Positive polarity epitaxial structure and growth method
By using the grouped Bragg mirror layer and active layer structure in red light diodes, replacing the traditional N-type AlInP restriction layer and N-type barrier layer, the problem of excessive size of conventional epitaxial structures is solved and high integration is achieved and high-efficiency red light diode chips.
Patent Information
- Application Number
- CN202411277579.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2025-01-17
AI Technical Summary
The epitaxial structure of conventional red light diodes is too large to meet the requirements of high-integration products.
Using a positive polarity epitaxial structure including a buffer layer, a Bragg mirror layer, an active layer, a P-type barrier layer and a P-type current expansion layer, the Bragg mirror layer, which is controlled by grouping design and Si doping level, replaces the traditional N-type The AlInP restriction layer and the N-type barrier layer achieve structural reduction.
While ensuring performance, it effectively reduces the size of the epitaxial structure, improves the external quantum efficiency to 98%, and reduces costs.
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Figure CN119325308A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of diodes, in particular to a positive polarity epitaxial structure and a growth method. Background Art
[0002] Light Emitting Diode (LED) is a semiconductor electronic component that can emit light. In recent years, LED has been widely used due to its advantages such as low power consumption, long life, small size, energy saving and environmental protection. For example, it can be used in indoor and outdoor lighting, traffic lights, backlight sources and other fields.
[0003] Red light diode is an important light source device, widely used in outdoor lighting and automobile taillights. Red light diode chip is the basic structure for preparing red light diode, among which the epitaxial structure plays the most important role as the front-end process of red light diode.
[0004] Conventional red epitaxial structure usually includes substrate and DBR, N-type AlInP limiting layer, N-type barrier layer, light-emitting layer, P-type barrier layer, P-type AlInP limiting layer, P-type AlGaInP transition layer and P-type GaP ohmic contact layer stacked on the substrate in sequence. With a long-term market share, its process structure has gradually become unified, and the basic structures of various companies are similar, but the conventional epitaxial structure has the problem of large size and cannot meet the current requirements for high product integration. Summary of the invention
[0005] In response to the above problems, the present application provides a positive polarity epitaxial structure and a growth method that effectively reduce the size of the epitaxial structure while ensuring performance.
[0006] The technical solution adopted by the present invention to solve the technical problem is:
[0007] A positive polarity epitaxial structure comprises a substrate, on which a buffer layer, a Bragg reflector layer, an active layer, a P-type barrier layer, a P-type confinement layer and a P-type current spreading layer are sequentially grown;
[0008] The Bragg reflector layer includes a plurality of first arrangement units, each of which includes an AlAs layer located at the bottom and an AlGaAs layer located at the top. According to different Si doping levels, the first arrangement units of the Bragg reflector layer are divided into a normal group, a restriction group and a blocking group from bottom to top. The Si doping concentration of the restriction group is twice that of the normal group.
[0009] Furthermore, the Bragg reflector layer includes 28 first arrangement units.
[0010] Furthermore, the blocking group includes 18 first arrangement units, and the limiting group includes 9 first arrangement units.
[0011] Furthermore, the active layer includes a plurality of second arrangement units, and each of the second arrangement units includes a well layer located at a lower layer and a barrier layer located at an upper layer.
[0012] Furthermore, the active layer includes 10-20 second arrangement units.
[0013] Furthermore, the well layer is GaInP, and the barrier layer is AlGaInP.
[0014] Furthermore, the Si doping concentration of the conventional group is 2E+18atom / cm3.
[0015] A method for producing a positive polarity epitaxial structure comprises the following steps:
[0016] S1, placing the substrate into a reaction chamber of a metal organic chemical vapor deposition device, and purging the reaction chamber with hydrogen to fill the reaction chamber with hydrogen;
[0017] S2, growing a buffer layer on the substrate;
[0018] S3, growing a Bragg reflector layer on the buffer layer;
[0019] 3.1 AsH3, TMAl and Si2H6 are introduced into the reaction chamber to grow an AlAs layer;
[0020] 3.2 Introduce TMAl, TMGa and Si2H6 into the reaction chamber to grow an AlGaAs layer;
[0021] 3.3 Repeat steps 3.1 and 3.2 as one operation unit to obtain a conventional group;
[0022] 3.4 AsH3, TMAl and Si2H6 are introduced into the reaction chamber to grow an AlAs layer, wherein the doping concentration of Si is twice the doping concentration of Si in step 3.1;
[0023] 3.5 TMAl, TMGa and Si2H6 are introduced into the reaction chamber to grow an AlGaAs layer, wherein the doping concentration of Si is twice the doping concentration of Si in step 3.2;
[0024] 3.6 Repeat steps 3.4 and 3.5 as one operation unit to obtain a restricted group;
[0025] 3.7 First, AsH3 and TMAl are introduced into the reaction chamber to grow an AlAs layer, and then TMAl and TMGa are introduced into the reaction chamber to grow an AlGaAs layer to obtain a barrier group;
[0026] S4, growing an active layer on the Bragg reflector layer;
[0027] S5, growing a P-type barrier layer on the active layer;
[0028] S6, growing a P-type confinement layer on the P-type barrier layer;
[0029] S7, growing a P-type current spreading layer on the P-type confinement layer.
[0030] Further, step 3.3 is repeated 18 times with step 3.1 and step 3.2 as one operation unit, and step 3.6 is repeated 9 times with step 3.4 and step 3.5 as one operation unit.
[0031] Further, step S4 includes the following steps:
[0032] 4.1 Growth of well layer;
[0033] 4.2 Growth barrier;
[0034] 4.3 Take step 4.1 and step 4.2 as an operation unit and repeat them 10-20 times to form an active layer.
[0035] The beneficial effects of the present invention are:
[0036] The embodiment of the present application provides a positive polarity epitaxial structure that grows a buffer layer (buffer) and a Bragg reflector layer (DBR) on a substrate in sequence, and then directly grows an active layer, a P-type barrier layer, a P-type confinement layer, and a P-type current expansion. The DBR is designed in groups, and the Si doping level of each group is controlled to match the band gap of the material itself, so that the functions of the N-type AlInP confinement layer and the N-type AGIP barrier layer in the conventional epitaxial structure are realized in the DBR layer. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 A schematic structural diagram of a positive polarity epitaxial structure provided in an embodiment of the present application; DETAILED DESCRIPTION
[0038] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the drawings in the embodiments of the present application, and the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by those skilled in the art without creative work on the basis of the embodiments of the present application shall belong to the protection scope of the present application.
[0039] like Figure 1As shown, a positive polarity epitaxial structure includes a substrate, on which a buffer layer, a Bragg reflector layer, an active layer, a P-type barrier layer, a P-type confinement layer and a P-type current spreading layer are sequentially arranged from bottom to top.
[0040] The Bragg reflector layer includes a plurality of first arrangement units arranged in a stacked manner, each of which includes an AlAs layer at the bottom and an AlGaAs layer at the top. The entire Bragg reflector layer presents a periodic structure in which AlAs layers and AlGaAs layers are alternately arranged. According to different Si doping levels, the first arrangement units of the Bragg reflector layer are divided into a regular group, a restricted group and a blocking group from bottom to top, wherein the Si doping concentration of the restricted group is twice that of the regular group, and the Si doping concentration of the blocking group is zero, that is, no Si is doped in the blocking group.
[0041] As a specific implementation, the Si doping concentration of the conventional group described in this embodiment is 2E+18atom / cm3.
[0042] Preferably, the Bragg reflector layer includes 28 first arrangement units. This DBR configuration can increase the external quantum efficiency to about 98%. On this basis, too much will affect the cost, and too little will reduce the reflection efficiency.
[0043] Preferably, the number of the first arrangement units in the conventional group is twice the number of the first arrangement units in the restricted group, and the blocking group includes one first arrangement unit. That is, the blocking group includes 18 first arrangement units, and the restricted group includes 9 first arrangement units. In order from bottom to top, the first 18 first arrangement units are the conventional group, the last first arrangement unit is the blocked group, and the 9 first arrangement units between the conventional group and the blocked group are the restricted group.
[0044] As a specific implementation manner, in this embodiment, the thickness of the AlAs layer is 550 Å, and the thickness of the AlGaAs layer is 500 Å.
[0045] The buffer layer is a GaAs layer, and its thickness is 0.5 μm-0.8 μm.
[0046] The active layer includes a plurality of stacked second arrangement units, each of which includes a well layer at the bottom and a barrier layer at the top, the well layer is GaInP, and the barrier layer is AlGaInP. The entire active layer presents a periodic structure in which the well layers and the barrier layers are alternately arranged.
[0047] The active layer includes 10-20 second arrangement units. As a specific implementation, the active layer in this embodiment includes 15 second arrangement units.
[0048] The thickness of the active layer is 0.15 μm-0.2 μm.
[0049] The P-type barrier layer is a ((AlaGa1-a)0.5In0.5P layer with a thickness of 1000A.
[0050] The P-type limiting layer is an AIP layer with a thickness of 3000A.
[0051] The P-type current spreading layer is a Gap layer, and the thickness is 4.5um.
[0052] A method for producing a positive polarity epitaxial structure comprises the following steps:
[0053] S1, placing the substrate into a reaction chamber of a metal organic chemical vapor deposition device, and using hydrogen to purge the reaction chamber so that the reaction chamber is filled with hydrogen.
[0054] S2, setting the reaction chamber pressure to 50-60 mbar and the temperature to 700-800°C, while introducing 100-120 sccm of TMGa into the reaction chamber for 4-6 minutes to grow a buffer layer on the substrate.
[0055] S3, growing a Bragg reflector layer on the buffer layer obtained in step S2.
[0056] 3.1 Growth of AlAs layer.
[0057] The reaction chamber pressure was set to 50-60 mbar, the temperature to 700-800°C, 300-500 sccm of AsH3, 400-800 sccm of TMAl and 30 sccm of Si2H6 were introduced into the reaction chamber, the doping concentration of Si was 2E+18 atom / cm3, and the duration was 50s-65s.
[0058] 3.2 Growth of AlGaAs layer.
[0059] The reaction chamber pressure was set to 50-60 mbar, the temperature to 700-800°C, 400-800 sccm of TMAl, 100-200 sccm of TMGa and 30 sccm of Si2H6 were introduced into the reaction chamber, the doping concentration of Si was 2E+18 atom / cm3, and the duration was 50s-65s.
[0060] 3.3 Take steps 3.1 and 3.2 as an operation unit and repeat them 18 times to obtain a regular group.
[0061] 3.4 Growth of AlAs layer.
[0062] The reaction chamber pressure was set to 50-60 mbar, the temperature to 700-800°C, 300-500 sccm of AsH3, 400-800 sccm of TMAl and 60 sccm of Si2H6 were introduced into the reaction chamber, the doping concentration of Si was 4E+18 atom / cm3, and the duration was 50s-65s.
[0063] 3.5 Growth of AlGaAs layer.
[0064] The reaction chamber pressure was set to 50-60 mbar, the temperature to 700-800°C, 400-800 sccm of TMAl, 100-200 sccm of TMGa and 60 sccm of Si2H6 were introduced into the reaction chamber, the doping concentration of Si was 4E+18 atom / cm3, and the duration was 50s-65s.
[0065] 3.6 Take steps 3.4 and 3.5 as one operation unit and repeat it 9 times to obtain a restricted group.
[0066] 3.7 Set the reaction chamber pressure to 50-60 mbar and the temperature to 700-800°C. First, introduce 300-500 sccm of AsH3 and 400-800 sccm of TMAl into the reaction chamber for 60s-150s to grow an AlAs layer. Then, introduce 400-800 sccm of TMAl and 100-200 sccm of TMGa into the reaction chamber for 60s-150s to grow an AlGaAs layer to obtain a barrier group.
[0067] S4, growing an active layer on the Bragg reflector layer obtained in step S3, wherein the active layer is a composite superlattice structure in which quantum wells and barriers are alternately grown.
[0068] 4.1 Introduce 1000 sccm of PH3 into the reaction chamber, set the reaction chamber pressure to 55 mbar, the temperature to 750°C, the duration to 20s-40s, and grow a GaInP well layer.
[0069] 4.2 Introduce 1000 sccm of PH3 into the reaction chamber, set the reaction chamber pressure to 55 mbar, the temperature to 750°C, the duration to 20s-40s, and grow an AlGaInP barrier layer.
[0070] 4.3 Take step 4.1 and step 4.2 as an operation unit and repeat them 10-20 times to form an active layer.
[0071] As a specific implementation, in this embodiment, step 4.1 and step 4.2 are taken as an operation unit, which is repeated 15 times to form an active layer.
[0072] S5, growing a P-type barrier layer on the active layer obtained in step S4.
[0073] The reaction chamber pressure was set to 55 mbar and the temperature to 700-800°C. 800 sccm of PH3, 300-500 sccm of TMIn, 150-200 sccm of TMAl and 30-40 sccm of TMGa were introduced into the reaction chamber for 2-5 minutes to form a P-type barrier layer.
[0074] S6, growing a P-type confinement layer on the P-type barrier layer obtained in step S5.
[0075] The reaction chamber pressure is set to 50-60 mbar, the temperature is set to 700-800°C, 800-1200 sccm of PH3, 300-500 sccm of TMIn and 150-200 sccm of TMAl are introduced into the reaction chamber, the Mg doping concentration is 1.5E+18 atom / cm3, and the reaction is continued for 5-15 minutes to form a P-type confinement layer.
[0076] S7, growing a P-type current spreading layer on the P-type confinement layer obtained in step S6.
[0077] The reaction chamber pressure is set to 50-60 mbar, the temperature is 800-1000°C, 400-800 sccm of PH3, 300-500 sccm of TMGa, and the Mg doping concentration is 1E+18 atom / cm3, and the reaction is continued for 20-30 minutes to form a P-type current extension layer.
[0078] Other embodiments obtained by those skilled in the art by combining, splitting, reorganizing, etc. the embodiments of the present application on the basis of the embodiments provided in the present application do not exceed the protection scope of the present application.
[0079] The above specific implementation methods have detailed the purpose, technical solutions and beneficial effects of the embodiments of the present application. The above are only specific implementation methods of the embodiments of the present application and are not used to limit the protection scope of the embodiments of the present application. That is, any modifications, equivalent substitutions, improvements, etc. made on the basis of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.
Claims
1. A positive polarity epitaxial structure, characterized in that: It comprises a substrate, on which a buffer layer, a Bragg reflector layer, an active layer, a P-type barrier layer, a P-type confinement layer and a P-type current spreading layer are sequentially grown; The Bragg reflector layer includes a plurality of first arrangement units, each of which includes an AlAs layer located at the bottom and an AlGaAs layer located at the top. According to different Si doping levels, the first arrangement units of the Bragg reflector layer are divided into a normal group, a restriction group and a blocking group from bottom to top. The Si doping concentration of the restriction group is twice that of the normal group.
2. A positive polarity epitaxial structure according to claim 1, characterized in that: The Bragg reflector layer includes 28 first arrangement units.
3. A positive polarity epitaxial structure according to claim 2, characterized in that: The blocking group includes 18 first arrangement units, and the limiting group includes 9 first arrangement units.
4. The positive polarity epitaxial structure according to claim 2, characterized in that: The active layer comprises a plurality of second arrangement units, and each second arrangement unit comprises a well layer located at a lower layer and a barrier layer located at an upper layer.
5. A positive polarity epitaxial structure according to claim 4, characterized in that: The active layer includes 10-20 second arrangement units.
6. The positive polarity epitaxial structure according to claim 4, characterized in that: The well layer is GaInP, and the barrier layer is AlGaInP.
7. The positive polarity epitaxial structure according to claim 1, characterized in that: The Si doping concentration of the conventional group is 2E+18atom / cm3.
8. A method for producing a positive epitaxial structure according to any one of claims 1 to 8, characterized in that: The following steps are included: S1, placing the substrate into a reaction chamber of a metal organic chemical vapor deposition device, and purging the reaction chamber with hydrogen to fill the reaction chamber with hydrogen; S2, growing a buffer layer on the substrate; S3, growing a Bragg reflector layer on the buffer layer; 3.1 AsH3, TMAl and Si2H6 are introduced into the reaction chamber to grow an AlAs layer; 3.2 Introduce TMAl, TMGa and Si2H6 into the reaction chamber to grow an AlGaAs layer; 3.3 Repeat steps 3.1 and 3.2 as one operation unit to obtain a conventional group; 3.4 AsH3, TMAl and Si2H6 are introduced into the reaction chamber to grow an AlAs layer, wherein the doping concentration of Si is twice the doping concentration of Si in step 3.1; 3.5 TMAl, TMGa and Si2H6 are introduced into the reaction chamber to grow an AlGaAs layer, wherein the doping concentration of Si is twice the doping concentration of Si in step 3.2; 3.6 Repeat steps 3.4 and 3.5 as one operation unit to obtain a restricted group; 3.7 First, AsH3 and TMAl are introduced into the reaction chamber to grow an AlAs layer, and then TMAl and TMGa are introduced into the reaction chamber to grow an AlGaAs layer to obtain a barrier group; S4, growing an active layer on the Bragg reflector layer; S5, growing a P-type barrier layer on the active layer; S6, growing a P-type confinement layer on the P-type barrier layer; S7, growing a P-type current spreading layer on the P-type confinement layer.
9. A method for producing a positive polarity epitaxial structure according to claim 8, characterized in that: Step 3.3 was repeated 18 times with step 3.1 and step 3.2 as one operation unit, and step 3.6 was repeated 9 times with step 3.4 and step 3.5 as one operation unit.
10. The method for producing a positive polarity epitaxial structure according to claim 8, characterized in that: Step S4 comprises the following steps, 4.1 Growth of well layer; 4.2 Growth barrier; 4.3 Take step 4.1 and step 4.2 as an operation unit and repeat them 10-20 times to form an active layer.