Method for manufacturing LED epitaxial wafer

Abstract

The present application discloses a method for fabricating an LED epitaxial wafer, which sequentially includes: processing a substrate, growing a low-temperature GaN buffer layer, growing an undoped GaN layer, growing an n-type GaN layer doped with Si, fabricating a carrier transition layer, growing a multi-quantum well layer, growing an AlGaN electron blocking layer, growing a p-type GaN layer doped with Mg, and cooling down. The fabrication of the carrier transition layer sequentially includes steps of sputtering a molybdenum oxide layer, ozone treatment, and fabricating a nitrogen atomic layer. The present invention improves the crystal quality of the quantum well by adopting a new fabrication method, thereby enhancing the light-emitting efficiency of the LED.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a method for manufacturing an LED epitaxial wafer. Background Art

[0002] Light-Emitting Diode (LED) is a semiconductor electronic device that converts electrical energy into light energy. When current flows through the LED, the electrons and holes in the LED recombine in its multi-quantum wells to emit monochromatic light. As a new type of efficient, environmentally friendly, green solid-state lighting source, LED has the advantages of low voltage, low energy consumption, small size, light weight, long life, high reliability and rich colors. At present, the scale of domestic LED production is gradually expanding, but LED still has the problem of low performance, which affects the energy-saving effect of LED.

[0003] The quantum efficiency of LED epitaxial multi-quantum wells prepared by the existing LED epitaxial wafer method is not high, which seriously hinders the improvement of LED performance and affects the energy-saving effect of LED.

[0004] In summary, it is urgent to develop new methods for manufacturing LED epitaxial wafers, improve the crystal quality of quantum wells, solve the problem of low quantum efficiency in existing LED multi-quantum wells, and thus improve the luminous efficiency of LEDs. Summary of the invention

[0005] The present invention improves the crystal quality of the quantum well by adopting a new epitaxial wafer manufacturing method, thereby improving the luminous efficiency of the LED.

[0006] The LED epitaxial wafer manufacturing method of the present invention comprises: processing a substrate, growing a low-temperature GaN buffer layer, growing a non-doped GaN layer, growing an Si-doped n-type GaN layer, making a carrier transition layer, growing a multi-quantum well layer, growing an AlGaN electron barrier layer, growing a Mg-doped P-type GaN layer, and cooling; the method is characterized in that the manufacturing of the carrier transition layer comprises: sputtering a molybdenum oxide layer, ozone treatment, and manufacturing a nitrogen atomic layer, and the specific steps are:

[0007] A. Control the temperature of the reaction chamber of the magnetron sputtering equipment to 250-400°C and the pressure of the reaction chamber to 5-18 Torr, introduce argon and oxygen into the reaction chamber, and sputter a molybdenum oxide layer with a thickness of 12-25 nm on the Si-doped n-type GaN layer. During the sputtering process, control the sputtering power of the equipment to gradually increase from 400w to 900w, and then gradually decrease from 900w to 600w;

[0008] B. Take the epitaxial wafer with the molybdenum oxide layer sputtered out from the reaction chamber of the magnetron sputtering equipment and place it in the reaction chamber of the plasma equipment. Introduce 150-250 sccm of ozone into the reaction chamber to treat the molybdenum oxide film layer for 2-4 minutes. During the treatment process, control the temperature to gradually increase from 200°C to 600°C.

[0009] C. Control the temperature in the reaction chamber of the plasma equipment to 100-300°C and the power to 40-120w. Periodically interrupt the nitrogen source to introduce nitrogen into the reaction chamber. Form a nitrogen atomic layer on the molybdenum oxide layer through plasma treatment. During the formation process, the time for nitrogen interruption and introduction into the reaction chamber is 4s and 8s respectively.

[0010] Preferably, the specific process of processing the substrate is:

[0011] At a temperature of 1000℃-1100℃, 100-130L / min of H 2 , maintain the reaction chamber pressure at 100-300 mbar, and process the sapphire substrate for 5-10 minutes.

[0012] Preferably, the specific process of growing the low-temperature GaN buffer layer is:

[0013] Cool down to 500-600℃, maintain the pressure of the reaction chamber at 300-600mbar, and introduce NH with a flow rate of 10000-20000sccm 3 , 50-100sccm TMGa and 100-130L / min H 2 , growing a low-temperature GaN buffer layer with a thickness of 20-40nm on a sapphire substrate;

[0014] Raise the temperature to 1000-1100°C, maintain the pressure in the reaction chamber at 300-600 mbar, and introduce NH at a flow rate of 30,000-40,000 sccm. 3 and 100-130L / min H 2 , keep warm for 300-500s, and corrode the low-temperature GaN buffer layer into irregular island shapes.

[0015] Preferably, the specific process of growing the undoped GaN layer is:

[0016] Raise the temperature to 1000-1200°C, maintain the pressure in the reaction chamber at 300-600 mbar, and introduce NH at a flow rate of 30,000-40,000 sccm. 3 , 200-400sccm TMGa and 100-130L / min H 2 , and continue to grow a 2-4μm undoped GaN layer.

[0017] Preferably, the specific process of growing the Si-doped n-type GaN layer is:

[0018] Maintain the reaction chamber pressure at 300-600 mbar, maintain the temperature at 1000-1200 °C, and introduce NH at a flow rate of 30000-60000 sccm. 3 , 200-400sccm TMGa, 100-130L / min H 2 and 20-50sccm SiH 4 , continue to grow 3m-4μm Si-doped n-type GaN layer, where the Si doping concentration is 5E18-5E19atoms / cm 3 .

[0019] Preferably, the specific process of growing the AlGaN electron blocking layer is:

[0020] At a temperature of 900-950°C and a pressure of 200-400 mbar, 50,000-70,000 sccm of NH 3 、30-60sccm TMGa、100-130L / min H 2 、100-130sccm TMAl、1000-1300sccm Cp 2 Under the condition of Mg, the AlGaN electron blocking layer is grown, the thickness of the AlGaN electron blocking layer is 40-60nm, wherein the concentration of Mg doping is 1E19-1E20atoms / cm 3 .

[0021] Preferably, the specific process of growing the Mg-doped P-type GaN layer is:

[0022] The reaction chamber pressure was maintained at 400-900 mbar and the temperature was 950-1000 °C. NH 3 , 20-100sccm TMGa, 100-130L / min H 2 and Cp of 1000-3000sccm 2 Mg, continue to grow 50-200nm Mg-doped P-type GaN layer, where the Mg doping concentration is 1E19-1E20atoms / cm 3 .

[0023] Preferably, the specific process of cooling down is:

[0024] Cool down to 650-680℃, keep warm for 20-30min, turn off the heating system and gas supply system, and cool with the furnace.

[0025] Compared with the traditional growth method, the LED epitaxial wafer manufacturing method of the present invention achieves the following effects:

[0026] The present invention can introduce a certain compressive stress by inserting a molybdenum oxide layer between the n-type GaN layer and the multi-quantum well layer, which can partially offset the tensile stress generated by the large difference in thermal expansion coefficient between the GaN and the sapphire substrate, thereby alleviating the problem of surface cracking of the GaN epitaxial material layer to a certain extent. In the process of sputtering the molybdenum oxide film layer, controlling the sputtering power to gradually increase first and then gradually decrease is conducive to obtaining a high-quality and uniform molybdenum oxide film. The high-quality molybdenum oxide film can improve the crystal quality of the subsequently grown multi-quantum well layer.

[0027] Treating the molybdenum oxide film with ozone can induce MoO X Mo inside the lattice 4+ and Mo 5+ ions into Mo 6+ Ion, Mo 6+ Ions can increase MoO X The work function of the ozone treatment can be increased by increasing the number of holes entering the quantum well light-emitting layer, thereby improving the internal quantum efficiency. 6+ The molybdenum oxide film with uniform ion content can further promote the injection of holes into the quantum well light-emitting layer and improve the light-emitting efficiency of the light-emitting diode.

[0028] By forming a nitrogen atomic layer on the molybdenum oxide layer to change the polarity of the molybdenum oxide layer, the crystal atoms of the subsequently grown multi-quantum well layer are arranged more neatly, thereby reducing material growth defects, improving the crystal quality of the quantum well layer, and improving the luminous efficiency of the LED. In the process of forming the nitrogen atomic layer, nitrogen is introduced by periodically interrupting the nitrogen source. On the one hand, it is beneficial to obtain a nitrogen atomic layer with good quality and uniformity. On the other hand, it can promote the grain size of the InGaN / GaN grown in the next step to become smaller, the nucleation density of the grains to become larger, and the roughness is reduced when the quantum well is further grown in the two-dimensional lateral direction, so that the quantum well film layer grown is the smoothest and brightest. The higher the crystal quality, the higher the brightness of the LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of the LED epitaxial prepared in Example 1;

[0031] Figure 2 This is a schematic diagram of the structure of the LED epitaxial prepared in Comparative Example 1;

[0032] Among them, 1. sapphire substrate, 2. low-temperature GaN buffer layer, 3. undoped GaN layer, 4. n-type GaN layer, 5. molybdenum oxide layer, 6. nitrogen atomic layer, 7. multiple quantum well layer, 8. AlGaN electron blocking layer, 9. P-type GaN layer, 71. InGaN well layer, 72. GaN barrier layer. DETAILED DESCRIPTION

[0033] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0034] In addition, this specification does not limit the components and method steps disclosed in the claims to the components and method steps of the embodiments. In particular, the size, material, shape, structural order and adjacent order, and manufacturing method of the structural components described in the embodiments are only illustrative examples unless specifically limited thereto, and the scope of the present invention is not limited thereto. The size and positional relationship of the structural components shown in the drawings are enlarged for the purpose of clear description.

[0035] The present application is further described in detail below in conjunction with the accompanying drawings, but is not intended to limit the present application.

[0036] Example 1

[0037] This embodiment adopts the LED epitaxial wafer manufacturing method provided by the present invention, adopts MOCVD to grow GaN-based LED epitaxial wafer, and adopts high-purity H 2 or high purity N 2 or high purity H 2 and high purity N 2 A mixed gas of high purity NH 3 As the N source, the metal organic source trimethyl gallium (TMGa) as the gallium source, trimethyl indium (TMIn) as the indium source, and the N-type dopant is silane (SiH 4 ), trimethylaluminum (TMAl) as aluminum source, and P-type dopant is bis(cyclopentadienyl)magnesium (CP 2Mg), the reaction pressure is between 70mbar and 600mbar. The specific growth method is as follows (for epitaxial structure, please refer to Figure 1 ):

[0038] The method for manufacturing an LED epitaxial wafer comprises: processing a sapphire substrate 1, growing a low-temperature GaN buffer layer 2, growing a non-doped GaN layer 3, growing an Si-doped n-type GaN layer 4, sputtering a molybdenum oxide layer 5, ozone treatment, manufacturing a nitrogen atom layer 6, growing a multi-quantum well layer 7, growing an AlGaN electron blocking layer 8, growing a Mg-doped P-type GaN layer 9, and cooling; wherein,

[0039] Step 1: Processing a sapphire substrate 1.

[0040] Specifically, the step 1 is further as follows:

[0041] At a temperature of 1000-1100°C, a reaction chamber pressure of 100-300 mbar, and a flow rate of 100-130 L / min of H 2 Under the conditions of , the sapphire substrate is treated for 5-10 minutes.

[0042] Step 2: growing a low-temperature GaN buffer layer 2 and forming irregular islands in the low-temperature GaN buffer layer 2 .

[0043] Specifically, the step 2 is further as follows:

[0044] At a temperature of 500-600°C and a pressure of 300-600 mbar, 10,000-20,000 sccm of NH 3 , 50-100sccm TMGa, 100-130L / min H 2 Under the condition of , growing the low-temperature GaN buffer layer 2 on the sapphire substrate 1, the thickness of the low-temperature GaN buffer layer 2 is 20-40nm;

[0045] At a temperature of 1000-1100°C and a pressure of 300-600 mbar, 30,000-40,000 sccm of NH 3 and 100-130L / min H 2 Under the conditions of , the temperature is kept constant for 300-500s to form the irregular islands on the low-temperature GaN buffer layer 2.

[0046] Step 3: growing a non-doped GaN layer 3.

[0047] Specifically, the step 3 is further as follows:

[0048] At a temperature of 1000-1200°C and a pressure of 300-600 mbar, 30,000-40,000 sccm of NH 3 , 200-400sccm TMGa and 100-130L / min H 2 Under the conditions, the undoped GaN layer 3 is grown; the thickness of the undoped GaN layer 3 is 2-4 μm.

[0049] Step 4: growing a Si-doped n-type GaN layer 4 .

[0050] Specifically, the step 4 is further as follows:

[0051] Maintain the reaction chamber pressure at 300-600 mbar, maintain the temperature at 1000-1200 °C, and introduce NH at a flow rate of 30000-60000 sccm. 3 , 200-400sccm TMGa, 100-130L / min H 2 and 20-50sccm SiH 4 , continue to grow a 3-4μm Si-doped n-type GaN layer 4, where the Si doping concentration is 5E18-1E19atoms / cm 3 .

[0052] Step 5: Sputtering a molybdenum oxide layer 5 .

[0053] Specifically, the step 5 is further as follows:

[0054] The reaction chamber temperature of the magnetron sputtering equipment is controlled to be 250-400°C, and the reaction chamber pressure is 5-18 Torr. Argon and oxygen are introduced into the reaction chamber to sputter a molybdenum oxide layer 5 with a thickness of 12-25 nm on the Si-doped n-type GaN layer 4. During the sputtering process, the sputtering power of the equipment is controlled to gradually increase from 400W to 900W, and then gradually decrease from 900W to 600W.

[0055] Step 6: Ozone treatment.

[0056] Specifically, the step 6 is further as follows:

[0057] The epitaxial wafer sputtered with the molybdenum oxide layer 5 is taken out from the reaction chamber of the magnetron sputtering equipment and placed in the reaction chamber of the plasma equipment. 150-250sccm of ozone is introduced into the reaction chamber to treat the molybdenum oxide film layer 5 for 2-4 minutes. During the treatment process, the temperature is controlled to gradually increase from 200°C to 600°C.

[0058] Step 7: Make a nitrogen atomic layer 6.

[0059] Specifically, the step 7 is further as follows:

[0060] The temperature in the reaction chamber of the plasma equipment is controlled to be 100-300°C, the power is 40-120w, and nitrogen is introduced into the reaction chamber by periodically interrupting the nitrogen source. A nitrogen atomic layer 6 is formed on the molybdenum oxide layer 5 by plasma treatment. The time for nitrogen interruption and introduction into the reaction chamber during the formation process is 4s and 8s respectively.

[0061] Step 8: growing a multi-quantum well layer 7 .

[0062] The growing of the multi-quantum well layer 7 further comprises:

[0063] The reaction chamber pressure was maintained at 300-400 mbar, the temperature was maintained at 720 °C, and NH was introduced at a flow rate of 50,000-70,000 sccm. 3 , 20-40sccm TMGa, 10000-15000sccm TMIn and 100-130L / min N 2 , growing an InGaN well layer 71 doped with In with a thickness of 3 nm;

[0064] Raise the temperature to 800°C, maintain the reaction chamber pressure at 300-400 mbar, and introduce NH at a flow rate of 50,000-70,000 sccm. 3 , 20-100sccm TMGa and 100-130L / min N 2 , growing a 10 nm GaN barrier layer 72;

[0065] The InGaN well layer 71 and the GaN barrier layer 72 are repeatedly grown alternately to obtain an InGaN / GaN multi-quantum well light-emitting layer, wherein the number of the alternate growth cycles of the InGaN well layer 71 and the GaN barrier layer 72 is 7-13.

[0066] Step 9: growing an AlGaN electron blocking layer 8.

[0067] Specifically, the step 9 is further as follows:

[0068] At a temperature of 900-950°C and a pressure of 200-400 mbar, 50,000-70,000 sccm of NH 3 、30-60sccm TMGa、100-130L / min H 2 , 100-130sccm TMAl and 1000-1300sccm Cp 2 Under the condition of Mg, the AlGaN electron blocking layer 8 is grown, the thickness of the AlGaN electron blocking layer 8 is 40-60nm, wherein the concentration of Mg doping is 1E19-1E20atoms / cm 3 .

[0069] Step 10: growing a Mg-doped P-type GaN layer 9.

[0070] Specifically, the step 10 is further as follows:

[0071] At a temperature of 950-1000°C and a pressure of 400-900 mbar, 50,000-70,000 sccm of NH 3 , 20-100sccm TMGa, 100-130L / min H 2 、Cp of 1000-3000sccm 2 Under the condition of Mg, a Mg-doped P-type GaN layer 9 with a thickness of 50-200nm is grown, and the Mg doping concentration is 1E19-1E20atoms / cm 3 .

[0072] Step 11: Keep the temperature at 650-680℃ for 20-30min, then turn off the heating system and the gas supply system, and cool with the furnace.

[0073] Comparative Example 1

[0074] The following is a comparative example, that is, a conventional LED epitaxial structure growth method (for epitaxial structure, please refer to Figure 2 ).

[0075] Step 1: At a temperature of 1000-1100°C and a pressure of 100-300 mbar, introduce 100-130 L / min of H 2 Under the conditions of , the sapphire substrate is treated for 5-10 minutes.

[0076] Step 2: growing a low-temperature GaN buffer layer 2 and forming irregular islands in the low-temperature GaN buffer layer 2 .

[0077] Specifically, the step 2 is further as follows:

[0078] At a temperature of 500-600°C and a pressure of 300-600 mbar, 10,000-20,000 sccm of NH 3 , 50-100sccm TMGa, 100-130L / min H 2 Under the condition of , growing the low-temperature GaN buffer layer 2 on the sapphire substrate 1, the thickness of the low-temperature GaN buffer layer 2 is 20-40nm;

[0079] At a temperature of 1000-1100°C and a pressure of 300-600 mbar, 30,000-40,000 sccm of NH 3, 100-130L / min H 2 Under the conditions of , the temperature is kept constant for 300-500s to form the irregular islands on the low-temperature GaN buffer layer 2.

[0080] Step 3: growing a non-doped GaN layer 3.

[0081] Specifically, the step 3 is further as follows:

[0082] At a temperature of 1000-1200°C and a pressure of 300-600 mbar, 30,000-40,000 sccm of NH 3 , 200-400sccm TMGa and 100-130L / min H 2 The undoped GaN layer is grown under the conditions of; the thickness of the undoped GaN layer 3 is 2-4 μm.

[0083] Step 4: growing a Si-doped n-type GaN layer 4 .

[0084] Specifically, the step 4 is further as follows:

[0085] At a temperature of 1000-1200°C and a pressure of 300-600 mbar, 30,000-60,000 sccm of NH 3 , 200-400sccm TMGa, 100-130L / min H 2 , 20-50sccm SiH 4 Under the conditions of , a Si-doped n-type GaN layer 4 is grown, wherein the thickness of the n-type GaN layer 4 is 3-4 μm, and the Si-doping concentration is 5E18-1E19 atoms / cm 3 .

[0086] Step 5: growing an InGaN / GaN multi-quantum well layer 7 .

[0087] Specifically, the growing of the multi-quantum well layer 7 is further:

[0088] The reaction chamber pressure was maintained at 300-400 mbar, the temperature was maintained at 720 °C, and NH was introduced at a flow rate of 50,000-70,000 sccm. 3 , 20-40sccm TMGa, 10000-15000sccm TMIn and 100-130L / min N 2 , growing an InGaN well layer 71 doped with In with a thickness of 3 nm;

[0089] Raise the temperature to 800°C, maintain the reaction chamber pressure at 300-400 mbar, and introduce NH at a flow rate of 50,000-70,000 sccm. 3 , 20-100sccm TMGa and 100-130L / min N 2 , growing a 10 nm GaN barrier layer 72;

[0090] The InGaN well layer 71 and the GaN barrier layer 72 are repeatedly grown alternately to obtain an InGaN / GaN multi-quantum well light-emitting layer, wherein the number of the alternate growth cycles of the InGaN well layer 71 and the GaN barrier layer 72 is 7-13.

[0091] Step 6: growing an AlGaN electron blocking layer 8.

[0092] Specifically, the step 6 is further as follows:

[0093] At a temperature of 900-950°C and a pressure of 200-400 mbar, 50,000-70,000 sccm of NH 3 、30-60sccm TMGa、100-130L / min H 2 、100-130sccm TMAl、1000-1300sccm Cp 2 Under the condition of Mg, the AlGaN electron blocking layer 8 is grown, the thickness of the AlGaN electron blocking layer 8 is 40-60nm, wherein the concentration of Mg doping is 1E19-1E20atoms / cm 3 .

[0094] Step 7: growing a Mg-doped P-type GaN layer 9.

[0095] Specifically, the step 7 is further as follows:

[0096] At a temperature of 950-1000°C and a pressure of 400-900 mbar, 50,000-70,000 sccm of NH 3 , 20-100sccm TMGa, 100-130L / min H 2 、Cp of 1000-3000sccm 2 Under the condition of Mg, a Mg-doped P-type GaN layer 9 with a thickness of 50-200nm is grown, and the Mg doping concentration is 1E19-1E20atoms / cm 3 .

[0097] Step 8: Keep the temperature at 650-680℃ for 20-30min, then turn off the heating system and the gas supply system, and cool with the furnace.

[0098] According to the above-mentioned Example 1 and Comparative Example 1, Sample 1 and Sample 2 were prepared respectively. Under the same pre-process conditions, the ITO layer of Sample 1 and Sample 2 was plated with about 150nm, the Cr / Pt / Au electrode was plated with about 1500nm, and the protective layer SiO was plated under the same conditions. 2 The sample was ground and cut into 635μm*635μm (25mil*25mil) chip particles under the same conditions. Then, 1000 grains were selected from the same position of sample 1 and sample 2, and packaged into white light LEDs under the same packaging process. The photoelectric performance of sample 1 and sample 2 was tested using an integrating sphere under a driving current of 350mA.

[0099] Table 1 Comparison of electrical parameters of sample 1 and sample 2

[0100]

[0101] The data obtained by the integrating sphere are analyzed and compared. It can be seen from Table 1 that the luminous flux of the LED (sample 1) prepared by the growth method of the present invention is significantly improved, and other LED electrical parameters such as voltage and antistatic ability are improved. This is because the technical solution of this patent improves the quantum well quality, improves the luminous efficiency, and improves other LED photoelectric properties.

[0102] The LED epitaxial wafer manufacturing method of the present invention achieves the following effects:

[0103] The present invention can introduce a certain compressive stress by inserting a molybdenum oxide layer between the n-type GaN layer and the multi-quantum well layer, which can partially offset the tensile stress generated by the large difference in thermal expansion coefficient between the GaN and the sapphire substrate, thereby alleviating the problem of surface cracking of the GaN epitaxial material layer to a certain extent. In the process of sputtering the molybdenum oxide film layer, controlling the sputtering power to gradually increase first and then gradually decrease is conducive to obtaining a high-quality and uniform molybdenum oxide film. The high-quality molybdenum oxide film can improve the crystal quality of the subsequently grown multi-quantum well layer.

[0104] Treating the molybdenum oxide film with ozone can induce MoO X Mo inside the lattice 4+ and Mo 5+ ions into Mo 6+ Ion, Mo 6+ Ions can increase MoO X The work function of the ozone treatment can be increased by increasing the number of holes entering the quantum well light-emitting layer, thereby improving the internal quantum efficiency. 6+ The molybdenum oxide film with uniform ion content can further promote the injection of holes into the quantum well light-emitting layer and improve the light-emitting efficiency of the light-emitting diode.

[0105] By forming a nitrogen atomic layer on the molybdenum oxide layer to change the polarity of the molybdenum oxide layer, the crystal atoms of the subsequently grown multi-quantum well layer are arranged more neatly, thereby reducing material growth defects, improving the crystal quality of the quantum well layer, and improving the luminous efficiency of the LED. In the process of forming the nitrogen atomic layer, nitrogen is introduced by periodically interrupting the nitrogen source. On the one hand, it is beneficial to obtain a nitrogen atomic layer with good quality and uniformity. On the other hand, it can promote the grain size of the InGaN / GaN grown in the next step to become smaller, the nucleation density of the grains to become larger, and the roughness is reduced when the quantum well is further grown in the two-dimensional lateral direction, so that the quantum well film layer grown is the smoothest and brightest. The higher the crystal quality, the higher the brightness of the LED.

[0106] Since the method part has described the embodiment of the present application in detail, the expanded description of the structure and method corresponding parts involved in the embodiment is omitted here and will not be repeated. For the description of the specific content in the structure, please refer to the content of the method embodiment, which is not specifically limited here.

[0107] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A method for fabricating an LED epitaxial wafer, successively including: processing a substrate, growing a low-temperature GaN buffer layer, growing an undoped GaN layer, growing an n-type GaN layer doped with Si, fabricating a carrier transition layer, growing a multi-quantum well layer, growing an AlGaN electron blocking layer, growing a p-type GaN layer doped with Mg, and cooling down; characterized in that the fabrication of the carrier transition layer successively includes: sputtering a molybdenum oxide layer, ozone treatment, and fabricating a nitrogen atom layer. The specific steps are as follows: A. Control the temperature of the reaction chamber of the magnetron sputtering equipment to be 250 - 400 °C, the pressure of the reaction chamber to be 5 - 18 Torr, introduce argon and oxygen into the reaction chamber, and sputter a molybdenum oxide layer with a thickness of 12 - 25 nm on the n-type GaN layer doped with Si. During the sputtering process, control the sputtering power of the equipment to gradually increase from 400 w to 900 w first, and then gradually decrease from 900 w to 600 w; B. Take out the epitaxial wafer sputtered with the molybdenum oxide layer from the reaction chamber of the magnetron sputtering equipment and place it into the reaction chamber of the plasma equipment. Introduce 150 - 250 sccm of ozone into the reaction chamber to treat the molybdenum oxide film layer for 2 - 4 min. During the treatment process, control the temperature to gradually increase from 200 °C to 600 °C; C. Control the temperature in the reaction chamber of the plasma equipment to be 100 - 300 °C, the power to be 40 - 120 w, and introduce nitrogen into the reaction chamber in a way of periodically interrupting the nitrogen source. Form a nitrogen atom layer on the molybdenum oxide layer through plasma treatment. During the formation process, the time for nitrogen interruption and introduction into the reaction chamber are 4 s and 8 s respectively.

2. The method for fabricating an LED epitaxial wafer according to claim 1, characterized in that, At a temperature of 1000 - 1100 °C, introduce H at a rate of 100 - 130 L / min 2 , maintain the reaction chamber pressure at 100 - 300 mbar, and process the sapphire substrate for 5 - 10 min.

3. The method for fabricating an LED epitaxial wafer according to claim 2, characterized in that, the specific process of growing the low-temperature GaN buffer layer is: Cool down to 500 - 600 °C, maintain the reaction chamber pressure at 300 - 600 mbar, and introduce NH with a flow rate of 10000 - 20000 sccm 3 , 50 - 100 sccm of TMGa and 100 - 130 L / min of H 2 , and grow a low-temperature GaN buffer layer with a thickness of 20 - 40 nm on a sapphire substrate; Raise the temperature to 1000 - 1100 °C, maintain the reaction chamber pressure at 300 - 600 mbar, and introduce NH with a flow rate of 30000 - 40000 sccm 3 and H with a flow rate of 100 - 130 L / min 2 , keep the temperature for 300 - 500 s, and etch the low-temperature GaN buffer layer into irregular islands.

4. The method for fabricating an LED epitaxial wafer according to claim 1, characterized in that, the specific process of growing the undoped GaN layer is: Raise the temperature to 1000 - 1200 °C, maintain the reaction chamber pressure at 300 - 600 mbar, and introduce NH with a flow rate of 30000 - 40000 sccm 3 , TMGa with a flow rate of 200 - 400 sccm and H with a flow rate of 100 - 130 L / min 2 , and continuously grow an undoped GaN layer with a thickness of 2 - 4 μm.

5. The method for fabricating an LED epitaxial wafer according to claim 1, characterized in that, the specific process of growing the n-type GaN layer doped with Si is: Maintain the reaction chamber pressure at 300 - 600 mbar, maintain the temperature at 1000 - 1200 °C, and introduce NH with a flow rate of 30000 - 60000 sccm 3 , TMGa with a flow rate of 200 - 400 sccm, H with a flow rate of 100 - 130 L / min 2 , and SiH with a flow rate of 20 - 50 sccm 4 , and continuously grow an n-type GaN layer doped with Si with a thickness of 3 - 4 μm. Among them, the Si doping concentration is 5E18 - 1E19 atoms / cm 3 .

6. The method for fabricating an LED epitaxial wafer according to claim 1, characterized in that, the specific process of growing the AlGaN electron blocking layer is: Under the conditions of a temperature of 900 - 950 °C, a reaction chamber pressure of 200 - 400 mbar, introducing 50000 - 70000 sccm of NH 3 , 30 - 60 sccm of TMGa, 100 - 130 L / min of H 2 , 100 - 130 sccm of TMAl, and 1000 - 1300 sccm of Cp 2 Mg, grow the AlGaN electron blocking layer, the thickness of the AlGaN electron blocking layer is 40 - 60 nm, wherein the Mg doping concentration is 1E19 - 1E20 atoms / cm 3 .

7. The method for fabricating an LED epitaxial wafer according to claim 1, characterized in that, the specific process of growing the p-type GaN layer doped with Mg is: Maintain the reaction chamber pressure at 400 - 900 mbar and the temperature at 950 - 1000 °C, and introduce NH with a flow rate of 50000 - 70000 sccm 3 , TMGa with a flow rate of 20 - 100 sccm, H with a flow rate of 100 - 130 L / min 2 , and CpMg with a flow rate of 1000 - 3000 sccm, and continuously grow a doped-Mg P-type GaN layer with a thickness of 50 - 200 nm, where the Mg doping concentration is 1E19 - 1E20 atoms / cm 2 . 3 .

8. The method for fabricating an LED epitaxial wafer according to claim 1, characterized in that, the specific process of cooling down is: Cool down to 650 - 680 °C, keep warm for 20 - 30 min, turn off the heating system and the gas supply system, and cool down with the furnace.

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