Light-emitting diode epitaxial wafer and preparation method thereof, and light-emitting diode
Patent Information
- Application Number
- CN202411898004.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-04-08
AI Technical Summary
[0002]目前GaN基发光二极管均采用的是异质衬底(包括蓝宝石衬底、碳化硅衬底、硅衬底等)，其与外延材料之间存在较大的晶格失配和热失配，导致外延材料在生长过程中会受到较大的应力，且容易形成位错产生缺陷，这些位错缺陷会延伸至有源区，降低辐射复合效率，降低发光效率
[0029]本发明一实施例中的发光二极管外延片的制备方法中，在生长第一三维非掺杂GaN层之后，依次生长了第二三维非掺杂GaN层、InGaN层交替生长形成的超晶格层以及二维非掺杂GaN层，三者整体形成了非掺杂GaN层。且控制第一三维非掺GaN层的生长温度大于第二三维非掺GaN层，基于该控制时，第一三维非掺GaN层主要呈岛状生长，而第二三维非掺GaN层则在岛状的第一三维非掺GaN层边缘形成三维、二维混合生长模式生长，再辅以周期性循环的InGaN层释放应力，可使得成核岛大幅均匀化，进而通过后期二维非掺杂GaN层进行合并，优化了非掺杂GaN层整体的平整度，大幅降低了缺陷密度，提升了发光效率。具体地，本实施例的非掺杂GaN层的位错密度可降低至1.5×108cm-3以下，而传统的非掺杂GaN层的位错密度达到了5～8×108cm-3。
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Figure CN119789622A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of semiconductor optoelectronic devices, and in particular to a light emitting diode epitaxial wafer and a preparation method thereof, and a light emitting diode. Background Art
[0002] At present, GaN-based light-emitting diodes all use heterogeneous substrates (including sapphire substrates, silicon carbide substrates, silicon substrates, etc.), which have large lattice mismatches and thermal mismatches with epitaxial materials, resulting in large stress on the epitaxial materials during growth and easy formation of dislocation defects. These dislocation defects will extend to the active area, reducing the radiation recombination efficiency and the luminescence efficiency. Especially when the substrate size is enlarged, more dislocation defects will be generated. Summary of the invention
[0003] The technical problem to be solved by the present invention is to provide a light emitting diode epitaxial wafer and a preparation method thereof, which can improve the light emitting efficiency of the light emitting diode.
[0004] In order to solve the above problems, the present invention discloses a method for preparing a light emitting diode epitaxial wafer, which comprises:
[0005] providing a substrate;
[0006] growing a buffer layer on the substrate;
[0007] growing a first three-dimensional non-doped GaN layer on the buffer layer;
[0008] Alternatingly growing second three-dimensional undoped GaN layers and InGaN layers on the first three-dimensional undoped GaN layer to obtain a superlattice layer;
[0009] Growing a two-dimensional non-doped GaN layer on the superlattice layer to obtain a non-doped GaN layer;
[0010] Growing an N-type GaN layer, a multi-quantum well layer and a P-type GaN layer in sequence on the non-doped GaN layer to obtain a light-emitting diode epitaxial wafer;
[0011] Wherein, the growth temperature of the first three-dimensional non-doped GaN layer is greater than that of the second three-dimensional non-doped GaN layer.
[0012] As an improvement of the above technical solution, the growth pressure of the first three-dimensional non-doped GaN layer is greater than the growth pressure of the second three-dimensional non-doped GaN layer;
[0013] The V / III ratio of the first three-dimensional non-doped GaN layer during growth is smaller than the V / III ratio of the second three-dimensional non-doped GaN layer during growth.
[0014] As an improvement of the above technical solution, the buffer layer is an AlN layer, which is grown by PVD;
[0015] When the buffer layer is grown, the sputtering power is 3kW-10kW, the sputtering temperature is 300°C-500°C, the Ar flow rate is 10sccm-80sccm, the N2 flow rate is 100sccm-300sccm, and the O2 flow rate is 2sccm-5sccm.
[0016] As an improvement of the above technical solution, the growth temperature of the first three-dimensional non-doped GaN layer is 1000° C. to 1200° C., the growth pressure is 300 torr to 600 torr, and the V / III ratio is 200 to 500;
[0017] The growth temperature of the two-dimensional non-doped GaN layer is 1000° C. to 1100° C., the growth pressure is 50 torr to 300 torr, and the V / III ratio is 2000 to 5000.
[0018] As an improvement of the above technical solution, the growth temperature of the second three-dimensional non-doped GaN layer is 800°C to 1000°C, the growth pressure is 50torr to 300torr, and the V / III ratio is 2000 to 5000;
[0019] The growth temperature of the InGaN layer is 790° C. to 820° C., and the growth pressure is 50 torr to 300 torr.
[0020] As an improvement of the above technical solution, the thickness of the first non-doped three-dimensional GaN layer is 500nm to 2000nm;
[0021] The thickness of the two-dimensional non-doped GaN layer is 800nm-1200nm.
[0022] As an improvement of the above technical solution, the thickness of the second non-doped three-dimensional GaN layer is 10nm to 30nm;
[0023] The thickness of the InGaN layer is 1 nm to 2 nm, and the In component ratio is 0.01 to 0.1.
[0024] As an improvement of the above technical solution, the Ga source used when growing the first three-dimensional non-doped GaN layer and the two-dimensional non-doped GaN layer is TMGa;
[0025] The Ga source used when growing the second three-dimensional non-doped GaN layer is TEGa.
[0026] Correspondingly, the present invention also discloses a light emitting diode epitaxial wafer, which is prepared by the above-mentioned method for preparing the light emitting diode epitaxial wafer.
[0027] Correspondingly, the present invention also discloses a light emitting diode, which comprises the light emitting diode epitaxial wafer mentioned above.
[0028] The implementation of the present invention has the following beneficial effects:
[0029] In the method for preparing a light-emitting diode epitaxial wafer in one embodiment of the present invention, after growing the first three-dimensional undoped GaN layer, the second three-dimensional undoped GaN layer, the superlattice layer formed by the alternating growth of the InGaN layer, and the two-dimensional undoped GaN layer are sequentially grown, and the three together form an undoped GaN layer. The growth temperature of the first three-dimensional undoped GaN layer is controlled to be greater than that of the second three-dimensional undoped GaN layer. Based on this control, the first three-dimensional undoped GaN layer mainly grows in an island shape, while the second three-dimensional undoped GaN layer grows in a three-dimensional and two-dimensional mixed growth mode at the edge of the island-shaped first three-dimensional undoped GaN layer. With the help of the periodic cycle of the InGaN layer to release stress, the nucleation island can be greatly homogenized, and then merged through the later two-dimensional undoped GaN layer, thereby optimizing the overall flatness of the undoped GaN layer, greatly reducing the defect density, and improving the luminous efficiency. Specifically, the dislocation density of the undoped GaN layer of this embodiment can be reduced to 1.5×10 8 cm -3 The dislocation density of the conventional non-doped GaN layer is 5-8×10 8 cm -3 . BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 is a flow chart of a method for preparing a light emitting diode epitaxial wafer in one embodiment of the present invention;
[0031] Figure 2 It is a schematic structural diagram of a light emitting diode epitaxial wafer in one embodiment of the present invention. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.
[0033] See also Figure 1 The present invention discloses a method for preparing a light emitting diode epitaxial wafer, which comprises the following steps:
[0034] S1. providing a substrate;
[0035] S2, growing a buffer layer on the substrate;
[0036] S3, growing a first three-dimensional non-doped GaN layer on the buffer layer;
[0037] S4, alternately growing a second three-dimensional undoped GaN layer and an InGaN layer on the first three-dimensional undoped GaN layer to obtain a superlattice layer;
[0038] S5, growing a two-dimensional non-doped GaN layer on the superlattice layer to obtain a non-doped GaN layer;
[0039] S6: sequentially growing an N-type GaN layer, a multi-quantum well layer and a P-type GaN layer on the two-dimensional non-doped GaN layer to obtain a light-emitting diode epitaxial wafer;
[0040] The growth temperature of the first three-dimensional non-doped GaN layer is greater than that of the second three-dimensional non-doped GaN layer.
[0041] In the method for preparing the light-emitting diode epitaxial wafer in the above embodiment of the present invention, after growing the first three-dimensional undoped GaN layer, the second three-dimensional undoped GaN layer, the superlattice layer formed by the alternating growth of the InGaN layer, and the two-dimensional undoped GaN layer are sequentially grown, and the three form an undoped GaN layer as a whole. And the growth temperature of the first three-dimensional undoped GaN layer is controlled to be higher than that of the second three-dimensional undoped GaN layer. Based on this control, the first three-dimensional undoped GaN layer mainly grows in an island shape, while the second three-dimensional undoped GaN layer grows in a three-dimensional and two-dimensional mixed growth mode at the edge of the island-shaped first three-dimensional undoped GaN layer. Assisted by the periodic cycle of the InGaN layer to release stress, the nucleation island can be greatly homogenized, and then merged through the later two-dimensional undoped GaN layer, the overall flatness of the undoped GaN layer is optimized, the defect density is greatly reduced, and the luminous efficiency is improved. Specifically, the dislocation density of the undoped GaN layer of this embodiment can be reduced to 1.5×10 8 cm -3 The dislocation density of the conventional non-doped GaN layer is 5-8×10 8 cm -3 .
[0042] Preferably, in some embodiments, the growth pressure of the first three-dimensional non-doped GaN layer is greater than the growth pressure of the second three-dimensional non-doped GaN layer; the V / III ratio of the first three-dimensional non-doped GaN layer during growth is less than the V / III ratio of the second three-dimensional non-doped GaN layer during growth. Based on this growth condition, the first three-dimensional non-doped GaN layer is more inclined to grow in a three-dimensional island manner, while the second three-dimensional non-doped GaN layer is more inclined to grow in a two-dimensional and three-dimensional mixed manner, so that the nucleation island formed by the first three-dimensional GaN layer undergoes multiple longitudinal and lateral growth processes, greatly reducing the thickness and size differences of the nucleation island and greatly reducing the dislocation density.
[0043] Specifically, in step S1, the substrate is a sapphire substrate, a silicon substrate, a silicon carbide substrate or a zinc oxide substrate, but is not limited thereto, and is preferably a sapphire substrate.
[0044] Specifically, in step S2, the buffer layer is a low-temperature GaN layer, an AlGaN layer or an AlN layer, but is not limited thereto. Specifically, when the buffer layer is a low-temperature GaN layer, it can be grown by MOCVD, and its growth temperature is 500°C to 600°C, and the growth pressure is 100torr to 500torr. The low-temperature GaN layer can become a nucleation center, which facilitates the growth of the subsequent non-doped GaN layer. When the buffer layer is an AlN layer, it can be grown by MOCVD or PVD, but is not limited thereto.
[0045] Preferably, in some embodiments, the buffer layer is an AlN layer, and its sputtering power is 3kW to 10kW, the sputtering temperature is 300°C to 500°C, the Ar flow rate is 10sccm to 80sccm, the N2 flow rate is 100sccm to 300sccm, and the O2 flow rate is 2sccm to 5sccm. The AlN layer obtained by sputtering has higher surface flatness and high crystal quality, and it is easier to make the first three-dimensional GaN layer grow in an island mode. Moreover, it will also promote the subsequent growth of the second three-dimensional GaN layer on a homogeneous GaN-type nucleation island, thereby optimizing the thickness and width uniformity of the nucleation island. In addition, in this embodiment, the O2 flow rate is controlled to be 2sccm to 5sccm, which can greatly optimize the crystal quality and flatness of the AlN layer. Lay a good foundation for the subsequent growth of the first three-dimensional GaN layer in an island mode.
[0046] Specifically, the thickness of the buffer layer is 10 nm to 50 nm, preferably 10 nm to 30 nm.
[0047] Specifically, in step S3, the first three-dimensional non-doped GaN layer is grown by MOCVD, and its growth temperature is 950°C to 1200°C, the growth pressure is 200torr to 600torr, and the V / III ratio is 200 to 500. Based on the growth conditions, the first three-dimensional non-doped GaN layer is more inclined to grow in an island mode. Preferably, in some embodiments, the growth temperature of the first three-dimensional non-doped GaN layer is 1000°C to 1200°C, the growth pressure is 300torr to 600torr, and the V / III ratio is 200 to 500.
[0048] Specifically, the thickness of the first three-dimensional non-doped GaN layer is 500nm to 2500nm. If the thickness is too small, when growing the second three-dimensional non-doped GaN layer, it is easy to cause the nucleation islands to partially merge, making it difficult to effectively reduce the dislocation density. If the thickness is too large, the thermal stress introduced is too large, reducing the luminous efficiency. Preferably, in some embodiments, the thickness of the first three-dimensional non-doped GaN layer is 500nm to 2000nm.
[0049] Specifically, when the first three-dimensional non-doped GaN layer grows, the MO source used includes a Ga source and an N source, and the carrier gas is N2 and H2, wherein the Ga source is TMGa or TEGa, and the N source is NH3. Preferably, in some embodiments, the Ga source is TMGa, which has a fast growth rate and is conducive to the formation of island growth. In addition, TMGa can optimize the surface flatness of the nucleation island, making the subsequent two-dimensional non-doped GaN layer growth easier, and improve its crystal quality and reduce dislocation density.
[0050] Specifically, in step S4, the second three-dimensional non-doped GaN layer is grown by MOCVD, and its growth temperature is 800°C to 1050°C, the growth pressure is 50torr to 500torr, and the V / III ratio is 200 to 5000. Based on the growth conditions, the second three-dimensional non-doped GaN layer tends to grow in a three-dimensional-two-dimensional mixed manner, thereby optimizing the uniformity of the nucleation island. Preferably, in some embodiments, the growth temperature of the second three-dimensional non-doped GaN layer is 800°C to 1000°C, the growth pressure is 50torr to 300torr, and the V / III ratio is 2000 to 5000.
[0051] Specifically, the thickness of the second three-dimensional non-doped GaN layer is 10nm to 50nm. If the thickness is too small, it is difficult to effectively release stress. If the thickness is too large, the nucleation islands may merge prematurely, making it difficult to effectively reduce the dislocation density. Preferably, in some embodiments, the thickness of the second three-dimensional non-doped GaN layer is 10nm to 30nm.
[0052] Specifically, when the second three-dimensional non-doped GaN layer grows, the MO source used includes a Ga source and a N source, and the carrier gas is N2 and H2, wherein the Ga source is TMGa or TEGa, and the N source is NH3. Preferably, in some embodiments, the Ga source is TEGa, which has high quality of grown crystals, is conducive to changing the dislocation growth direction, and reducing the dislocation density. In addition, TEGa decomposes and reacts relatively slowly, so it is more conducive to growing around the nucleation island and optimizing the uniformity of the nucleation island.
[0053] Specifically, in step S4, the InGaN layer is grown by MOCVD at a growth temperature of 780°C to 880°C and a growth pressure of 50 torr to 500 torr. Preferably, in some embodiments, the InGaN layer is grown at a growth temperature of 790°C to 820°C and a growth pressure of 50 torr to 300 torr.
[0054] Specifically, the thickness of the InGaN layer is 1 nm to 3 nm to better control the stress. Preferably, in some embodiments, the thickness of the InGaN layer is 1 nm to 2 nm. Specifically, the proportion of In component in the InGaN layer is 0.01 to 0.1.
[0055] Specifically, when the InGaN layer grows, the MO sources used include Ga source, In source and N source, and the carrier gas is N2, wherein the Ga source is TMGa or TEGa, the In source is TMIn or TEIn, and the N source is NH3. Preferably, in some embodiments, the Ga source is TMGa, and the In source is TMIn, which has a fast growth rate.
[0056] Specifically, in step S4, the number of cycles of the alternating growth is 2-8, preferably 2-6.
[0057] Specifically, in step S5, the two-dimensional non-doped GaN layer is grown by MOCVD, and its growth temperature is 1000°C to 1200°C, the growth pressure is 50torr to 300torr, and the V / III ratio is 2000 to 5000. Based on this growth condition, the two-dimensional non-doped GaN layer is more inclined to grow in a two-dimensional mode. Preferably, in some embodiments, the growth temperature of the two-dimensional non-doped GaN layer is 1000°C to 1100°C, the growth pressure is 50torr to 300torr, and the V / III ratio is 2000 to 5000.
[0058] Specifically, the thickness of the two-dimensional non-doped GaN layer is 500nm to 2500nm. If the thickness is too small, it is difficult to fully merge into a core island. If the thickness is too large, the thermal stress introduced is too large, reducing the luminous efficiency. Preferably, in some embodiments, the thickness of the two-dimensional non-doped GaN layer is 800nm to 1200nm.
[0059] Specifically, when the two-dimensional non-doped GaN layer grows, the MO source used includes a Ga source and a N source, and the carrier gas is N2 and H2, wherein the Ga source is TMGa or TEGa, and the N source is NH3. Preferably, in some embodiments, the Ga source is TMGa, which has a fast growth rate.
[0060] Specifically, in some embodiments, step S6 includes:
[0061] S61: growing an N-type GaN layer on the non-doped GaN layer;
[0062] Specifically, in some embodiments, the N-type GaN layer is grown by MOCVD, and the growth temperature is 1100° C. to 1150° C. and the growth pressure is 100 torr to 500 torr.
[0063] Specifically, in some embodiments, the N-type doping element of the N-type GaN layer is Si, but not limited thereto. The N-type doping concentration of the N-type GaN layer is 5×10 18 cm -3 ~5×10 19 cm -3, and its thickness is 1μm~5μm.
[0064] S62: growing a multi-quantum well layer on the N-type GaN layer;
[0065] Specifically, in some embodiments, InGaN quantum well layers and GaN quantum barrier layers are periodically grown by MOCVD until a multi-quantum well layer is obtained, wherein the growth temperature of the InGaN quantum well layer is 730°C to 820°C, the growth pressure is 100 torr to 300 torr, and the growth temperature of the GaN quantum barrier layer is 850°C to 950°C, the growth pressure is 100 torr to 300 torr.
[0066] Specifically, in some embodiments, the multi-quantum well layer is a periodic structure, and the number of periods is 3 to 15. Each period includes an InGaN quantum well layer and a GaN quantum barrier layer stacked in sequence. The thickness of the InGaN quantum well layer is 3nm to 5nm, and the In component ratio is 0.1 to 0.3, and the thickness of the GaN quantum barrier layer is 5nm to 15nm.
[0067] S63: growing a P-type GaN layer on the multi-quantum well layer;
[0068] Specifically, in some embodiments, the P-type GaN layer is grown by MOCVD, and the growth temperature is 900° C. to 1000° C. and the growth pressure is 100 torr to 300 torr.
[0069] Specifically, in some embodiments, the P-type doping element in the P-type GaN layer is Mg, but is not limited thereto. The P-type doping concentration in the P-type GaN layer is 1×10 19 cm -3 ~1×10 21 cm -3 , and its thickness is 100nm~200nm.
[0070] Accordingly, see Figure 2The present invention also discloses a light-emitting diode epitaxial wafer, which is prepared by the above-mentioned preparation method. Specifically, the light-emitting diode epitaxial wafer includes a substrate 100, a buffer layer 200, a non-doped GaN layer 300, an N-type GaN layer 400, a multi-quantum well layer 500 and a P-type GaN layer 600 sequentially stacked on the substrate 100. Among them, the non-doped GaN layer 300 includes a first three-dimensional non-doped GaN layer 310, a superlattice layer 320, and a two-dimensional non-doped GaN layer 330 sequentially stacked on the buffer layer. Among them, the superlattice layer 320 includes a second three-dimensional non-doped GaN layer 321 and an InGaN layer 322 alternately stacked. In this embodiment, the growth temperature of the first three-dimensional non-doped GaN layer is controlled to be higher than that of the second three-dimensional non-doped GaN layer. Based on this control, the first three-dimensional non-doped GaN layer mainly grows in an island shape, while the second three-dimensional non-doped GaN layer grows in a three-dimensional and two-dimensional mixed growth mode at the edge of the island-shaped first three-dimensional non-doped GaN layer. With the help of the periodic cycle of the InGaN layer to release stress, the nucleation island can be greatly uniformed, and then merged through the later two-dimensional non-doped GaN layer, the overall flatness of the non-doped GaN layer is optimized, the defect density is greatly reduced, and the luminous efficiency is improved. Specifically, the dislocation density of the non-doped GaN layer in this embodiment can be reduced to 1.5×10 8 cm -3 The dislocation density of the conventional non-doped GaN layer is 5-8×10 8 cm -3 .
[0071] Correspondingly, the present invention also discloses a light-emitting diode, which includes the above-mentioned light-emitting diode epitaxial wafer, in which the superlattice layer formed by the alternating growth of the first three-dimensional non-doped GaN layer, the second three-dimensional non-doped GaN layer, and the InGaN layer and the two-dimensional non-doped GaN layer form a non-doped GaN layer as a whole. And the growth temperature of the first three-dimensional non-doped GaN layer is controlled to be higher than that of the second three-dimensional non-doped GaN layer. Based on this control, the first three-dimensional non-doped GaN layer mainly grows in an island shape, while the second three-dimensional non-doped GaN layer grows in a three-dimensional and two-dimensional mixed growth mode at the edge of the island-shaped first three-dimensional non-doped GaN layer, and then with the help of the periodic cycle of the InGaN layer to release stress, the nucleation island can be greatly homogenized, and then merged through the later two-dimensional non-doped GaN layer, the overall flatness of the non-doped GaN layer is optimized, the defect density is greatly reduced, and the luminous efficiency of the light-emitting diode is improved.
[0072] The present invention will be further described below with specific embodiments:
[0073] Example 1
[0074] This embodiment provides a method for preparing a light emitting diode epitaxial wafer, which comprises the following steps:
[0075] (1) Providing a sapphire substrate;
[0076] (2) growing a buffer layer on a sapphire substrate;
[0077] A low-temperature GaN layer is grown by MOCVD as a buffer layer at a growth temperature of 550° C. and a growth pressure of 300 torr. The Ga source used in the growth is TMGa, and the N source is NH3.
[0078] The thickness of the buffer layer is 50 nm.
[0079] (3) growing a first three-dimensional non-doped GaN layer on the buffer layer;
[0080] The first three-dimensional non-doped GaN layer is grown by MOCVD, with a growth temperature of 1120° C., a growth pressure of 500 torr, and a V / III ratio of 300; the Ga source used during the growth is TMGa, and the N source is NH3.
[0081] The thickness of the first three-dimensional non-doped GaN layer is 500 nm.
[0082] (4) periodically growing a second three-dimensional GaN layer and an InGaN layer on the first three-dimensional non-doped GaN layer to obtain a superlattice layer;
[0083] The second three-dimensional non-doped GaN layer is grown by MOCVD at a growth temperature of 1000° C., a growth pressure of 500 torr, and a V / III ratio of 300. The Ga source used during the growth is TMGa, and the N source is NH3.
[0084] The InGaN layer is grown by MOCVD at a growth temperature of 830°C and a growth pressure of 500 torr. The Ga source used in the growth is TMGa, the In source is TMIn, and the N source is NH3.
[0085] The thickness of the second three-dimensional non-doped GaN layer is 30 nm, the thickness of the InGaN layer is 2 nm, and the In component ratio is 0.08. The number of periods of the superlattice layer is 3.
[0086] (5) growing a two-dimensional non-doped GaN layer on the superlattice layer to obtain a non-doped GaN layer;
[0087] The two-dimensional non-doped GaN layer is grown by MOCVD at a growth temperature of 1080°C, a growth pressure of 100 torr, and a V / III ratio of 4000; the Ga source used during the growth is TMGa, and the N source is NH3.
[0088] The thickness of the two-dimensional non-doped GaN layer is 1200nm.
[0089] (6) growing an N-type GaN layer on the non-doped GaN layer;
[0090] The N-type GaN layer is grown by MOCVD at a growth temperature of 1120° C. and a growth pressure of 300 torr.
[0091] The thickness of the N-type GaN layer is 3 μm, and the Si doping concentration is 5×10 18 cm -3 .
[0092] (7) Growth of multi-quantum well layers on N-type GaN layers
[0093] The InGaN quantum well layer and the GaN quantum barrier layer are periodically grown by MOCVD until a multi-quantum well layer is obtained. The growth temperature of the InGaN quantum well layer is 760°C and the growth pressure is 200 torr, and the growth temperature of the GaN quantum barrier layer is 880°C and the growth pressure is 200 torr.
[0094] Among them, the thickness of the InGaN quantum well layer is 3nm, the In component ratio is 0.15, and the thickness of the GaN quantum barrier layer is 10nm.
[0095] (8) a P-type GaN layer on the multi-quantum well layer;
[0096] The P-type GaN layer is grown by MOCVD at a growth temperature of 980° C. and a growth pressure of 200 torr.
[0097] The thickness of the P-type GaN layer is 150 nm and the Mg doping concentration is 8×10 20 cm -3 .
[0098] Example 2
[0099] This embodiment provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Embodiment 1 in that:
[0100] In step (4), the growth pressure of the second three-dimensional non-doped GaN layer is 200 torr, and the V / III ratio is 2500.
[0101] The rest are the same as in Example 1.
[0102] Example 3
[0103] This embodiment provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Embodiment 2 in that:
[0104] In step (2), an AlN layer is grown by PVD as a buffer layer, with a growth temperature of 420°C, a sputtering power of 5 kW, an Ar flow rate of 35 sccm, a N2 flow rate of 100 sccm, and an O2 flow rate of 3 sccm.
[0105] The thickness of the buffer layer is 20 nm.
[0106] Example 4
[0107] This embodiment provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Embodiment 3 in that:
[0108] In step (4), when growing the second three-dimensional GaN layer, TEGa is used as the Ga source.
[0109] Example 5
[0110] This embodiment provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Embodiment 4 in that:
[0111] The thickness of the second three-dimensional non-doped GaN layer is 20 nm, and the thickness of the InGaN layer is 1.5 nm.
[0112] The rest is the same as Example 4.
[0113] Comparative Example 1
[0114] This comparative example provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Example 1 in that:
[0115] The growth temperature of the non-doped GaN layer is 1020° C. and the growth pressure is 200 torr.
[0116] The rest are the same as in Example 1.
[0117] Comparative Example 2
[0118] This comparative example provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Example 1 in that:
[0119] In step (3), the growth temperature of the first three-dimensional non-doped GaN layer is 1000° C., the growth pressure is 500 torr, and the V / III ratio is 300;
[0120] In step (4), the growth temperature of the second three-dimensional non-doped GaN layer is 1120° C., the growth pressure is 500 torr, and the V / III ratio is 300; the Ga source used during the growth is TMGa, and the N source is NH3.
[0121] The rest are the same as in Example 1.
[0122] Comparative Example 3
[0123] This comparative example provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Example 1 in that:
[0124] Excluding step (3), the rest is the same as Example 1.
[0125] Comparative Example 4
[0126] This comparative example provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Example 1 in that:
[0127] Excluding step (4), the rest is the same as Example 1.
[0128] Comparative Example 5
[0129] This comparative example provides a method for preparing a light-emitting diode epitaxial wafer, which differs from Example 1 in that:
[0130] Excluding step (5), the rest is the same as Example 1.
[0131] The light emitting diode epitaxial wafers of Examples 1 to 5 and Comparative Examples 1 to 5 were made into a 22mil*35mil front-mounted LED chip, and the performance was tested at 60mA, as shown in the following table:
[0132]
[0133]
[0134] It can be seen from the table that when the non-doped GaN layer in the conventional light-emitting diode epitaxial wafer (Comparative Example 1) is replaced by the non-doped GaN layer of the present invention, the luminous brightness of the light-emitting diode epitaxial wafer is effectively improved.
[0135] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.
Claims
1. A method for preparing a light emitting diode epitaxial wafer, characterized in that: include: providing a substrate; growing a buffer layer on the substrate; growing a first three-dimensional non-doped GaN layer on the buffer layer; Alternatingly growing second three-dimensional undoped GaN layers and InGaN layers on the first three-dimensional undoped GaN layer to obtain a superlattice layer; Growing a two-dimensional non-doped GaN layer on the superlattice layer to obtain a non-doped GaN layer; Growing an N-type GaN layer, a multi-quantum well layer and a P-type GaN layer in sequence on the non-doped GaN layer to obtain a light-emitting diode epitaxial wafer; Wherein, the growth temperature of the first three-dimensional non-doped GaN layer is greater than that of the second three-dimensional non-doped GaN layer.
2. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The growth pressure of the first three-dimensional non-doped GaN layer is greater than the growth pressure of the second three-dimensional non-doped GaN layer; The V / III ratio of the first three-dimensional non-doped GaN layer during growth is smaller than the V / III ratio of the second three-dimensional non-doped GaN layer during growth.
3. The method for preparing a light emitting diode epitaxial wafer according to claim 1 or 2, characterized in that: The buffer layer is an AlN layer grown by PVD; When the buffer layer is grown, the sputtering power is 3kW-10kW, the sputtering temperature is 300°C-500°C, the Ar flow rate is 10sccm-80sccm, the N2 flow rate is 100sccm-300sccm, and the O2 flow rate is 2sccm-5sccm.
4. The method for preparing a light emitting diode epitaxial wafer according to claim 3, characterized in that: The growth temperature of the first three-dimensional non-doped GaN layer is 1000° C. to 1200° C., the growth pressure is 300 torr to 600 torr, and the V / III ratio is 200 to 500; The growth temperature of the two-dimensional non-doped GaN layer is 1000° C. to 1100° C., the growth pressure is 50 torr to 300 torr, and the V / III ratio is 2000 to 5000.
5. The method for preparing a light emitting diode epitaxial wafer according to claim 3, characterized in that: The growth temperature of the second three-dimensional non-doped GaN layer is 800° C. to 1000° C., the growth pressure is 50 torr to 300 torr, and the V / III ratio is 2000 to 5000; The growth temperature of the InGaN layer is 790° C. to 820° C., and the growth pressure is 50 torr to 300 torr.
6. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the first non-doped three-dimensional GaN layer is 500nm to 2000nm; The thickness of the two-dimensional non-doped GaN layer is 800nm-1200nm.
7. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the second non-doped three-dimensional GaN layer is 10nm to 30nm; The thickness of the InGaN layer is 1 nm to 2 nm, and the In component ratio is 0.01 to 0.
1.
8. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The Ga source used when growing the first three-dimensional non-doped GaN layer and the two-dimensional non-doped GaN layer is TMGa; The Ga source used when growing the second three-dimensional non-doped GaN layer is TEGa.
9. A light emitting diode epitaxial wafer, characterized in that: The light emitting diode epitaxial wafer is prepared by the method for preparing the light emitting diode epitaxial wafer as claimed in any one of claims 1 to 8.
10. A light emitting diode, characterized in that: It comprises the light emitting diode epitaxial wafer as claimed in claim 9.