide (KOH) solution with a mass concentration of 30% and a temperature of 50 ^o C for 30 minutes to corrode the GaN hexagonal pyramid microstructure {1 The -101} side is etched away to form a GaN nanowire with a {1-100} plane on the side, a (0001) plane on the top, a height of about 5 μm, and a diameter of less than 200 nm. The structure is shown in Figure 2B.

Example 2

GaN nanowires with a diameter of about 500 nm and a height of about 4 μm are prepared on a Si substrate. The material structure of this embodiment is, from bottom to top, Si substrate, AlN/GaN group III nitride film, _SiO2 pattern masking film, GaN nanowires. That is, in this embodiment, the substrate 1 is a Si substrate, the III-nitride thin film 2 is an AlN/GaN III-nitride thin film, and the patterned masking film 3 is a _SiO2 patterned masking film.

Its preparation method comprises the following steps in turn:

Step 1: Put the Si substrate into the MOCVD reaction chamber, and epitaxially grow an AlN epitaxial layer with a thickness of 100 nm and a GaN epitaxial layer with a thickness of 800 nm on the Si substrate in sequence;

Step 2: Deposit a 100 nm _SiO2 dielectric layer on the above-mentioned AlN/GaN group-III nitride film (the AlN/GaN film grown on the Si substrate is an epitaxial wafer) by PECVD, and use conventional photolithography and wet The SiO ₂ dielectric layer is prepared into a patterned masking film with a periodic hole structure, and the pattern of the patterned masking film is a circle with a hole diameter of 3 μm;

Step 3: Put the above-mentioned epitaxial wafer with a patterned mask into the ^MOCVD reaction chamber, and pass 10000 sccm of ammonia gas (NH3) and 40 sccm of trimethylgallium ( TMGa) for 25 minutes, a GaN hexagonal pyramid microstructure is selectively grown. The side of the GaN hexagonal pyramid microstructure is {1-101} plane, the top plane is (0001) plane, the height is about 4 μm, and the diameter of the top plane is about 500 nm, and its structure is shown in Figure 3A;

Step 4: Put the above-mentioned epitaxial wafer with the GaN hexagonal pyramid microstructure in a potassium hydroxide (KOH) solution with a mass concentration of 30% and a temperature of 50 ^o C for 25 minutes to corrode the GaN hexagonal pyramid microstructure {1 The -101} side was etched away to form a GaN nanowire with a {1-100} plane on the side, a (0001) plane on the top, a height of about 4 μm, and a diameter of about 500 nm. The structure is shown in Figure 3B.

Example 3

GaN nanowire arrays with a diameter of less than 200 nm and a height of about 5 μm were prepared on a Si substrate. This embodiment adopts the same material structure as that of Embodiment 1, and the material structure from bottom to top is Si substrate, AlN group III nitride thin film, SiO ₂ patterned masking film, and GaN nanowire. That is, in this embodiment, the substrate 1 is a Si substrate, the III-nitride film 2 is an AlN III-nitride film, and the patterned masking film 3 is a _SiO2 patterned masking film.

The specific preparation process is basically the same as that in Example 1, wherein when preparing the patterned masking film 3 in step 2, the pattern of the masking film is prepared into periodically arranged circular holes with a diameter of 3 μm and a period of 10 μm. Therefore, the array-arranged GaN hexagonal pyramid microstructure can be epitaxially grown in the subsequent MOCVD selective region growth process, and a GaN nanowire array can be prepared by subsequent KOH etching, as shown in FIG. 4 .

Example 4

A nanowire InGaN/GaN LED with a core/shell structure with a diameter of about 200 nm and a height of about 5 μm is prepared on a Si substrate. The material structure of this embodiment is, from bottom to top, Si substrate, AlN/n- GaN III-nitride film, SiO ₂ patterned masking film, n-GaN nanowire, InGaN/GaN active layer, p-GaN capping layer. That is, in this embodiment, the substrate 1 is a Si substrate, the III-nitride thin film 2 is an AlN/n-GaN III-nitride thin film, the patterned masking film 3 is _SiO2 patterned masking film, and the GaN nanowire 5 is n-GaN nanowires.

Its preparation method comprises the following steps in turn:

Step 1: Put the Si substrate into the MOCVD reaction chamber, and epitaxially grow an AlN epitaxial layer with a thickness of 100 nm and an n-GaN epitaxial layer with a thickness of 800 nm on the Si substrate in sequence;

Step 2: Deposit a _SiO2 dielectric layer with a thickness of 100 nm on the above-mentioned epitaxial wafer by PECVD, and use conventional photolithography and wet etching methods to prepare the _SiO2 dielectric layer into a patterned masking film with a periodic hole structure, The pattern of the patterned masking film is a circle with an opening diameter of 3 μm;

Step 3: Put the above-mentioned epitaxial wafer with a patterned mask into the ^MOCVD reaction chamber, and pass 10000 sccm of ammonia gas (NH3) and 40 sccm of trimethylgallium ( TMGa) for 30 minutes, the n-GaN hexagonal pyramid microstructure is selectively grown. The side of the n-GaN hexagonal pyramid microstructure is {1-101} plane, the top surface is (0001) plane, and the height is about 5 μm. The diameter of the top surface is about 200 nm;

Step 4: Put the above-mentioned epitaxial wafer with n-GaN hexagonal pyramid microstructure in a potassium hydroxide (KOH) solution with a concentration of 30% and a temperature of 50 ^o C for 30 minutes, and put {1-101} sides Etched away to form n-GaN nanowires with {1-100} planes on the sides, (0001) planes on the top, a height of about 5 μm, and a diameter of about 200 nm;

Step 5: Put the above-mentioned epitaxial wafer with n-GaN nanowires into the MOCVD reaction chamber, and epitaxially grow InGaN/GaN active layer and p-GaN covering layer on the surface of n-GaN nanowires in sequence to prepare a core/shell structure Nanowire InGaN/GaN LED, as shown in Figure 5.

Example 5

A nanowire InGaN/GaN LED with a rod-like structure with a diameter of about 200 nm and a height of about 5 μm is prepared on a Si substrate. The material structure of this example is, from bottom to top, Si substrate, AlN/n-GaN family Nitride film, SiO ₂ patterned masking film, n-GaN nanowires, SiO ₂ capping layer, InGaN/GaN active layer 6, p-GaN capping layer 7. That is, in this embodiment, the substrate 1 is a Si substrate, the III-nitride thin film 2 is an AlN/n-GaN III-nitride thin film, the patterned masking film 3 is _SiO2 patterned masking film, and the GaN nanowire 5 is n-GaN nanowires.

Its preparation method comprises the following steps in turn:

Step 1: Put the Si substrate into the MOCVD reaction chamber, and epitaxially grow an AlN epitaxial layer with a thickness of 100 nm and an n-GaN epitaxial layer with a thickness of 800 nm on the Si substrate in sequence;

Step 2: Deposit a _SiO2 dielectric layer with a thickness of 100 nm on the above-mentioned epitaxial wafer by PECVD, and use conventional photolithography and wet etching methods to prepare the _SiO2 dielectric layer into a patterned masking film with a periodic hole structure, The pattern of the patterned masking film is a circle with an opening diameter of 3 μm;

Step 3: Put the above-mentioned epitaxial wafer with a patterned mask into the ^MOCVD reaction chamber, and pass 10000 sccm of ammonia gas (NH3) and 40 sccm of trimethylgallium ( TMGa) for 30 minutes, the n-GaN hexagonal pyramid microstructure is selectively grown. The side of the n-GaN hexagonal pyramid microstructure is {1-101} plane, the top surface is (0001) plane, and the height is about 5 μm. The diameter of the top surface is about 200 nm;

Step 4: Put the epitaxial wafer with the above-mentioned n-GaN hexagonal pyramid microstructure in a potassium hydroxide (KOH) solution with a mass concentration of 30% and a temperature of 50 ^o C for 30 minutes, and etch the {1-101} side to form an n-GaN nanowire with a {1-100} plane on the side, a (0001) plane on the top, a height of about 5 μm, and a diameter of about 200 nm;

Step 5: preparing a SiO ₂ capping layer exposing the top of the n-GaN nanowire surface;

Step 6: Put the above-mentioned epitaxial wafer with n-GaN nanowires into the MOCVD reaction chamber, and epitaxially grow the InGaN/GaN active layer and p-GaN capping layer on the top of the n-GaN nanowires in turn to prepare a rod-shaped nanometer Line InGaN/GaN LED, as shown in Figure 6.

Example 6

A nanowire InGaN/GaN LED array with a core/shell structure with a diameter of about 200 nm and a height of about 5 μm was prepared on a Si substrate. This embodiment adopts the same material structure as that of Embodiment 4, and the material structure from bottom to top is Si substrate, AlN/n-GaN group-III nitride thin film, SiO ₂ patterned masking film, n-GaN nanowire, InGaN/GaN active layer, p-GaN cladding layer. The specific preparation process is basically the same as that of Example 4, wherein when preparing the patterned masking film in step 2, the pattern of the masking film is prepared as circular holes arranged periodically, the diameter of the circular holes is 3 μm, and the period is 10 μm. Therefore, the array-arranged n-GaN hexagonal pyramid microstructure can be epitaxially grown in the subsequent MOCVD selective region growth process, and the n-GaN nanowire array can be prepared by subsequent KOH etching. Finally, the InGaN/GaN active layer and the p-GaN capping layer are epitaxially grown on the n-GaN nanowire array in sequence by MOCVD to prepare a nanowire InGaN/GaN LED array with a core/shell structure.

Claims (9)

1. A preparation method for GaN nanowires, characterized in that, Step 1: epitaxially growing a III-nitride thin film (2) on the substrate (1) by MOCVD; Step 2: Depositing a dielectric layer on the above-mentioned III-nitride thin film (2), and preparing the dielectric layer into a patterned masking film (3); Step 3: Epitaxial growth of a GaN hexagonal pyramid microstructure (4 ); Step 4: Etch the {1-101} plane of the GaN hexagonal pyramid microstructure (4) by etching with an alkaline solution, and finally prepare a GaN nanometer with a {1-100} plane on the side and a (0001) plane on the top. line (5). 2. The method for preparing GaN nanowires according to claim 1, wherein the alkaline solution is KOH or NaOH solution, and the mass concentration range of the solution is 5%-80%. 3. the preparation method of GaN nanowire according to claim 1 is characterized in that, adopts wet etching method to corrode GaN hexagonal pyramid microstructure into GaN nanowire in described step 4, and the solution temperature range of etching process is 20 ^o C -100 ^o C. 4. The preparation method of GaN nanowire according to claim 1, characterized in that, the material of the patterned masking film is SiO ₂ or SiN _x , the pattern structure of the opening is circular, and the diameter range of the circular hole is 1 μm-20 μm. 5. The method for preparing GaN nanowires according to claim 1, wherein the substrate is a Si, sapphire, SiC, GaN, AlN or ZnO substrate. 6 . The method for preparing GaN nanowires according to claim 1 , wherein the group-III nitride thin film is an AlN thin film, a GaN thin film, or a composite layer composed of AlN and GaN thin films. 7. The preparation method of GaN nanowire according to any one of claims 1 to 6, characterized in that, by changing the specific pattern structure of the patterned masking film, the position and arrangement of the GaN hexagonal pyramid structure grown by MOCVD epitaxial growth can be controlled form, so as to control the position and arrangement form of the GaN nanowires or nanowire arrays formed after the alkaline solution etching. 8. according to the preparation method of the described GaN nano wire according to any one of claim 1 to 6, it is characterized in that, the height of GaN nano wire is controlled by the height of GaN hexagonal pyramid microstructure, through the (0001) of GaN hexagonal pyramid microstructure The top surface controls the radius of the GaN nanowire. 9. A GaN nanowire prepared by the preparation method described in any one of claims 1 to 8, characterized in that it is a GaN nanowire whose side is a {1-100} plane and whose top surface is a (0001) plane, the From top to bottom, the bottom of the GaN nanowire is a patterned masking film (3), a group III nitride film (2) and a substrate (1).