An epitaxial wafer of a green light-emitting diode and a preparation method thereof

Abstract

The present invention provides an epitaxial wafer of a green light-emitting diode and a preparation method thereof. The epitaxial wafer of the green light-emitting diode includes a multi-quantum well layer and further includes a multi-quantum well preparation layer. The multi-quantum well layer is grown on the multi-quantum well preparation layer. The multi-quantum well preparation layer includes an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer which are epitaxially grown in sequence. The multi-quantum well layer is grown on the InN layer. By growing a multi-quantum well preparation layer with a special structure design before the multi-quantum well, the present invention successfully reduces the defects in the quantum well, makes the lattice of the bottom layer and the quantum well more matched, releases the stress of the green multi-quantum well layer, provides an In-rich environment, increases the incorporation of the green In component, reduces the polarization effect in the quantum well, thereby reducing the In clustering phenomenon, making the In component distribution more uniform and the light-emitting region more uniform, and finally significantly improving the uniformity of the emission wavelength.

Description

Technical Field

[0001] The present invention relates to the technical field of light-emitting diodes, and particularly relates to an epitaxial wafer of a green light-emitting diode and a preparation method thereof. Background Art

[0002] As is well known, light-emitting diodes (LEDs) have been widely used in the fields of solid-state lighting and displays due to their advantages such as high efficiency, energy conservation, and environmental friendliness. Among them, as the core structure for LED light emission, defects in the multi-quantum well structure will directly affect the quality of LED light emission. Therefore, multi-quantum wells have always been one of the main research objects in the industry.

[0003] Currently, there are certain defects such as a strong polarization electric field and a high dislocation density inside the multi-quantum well. Especially for high-In-component GaN-based LEDs such as green LEDs, not only is there a greater polarization electric field inside the quantum well, but there are also more defects. This leads to In clusters, uneven In component distribution, and non-concentrated light-emitting regions inside the multi-quantum well, resulting in poor wavelength uniformity of green light and seriously affecting the yield. Summary of the Invention

[0004] Based on this, an object of the present invention is to provide an epitaxial wafer of a green light-emitting diode and a preparation method thereof, aiming to solve at least one technical problem in the background art.

[0005] According to an epitaxial wafer of a green light-emitting diode in an embodiment of the present invention, it includes a multi-quantum well layer and also includes a multi-quantum well preparation layer. The multi-quantum well layer grows on the multi-quantum well preparation layer. The multi-quantum well preparation layer includes an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer that are epitaxially grown in sequence. The multi-quantum well layer grows on the InN layer;

[0006] Wherein, the growth temperature of the AlGaN layer is greater than the growth temperature of the InGaN layer, and the growth temperature difference between the AlGaN layer and the InGaN layer is between 100 - 230 °C. The growth temperature of the InAlGaN layer gradually decreases from the growth temperature of the AlGaN layer to the growth temperature of the InGaN layer, and the growth temperatures of the InGaN layer and the InN layer are equal.

[0007] Preferably, the In component content of the InAlGaN layer gradually increases, and the Al component content of the InAlGaN layer gradually decreases.

[0008] Preferably, the In component content of the InAlGaN layer gradually increases from 0 to the In component content of the InGaN layer;

[0009] Among them, the Al component content of the InAlGaN layer gradually decreases from the Al component content of the AlGaN layer to 0.

[0010] Preferably, the In component content of the InGaN layer is 0.1 - 0.2, and the Al component content of the AlGaN layer is 0.1 - 0.3.

[0011] Preferably, the multiple quantum well layer is a periodic structure in which quantum well layers and quantum barrier layers grow alternately, and the InN layer is in contact with the quantum well layer in the multiple quantum well layer;

[0012] The In component content of the InN layer is greater than or equal to the In component content of the quantum well layer, and the In component content of the quantum well layer is 0.1 - 0.4.

[0013] Preferably, the thickness of the multiple quantum well preparation layer is 30 - 60 nm, the thickness of the AlGaN layer is 3 - 6 nm, the thickness of the InAlGaN layer is 5 - 20 nm, the thickness of the InGaN is 5 - 20 nm, and the thickness of the InN layer is 3 - 6 nm.

[0014] Preferably, it further includes a substrate, a GaN low-temperature buffer layer, an undoped GaN layer, an N-type doped GaN layer, an electron blocking layer, and a p-type doped GaN layer;

[0015] The GaN low-temperature buffer layer, the undoped GaN layer, the N-type doped GaN layer, the multiple quantum well preparation layer, the multiple quantum well layer, the electron blocking layer, and the p-type doped GaN layer are sequentially grown on the substrate.

[0016] According to a method for preparing an epitaxial wafer of a green light-emitting diode in an embodiment of the present invention, for preparing the epitaxial wafer of the above-mentioned green light-emitting diode, the preparation method includes:

[0017] Epitaxially grow an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer in sequence to grow a multiple quantum well preparation layer;

[0018] Epitaxially grow a multiple quantum well layer on the InN layer of the multiple quantum well preparation layer.

[0019] Preferably, the step of epitaxially growing an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer in sequence to grow a multiple quantum well preparation layer includes:

[0020] Control the reaction chamber temperature to be 1000 - 1030 °C, the reaction chamber pressure to be 100 - 300 torr, introduce an Al source and a Ga source, and grow the AlGaN layer;

[0021] Keep the pressure constant, turn on the In source, control the Al source input amount to gradually decrease to 0, control the In source input amount to gradually increase from 0, continuously input the Ga source, and gradually lower the reaction chamber temperature to 800 - 900 °C to grow the InGaN layer;

[0022] Keep the reaction chamber pressure constant and the temperature controlled at 800 - 900 °C unchanged, continuously input the In source and the Ga source to grow the InGaN layer;

[0023] Keep the reaction chamber pressure and temperature unchanged, turn off the Ga source, continuously input the In source to grow the InN layer, and finally grow to obtain the multi - quantum well preparation layer.

[0024] Preferably, before the step of epitaxially growing the AlGaN layer, InAlGaN layer, InGaN layer, and InN layer in sequence to grow the multi - quantum well preparation layer, it further includes:

[0025] Provide a substrate for epitaxial growth;

[0026] Epitaxially grow a GaN low - temperature buffer layer, an undoped GaN layer, and an N - type doped GaN layer on the substrate in sequence, and grow the multi - quantum well preparation layer on the N - type doped GaN layer;

[0027] After the step of epitaxially growing the multi - quantum well layer on the InN layer of the multi - quantum well preparation layer, it further includes:

[0028] Epitaxially grow an electron blocking layer and a p - type doped GaN layer on the multi - quantum well layer in sequence.

[0029] Compared with the prior art: Before growing the multi-quantum well, a multi-quantum well preparation layer is grown first. The multi-quantum well preparation layer is a composite layer structure obtained by sequentially growing an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer. First, a thin AlGaN layer is grown at a high temperature. Since the lattice constant of Al atoms is relatively small, high temperature is beneficial to improving the lattice quality of the epitaxial layer, which can block the defects extending from the bottom layer, avoid excessive defects extending into the quantum well, reduce the defects in the multi-quantum well, and thus increase the uniformity of the In composition distribution. Then, an InAlGaN layer with a gradually decreasing temperature is grown. This layer can better connect with the previous AlGaN thin layer and the subsequent InGaN layer. The gradual change in temperature can make the front and back lattices more matched, reduce the generation of stress, and reduce the problem of uneven In composition distribution caused by the polarization effect. Then, an InGaN layer is grown. Since the quantum well layer is an InGaN layer with a high In composition, this layer introduces In atoms to be more matched with the lattice of the quantum well layer, thereby releasing the stress of the green light multi-quantum well layer and reducing the polarization within the quantum well. Finally, an InN layer is grown. The InN layer connects with the multi-quantum well, provides an In-rich environment, can increase the incorporation of In composition in the high-In composition quantum well, reduce the polarization field in the quantum well, and reduce the energy band tilt within the quantum well, thereby enhancing the injection and diffusion of carriers in the well layer, and thus making the quantum well light-emitting region uniform. And the InGaN layer and the InN layer have a larger temperature reduction amplitude compared with the AlGaN layer. The low-temperature growth method plays a role in releasing stress and is more conducive to the incorporation of In;

[0030] Therefore, the multi-quantum well preparation layer designed by the present invention has successfully reduced the defects in the quantum well, made the lattice of the bottom layer and the quantum well more matched, released the stress of the green light multi-quantum well layer, provided an In-rich environment, increased the incorporation of green light In composition, reduced the polarization effect within the quantum well, thereby reducing the clustering phenomenon of In, making the In composition distribution more uniform, the light-emitting region more uniform, and improving the uniformity of the emission wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the epitaxial wafer of the green light-emitting diode in the first embodiment of the present invention.

[0032] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. SPECIFIC EMBODIMENTS

[0033] For ease of understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0034] It should be noted that when an element is referred to as being "fixed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the specification of this invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] Embodiment 1

[0037] Please refer to Figure 1 , which shows the epitaxial wafer of the green light-emitting diode in Embodiment 1 of the present invention, including a substrate 1, and a GaN low-temperature buffer layer 2, an undoped GaN layer 3, an N-type doped GaN layer 4, a multi-quantum well preparation layer 5, a multi-quantum well layer 6, an electron blocking layer 7, and a p-type doped GaN layer 8 that are sequentially epitaxially grown on the substrate 1. In this embodiment, a multi-quantum well preparation layer 5 is grown first before the multi-quantum well layer 6, that is, a multi-quantum well preparation layer 5 is inserted between the N-type doped GaN layer 4 and the multi-quantum well layer 6, mainly to reduce the defects inside the multi-quantum well layer 5 and improve the uniformity of the emission wavelength.

[0038] Specifically, the multi-quantum well preparation layer 5 includes an AlGaN layer 51, an InAlGaN layer 52, an InGaN layer 53, and an InN layer 54 that are sequentially epitaxially grown. The multi-quantum well layer 6 is grown on the InN layer 54. In this embodiment, the growth temperature of the AlGaN layer 51 is higher than that of the InGaN layer 53, the growth temperature of the InAlGaN layer 52 gradually decreases from the growth temperature of the AlGaN layer 51 to the growth temperature of the InGaN layer 53, and the growth temperatures of the InGaN layer 53 and the InN layer 54 are equal. Specifically, the AlGaN layer 51 is grown at a high temperature, and the specific growth temperature can be 1000 °C. The InGaN layer 53 and the InN layer 54 are grown at a low temperature, and the specific growth temperature is 800 °C. The temperature difference between the AlGaN layer 51 and the InGaN layer 53 is 200 °C, with a large temperature drop amplitude, which can achieve a better stress release effect and is more conducive to the incorporation of In.

[0039] In addition, the In content of the InAlGaN layer 52 gradually increases, and the Al content of the InAlGaN layer 52 gradually decreases. This InAlGaN layer 52 with a gradual change in temperature and composition can be better adapted to the AlGaN layer 51 and the InGaN layer 53 before and after it, significantly reducing crystal defects. In some preferred embodiments of this embodiment, the In content of the InAlGaN layer 52 gradually increases from 0 to the In content of the InGaN layer 53, and the Al content of the InAlGaN layer 52 gradually decreases from the Al content of the AlGaN layer 51 to 0. Specifically, in this embodiment, the In content of the InGaN layer 53 is 0.2, and the Al content of the AlGaN layer 51 is 0.3. That is, the Al content of the InAlGaN layer 52 gradually decreases from 0.3 to 0, and the In content gradually increases from 0 to 0.2. Among them, the composition of the InAlGaN layer 52 can be represented by In a Al b Ga 1-a-b N. Then a gradually increases from 0 to 0.2, and b gradually decreases from 0.3 to 0. In addition, the multi-quantum well layer 6 is a periodic structure in which quantum well layers and quantum barrier layers grow alternately. Among them, the quantum well layer is specifically an InGaN quantum well layer, and the quantum barrier layer is specifically a GaN quantum barrier layer or an InGaN quantum barrier layer. The InN layer 54 is in contact with the quantum well layer in the multi-quantum well layer. The In content of the InN layer 54 is greater than or equal to the In content of the quantum well layer. The In content of the quantum well layer is 0.1 - 0.4. Among them, the composition of the quantum well layer can be represented by In x Ga 1-x N. Then x is 0.1 - 0.4, and in this embodiment, it is specifically 0.4. That is, the In content of the InN layer 54 is greater than or equal to 0.4. In this embodiment, the In content of the InN layer 54 is 0.4. Among them, the so-called composition content can specifically refer to the relative molar ratio of the component.

[0040] In this embodiment, the thickness of the multi-quantum well preparation layer is 30 - 60 nm, the thickness of the AlGaN layer 51 is 3 - 6 nm, the thickness of the InAlGaN layer 52 is 5 - 20 nm, the thickness of the InGaN 53 is 5 - 20 nm, and the thickness of the InN layer 54 is 3 - 6 nm.

[0041] On the other hand, this embodiment also proposes a method for preparing an epitaxial wafer of a green light-emitting diode for preparing the epitaxial wafer of the green light-emitting diode in this embodiment. The preparation method specifically includes:

[0042] Step 201: Provide a substrate for epitaxial growth, control the temperature of the reaction chamber to 1100 °C, and in H 2The substrate surface is heat-treated in an atmosphere. The heat treatment time is about 5 minutes. The main purpose of the heat treatment is to remove the internal stress of the substrate. After the heat treatment, the substrate is cleaned.

[0043] Among them, the substrate can be a sapphire substrate or an Si substrate.

[0044] Step 202: Epitaxially grow a GaN low-temperature buffer layer on the substrate;

[0045] Exemplarily, the reaction chamber temperature of the GaN low-temperature buffer layer is about 550 °C, and the reaction chamber pressure is 200 - 400 Torr; the thickness of the GaN low-temperature buffer layer can be 10 - 30 nm.

[0046] Step 203: Epitaxially grow an undoped GaN layer on the GaN low-temperature buffer layer.

[0047] Exemplarily, the controlled reaction chamber temperature of the undoped GaN layer is 1000 - 1150 °C, and the reaction chamber pressure is 200 - 400 Torr; the thickness of the undoped GaN layer can be 1 - 3 μm;

[0048] Step 204: Epitaxially grow an N-type doped GaN layer on the undoped GaN layer.

[0049] Exemplarily, the controlled reaction chamber temperature of the N-type doped GaN layer is 1000 - 1150 °C, and the pressure is 200 - 400 Torr; the N-type doped GaN layer is a GaN layer doped with Si, and its thickness is about 1 - 3 μm;

[0050] Step 205: Epitaxially grow an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer in sequence on the N-type doped GaN layer to grow a multi-quantum well preparation layer.

[0051] Among them, the specific growth process of the multi-quantum well preparation layer is as follows:

[0052] First, control the reaction chamber temperature to 1000 °C, the reaction chamber pressure to 100 - 300 torr, introduce an Al source and a Ga source, and grow an AlGaN layer;

[0053] Secondly, keep the pressure unchanged, turn on the In source, control the introduction amount of the Al source to gradually decrease to 0, control the introduction amount of the In source to gradually increase from 0, and continuously introduce the Ga source. Among them, the reaction chamber temperature gradually decreases to 800 °C, and grow an InGaN layer;

[0054] Furthermore, keep the reaction chamber pressure unchanged, control the temperature at 800 °C unchanged, and continuously introduce the In source and the Ga source to grow an InGaN layer;

[0055] Finally, with the pressure and temperature of the reaction chamber kept constant, turn off the Ga source, continuously introduce the In source, grow the InN layer, and finally grow the multi-quantum well preparation layer.

[0056] Step 206: Periodically and alternately grow quantum well layers and quantum barrier layers on the multi-quantum well preparation layer to epitaxially grow the multi-quantum well layer.

[0057] Optionally, the period of the quantum well layers in the multi-quantum well layer can be 3 to 15 layers, and the growth pressure is 100 to 500 Torr; the thickness of each period of quantum well layers is about 2 to 4 nm, and the growth temperature of the quantum well layers is 700 to 800 °C; the thickness of each period of quantum barrier layers is 5 to 15 nm, and the growth temperature is 850 to 950 °C, and the growth temperature of the last quantum barrier layer is 800 to 950 °C.

[0058] Step 207: Epitaxially grow an electron blocking layer on the multi-quantum well layer, with a growth temperature of 800 to 1000 °C and a growth pressure of 100 to 300 Torr;

[0059] Exemplarily, the electron blocking layer can be a superlattice structure of GaN and ALGaN;

[0060] Step 208: Epitaxially grow a P-type GaN layer on the electron blocking layer. Its growth temperature is about 800 to 1000 °C, and the growth pressure is 100 to 300 Torr;

[0061] Exemplarily, the thickness of the P-type GaN layer is about 50 to 300 nm.

[0062] To sum up, the multi-quantum well preparation layer in this embodiment is a composite layer composed of 4 sub-layers, specifically as follows:

[0063] The first sub-layer is a high-temperature AlGaN thin layer. Since the lattice constant of Al atoms is relatively small, high temperature is beneficial to improving the lattice quality of the epitaxial layer. Grow a high-temperature ALGaN thin layer on the first layer of the preparation layer, mainly to block the defects extending from the bottom layer, avoid excessive defects extending into the quantum well, reduce the defects in the multi-quantum well, and thus increase the distribution uniformity of the In component;

[0064] The second sub-layer is an InALGaN layer with a gradually decreasing temperature, where the In component gradually increases from 0 and the AL component gradually decreases. This layer is the connection layer between the first sub-layer and the third and fourth sub-layers. The gradual change in temperature and the gradual change in components are mainly to make the front and rear lattices more matched, reduce the generation of stress, and reduce the problem of uneven In component distribution caused by the polarization effect;

[0065] The third sub-layer is an InGaN layer. Since the quantum well layer is an InGaN layer with a high In composition, In atoms are introduced in this layer to better match the lattice of the quantum well layer, thereby relaxing the stress of the green multi-quantum well layer and reducing the polarization within the quantum wells.

[0066] The last sub-layer is an InN layer, which connects to the multi-quantum wells and provides an In-rich environment. This can increase the incorporation of In composition in the high-In composition quantum wells, reduce the polarization field in the quantum wells, decrease the band tilt within the quantum wells, thereby enhancing the injection and diffusion of carriers in the well layers, and making the light-emitting region of the quantum wells uniform.

[0067] Example Two

[0068] Example Two of the present invention also provides an epitaxial wafer for a green light-emitting diode and a method for preparing the same. The differences between the epitaxial wafer for a green light-emitting diode and the method for preparing the same in this example and those in Example One are as follows:

[0069] The growth temperature of the AlGaN layer is 1000 °C, the growth temperatures of the InGaN layer and the InN layer are 850 °C, the growth temperature of the InAlGaN layer gradually decreases from 1000 °C to 850 °C, and the growth temperature difference between the AlGaN layer and the InGaN layer is 150 °C.

[0070] Example Three

[0071] Example Three of the present invention also provides an epitaxial wafer for a green light-emitting diode and a method for preparing the same. The differences between the epitaxial wafer for a green light-emitting diode and the method for preparing the same in this example and those in Example One are as follows:

[0072] The growth temperature of the AlGaN layer is 1000 °C, the growth temperatures of the InGaN layer and the InN layer are 900 °C, the growth temperature of the InAlGaN layer gradually decreases from 1000 °C to 900 °C, and the growth temperature difference between the AlGaN layer and the InGaN layer is 100 °C.

[0073] Example Four

[0074] Example Four of the present invention also provides an epitaxial wafer for a green light-emitting diode and a method for preparing the same. The differences between the epitaxial wafer for a green light-emitting diode and the method for preparing the same in this example and those in Example One are as follows:

[0075] The growth temperature of the AlGaN layer is 1030 °C, the growth temperatures of the InGaN layer and the InN layer are 800 °C, the growth temperature of the InAlGaN layer gradually decreases from 1030 °C to 800 °C, and the growth temperature difference between the AlGaN layer and the InGaN layer is 230 °C.

[0076] Example Five

[0077] Example Five of the present invention also provides an epitaxial wafer for a green light emitting diode and a preparation method thereof. The differences between the epitaxial wafer for a green light emitting diode and the preparation method thereof in this example and those in Example One are as follows:

[0078] The In component content of the InGaN layer is 0.15, the Al component content of the AlGaN layer is 0.2, the Al component content of the InAlGaN layer gradually decreases from 0.2 to 0, and the In component content gradually increases from 0 to 0.15.

[0079] Example Six

[0080] Example Six of the present invention also provides an epitaxial wafer for a green light emitting diode and a preparation method thereof. The differences between the epitaxial wafer for a green light emitting diode and the preparation method thereof in this example and those in Example One are as follows:

[0081] The In component content of the InGaN layer is 0.1, the Al component content of the AlGaN layer is 0.1, the Al component content of the InAlGaN layer gradually decreases from 0.1 to 0, and the In component content gradually increases from 0 to 0.1.

[0082] Example Seven

[0083] Example Seven of the present invention also provides an epitaxial wafer for a green light emitting diode and a preparation method thereof. The differences between the epitaxial wafer for a green light emitting diode and the preparation method thereof in this example and those in Example One are as follows:

[0084] The In component content of the quantum well layer is 0.2, and the In component content of the InN layer is 0.3.

[0085] Example Eight

[0086] Example Eight of the present invention also provides an epitaxial wafer for a green light emitting diode and a preparation method thereof. The differences between the epitaxial wafer for a green light emitting diode and the preparation method thereof in this example and those in Example One are as follows:

[0087] The In component content of the quantum well layer is 0.4, and the In component content of the InN layer is 0.6.

[0088] Comparative Example 1

[0089] Among them, Comparative Example 1 of the present invention also proposes an epitaxial wafer of a green light-emitting diode and a preparation method thereof. The difference between the epitaxial wafer of the green light-emitting diode and the preparation method thereof in this embodiment and those in Embodiment 1 is as follows:

[0090] The AlGaN layer, InAlGaN layer, InGaN layer, and InN layer of the multi-quantum well preparation layer are all grown at a constant temperature of 1000 °C.

[0091] Comparative Example 2

[0092] Among them, Comparative Example 2 of the present invention also proposes an epitaxial wafer of a green light-emitting diode and a preparation method thereof. The difference between the epitaxial wafer of the green light-emitting diode and the preparation method thereof in this embodiment and those in Embodiment 1 is as follows:

[0093] The In component content of the InAlGaN layer is constantly 0.1, and the Al component content of the InAlGaN layer is constantly 0.2.

[0094] Comparative Example 3

[0095] Among them, Comparative Example 3 of the present invention also proposes an epitaxial wafer of a green light-emitting diode and a preparation method thereof. The difference between the epitaxial wafer of the green light-emitting diode and the preparation method thereof in this embodiment and those in Embodiment 1 is as follows:

[0096] The In component content of the InN layer is 0.2, and the In component content of the quantum well layer is 0.4.

[0097] Comparative Example 4

[0098] Among them, Comparative Example 4 of the present invention also proposes an epitaxial wafer of a green light-emitting diode and a preparation method thereof. The difference between the epitaxial wafer of the green light-emitting diode and the preparation method thereof in this embodiment and those in Embodiment 1 is as follows:

[0099] The epitaxial wafer of the green light-emitting diode in Comparative Example 4 is an epitaxial wafer of a traditional green light-emitting diode, and its multi-quantum well layer is directly epitaxially grown on the N-type layer without inserting a multi-quantum well preparation layer in the middle.

[0100] Please refer to Table 1 below, which shows the corresponding parameters of Embodiments 1-8 and Comparative Examples 1-4 of the present invention.

[0101] Table 1

[0102]

[0103]

[0104] In Table 1 above, "→" represents a change. For example, 0→0.2 means that the In composition content of the InAlGaN layer gradually increases from 0 to 0.2.

[0105] In practical applications, the preparation methods and parameters corresponding to the first to eighth embodiments and the first to fourth comparative examples of the present invention are respectively used to prepare the corresponding green light emitting diodes, and the emission wavelength uniformity of the green light emitting diodes prepared in each example is tested. The test data are shown in Table 2 below. It should be noted that in order to ensure the reliability of the verification results, in the preparation of the light emitting diodes corresponding to the first to eighth embodiments and the first to fourth comparative examples of the present invention, except for the above different parameters, others should be the same, that is, the preparation processes and parameters of other layers should be kept consistent.

[0106] Table 2:

[0107]

[0108] Combining the data in Table 1 and Table 2 above, it can be clearly seen that by growing a multi-quantum well preparation layer with a special structure design before growing the multi-quantum well, the present invention successfully reduces the defects in the quantum well, makes the lattice of the bottom layer and the quantum well more matched, releases the stress of the green light multi-quantum well layer, provides a rich In environment, increases the incorporation of the green light In component, reduces the polarization effect in the quantum well, thereby reducing the In clustering phenomenon, making the In component distribution more uniform and the light emitting area more uniform, and finally significantly improving the emission wavelength uniformity.

[0109] The above embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. An epitaxial wafer of a green light-emitting diode, including a multi-quantum well layer, Characterized in that, It further includes a multi-quantum well preparation layer, the multi-quantum well layer is grown on the multi-quantum well preparation layer, the multi-quantum well preparation layer includes an AlGaN layer, an InAlGaN layer, an InGaN layer and an InN layer which are epitaxially grown in sequence, and the multi-quantum well layer is grown on the InN layer; Wherein, the growth temperature of the AlGaN layer is greater than the growth temperature of the InGaN layer, and the growth temperature difference between the AlGaN layer and the InGaN layer is between 100 - 230 °C, the growth temperature of the InAlGaN layer gradually decreases from the growth temperature of the AlGaN layer to the growth temperature of the InGaN layer, and the growth temperatures of the InGaN layer and the InN layer are equal.

2. The epitaxial wafer of a green light-emitting diode according to claim 1, Characterized in that, The In composition content of the InAlGaN layer gradually increases, and the Al composition content of the InAlGaN layer gradually decreases.

3. The epitaxial wafer of a green light-emitting diode according to claim 2, Characterized in that, The In composition content of the InAlGaN layer gradually increases from 0 to the In composition content of the InGaN layer; Wherein, the Al composition content of the InAlGaN layer gradually decreases from the Al composition content of the AlGaN layer to 0.

4. The epitaxial wafer of a green light-emitting diode according to claim 3, Characterized in that, The In composition content of the InGaN layer is 0.1 - 0.2, and the Al composition content of the AlGaN layer is 0.1 - 0.

3.

5. The epitaxial wafer of a green light-emitting diode according to claim 1, Characterized in that, The multi-quantum well layer is a periodic structure in which a quantum well layer and a quantum barrier layer grow alternately, and the InN layer is in contact with the quantum well layer in the multi-quantum well layer; The In composition content of the InN layer is greater than or equal to the In composition content of the quantum well layer, and the In composition content of the quantum well layer is 0.1 - 0.

4.

6. The epitaxial wafer of a green light-emitting diode according to claim 1, Characterized in that, The thickness of the multi-quantum well preparation layer is 30 - 60 nm, the thickness of the AlGaN layer is 3 - 6 nm, the thickness of the InAlGaN layer is 5 - 20 nm, the thickness of the InGaN is 5 - 20 nm, and the thickness of the InN layer is 3 - 6 nm.

7. The epitaxial wafer of a green light-emitting diode according to claim 1, Characterized in that, It further includes a substrate, a GaN low-temperature buffer layer, an undoped GaN layer, an N-type doped GaN layer, an electron blocking layer and a p-type doped GaN layer; The GaN low-temperature buffer layer, the undoped GaN layer, the N-type doped GaN layer, the multi-quantum well preparation layer, the multi-quantum well layer, the electron blocking layer and the p-type doped GaN layer are sequentially grown on the substrate.

8. A preparation method of an epitaxial wafer of a green light-emitting diode, Characterized in that, An epitaxial wafer for preparing the green light-emitting diode according to any one of claims 1-7, and the preparation method includes: Epitaxially growing an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer in sequence to grow a multi-quantum well preparation layer; Epitaxially growing a multi-quantum well layer on the InN layer of the multi-quantum well preparation layer.

9. The preparation method of the epitaxial wafer of the green light-emitting diode according to claim 8, characterized in that, The step of epitaxially growing an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer in sequence to grow a multi-quantum well preparation layer includes: Controlling the reaction chamber temperature to be 1000-1030 °C and the reaction chamber pressure to be 100-300 torr, introducing an Al source and a Ga source to grow the AlGaN layer; Keeping the pressure unchanged, turning on the In source, controlling the gradual decrease of the Al source introduction amount to 0, controlling the gradual increase of the In source introduction amount from 0, and continuously introducing the Ga source, wherein the reaction chamber temperature gradually decreases to 800-900 °C to grow the InGaN layer; Keeping the reaction chamber pressure unchanged and the temperature controlled at 800-900 °C unchanged, continuously introducing the In source and the Ga source to grow the InGaN layer; Keeping the reaction chamber pressure and temperature unchanged, turning off the Ga source, and continuously introducing the In source to grow the InN layer, and finally growing a multi-quantum well preparation layer.

10. The preparation method of the epitaxial wafer of the green light-emitting diode according to claim 8, characterized in that, Before the step of epitaxially growing an AlGaN layer, an InAlGaN layer, an InGaN layer, and an InN layer in sequence to grow a multi-quantum well preparation layer, it further includes: Providing a substrate for epitaxial growth; Epitaxially growing a GaN low-temperature buffer layer, an undoped GaN layer, and an N-type doped GaN layer on the substrate in sequence, and the multi-quantum well preparation layer is grown on the N-type doped GaN layer; After the step of epitaxially growing a multi-quantum well layer on the InN layer of the multi-quantum well preparation layer, it further includes: Epitaxially growing an electron blocking layer and a p-type doped GaN layer on the multi-quantum well layer in sequence.

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