CN108807625A - A kind of AlN buffer layer structures and preparation method thereof - Google Patents

Abstract

The invention discloses an AlN buffer layer structure, which comprises a substrate, an AlN nano column array buffer layer, an AlGaN buffer layer, an n-GaN layer, multiple quantum wells, an electron blocking layer and a P-GaN. Wherein, the AlN buffer layer structure is a nano-column array structure. Compared with the film-type buffer layer, the contact area between the nano-pillar array buffer layer and the substrate is small, the stress is easily released, and the crack length can be greatly shortened; the nano-pillar material has a defect self-exclusion effect, which can greatly reduce the defect density. Based on the above two points, using AlN nanocolumn arrays as a buffer material makes it easier to obtain crack-free and high-quality GaN films, thereby improving the overall performance of GaN-based LED devices. At the same time, the invention also discloses a method for preparing the structure of the AlN buffer layer, which adopts a two-step method to prepare the LED epitaxial wafer, first grows the AlN nano-array buffer layer by PECVD, and then grows the subsequent material by MOCVD, which obviously improves the preparation efficiency of the LED epitaxial wafer.

Description

A kind of AlN buffer layer structure and preparation method thereof

technical field

The invention belongs to the technical field of semiconductors, and relates to an AlN buffer layer and a preparation method thereof, in particular to an AlN buffer layer structure of a GaN-based light-emitting diode on a Si substrate and a preparation method thereof.

Background technique

Light-emitting diodes (light-emitting diodes, LEDs) are expected to replace traditional incandescent lamps, fluorescent lamps and gas discharge lamps as a new generation of lighting sources due to their advantages of high efficiency, energy saving and environmental protection, long life, and small size. widespread attention. Since the first LED was born in 1962, the performance of LEDs has been greatly improved in all aspects, and the application fields have become wider and wider.

At present, if LEDs are to be widely used on a large scale, it is necessary to further improve the luminous efficiency of LED chips. However, the luminous efficiency of commercial LEDs still needs to be improved, which is mainly due to the use of epitaxial growth on sapphire substrates. On the one hand, due to the lattice mismatch between sapphire and GaN as high as 13.3%, a high dislocation density is formed during the epitaxial GaN film process, which reduces the carrier mobility of the material and shortens the carrier lifetime, which ultimately affects performance of GaN-based devices. On the other hand, due to the high thermal mismatch between sapphire (thermal expansion coefficient 6.63×10 ^-6 K ^-1 ) and GaN (thermal expansion coefficient 5.6×10 ^-6 K ^-1 ) at room temperature, after the growth of the epitaxial layer is completed, The process of cooling the device from the high temperature of epitaxial growth to room temperature will generate a lot of compressive stress, which will easily lead to cracks in the film and substrate. In addition, due to the low thermal conductivity of sapphire, which is 25W/m·K at room temperature, it is difficult to discharge the heat generated in the chip in time, resulting in heat accumulation, which reduces the internal quantum efficiency of the device and ultimately affects the performance of the device.

In this context, a large-area high-quality Si substrate with a mature production process and low cost can effectively reduce the manufacturing cost of LEDs, and is also very suitable for the preparation of high-power LED devices. In the early stage of the development of Si substrate LEDs, due to the problems of thermal mismatch, lattice mismatch and remelting etching between Si substrate and GaN, it is difficult to obtain high-quality GaN films without cracks. To solve this problem, the general idea is to insert AlN and AlGaN film buffer layers to comprehensively control the nucleation process and stress state of GaN growth, but the quality of the obtained GaN film is still not satisfactory.

Contents of the invention

In order to overcome the deficiencies in the prior art, one of the purposes of the present invention is to provide a kind of AlN buffer layer structure, it adopts AlN nano-column array buffer layer, with respect to thin-film type buffer layer, the contact area of nano-column array buffer layer and substrate Small, the stress is easily released, which can greatly shorten the crack length; the nano-column material has a defect self-exclusion effect, which can greatly reduce the defect density. Based on the above two points, using AlN nanocolumn arrays as a buffer material makes it easier to obtain crack-free and high-quality GaN films, thereby improving the overall performance of GaN-based LED devices.

The second object of the present invention is to provide a method for preparing an AlN buffer layer structure. A two-step method is used to prepare LED epitaxial wafers. First, PECVD is used to grow AlN nano-array buffer layers, and then MOCVD is used to grow subsequent materials, which significantly improves the performance of LED epitaxial wafers. production efficiency.

One of purpose of the present invention adopts following technical scheme to realize:

A kind of AlN buffer layer structure, it is characterized in that, it comprises substrate, grows AlN nanocolumn array buffer layer, AlGaN buffer layer, GaN three-dimensional layer, n-GaN layer, InGaN/GaN multiple quantum well layer sequentially on substrate , an electron blocking layer and a p-GaN layer.

Further, the substrate includes sapphire, Si, SiC, GaN, ZnO, LiGaO ₂ , LaSrAlTaO ₆ , Al or Cu.

Further, the height of the AlN nanocolumn array buffer layer is 200-400nm.

Further, the thickness of the AlGaN buffer layer is 400-500 nm, wherein the molar ratio of the Al component is 10%-90%; the thickness of the GaN three-dimensional layer is 500-1500 nm.

Further, the thickness of the n-GaN layer is 1500-3000 nm, and the Si doping concentration is 1×10 ¹⁷ -1×10 ¹⁹ cm ⁻³ .

Further, the InGaN/GaN multi-quantum well layer is a multi-period repeating structure, and each period is composed of a quantum barrier layer and a quantum well layer; the material of the quantum barrier layer is GaN, InGaN, AlGaN or AlInGaN, and the material of the quantum well layer is It is InGaN; the band gap of the quantum barrier layer material is larger than that of the quantum well layer material; the thickness of the quantum barrier layer is larger than the thickness of the quantum well layer; the number of periods of the multi-quantum well is 3-20; the last multi-quantum well layer is a quantum barrier layer.

Further, the material of the electron blocking layer is AlGaN, InAlN or AlInGaN, the thickness is 20-50 nm, and the Mg doping concentration is 1×10 ¹⁷ -1×10 ¹⁹ cm ⁻³ .

Further, the thickness of the p-GaN layer is 200-300 nm, and the Mg doping concentration is 1×10 ¹⁷ -1×10 ¹⁹ cm ^-3 .

Two of the purpose of the present invention adopts following technical scheme to realize:

A method for preparing an AlN buffer layer structure, characterized in that it comprises:

1) The growth step of the AlN nanocolumn array buffer layer: the AlN nanocolumn array buffer layer is grown on the substrate by a plasma-enhanced chemical vapor deposition process;

2) The growth steps of AlGaN buffer layer, GaN three-dimensional layer and n-GaN layer: using metal organic chemical vapor deposition process to sequentially grow AlGaN buffer layer, GaN three-dimensional layer and n-GaN layer on the AlN nanocolumn array buffer layer;

3) InGaN/GaN multi-quantum well layer growth step: growing an InGaN/GaN multi-quantum well layer on the n-GaN layer by metal-organic chemical vapor deposition;

4) The step of growing the electron blocking layer and the p-GaN layer: the electron blocking layer and the p-GaN layer are sequentially grown on the multi-quantum well layer by metal organic chemical vapor deposition process.

further,

In step 1), the specific process conditions are as follows: the temperature of the reaction chamber is maintained at 750° C., the radio frequency power is 150 W, the amount of AlCl powder added is 0.500 g, and 100 sccm of ammonia gas and 30 sccm of argon gas are introduced;

Step 2) in, concrete processing condition is as follows:

The process conditions of the AlGaN buffer layer are: the temperature of the reaction chamber is 1000°C, the pressure of the reaction chamber is 100Torr, 180sccm of ammonia gas, 60sccm of hydrogen gas, 300sccm of trimethylgallium and 250sccm of trimethylaluminum are introduced;

The process conditions of the u-GaN layer are: the temperature of the reaction chamber is 800°C, the pressure of the reaction chamber is 200Torr, 200sccm ammonia gas, 100sccm nitrogen gas and 380sccm trimethylgallium are introduced; the process conditions of the n-GaN layer are: the reaction chamber temperature is 1000°C, the reaction chamber pressure is 200 Torr, 60 sccm of silane, 200 sccm of ammonia gas, 100 sccm of nitrogen gas, and 380 sccm of trimethylgallium are introduced; in step 3), the specific process conditions are as follows:

3-1) The temperature of the reaction chamber is kept at 850° C., the air pressure is kept at 100 Torr, and 60 sccm of silane, 250 sccm of ammonia gas, 100 sccm of nitrogen gas and 380 sccm of trimethylgallium are introduced to grow a GaN barrier layer on the n-GaN layer;

3-2) The temperature of the reaction chamber is kept at 750° C., the air pressure is kept at 200 Torr, 250 sccm of ammonia gas, 100 sccm of nitrogen gas, 380 sccm of trimethylgallium and 80 sccm of trimethylindium are fed into the reaction chamber, and an InGaN potential well layer is grown on the GaN barrier layer;

3-3) repeat step 3-1) and step 3-2) sequentially according to the set number of cycles to obtain InGaN/GaN multiple quantum wells;

Step 4) in, concrete processing condition is as follows:

The process conditions of the electron blocking layer are: the temperature of the reaction chamber is 900° C., the pressure of the reaction chamber is 100 Torr, and 50 sccm of magnesium, 250 sccm of ammonia, 100 sccm of nitrogen, 380 sccm of trimethylgallium and 150 sccm of trimethylaluminum are introduced;

The process conditions of the p-GaN layer are as follows: the temperature of the reaction chamber is 900° C., the pressure of the reaction chamber is 100 Torr, and 50 sccm magnesium, 250 sccm ammonia, 100 sccm nitrogen and 380 sccm trimethylgallium are fed. Compared with the prior art, the beneficial effects of the present invention are:

The present invention uses the AlN nano-column array as the buffer layer. Compared with the thin-film buffer layer, the contact area between the nano-column array buffer layer and the substrate is small, the stress is easily released, and the crack length can be greatly shortened; the nano-column material has a defect self-exclusion effect , can greatly reduce the defect density. Based on the above two points, using the AlN nanopillar array as a buffer material, it is easier to obtain a crack-free and high-quality GaN film, thereby improving the electrical performance of GaN-based LED devices. At the same time, a two-step method is used to prepare LED epitaxial wafers. First, PECVD is used to grow the AlN nano-array buffer layer, and then MOCVD is used to grow subsequent materials, which significantly improves the preparation efficiency of LED epitaxial wafers.

Description of drawings

Fig. 1 is the structural representation of the AlN buffer layer structure in embodiment 1;

In Figure 1: 1. Substrate; 2. AlN nanocolumn array buffer layer; 3. AlGaN buffer layer; 4. GaN three-dimensional layer; 5. n-GaN layer; 6. InGaN/GaN multiple quantum well layer; 61. InGaN Potential well layer; 62, GaN barrier layer; 7, electron blocking layer; 8, P-GaN layer.

FIG. 2 is a top view of the buffer layer of the AlN nanocolumn array in Embodiment 1.

Fig. 3 is an x-ray diffraction pattern of GAN (0002) using an AlN nanocolumn array buffer layer.

Fig. 4 is an x-ray diffraction pattern of GAN (0002) using an AlN film buffer layer.

Fig. 5 is an x-ray diffraction pattern of GAN (1012) using an AlN nanocolumn array buffer layer.

Fig. 6 is an x-ray diffraction pattern of GAN (1012) using an AlN film buffer layer.

FIG. 7 is a graph showing the electrical test results of an LED chip using an AlN nanocolumn array buffer layer.

FIG. 8 is a graph showing the electrical test results of an LED chip using an AlN film buffer layer.

Specific embodiments

In the following, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, on the premise of not conflicting, the various embodiments or technical features described below can be combined arbitrarily to form new implementations. example. Unless otherwise specified, the materials and equipment used in this embodiment can be purchased from the market.

An AlN buffer layer structure, which includes a substrate, on which an AlN nanocolumn array buffer layer, an AlGaN buffer layer, a GaN three-dimensional layer, an n-GaN layer, an InGaN/GaN multi-quantum well layer, and an electron blocking layer are sequentially grown And p-GaN layer.

As a preferred embodiment, the substrate includes sapphire, Si, SiC, GaN, ZnO, LiGaO ₂ , LaSrAlTaO ₆ , Al or Cu.

As a preferred embodiment, the buffer layer of the AlN nanocolumn array has a height of 200-400 nm.

As a preferred embodiment, the thickness of the AlGaN buffer layer is 400-500nm respectively, wherein the molar proportion of the Al component is 10%-90%.

As a preferred implementation manner, the thickness of the GaN three-dimensional layer is 500-1500 nm.

As a preferred embodiment, the thickness of the n-GaN layer is 1500-3000 nm, and the Si doping concentration is 1×10 ¹⁷ -1×10 ¹⁹ cm ^-3 .

As a preferred embodiment, the InGaN/GaN multi-quantum well layer is a multi-period repeating structure, and each period is composed of a quantum barrier layer and a quantum well layer; the material of the quantum barrier layer is GaN, InGaN, AlGaN or AlInGaN, and the quantum well The material of the layer is InGaN; the band gap of the quantum barrier layer material is larger than that of the quantum well layer material; the thickness of the quantum barrier layer is larger than the thickness of the quantum well layer; the period number of the multi-quantum well is 3-20; the multi-quantum The last layer of the well is the quantum barrier layer.

As a preferred embodiment, the material of the electron blocking layer is AlGaN, InAlN or AlInGaN, the thickness is 20-50 nm, and the Mg doping concentration is 1×10 ¹⁷ -1×10 ¹⁹ cm ^-3 .

As a preferred embodiment, the thickness of the p-GaN layer is 200-300 nm, and the Mg doping concentration is 1×10 ¹⁷ -1×10 ¹⁹ cm ^-3 .

A method for preparing an AlN buffer layer structure, characterized in that it comprises:

1) The growth step of the AlN nanocolumn array buffer layer: the AlN nanocolumn array buffer layer is grown on the substrate by a plasma-enhanced chemical vapor deposition process;

2) The growth steps of AlGaN buffer layer, GaN three-dimensional layer and n-GaN layer: using metal organic chemical vapor deposition process to sequentially grow AlGaN buffer layer, GaN three-dimensional layer and n-GaN layer on the AlN nanocolumn array buffer layer;

3) InGaN/GaN multi-quantum well layer growth step: growing an InGaN/GaN multi-quantum well layer on the n-GaN layer by metal-organic chemical vapor deposition;

4) The step of growing the electron blocking layer and the p-GaN layer: the electron blocking layer and the p-GaN layer are sequentially grown on the multi-quantum well layer by metal organic chemical vapor deposition process.

As a preferred embodiment,

In step 1), the specific process conditions are as follows: the temperature of the reaction chamber is maintained at 750° C., the radio frequency power is 150 W, the amount of AlCl powder added is 0.500 g, and 100 sccm of ammonia gas and 30 sccm of argon gas are introduced;

Step 2) in, concrete processing condition is as follows:

The process conditions of the AlGaN buffer layer are as follows: the temperature of the reaction chamber is 1000°C, the pressure of the reaction chamber is 100Torr, 180sccm of ammonia gas, 60sccm of hydrogen gas, 300sccm of trimethylgallium and 250sccm of trimethylaluminum are introduced;

The process conditions of the u-GaN layer are: the temperature of the reaction chamber is 800°C, the pressure of the reaction chamber is 200Torr, and 200sccm ammonia gas, 100sccm nitrogen gas and 380sccm trimethylgallium are introduced;

The process conditions of the n-GaN layer are: the temperature of the reaction chamber is 1000° C., the pressure of the reaction chamber is 200 Torr, 60 sccm of silane, 200 sccm of ammonia gas, 100 sccm of nitrogen gas, and 380 sccm of trimethylgallium are introduced; in step 3), specifically The process conditions are as follows:

3-1) The temperature of the reaction chamber is kept at 850° C., the air pressure is kept at 100 Torr, and 60 sccm of silane, 250 sccm of ammonia gas, 100 sccm of nitrogen gas and 380 sccm of trimethylgallium are introduced to grow a GaN barrier layer on the n-GaN layer;

3-2) The temperature of the reaction chamber is kept at 750° C., the air pressure is kept at 200 Torr, 250 sccm of ammonia gas, 100 sccm of nitrogen gas, 380 sccm of trimethylgallium and 80 sccm of trimethylindium are fed into the reaction chamber, and an InGaN potential well layer is grown on the GaN barrier layer;

3-3) repeat step 3-1) and step 3-2) sequentially according to the set number of cycles to obtain InGaN/GaN multiple quantum wells;

Step 4) in, concrete processing condition is as follows:

The process conditions of the electron blocking layer are as follows: the temperature of the reaction chamber is 900°C, the pressure of the reaction chamber is 100Torr, and 50sccm magnesium, 250sccm ammonia, 100sccm nitrogen, 380sccm trimethylgallium and 150sccm trimethylaluminum are introduced; p-GaN The process conditions of the layer are: the temperature of the reaction chamber is 900° C., the pressure of the reaction chamber is 100 Torr, and 50 sccm of magnesocene, 250 sccm of ammonia gas, 100 sccm of nitrogen gas and 380 sccm of trimethylgallium are fed. Example 1:

Referring to Fig. 1, the present invention provides an AlN buffer layer structure, which includes a substrate on which an AlN nanocolumn array buffer layer, an AlGaN buffer layer, a GaN three-dimensional layer, an n-GaN layer, and an InGaN/GaN layer are sequentially grown. Multi-quantum well layer, electron blocking layer and p-GaN layer.

This embodiment discloses an LED epitaxial wafer structure that increases the crystal quality and electrical properties of a GaN epitaxial film by using an AlN nanocolumn array as a buffer layer, which includes a Si substrate 1, an AlN nanocolumn array buffer layer 2 with a height of 300nm, Al _0.7 Ga _0.3 N buffer layer 3 with a thickness of 400nm, GaN three-dimensional layer 4 with a thickness of 500nm, n-GaN layer 5 with a thickness of 1.5μm and a Si doping concentration of 1×10 ¹⁸ cm ^-3 , with a total thickness of 100nm InGaN/GaN multi-quantum well layer 6 (wherein, the thickness of the GaN multi-quantum well barrier layer 61 is 12nm, the thickness of the In _0.15 Ga _0.85 N multi-quantum well layer 62 is 8nm, and the multi-quantum well of 5 cycles is grown) , 20nm thick Al _0.15 Ga _0.85 N electron blocking layer 7 with a Mg doping concentration of 1×10 ¹⁸ cm ^-3 and a 200 nm thick p-GaN with a Mg doping concentration of 1×10 ¹⁸ cm ^-3 Layer 8.

A method for preparing an AlN buffer layer structure, comprising the following steps:

1) The growth step of the AlN nanocolumn array buffer layer: the AlN nanocolumn array buffer layer is grown on the substrate by a plasma-enhanced chemical vapor deposition process;

At room temperature, put the single crystal Si(111) substrate into a 10% hydrofluoric acid solution and ultrasonically clean it for 30 seconds, then ultrasonically clean it with deionized water for 60 seconds, and finally put it into a spin dryer and dry it with high purity. Blow dry with nitrogen for later use; send the single crystal Si(111) substrate into the PECVD reaction chamber, keep the reaction chamber temperature at 750°C, radio frequency power 150W, AlCl powder 0.500g, feed 100sccm of ammonia gas and 30sccm of argon gas, growing an AlN nanocolumn array buffer layer 2 on the substrate with a thickness of 300nm;

2) The growth steps of AlGaN buffer layer, GaN three-dimensional layer and n-GaN layer: using metal organic chemical vapor deposition process to sequentially grow AlGaN buffer layer, GaN three-dimensional layer and n-GaN layer on the AlN nanocolumn array buffer layer;

The temperature of the reaction chamber was kept at 1000° C., the air pressure was kept at 100 Torr, and 180 sccm of ammonia gas, 60 sccm of hydrogen gas, 300 sccm of trimethylgallium and 250 sccm of trimethylaluminum were injected to grow Al _0.7 on the AlN nanocolumn array buffer layer 2 Ga _0.3 N buffer layer 3 with a thickness of 400nm;

The temperature of the reaction chamber is kept at 800° C., the air pressure is kept at 200 Torr, 200 sccm of ammonia gas, 100 sccm of nitrogen gas and 380 sccm of trimethylgallium are fed into the reaction chamber, and a GaN three-dimensional layer 4 is grown on the AlGaN buffer layer 3 with a thickness of 500 nm;

The chamber temperature is kept at 1000°C, the air pressure is kept at 100 Torr, and 60 sccm of silane, 250 sccm of ammonia gas, 100 sccm of nitrogen gas, and 380 sccm of trimethylgallium are fed into the chamber, and an n-GaN layer 5 is grown on the GaN three-dimensional layer 4 with a thickness of 1.5 μm. The doping concentration is 1×10 ¹⁸ cm ^-3 .

3) InGaN/GaN multi-quantum well layer growth step: growing an InGaN/GaN multi-quantum well layer on the n-GaN layer by metal-organic chemical vapor deposition;

3-1) The temperature of the reaction chamber is kept at 850° C., the air pressure is kept at 100 Torr, 60 sccm of silane, 250 sccm of ammonia gas, 100 sccm of nitrogen gas and 380 sccm of trimethylgallium are fed into the reaction chamber, and a GaN barrier layer 61 is grown on the n-GaN layer 5 with a thickness of 3.0nm, Si doping concentration is 1×10 ¹⁸ cm ^-3 ;

3-2) The temperature of the reaction chamber is kept at 750° C., the air pressure is kept at 200 Torr, and 250 sccm of ammonia gas, 100 sccm of nitrogen gas, 380 sccm of trimethylgallium and 80 sccm of trimethyl indium are fed into the reaction chamber to grow In _0.15 Ga _0.85 on the GaN barrier layer 61 The N potential well layer 62 has a thickness of 8nm;

Steps 3-1) and 3-2) are repeated 5 times in sequence to obtain InGaN/GaN multiple quantum wells 6;

4) The step of growing the electron blocking layer and the p-GaN layer: the electron blocking layer and the p-GaN layer are sequentially grown on the multi-quantum well layer by metal organic chemical vapor deposition process.

The temperature of the reaction chamber is kept at 900°C, the air pressure is kept at 100Torr, and 50sccm of magnesium, 250sccm of ammonia, 100sccm of nitrogen, 380sccm of trimethylgallium and 150sccm of trimethylaluminum are introduced; the InGaN/GaN multi-quantum An Al _0.15 Ga _0.85 N electron blocking layer 7 is grown on the well 6 with a thickness of 20 nm and a doping concentration of 1×10 ¹⁸ cm ^-3 ;

The temperature of the reaction chamber is kept at 900° C., the air pressure is kept at 100 Torr, 50 sccm of magnesocene, 250 sccm of ammonia gas, 100 sccm of nitrogen gas and 380 sccm of trimethylgallium are fed into the reaction chamber, and a p-GaN layer 8 is grown on the Al _0.15 Ga _0.85 N electron blocking layer 7, The thickness is 200nm, and the Mg doping concentration is 1×10 ¹⁸ cm ^-3 .

The n-GaN layer 5 is the core of the LED epitaxial wafer, and the preparation of a crack-free and high-quality GaN layer is the basis of a high-efficiency GaN-based LED epitaxial wafer. AlN and AlGaN thin film materials are commonly used as buffer layers. Although they can avoid problems such as thermal mismatch between Si substrate and GaN, lattice mismatch and remelt etching, the crystal quality and electrical properties of GaN epitaxial films are affected by AlN and GaN. Quality constraints of AlGaN thin films.

Example 2:

The characteristics of this embodiment are: in step 3), multiple quantum wells of 6 periods are grown; other is the same as that of embodiment 1.

Example 3:

The characteristics of this embodiment are: in step 3), multi-quantum wells of 7 periods are grown; others are the same as in embodiment 1.

Example 4:

The characteristics of this embodiment are: in step 3), multiple quantum wells of 10 periods are grown; other is the same as that of embodiment 1.

Comparative example 1:

The feature of this embodiment is that the buffer layer of the AlN nano-column array is replaced by an AlN thin film, and the others are the same as in Embodiment 1.

Performance testing:

1. XRD, the abbreviation of X-ray diffraction, is X-ray diffraction, which is a research method for obtaining information such as the composition of materials, the structure or shape of atoms or molecules inside materials, and the like by analyzing X-ray diffraction patterns of materials.

Referring to Figures 3-6, compared with Comparative Example 1 using the AlN film as the buffer layer, after Example 1 uses the AlN nanopillar array as the buffer layer, the crystal quality of the GaN film has been significantly improved: GaN (0002) has increased by 200arcsec, GaN (1012) has increased by 321arcsec, indicating that it is easier to obtain high-quality GaN thin films using AlN nanopillar arrays as a buffer layer.

2. LED chip electrical performance test: use LED spot tester to test:

Referring to Figures 7-8, compared to Comparative Example 1 using the AlN thin film as the buffer layer, and Example 1 using the AlN nanocolumn array as the buffer layer, under the test conditions of @5.0000mA, and when the emission wavelength is close to 449nm, the same size The average luminous intensity of the LED chip has increased by about 83mW, which shows that the electrical performance of the LED can be significantly improved by using the AlN nanopillar array as a buffer layer.

The above-mentioned embodiments are only preferred embodiments of the present invention, and cannot be used to limit the protection scope of the present invention. Any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the present invention scope of protection claimed.

Claims (10)

1. a kind of AlN buffer layer structures, which is characterized in that it includes substrate, grows AlN nano column arrays successively on substrate Buffer layer, AlGaN buffer layers, GaN three-dimension layers, n-GaN layers, InGaN/GaN multiple quantum well layers, electronic barrier layer and p-GaN layer.

2. AlN buffer layer structures as described in claim 1, which is characterized in that the substrate include sapphire, Si, SiC, GaN、ZnO、LiGaO₂、LaSrAlTaO₆, Al or Cu.

3. AlN buffer layer structures as described in claim 1, which is characterized in that the height of the AlN nano column arrays buffer layer For 200-400nm.

4. AlN buffer layer structures as described in claim 1, which is characterized in that the thickness of the AlGaN buffer layers is respectively 400-500nm, wherein the molar ratio shared by Al components is 10%-90%；The thickness of the GaN three-dimension layers is 500- 1500nm。

5. AlN buffer layer structures as described in claim 1, which is characterized in that n-GaN layers of the thickness is 1500- 3000nm, Si doping concentration are 1 × 10¹⁷-1×10¹⁹cm^-3。

6. AlN buffer layer structures as described in claim 1, which is characterized in that the InGaN/GaN multiple quantum well layers are mostly all Phase repetitive structure, each period are made of quantum barrier layer and quantum well layer；The material of quantum barrier layer be GaN, InGaN, AlGaN or The material of AlInGaN, quantum well layer are InGaN；The band gap of quantum barrier layer material is bigger than the band gap of Quantum well layer materials；Quantum is built The thickness of layer is bigger than the thickness of quantum well layer；The periodicity of multiple quantum wells is 3-20；Last layer of the multiple quantum wells is built for quantum Layer.

7. AlN buffer layer structures as described in claim 1, which is characterized in that the material of the electronic barrier layer be AlGaN, InAlN or AlInGaN, thickness 20-50nm, Mg doping concentration are 1 × 10¹⁷-1×10¹⁹cm^-3。

8. AlN buffer layer structures as described in claim 1, which is characterized in that the thickness of the p-GaN layer is 200-300nm, Mg doping concentrations are 1 × 10¹⁷-1×10¹⁹cm^-3。

9. the preparation method of the AlN buffer layer structures as described in claim 1-8 any one, which is characterized in that including：

1) growth step of AlN nano column arrays buffer layer：It is given birth on substrate using plasma reinforced chemical vapour deposition technique Long AlN nano column arrays buffer layer；

2) AlGaN buffer layers, GaN three-dimension layers, n-GaN layers of growth step：Existed using metal organic chemical vapor deposition technique Grown successively on AlN nano column array buffer layers AlGaN buffer layers, GaN three-dimension layers, n-GaN layers；

3) InGaN/GaN multiple quantum well layers growth step：It is grown at n-GaN layers using metal organic chemical vapor deposition technique InGaN/GaN multiple quantum well layers；

4) electronic barrier layer, p-GaN layer growth step：Using metal organic chemical vapor deposition technique on multiple quantum well layer Electronic barrier layer, p-GaN layer are grown successively.

10. the preparation method of AlN buffer layer structures as claimed in claim 9, which is characterized in that

In step 1), concrete technology condition is as follows：Reaction chamber temperature remains 750 DEG C, and radio-frequency power 150W, AlCl powder adds It is 0.500g to enter amount, is passed through the ammonia of 100sccm and the argon gas of 30sccm；

In step 2), concrete technology condition is as follows：

The process conditions of AlGaN buffer layers are：Reaction chamber temperature is 1000 DEG C, and chamber pressure 100Torr is passed through The trimethyl aluminium of the ammonia of 180sccm, the hydrogen of 60sccm, the trimethyl gallium of 300sccm and 250sccm；

U-GaN layers of process conditions are：Reaction chamber temperature is 800 DEG C, and chamber pressure 200Torr is passed through 200sccm ammonia Gas, 100sccm nitrogen and 380sccm trimethyl galliums；

N-GaN layers of process conditions are：Reaction chamber temperature is 1000 DEG C, and chamber pressure 200Torr is passed through the silicon of 60sccm The trimethyl gallium of alkane, the ammonia of 200sccm, the nitrogen of 100sccm, 380sccm；

In step 3), concrete technology condition is as follows：

3-1) reaction chamber temperature remains 850 DEG C, and air pressure remains 100Torr, be passed through 60sccm silane, 250sccm ammonias, 100sccm nitrogen and 380sccm trimethyl galliums grow GaN barrier layers on n-GaN layers；

3-2) reaction chamber temperature remains 750 DEG C, and air pressure remains 200Torr, be passed through 250sccm ammonias, 100sccm nitrogen, 380sccm trimethyl galliums and 80sccm trimethyl indiums grow InGaN potential well layers on GaN barrier layers；

3-3) according to the cycle-index of setting successively circulating repetition step 3-1) and step 3-2), obtain InGaN/GaN Multiple-quantums Trap；

In step 4), concrete technology condition is as follows：

The process conditions of electronic barrier layer are：Reaction chamber temperature is 900 DEG C, and chamber pressure 100Torr is passed through 50sccm bis- Luxuriant magnesium, 250sccm ammonias, 100sccm nitrogen, 380sccm trimethyl galliums and 150sccm trimethyl aluminiums；

The process conditions of p-GaN layer are：Reaction chamber temperature is 900 DEG C, chamber pressure 100Torr, is passed through bis- cyclopentadienyls of 50sccm Magnesium, 250sccm ammonias, 100sccm nitrogen and 380sccm trimethyl galliums.