CN108878261B

CN108878261B - A kind of nanoporous GaN structure and preparation method thereof

Info

Publication number: CN108878261B
Application number: CN201810567400.9A
Authority: CN
Inventors: 许并社; 贾伟; 樊腾; 张竹霞; 李天保; 董海亮
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2018-06-05
Filing date: 2018-06-05
Publication date: 2021-10-29
Anticipated expiration: 2038-06-05
Also published as: CN108878261A

Abstract

A nanoporous GaN structure and a preparation method thereof belong to the technical field of semiconductors. The existing preparation method of the nanoporous GaN structure has the disadvantages of not being able to precisely control the shape of the nanopore, complicated preparation process and expensive equipment. The structure includes a sapphire substrate. A nucleation layer and an undoped GaN layer formed on the c-plane of the substrate are stacked; a gold spraying step is performed after the growth of the undoped GaN layer; a pyrolysis step is performed after the gold spraying step. The method takes advantage of the properties of gold nanoparticles to catalyze the decomposition of GaN at high temperatures. At high temperatures, GaN decomposes slowly, while the regions covered by gold nanoparticles decompose faster, resulting in the formation of nanoporous GaN structures. Therefore, by controlling the density of gold nanoparticles, the density of nanopores can be precisely controlled.

Description

Nano porous GaN structure and preparation method thereof

Technical Field

The invention belongs to the technical field of semiconductors, and particularly relates to a nano porous GaN structure and a preparation method thereof.

Background

GaN is a wide bandgap semiconductor material, has a direct band gap width of 3.39eV at room temperature, has the characteristics of high thermal conductivity, high temperature resistance, radiation resistance, acid and alkali resistance, high strength, high hardness and the like, is a representative of third generation semiconductors, and is widely applied in the fields of high-brightness blue, green, violet and white diodes, blue and violet lasers, radiation resistance, high-temperature and high-power microwave devices and the like. Compared with the GaN with the two-dimensional film structure, the three-dimensional porous GaN has larger specific surface area, so that the application range of the GaN-based material is further expanded. When the porous GaN electrode is applied to the field of water photolysis, the contact area between water and the porous GaN electrode is increased due to the large specific surface area, the efficiency of water photolysis is greatly improved, meanwhile, the migration distance of a photon-generated carrier to the surface of the electrode-solution is shortened, the recombination of the photon-generated carrier is inhibited, and the photon-generated current is increased; when the porous Pb/GaN electrode is applied to a Pb/GaN gas sensor, the porous Pb/GaN electrode has a larger specific surface area, the sensitivity of the sensor is obviously improved, and the blue-shift luminescence performance of the porous GaN with different sizes, shapes and high-density holes can be enhanced, so that the sensitivity of a device is improved; when the nano-hole is applied to an LED, the luminous efficiency is improved due to the larger luminous area, the scattering effect of the nano-hole on light is enhanced, and the internal quantum efficiency and the light extraction efficiency are improved; the GaN epitaxial thin film grown on the sapphire substrate has high dislocation density, which can attenuate the luminous efficiency of the GaN-based LED, and the nano porous GaN as the intermediate layer can release the stress in the GaN epitaxial thin film, reduce the dislocation density and improve the crystal quality. The application of the nano-porous GaN structure is not limited to the above fields, and scientific researchers are required to continuously and deeply explore the nano-porous GaN structure.

The existing method for preparing the nano-porous GaN mainly comprises a photoelectrochemical corrosion method, a platinum-assisted electroless etching method and the like, but the methods are too complex in process, and the obtained nano-pores are uneven in size and not steep; although the size of the nanopore can be accurately controlled by an inductively coupled plasma etching method and focused ion beam etching, large-scale production is difficult due to expensive equipment and complex process; the electron beam lithography process is simple, but has low production efficiency and low yield, and is more impractical for mass production.

Disclosure of Invention

The invention provides a nano-porous GaN structure and a preparation method thereof, aiming at the defects that the existing preparation method of the nano-porous GaN structure can not accurately control the appearance of nano-pores, the preparation process is complex and the equipment is expensive. And (3) carrying out gold spraying on the GaN epitaxial layer and then carrying out pyrolysis by utilizing the property that the gold nanoparticles catalyze the decomposition of the GaN at high temperature so as to obtain the nano porous GaN structure.

The invention adopts the following technical scheme:

a nano-porous GaN structure comprises a sapphire substrate, a nucleation layer, a non-doped GaN layer and gold nanoparticles, wherein the nucleation layer, the non-doped GaN layer and the gold nanoparticles are sequentially stacked on the c surface of the substrate.

The growth time of the non-doped GaN layer is 30-150min, and the thickness of the non-doped GaN layer is 1-5 mu m.

A preparation method of a nano-porous GaN structure comprises the following steps:

a first step of forming a nucleation layer on a sapphire substrate;

secondly, forming an undoped GaN layer on the nucleation layer;

thirdly, spraying gold to form gold nanoparticles on the non-doped GaN layer;

and fourthly, carrying out pyrolysis on the sample formed in the third step in a reaction cavity to obtain the nano porous GaN structure.

Wherein, in the first step, the gallium source of the nucleation layer is TMGa, and the nitrogen source is NH₃The growth temperature of the nucleation layer is 500-570 ℃.

In the second step, the gallium source of the non-doped GaN layer is TMGa, and the nitrogen source is NH₃The growth temperature of the non-doped GaN layer is 1000-1100 ℃.

And the gold spraying time in the third step is 10-100 s.

In the fourth step, H is introduced into the reaction cavity in a ratio of 5:5 during pyrolysis₂And N₂The mixed gas of (3); the high-temperature decomposition temperature is 900-1100 ℃; the pyrolysis time is 10-30 min.

The invention has the following beneficial effects:

1. according to the preparation method of the nano porous GaN structure, the density of the gold nanoparticles can be controlled by the gold spraying time, the gold nanoparticles are used for catalyzing the decomposition of GaN at high temperature, and the region covered by the nanoparticles is quickly decomposed downwards to form the nano holes, so that the density of the nano holes is equal to that of the gold nanoparticles, the density of the nano holes can be regulated by controlling the gold spraying time, and the operation process is very simple.

2. According to the preparation method of the nano-porous GaN structure, the depth of the nano-pores is determined by the thickness of the undoped GaN layer, so that the depth of the nano-pores can be controlled by controlling the growth time of the undoped GaN layer.

3. The invention relates to a nano-porous GaN structure which comprises a sapphire substrate, a nucleation layer and a non-doped GaN layer, wherein the nucleation layer and the non-doped GaN layer are sequentially stacked on the c surface of the substrate; spraying gold after the growth of the non-doped GaN layer is finished; and carrying out a pyrolysis step after the gold spraying step. The specific surface area of the three-dimensional nano porous GaN structure is 3-5 times that of the traditional two-dimensional GaN film, and the three-dimensional nano porous GaN film can be applied to the fields of gas monitoring sensors, water photolysis devices and the like.

Drawings

FIG. 1 shows the experimental steps of a method for fabricating a nanoporous GaN structure according to the invention.

FIG. 2 is a SEM photograph of a sample of example 1 of the present invention.

FIG. 3 is an SEM image of a sample of example 2 of the present invention.

FIG. 4 is an SEM image of a sample of example 3 of the present invention.

Detailed Description

This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, this embodiment is provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. It will be understood that when an element such as a layer, region or substrate is referred to as being "formed on" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly formed on" or "directly disposed on" another element, there are no intervening elements present.

Example 1

S1, as shown in figure 1a, forming a nucleation layer on the c surface of the sapphire substrate by an in-situ growth method, wherein the growth temperature is 500 ℃;

s2, forming an undoped GaN layer on the nucleation layer, wherein the growth temperature is 1000 ℃, the growth time is 30min, and the thickness is 1 μm;

s3, carrying out gold spraying on the surface of the sample obtained in the step S2, wherein the gold spraying time is 10S, and is shown in a figure 1 b;

s4, carrying out pyrolysis on the structure obtained in the step S3, wherein the pyrolysis temperature is 900 ℃, and H is introduced into the reaction cavity during pyrolysis₂:N₂A mixed gas of = 5: 5;

s5, passing through 10min, resulting in a nanoporous structure as shown in fig. 1c and fig. 2, with a density of nanopores of about 3.64 x 10⁸cm^-2The depth was 1 μm.

Example 2

S1, as shown in figure 1a, forming a nucleation layer on the c surface of the sapphire substrate by an in-situ growth method, wherein the growth temperature is 540 ℃;

s2, forming an undoped GaN layer on the nucleation layer, wherein the growth temperature is 1050 ℃, the growth time is 90min, and the thickness is 3 μm;

s3, carrying out gold spraying on the surface of the sample obtained in the step S2, wherein the gold spraying time is 50S, and is shown in a figure 1 b;

s4, carrying out pyrolysis on the structure obtained in the step S3, wherein the pyrolysis temperature is 1000 ℃, and H is introduced into the reaction cavity during pyrolysis₂:N₂A mixed gas of = 5: 5;

s5, obtaining the nano porous structure shown in the figure 1c and the figure 3 after 20min, wherein the density of the nano holes is about 5.93 multiplied by 10⁸cm^-2The depth was 3 μm.

Example 3

S1, as shown in figure 1a, forming a nucleation layer on the c surface of the sapphire substrate by an in-situ growth method, wherein the growth temperature is 570 ℃;

s2, forming an undoped GaN layer on the nucleation layer, wherein the growth temperature is 1100 ℃, the growth time is 150min, and the thickness is 5 microns;

s3, carrying out gold spraying on the surface of the sample obtained in the step S2, wherein the gold spraying time is 100S, and is shown in a figure 1 b;

s4, carrying out pyrolysis on the structure obtained in the step S3, wherein the pyrolysis temperature is 1100 ℃, and H is introduced into the reaction cavity during pyrolysis₂:N₂A mixed gas of = 5: 5;

s5, obtaining the nano porous structure shown in the figure 1c and the figure 4 after 30min, wherein the density of the nano holes is about 7.71 multiplied by 10⁸cm^-2The depth was 5 μm.

Claims

1. a preparation method of a nanoporous GaN structure, the nanoporous GaN structure, comprising a sapphire substrate, sequentially laminating a nucleation layer, a non-doped GaN layer and a non-doped GaN layer formed on the c-plane of the substrate. The gold nanoparticles on the GaN layer are characterized in that: the preparation method comprises the following steps:

The first step is to form a nucleation layer on the sapphire substrate; the gallium source of the nucleation layer is TMGa, the nitrogen source is NH ₃ , and the growth temperature of the nucleation layer is 500-570°C;

In the second step, an undoped GaN layer is formed on the nucleation layer; the gallium source of the undoped GaN layer is TMGa, the nitrogen source is NH ₃ , and the growth temperature of the undoped GaN layer is 1000-1100° C. The growth time of the doped GaN layer is 30-150min, and the thickness is 1-5μm;

The third step is to spray gold to form gold nanoparticles on the non-doped GaN layer; the gold spray time is 10-100s;

In the fourth step, the sample formed in the third step is subjected to high temperature decomposition in the reaction chamber, and the gold nanoparticles are used to catalyze the decomposition of GaN at high temperature, and the area covered by the nanoparticles is rapidly decomposed downward to form nanopores to obtain a nanoporous GaN structure; high temperature decomposition When the temperature is 5:5, a mixture of H ₂ and N ₂ is introduced into the reaction chamber; the high-temperature decomposition temperature is 900-1100° C.; the high-temperature decomposition time is 10-30 min.