Nitride light-emitting diode epitaxial wafer and preparation method

Abstract

The present invention discloses a method for preparing a nitride light-emitting diode epitaxial wafer, comprising: S1, growing an n-type GaN layer on a substrate; S2, growing a nitride superlattice layer on the n-type GaN layer; S3, growing a GaN back barrier layer on the nitride superlattice layer; S4, growing a nitride quantum well light-emitting layer on the GaN back barrier layer, comprising a periodically grown InGaN quantum well layer and a GaN quantum barrier layer; S41, growing an InGaN quantum well layer on the GaN back barrier layer; comprising: S411 , growing a first InGaN quantum well layer on the GaN back barrier layer; S412, growing a second InGaN quantum well layer on the first InGaN quantum well layer; S413, interrupting the growth of the InGaN quantum well layer; S414, repeating steps S412 and S413 multiple times; S42, growing a GaN quantum barrier layer on the InGaN quantum well layer; S43, repeating steps S41 and S42 multiple times to obtain a nitride quantum well light-emitting layer; S5, growing a p-type nitride layer on the nitride quantum well light-emitting layer. The present invention improves the wavelength uniformity and luminous efficiency of the epitaxial wafer and exhibits better ESD and leakage characteristics.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an epitaxial wafer of a nitride light emitting diode and a preparation method thereof. Background Art

[0002] Micro-LED displays offer numerous advantages, including self-luminescence, high efficiency, low power consumption, high integration, and high stability. They are also compact, flexible, and easily disassembled and combined, making them suitable for any display application, from small to large. As modern society enters the information age and moves toward intelligence, display is a key component in achieving information exchange and intelligence. Among the many current display technologies, Micro-LED display technology is considered a disruptive, next-generation display technology.

[0003] Existing research shows that as the size of Micro-LED devices decreases, the quantum efficiency of the device decreases significantly, and the peak efficiency shifts toward higher current densities. Micro-LEDs are based on different transfer technologies, and the wavelength of a single chip is required to be controlled to even ±1nm. Improving the luminous efficiency and wavelength consistency of LEDs is also a technical challenge for epitaxial stacking and chip technology. The luminous efficiency of LEDs is largely related to the material properties of the epitaxial layer, so the production of a high-quality light-emitting layer is key to improving LED luminous efficiency. During the epitaxial growth process, the In component of the InGaN quantum well layer increases with increasing thickness, and the incorporation efficiency of In atoms increases. Therefore, as the InGaN quantum well layer grows away from the substrate, the In component is significantly higher than that of the InGaN quantum well layer close to the substrate. In particular, the In component difference is greater in the epitaxial growth of long-wavelength LEDs such as green, yellow, and red, seriously affecting the uniformity and optoelectronic performance of the LED epitaxial wafer. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a nitride light-emitting diode epitaxial wafer, which greatly improves the anti-electrostatic discharge (ESD) performance of the epitaxial wafer under high current density and improves the luminous efficiency.

[0005] In order to solve the above problems, the present invention provides a method for preparing a nitride light-emitting diode epitaxial wafer, which comprises the following steps:

[0006] S1, growing an n-type GaN layer on a substrate;

[0007] S2, growing a nitride superlattice layer on the n-type GaN layer;

[0008] S3, growing a GaN back barrier layer on the nitride superlattice layer, the steps comprising:

[0009] S31, growing a first n-type nitride back barrier layer on the nitride superlattice layer;

[0010] S32, growing a second nitride back barrier layer on the first n-type nitride back barrier layer; the steps include:

[0011] S321, growing a first n-type nitride back barrier sub-layer on the first n-type nitride back barrier layer;

[0012] S322, growing a second non-doped nitride back barrier intermediate layer on the first n-type nitride back barrier sub-layer;

[0013] S323, growing a second p-type nitride back barrier sub-layer on the second undoped nitride back barrier intermediate layer;

[0014] S324, repeat steps S321-S323 multiple times;

[0015] S33, growing a third non-doped nitride back barrier layer on the second nitride back barrier layer;

[0016] S4, growing a nitride quantum well light-emitting layer on the GaN back barrier layer, including a periodically grown InGaN quantum well layer and a GaN quantum barrier layer, including:

[0017] S41, growing an InGaN quantum well layer on the GaN back barrier layer; wherein the InGaN quantum well layer includes a first InGaN quantum well layer and a second InGaN quantum well layer; the steps include:

[0018] S411, growing a first InGaN quantum well layer on the GaN back barrier layer;

[0019] S412, growing a second InGaN quantum well layer on the first InGaN quantum well layer;

[0020] S413, interrupting the growth of the second InGaN quantum well layer;

[0021] S414, repeating steps S412 and S413 multiple times to form a second InGaN quantum well layer;

[0022] S42, growing a GaN quantum barrier layer on the InGaN quantum well layer;

[0023] S43, repeating steps S41 and S42 multiple times to obtain a nitride quantum well light-emitting layer;

[0024] S5. Growing a p-type nitride layer on the nitride quantum well light-emitting layer.

[0025] As a further improvement of the present invention, the first n-type nitride back barrier layer and the first n-type nitride back barrier sub-layer are doped with Si, and the second p-type nitride back barrier sub-layer is doped with Mg.

[0026] As a further improvement of the present invention, the thickness of the InGaN quantum well layer is 1-3 nm, the thickness of the first InGaN quantum well layer is 0.5-1 nm; and the thickness of the second InGaN quantum well layer is 0.5-2 nm.

[0027] As a further improvement of the present invention, the nitride superlattice layer includes a 1-3 nm InGaN superlattice well layer and a 2-4 nm GaN superlattice barrier layer that are periodically grown 2-6 times.

[0028] As a further improvement of the present invention, the ratio of the growth time in step S412 to the interruption time in step S413 is 9:1-1:1.

[0029] As a further improvement of the present invention, the interruption time in step S413 is 1-5s.

[0030] As a further improvement of the present invention, the growth atmosphere in step S413 is N2 and H2, and in each cycle of step S414, the molar flow ratio of N2:H2 decreases linearly.

[0031] As a further improvement of the present invention, the growth atmosphere in steps S411 and S412 is N2.

[0032] The present invention also provides a Micro-LED epitaxial wafer, which is prepared using any of the above-mentioned methods for preparing a nitride light-emitting diode epitaxial wafer.

[0033] Beneficial effects of the present invention:

[0034] The method for preparing a nitride light-emitting diode epitaxial wafer of the present invention comprises segmented growth of a nitride quantum well layer and periodic cyclic interruption during the second half of the growth of the nitride quantum well layer in each cycle to reduce In incorporation. During the interruption, In fully migrates to redistribute atoms within the nitride quantum well layer, while excess In atoms are desorbed from the surface of the nitride quantum well layer, thereby reducing In incorporation in the second half of the nitride quantum well layer. This ensures that the In component of the entire nitride quantum well layer is uniformly distributed, improves the crystal quality of the nitride quantum well layer, and overcomes the problem of In component inhomogeneity in the InGaN quantum well layer, as the In atom incorporation efficiency increases with increasing thickness.

[0035] In addition, when growing the second nitride back barrier layer, the present invention utilizes the introduction of Mg atoms in the nitride back barrier layer to increase the lattice constant of the nitride back barrier layer, more closely matching the lattice of the nitride quantum well light-emitting layer, providing a basis for the growth of the nitride quantum well light-emitting layer, improving the uniformity of the components of the nitride quantum well light-emitting layer, improving the wavelength uniformity of the epitaxial wafer, and improving the luminous efficiency of the epitaxial wafer.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 1 is a structural diagram of a Micro-LED epitaxial wafer in Example 1 of the present invention;

[0038] Figure 2 It is a structural diagram of the GaN back barrier layer in the second embodiment of the present invention.

[0039] Marking explanation: 1. Substrate; 2. n-type GaN layer; 3. Nitride superlattice layer; 31. InGaN superlattice well layer; 32. GaN superlattice barrier layer; 4. GaN back barrier layer; 41. First n-type nitride back barrier layer; 42. Second nitride back barrier layer; 421. First n-type nitride back barrier sublayer; 422. Second undoped nitride back barrier intermediate layer; 423. Second p-type nitride back barrier sublayer; 43. Third undoped nitride back barrier layer; 5. Nitride quantum well light-emitting layer; 51. InGaN quantum well layer; 511. First InGaN quantum well layer; 512. Second InGaN quantum well layer; 52. GaN quantum barrier layer; 6. p-type nitride layer. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0041] Example 1

[0042] Reference Figure 1 As shown, this embodiment discloses a method for preparing a nitride light-emitting diode epitaxial wafer, which includes the following steps:

[0043] S1, growing an n-type GaN layer 2 on a substrate 1; specifically, growing an n-type GaN layer 2 with a thickness of 2.5 μm on the substrate 1 at a temperature of 1080°C, and a Si doping concentration of 2×10 18 cm -3 ;

[0044] S2. Growing a nitride superlattice layer 3 on the n-type GaN layer 2; specifically, growing the nitride superlattice layer 3 on the n-type GaN layer 2 at 920° C., including a 1.5 nm thick InGaN superlattice well layer 31 and a 3 nm thick GaN superlattice barrier layer 32, which are grown three times in a periodic cycle;

[0045] S3, growing a GaN back barrier layer 4 on the nitride superlattice layer 3; specifically, growing an n-type GaN back barrier layer 4 with a thickness of 178 nm on the nitride superlattice layer 3 at 950°C, with a Si doping concentration of 2×10 17 cm -3 ;

[0046] S4, growing a nitride quantum well light-emitting layer 5 on the GaN back barrier layer 4, including an InGaN quantum well layer 51 and a GaN quantum barrier layer 52 grown three times in a periodic cycle, including;

[0047] S41, growing an InGaN quantum well layer 51 on the GaN back barrier layer 4 at 750° C., wherein the InGaN quantum well layer 51 includes a first InGaN quantum well layer 511 and a second InGaN quantum well layer 512; the steps include:

[0048] S411, growing a first InGaN quantum well layer 511 on the GaN back barrier layer 4; specifically, growing the first InGaN quantum well layer 511 with a thickness of 0.8 nm in an N2 atmosphere;

[0049] S412, growing a second InGaN quantum well layer 512 on the first InGaN quantum well layer 511; specifically, growing a second InGaN quantum well sublayer 512 with a thickness of 0.2 nm in an N2 atmosphere; during the epitaxial growth process, the In component in the InGaN quantum well layer increases with the increase in thickness, so as the In component of the InGaN quantum well layer grows away from the substrate, the In component is significantly higher than that of the InGaN quantum well layer close to the substrate, and the growth of the nitride quantum well layer in the second half of each cycle is periodically interrupted to reduce the incorporation of In. During the interruption process, In fully migrates to redistribute the atoms in the nitride quantum well layer, and excess In atoms are parsed from the surface of the nitride quantum well layer, reducing the incorporation of In in the second half of the nitride quantum well layer, so that the In component of the entire nitride quantum well layer is evenly distributed.

[0050] S413, interrupting the growth of the second InGaN quantum well layer 512; specifically, introducing H2 in a mixed atmosphere of N2 and H2 with a N2:H2 molar flow ratio of 100:1.5, interrupting the growth of the second InGaN quantum well sublayer 512, and maintaining for 2 seconds;

[0051] S414. Repeat steps S412 and S413 10 times; wherein, the ratio of the growth time in step S412 to the interruption time in step S413 is 9:1; because, if the ratio of the growth time to the interruption time is not enough, during the interruption process, In atoms cannot be fully migrated to redistribute the atoms in the nitride quantum well layer, and the excess In atoms do not have time to be resolved from the surface of the nitride quantum well layer; if the ratio of the growth time to the interruption time is not enough, the InGaN quantum well will be etched in the H2 atmosphere, causing the surface roughness of the InGaN quantum well to increase, and a light-emitting layer with a clear interface cannot be formed, affecting the light-emitting efficiency of the epitaxial wafer.

[0052] S42 , growing a GaN quantum barrier layer 52 on the InGaN quantum well layer 51 ; specifically, growing the GaN quantum barrier layer 52 with a thickness of 10 nm at 980° C. in an H 2 atmosphere.

[0053] S43, repeating steps S41 and S42 three times to obtain a nitride quantum well light-emitting layer 5;

[0054] S5. Grow a p-type nitride layer 6 on the nitride quantum well light emitting layer 5. Specifically, grow a p-type GaN layer with a thickness of 150 nm on the nitride quantum well light emitting layer 5 at 1050°C.

[0055] Optionally, the thickness of the InGaN quantum well layer 51 is 1-3 nm, the thickness of the first InGaN quantum well layer 511 is 0.5-1 nm, and the thickness of the second InGaN quantum well layer 512 is 0.5-2 nm.

[0056] Optionally, the nitride superlattice layer includes a 1-3 nm InGaN superlattice well layer 31 and a 2-4 nm GaN superlattice barrier layer 32 that are grown in a periodic cycle of 2-6 times.

[0057] Optionally, the ratio of the growth time in step S412 to the interruption time in step S413 is 9:1-1:1.

[0058] Optionally, the growth atmosphere in step S413 is N2 and H2, with a N2:H2 molar flow ratio of 100:1-100:5.

[0059] Optionally, the interruption time in step S413 is 1-5s.

[0060] The method for preparing the nitride light-emitting diode epitaxial wafer of this embodiment grows the nitride quantum well layer in sections and periodically interrupts the growth of the nitride quantum well layer in the second half of each cycle to reduce In incorporation. During the interruption process, In fully migrates, causing atoms in the nitride quantum well layer to be redistributed, while excess In atoms are desorbed from the surface of the nitride quantum well layer, reducing In incorporation in the second half of the nitride quantum well layer. This ensures that the In component of the entire nitride quantum well layer is evenly distributed, improves the crystal quality of the nitride quantum well layer, overcomes the problem of In component inhomogeneity in the InGaN quantum well layer, as the In atom incorporation efficiency increases with increasing thickness, and improves the luminous efficiency of the epitaxial wafer.

[0061] Example 2

[0062] Reference Figure 1-2 As shown, this embodiment discloses a method for preparing a nitride light-emitting diode epitaxial wafer, which includes the following steps:

[0063] S1, growing an n-type GaN layer 2 on a substrate 1; specifically, growing an n-type GaN layer 2 with a thickness of 2.5 μm on the substrate 1 at a temperature of 1080°C, and a Si doping concentration of 2×10 18 cm -3 ;

[0064] S2. Growing a nitride superlattice layer 3 on the n-type GaN layer 2; specifically, growing the nitride superlattice layer 3 on the n-type GaN layer 2 at 920° C., including a 1.5 nm thick InGaN superlattice well layer 31 and a 3 nm thick GaN superlattice barrier layer 32, which are grown three times in a periodic cycle;

[0065] S3, growing a GaN back barrier layer 4 on the nitride superlattice layer 3; comprising:

[0066] S31, growing a first n-type nitride back barrier layer 41 on the nitride superlattice layer 3;

[0067] S32, growing a second nitride back barrier layer 42 on the first n-type nitride back barrier layer 41; comprising:

[0068] S321 , growing a first n-type nitride rear barrier sub-layer 421 on the first n-type nitride rear barrier layer 41 ;

[0069] S322 , growing a second non-doped nitride back barrier intermediate layer 422 on the first n-type nitride back barrier sub-layer 421 ;

[0070] S323 , growing a second p-type nitride back barrier sublayer 423 on the second non-doped nitride back barrier intermediate layer 422 ;

[0071] S324, repeat steps S321-S323 three times;

[0072] S33 , growing a third undoped nitride rear barrier layer 43 on the second nitride rear barrier layer 423 .

[0073] Among them, the nitride in the above-mentioned first n-type nitride back barrier layer 41, the second nitride back barrier layer 42, the first n-type nitride back barrier sublayer 421, the second undoped nitride back barrier intermediate layer 422, the second p-type nitride back barrier sublayer 423, and the third undoped nitride back barrier layer 43 can all be GaN.

[0074] Specifically, a first n-type GaN back barrier layer 41 with a thickness of 120 nm is grown on the nitride superlattice layer 3, and the doping concentration of Si is 5×10 17 cm -3 ; grow a 2nm first n-type nitride back barrier sublayer 421; grow a 3nm second non-doped nitride back barrier intermediate layer 422; grow a 1nm second p-type GaN back barrier sublayer 423.

[0075] The first n-type nitride back barrier layer 41 and the first n-type nitride back barrier sublayer 421 are doped with Si, and the second p-type nitride back barrier sublayer 423 is doped with Mg; the n-type doping concentration is 9×10 16 cm -3 , p-type doping concentration 2×10 17 cm -3 .

[0076] Specifically, a third non-doped GaN back barrier layer 43 with a thickness of 40 nm is grown.

[0077] S4, growing a nitride quantum well light-emitting layer 5 on the GaN back barrier layer 4, including an InGaN quantum well layer 51 and a GaN quantum barrier layer 52 grown three times in a periodic cycle, including;

[0078] S41, growing an InGaN quantum well layer 51 on the GaN back barrier layer 4 at 750° C., wherein the InGaN quantum well layer 51 includes a first InGaN quantum well layer 511 and a second InGaN quantum well layer 512; the steps include:

[0079] S411, growing a first InGaN quantum well layer 511 on the GaN back barrier layer 4; specifically, growing the first InGaN quantum well layer 511 with a thickness of 0.8 nm in an N2 atmosphere;

[0080] S412, growing a second InGaN quantum well layer 512 on the first InGaN quantum well layer 511; specifically, growing the second InGaN quantum well layer 512 with a thickness of 0.2 nm under an N2 atmosphere;

[0081] S413, interrupting the growth of the second InGaN quantum well layer 512; specifically, introducing H2 in a mixed atmosphere of N2 and H2 with a N2:H2 molar flow ratio of 100:1.5, interrupting the growth of the second InGaN quantum well layer 512, and maintaining for 2 seconds;

[0082] S414, repeating steps S412 and S413 10 times; wherein the ratio of the growth time in step S412 to the interruption time in step S413 is 9:1;

[0083] S42 , growing a GaN quantum barrier layer 52 on the InGaN quantum well layer 51 ; specifically, growing the GaN quantum barrier layer 52 with a thickness of 10 nm at 980° C. in an H 2 atmosphere.

[0084] S43, repeating steps S41 and S42 three times to obtain a nitride quantum well light-emitting layer 5;

[0085] S5. Grow a p-type nitride layer 6 on the nitride quantum well light emitting layer 5. Specifically, grow a p-type GaN layer with a thickness of 150 nm on the nitride quantum well light emitting layer 5 at 1050°C.

[0086] Optionally, the thickness of the InGaN quantum well layer 51 is 1-3 nm, the thickness of the first InGaN quantum well layer 511 is 0.5-1 nm, and the thickness of the second InGaN quantum well layer 512 is 0.5-2 nm.

[0087] Optionally, the nitride superlattice layer includes a 1-3 nm InGaN superlattice well layer 31 and a 2-4 nm GaN superlattice barrier layer 32 that are grown in a periodic cycle of 2-6 times.

[0088] Optionally, the ratio of the growth time in step S412 to the interruption time in step S413 is 9:1-1:1.

[0089] Optionally, the growth atmosphere in step S413 is N2 and N2, with a N2:H2 molar flow ratio of 100:1-100:5.

[0090] Optionally, the growth thickness of the first n-type GaN back barrier layer 41 is 20-200 nm, and the doping concentration of Si is 1×10 17 cm -3 -8×10 17 cm -3 ; In step S324, repeat steps S321-S323 2-6 times; the thickness of the first n-type GaN back barrier sublayer 421 is 1-3nm; the thickness of the second undoped GaN back barrier intermediate layer 422 is 2-5nm; the thickness of the second p-type GaN back barrier sublayer 423 is 0.5-1.5nm.

[0091] The method for preparing the nitride light-emitting diode epitaxial wafer of this embodiment grows the nitride quantum well layer in sections and periodically interrupts the growth of the nitride quantum well layer in the second half of each cycle to reduce In incorporation. During the interruption process, In fully migrates, causing atoms in the nitride quantum well layer to be redistributed, while excess In atoms are desorbed from the surface of the nitride quantum well layer, reducing In incorporation in the second half of the nitride quantum well layer. This ensures that the In component of the entire nitride quantum well layer is evenly distributed, improves the crystal quality of the nitride quantum well layer, overcomes the problem of In component inhomogeneity in the InGaN quantum well layer, as the In atom incorporation efficiency increases with increasing thickness, and improves the luminous efficiency of the epitaxial wafer.

[0092] At the same time, the epitaxial wafer structure of this embodiment can utilize the capacitance effect to improve the anti-electrostatic discharge (ESD) performance of the epitaxial wafer. On the other hand, the introduction of Mg atoms in the nitride back barrier layer increases the lattice constant of the nitride back barrier layer (In>Mg>Ga>Al>Si), which better matches the lattice of the nitride quantum well light-emitting layer. In particular, the size of In and Mg atoms is similar. Therefore, the nitride back barrier layer doped with Mg atoms can better match the lattice of the InGaN quantum well layer, providing a foundation for the growth of the nitride quantum well light-emitting layer. On the one hand, it improves the composition uniformity of the nitride quantum well light-emitting layer and improves the wavelength uniformity of the epitaxial wafer. On the other hand, under the forward working bias, the second p-type nitride back barrier layer and the first n-type nitride back barrier layer form an electric field in the same direction as the applied forward bias. Before the electrons provided by the n-type nitride layer are injected into the light-emitting layer, they can form a buffer to prevent the electrons from being injected into the light-emitting layer, reducing the lattice mismatch and growth stress of the nitride light-emitting layer, improving the uniformity of the carrier distribution in the nitride quantum well layer, and improving the luminous efficiency.

[0093] The second non-doped nitride back barrier intermediate layer serves to space the first n-type nitride back barrier sub-layer and the second p-type nitride back barrier sub-layer;

[0094] The second non-doped nitride back barrier layer serves to space the second p-type nitride back barrier sub-layer and the nitride light-emitting layer, thereby preventing the p-type dopant from diffusing into the nitride quantum well.

[0095] Example 3

[0096] The difference between this embodiment and the second embodiment is that in step S414, steps S412 and S413 are repeated 10 times; in each cycle of step S414, the N2:H2 molar flow ratio in step S413 is linearly reduced from 100:1 to 100:3.

[0097] Among them, with the increase of cycle period, the incorporation efficiency of In atoms will increase. The gradual increase of the N2:H2 ratio can suppress the incorporation efficiency of In by increasing the proportion of H2, so that In is evenly distributed in all cycle periods.

[0098] Comparative Example 1

[0099] This comparative example discloses a method for preparing a nitride light-emitting diode epitaxial wafer, which comprises the following steps:

[0100] S1, growing an n-type GaN layer 2 on a substrate 1; specifically, growing an n-type GaN layer 2 with a thickness of 2.5 μm on the substrate 1 at a temperature of 1080°C, and a Si doping concentration of 2×10 18 cm -3 ;

[0101] S2. Growing a nitride superlattice layer 3 on the n-type GaN layer 2; specifically, growing the nitride superlattice layer 3 on the n-type GaN layer 2 at 920° C., including a 1.5 nm thick InGaN superlattice well layer 31 and a 3 nm thick GaN superlattice barrier layer 32, which are grown three times in a periodic cycle;

[0102] S3, growing a GaN back barrier layer 4 on the nitride superlattice layer 3; specifically, growing an n-type GaN back barrier layer 4 with a thickness of 178 nm on the nitride superlattice layer 3 at 950°C, with a Si doping concentration of 2×10 17 cm -3 ;

[0103] S4, growing a nitride quantum well light-emitting layer 5 on the GaN back barrier layer 4, including an InGaN quantum well layer 51 and a GaN quantum barrier layer 52 grown three times in a periodic cycle, including;

[0104] S41, growing an InGaN quantum well layer 51 on the GaN back barrier layer 4 at 750° C.; comprising:

[0105] S411, growing an InGaN quantum well layer with a thickness of 2.8 nm on the GaN back barrier layer 4 in an N2 atmosphere;

[0106] S42 , growing a GaN quantum barrier layer 52 on the InGaN quantum well layer; specifically, growing the GaN quantum barrier layer 52 with a thickness of 10 nm at 980° C. in an H 2 atmosphere.

[0107] S43, repeating steps S41 and S42 three times to obtain a nitride quantum well light-emitting layer 5;

[0108] S5. Grow a p-type nitride layer 6 on the nitride quantum well light emitting layer 5. Specifically, grow a p-type GaN layer with a thickness of 150 nm on the nitride quantum well light emitting layer 5 at 1050°C.

[0109] Through photoluminescence (PL) spectrum testing, it was found that compared with Comparative Example 1, the epitaxial wafer of Example 1 of the present invention has better wavelength uniformity, and the wavelength std is reduced from 2.672nm in Comparative Example 1 to 1.544nm, while Example 2 has better wavelength uniformity, with an std of 0.97nm. Example 3 has the best wavelength uniformity, with an std of 0.68nm, which can meet the wavelength uniformity requirements of Micro-LED epitaxial wafers.

[0110] The same chip process was used in Examples 1, 2, 3 and Comparative Example 1 to prepare chips with the same specifications (80μ*100μm). The obtained performance parameters are shown in Table 1: It can be seen that the epitaxial wafers obtained by the preparation methods of Examples 1, 2 and 3 have excellent brightness and voltage performance; at the same time, the epitaxial wafers exhibit better ESD and leakage characteristics.

[0111] Brightness (mW) Voltage (V) ESD (%) Leakage (%) Example 1 12.9 2.86 97 99 Example 2 13.2 2.87 98 99 Example 3 13.3 2.88 98 99 Comparative Example 1 11.8 2.86 97 96

[0112] Table 1

[0113] The method for preparing the nitride light-emitting diode epitaxial wafer of this embodiment grows the nitride quantum well layer in sections and periodically interrupts the growth of the nitride quantum well layer in the second half of each cycle to reduce In incorporation. During the interruption process, In fully migrates, causing atoms in the nitride quantum well layer to be redistributed, while excess In atoms are desorbed from the surface of the nitride quantum well layer, reducing In incorporation in the second half of the nitride quantum well layer. This ensures that the In component of the entire nitride quantum well layer is evenly distributed, improves the crystal quality of the nitride quantum well layer, overcomes the problem of In component inhomogeneity in the InGaN quantum well layer, as the In atom incorporation efficiency increases with increasing thickness, and improves the luminous efficiency of the epitaxial wafer.

[0114] At the same time, the epitaxial wafer structure of this embodiment can utilize the capacitance effect to improve the epitaxial wafer's anti-electrostatic discharge (ESD) performance. Furthermore, the introduction of Mg atoms into the nitride back barrier layer increases the lattice constant of the nitride back barrier layer (In>Mg>Ga>Al>Si), better matching the lattice of the nitride quantum well light-emitting layer and providing a foundation for the growth of the nitride quantum well light-emitting layer. This improves the compositional uniformity of the nitride quantum well light-emitting layer and the wavelength uniformity of the epitaxial wafer. Furthermore, under a forward operating bias, an electric field in the same direction as the applied forward bias is formed between the second p-type nitride back barrier layer and the first n-type nitride back barrier layer. Before the electrons provided by the n-type nitride layer are injected into the light-emitting layer, they can form a buffer to prevent them from being injected into the light-emitting layer. This reduces the lattice mismatch and growth stress of the nitride light-emitting layer, improves the uniformity of carrier distribution in the nitride quantum well layer, and improves luminous efficiency.

[0115] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A method for preparing a nitride light-emitting diode epitaxial wafer, characterized in that: The following steps are involved: S1, growing an n-type GaN layer on a substrate; S2, growing a nitride superlattice layer on the n-type GaN layer; S3, growing a GaN back barrier layer on the nitride superlattice layer, the steps comprising: S31, growing a first n-type nitride back barrier layer on the nitride superlattice layer; S32, growing a second nitride back barrier layer on the first n-type nitride back barrier layer; the steps include: S321, growing a first n-type nitride back barrier sub-layer on the first n-type nitride back barrier layer; S322, growing a second non-doped nitride back barrier intermediate layer on the first n-type nitride back barrier sub-layer; S323, growing a second p-type nitride back barrier sub-layer on the second undoped nitride back barrier intermediate layer; S324, repeat steps S321-S323 multiple times; S33, growing a third non-doped nitride back barrier layer on the second nitride back barrier layer; S4, growing a nitride quantum well light-emitting layer on the GaN back barrier layer, including a periodically grown InGaN quantum well layer and a GaN quantum barrier layer, including: S41, growing an InGaN quantum well layer on the GaN back barrier layer; wherein the InGaN quantum well layer includes a first InGaN quantum well layer and a second InGaN quantum well layer; the steps include: S411, growing a first InGaN quantum well layer on the GaN back barrier layer; S412, growing a second InGaN quantum well sublayer on the first InGaN quantum well layer; S413, interrupting the growth of the second InGaN quantum well layer; S414, repeating steps S412 and S413 multiple times to form a second InGaN quantum well layer; S42, growing a GaN quantum barrier layer on the InGaN quantum well layer; S43, repeating steps S41 and S42 multiple times to obtain a nitride quantum well light-emitting layer; S5. Growing a p-type nitride layer on the nitride quantum well light-emitting layer.

2. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The first n-type nitride back barrier layer and the first n-type nitride back barrier sublayer are doped with Si, and the second p-type nitride back barrier sublayer is doped with Mg.

3. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The thickness of the InGaN quantum well layer is 1-3 nm, the thickness of the first InGaN quantum well layer is 0.5-1 nm, and the thickness of the second InGaN quantum well layer is 0.5-2 nm.

4. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The nitride superlattice layer includes a 1-3 nm InGaN superlattice well layer and a 2-4 nm GaN superlattice barrier layer that are grown periodically 2-6 times.

5. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The ratio of the growth time in step S412 to the interruption time in step S413 is 9:1-1:

1.

6. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The interruption time in step S413 is 1-5s.

7. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The growth atmosphere in step S413 is N2 and H2, and in each cycle of step S414, the N2:H2 molar flow ratio decreases linearly.

8. The method for preparing a nitride light-emitting diode epitaxial wafer according to claim 1, wherein: The growth atmosphere in steps S411 and S412 is N2.

9. Nitride light-emitting diode epitaxial wafer, characterized in that: The nitride light-emitting diode epitaxial wafer is prepared by the preparation method of any one of claims 1 to 8.

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