Light emitting diode with improved reliability and method of manufacturing the same

Abstract

The present disclosure provides a light-emitting diode with improved reliability and a preparation method thereof, and belongs to the technical field of optoelectronic manufacturing. The light-emitting diode comprises an n-type layer, a multi-quantum well layer and a p-type layer which are sequentially stacked, wherein the p-type layer comprises a p-type contact layer on the multi-quantum well layer; the p-type contact layer comprises a plurality of stacked layer structures, each of the layer structures comprises a first sub-layer and a second sub-layer which are stacked, the first sub-layer is an AlGaN layer doped with Al and not doped with Mg and In, and the second sub-layer is an InGaN layer doped with Mg and In and not doped with Al. The embodiments of the present disclosure can improve the problem of lattice defects that easily occur when the p-type contact layer is prepared, and improve the preparation quality of the light-emitting diode.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light-emitting diode with improved reliability and a method for its fabrication. Background Technology

[0002] Light-emitting diodes (LEDs) are highly influential new products in the optoelectronics industry. They are characterized by their small size, long lifespan, rich and colorful colors, and low energy consumption. They are widely used in lighting, displays, signal lights, backlights, toys, and other fields.

[0003] A light-emitting diode (LED) typically comprises an n-type layer, a multiple quantum well layer, and a p-type layer stacked sequentially. The p-type layer includes a p-type contact layer for connection to electrodes.

[0004] When preparing the p-type contact layer, Mg, Al, and In are typically doped simultaneously. However, the simultaneous doping of Mg, Al, and In results in Mg and In atoms existing as impurities in the p-type contact layer, forming lattice defects. This leads to high-magnification surface defects on the epitaxial layer surface under an electron microscope, reducing the reliability of the light-emitting diode. Summary of the Invention

[0005] This disclosure provides an improved reliability light-emitting diode and its fabrication method, which can improve the problem of lattice defects that easily occur during the fabrication of the p-type contact layer and improve the fabrication quality of the light-emitting diode. The technical solution is as follows:

[0006] On one hand, embodiments of this disclosure provide a light-emitting diode (LED) comprising an n-type layer, a multiple quantum well layer, and a p-type layer stacked sequentially. The p-type layer includes a p-type contact layer located on the multiple quantum well layer. The p-type contact layer includes multiple stacked structures, each stacked structure including a first sub-layer and a second sub-layer. The first sub-layer is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer is an InGaN layer doped with Mg and In but not doped with Al.

[0007] Optionally, the p-type contact layer comprises two stacked structures.

[0008] Optionally, the two stacked structures include a first stacked structure and a second stacked structure; the content of Al component in the first sublayer of the first stacked structure is greater than the content of Al component in the first sublayer of the second stacked structure.

[0009] Optionally, the first sublayer of the first stacked structure is Al. w Ga 1-w N layers, where 0 < w < 0.3, and the first sublayer of the second stacked structure is Al.y Ga 1-y N layers, where 0 < y < 0.1.

[0010] Optionally, the two stacked structures include a first stacked structure and a second stacked structure; the Mg doping concentration of the second sublayer of the first stacked structure is less than the Mg doping concentration of the second sublayer of the second stacked structure.

[0011] Optionally, the Mg doping concentration of the second sublayer of the first stacked structure is 1×10⁻⁶. 19 cm -3 Up to 1×10 21 cm -3 The Mg doping concentration of the second sublayer of the second stacked structure is 1×10⁻⁶. 20 cm -3 Up to 1×10 22 cm -3 .

[0012] Optionally, the two stacked structures include a first stacked structure and a second stacked structure; the In content of the second sublayer of the first stacked structure is less than or equal to the In content of the second sublayer of the second stacked structure.

[0013] On the other hand, embodiments of this disclosure also provide a method for fabricating a light-emitting diode, the method comprising: providing a substrate; forming an n-type layer, a multiple quantum well layer, and a p-type layer on the substrate, the p-type layer including a p-type contact layer located on the multiple quantum well layer; the p-type contact layer including a plurality of stacked layer structures, the stacked layer structures including a first sub-layer and a second sub-layer, the first sub-layer being an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer being an InGaN layer doped with Mg and In but not doped with Al.

[0014] Optionally, the p-type contact layer includes a first stacked structure. Growing the first stacked structure includes: controlling the growth pressure to 75 torr to 100 torr, the growth rotation speed to 1200 ± 100 rpm, the growth temperature to 960 ± 50°C, and controlling the growth atmosphere to be a mixture of nitrogen and ammonia to grow a first sublayer; controlling the growth pressure to 200 torr to 500 torr, the growth rotation speed to 1200 ± 100 rpm, the growth temperature to 930 ± 50°C, and the growth atmosphere to be a mixture of nitrogen, hydrogen, and ammonia, with a Mg doping concentration of 5 × 10⁻⁶. 19 cm -3 A second sublayer is grown on the first sublayer to obtain the first stacked structure.

[0015] Optionally, the p-type contact layer further includes a second stacked structure layered on the first stacked structure. Growing the second stacked structure includes: controlling the growth pressure to 75 torr to 100 torr, the growth rotation speed to 1200 ± 100 rpm, the growth temperature to 950 ± 50°C, and the growth atmosphere to be a mixture of nitrogen and ammonia, to grow the first sublayer; controlling the growth pressure to 200 torr to 500 torr, the growth rotation speed to 1200 ± 100 rpm, the growth temperature to 910 ± 50°C, and the growth atmosphere to be a mixture of nitrogen, hydrogen, and ammonia, with a Mg doping concentration of 5 × 10⁻⁶. 21 cm -3 A second sublayer is grown on the first sublayer to obtain the second stacked structure.

[0016] The beneficial effects of the technical solutions provided in this disclosure include at least the following:

[0017] The p-type contact layer in the light-emitting diode provided in this embodiment includes multiple stacked structures, and the stacked structure includes a first sub-layer and a second sub-layer. The first sub-layer is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer is an InGaN layer doped with Mg and In but not doped with Al.

[0018] The co-doping of Mg, Al, and In leads to Mg and In atoms existing as impurities in the p-type contact layer, forming lattice defects. This results in high-magnification surface defects on the epitaxial wafer surface under an electron microscope, reducing the reliability of the LED. Furthermore, the highly reactive nature of Al atoms allows them to readily combine with N atoms released from NH3, further reducing the effective doping efficiency of Mg and In atoms, significantly decreasing the hole concentration, and consequently increasing the operating voltage of the LED.

[0019] In this embodiment, Mg, Al, and In are incorporated into the p-type contact layer in a separate manner; that is, Al is incorporated without Mg and In, and Mg and In are incorporated without Al during growth. Therefore, the Mg doping efficiency is effectively improved, the dislocation density of the p-type contact layer is reduced, and the self-compensation of Mg acceptors is further reduced, thereby significantly increasing the hole concentration in the material and lowering the operating voltage of the light-emitting diode. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure;

[0022] Figure 2 This is a flowchart of a method for fabricating a light-emitting diode according to an embodiment of this disclosure.

[0023] The markings in the diagram are explained as follows:

[0024] 10. Substrate;

[0025] 20. n-type layer;

[0026] 30. Multiple quantum well layer; 31. Quantum well layer; 32. Quantum barrier layer;

[0027] 40. P-type contact layer; 410. First stacked structure; 420. Second stacked structure; 401. First sublayer; 402. Second sublayer;

[0028] 41. Low-temperature p-type AlGaN layer; 42. p-type electron blocking layer; 43. High-temperature p-type GaN layer;

[0029] 51. Buffer layer; 52. Nucleation layer; 53. Undoped GaN layer. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure. For example... Figure 1 As shown, the light-emitting diode includes an n-type layer 20, a multi-quantum well layer 30, and a p-type layer stacked sequentially. The p-type layer includes a p-type contact layer 40 located on the multi-quantum well layer 30. The p-type contact layer 40 includes at least one stacked structure, which includes a first sub-layer 401 and a second sub-layer 402 stacked sequentially. The first sub-layer 401 is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer 402 is an InGaN layer doped with Mg and In but not doped with A.

[0032] The p-type contact layer 40 in the light-emitting diode provided in this embodiment includes multiple stacked structures, and each stacked structure includes a first sub-layer 401 and a second sub-layer 402. The first sub-layer is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer is an InGaN layer doped with Mg and In but not doped with Al.

[0033] The co-doping of Mg, Al, and In leads to Mg and In atoms existing as impurities in the p-type contact layer 40, forming lattice defects. This results in high-magnification surface defects on the epitaxial wafer surface under an electron microscope, reducing the reliability of the LED. Furthermore, the highly reactive nature of Al atoms allows them to readily combine with N atoms released from NH3, further reducing the effective doping efficiency of Mg and In atoms, significantly decreasing the hole concentration, and consequently increasing the operating voltage of the LED.

[0034] In this embodiment, Mg, Al, and In are incorporated into the p-type contact layer 40 in a separate manner; that is, Al is incorporated without Mg and In, and Mg and In are incorporated without Al during growth. Therefore, the Mg doping efficiency is effectively improved, the dislocation density of the p-type contact layer 40 is reduced, and the self-compensation of the Mg acceptor is further reduced, thereby significantly increasing the hole concentration in the material and lowering the operating voltage of the light-emitting diode.

[0035] Optionally, such as Figure 1 As shown, the p-type contact layer 40 includes a first stacked structure 410 and a second stacked structure 420, with the first sub-layer 401 of the second stacked structure 420 stacked on the second sub-layer 402 of the first stacked structure 410.

[0036] In the above implementation, the p-type contact layer 40 includes two stacked structures, namely, the p-type layer includes a first sublayer 401, a second sublayer 402, and a second sublayer 402 stacked sequentially. Among them, the first sublayer 401 is an AlGaN layer, and the second sublayer 402 is an InGaN layer.

[0037] By sandwiching an AlGaN layer between two InGaN layers, a structure similar to a "capacitor layer" can be formed. This is beneficial for the uniform distribution of charge carriers in the p-type contact layer 40, reducing the probability of high-voltage electrostatic breakdown and improving the anti-static capability of the light-emitting diode.

[0038] Optionally, the two stacked structures include a first stacked structure 410 and a second stacked structure 420 stacked together; the content of Al component in the first sublayer 401 of the first stacked structure 410 is greater than the content of Al component in the first sublayer 401 of the second stacked structure 420.

[0039] In this embodiment of the disclosure, the content of the Al component refers to the weight percentage of Al.

[0040] By making the Al content of the first sublayer 401 of the first stacked structure 410 greater than the Al content of the first sublayer 401 of the second stacked structure 420, and by setting a Mg-doped p-type InGaN layer between the two first sublayers 401, a two-dimensional electron gas layer with different Al content can be formed, thereby enhancing the effective spread of current in the p-type contact layer 40.

[0041] For example, the first sublayer 401 of the first stacked structure 410 is Al w Ga 1-w N layers, where 0 < w < 0.3.

[0042] As an example, in this embodiment of the present disclosure, the first sub-layer 401 of the first stacked structure 410 is Al. 0.1 Ga 0.9 N layers, i.e., w = 0.1.

[0043] For example, the first sublayer 401 of the second stacked structure 420 is Al y Ga 1-y N layers, where 0 < y < 0.1.

[0044] As an example, in this embodiment of the present disclosure, the first sublayer 401 of the second stacked structure 420 is Al. 0.05 Ga 0.95 N layers, i.e., y = 0.05.

[0045] Optionally, the two stacked structures include a first stacked structure 410 and a second stacked structure 420 stacked together; the Mg doping concentration of the second sublayer 402 of the first stacked structure 410 is less than the Mg doping concentration of the second sublayer 402 of the second stacked structure 420.

[0046] Heavy Mg doping of the p-type contact layer 40 tends to reduce the bandgap, making it more susceptible to light absorption and affecting the light emission performance of the LED. Therefore, controlling the Mg doping concentration of the second sublayer 402 of the first stacked structure 410 to be relatively low minimizes the reduction in bandgap, thus preventing excessive light absorption of the p-type contact layer 40. Conversely, increasing the Mg doping concentration of the second sublayer 402 of the second stacked structure 420 enhances the overall Mg doping concentration of the p-type contact layer 40, preventing insufficient Mg doping and ensuring the fabrication quality of the p-type contact layer 40.

[0047] Optionally, the Mg doping concentration of the second sublayer 402 of the first stacked structure 410 is 1×10⁻⁶. 19 cm -3 Up to 1×10 21 cm -3 .

[0048] For example, the Mg doping concentration of the second sublayer 402 of the first stacked structure 410 is 5 × 10⁻⁶. 19 cm -3 .

[0049] Optionally, the Mg doping concentration of the second sublayer 402 of the second stacked structure 420 is 1×10⁻⁶.20 cm -3 Up to 1×10 22 cm -3 .

[0050] For example, the Mg doping concentration of the second sublayer 402 of the second stacked structure 420 is 5 × 10⁻⁶. 21 cm -3 .

[0051] Optionally, the two stacked structures include a first stacked structure 410 and a second stacked structure 420.

[0052] The second sublayer 402 includes an InGaN layer, and the In content of the second sublayer 402 of the first stacked structure 410 is less than or equal to the In content of the second sublayer 402 of the second stacked structure 420.

[0053] In this embodiment of the disclosure, the content of the In component refers to the weight percentage of In.

[0054] Since the stress in the InGaN layer increases with the increase of the In content, controlling the In content of the second sublayer 402 of the first stacked structure 410 to be smaller than the In content of the second sublayer 402 of the second stacked structure 420, i.e., controlling the In content of the second sublayer 402 of the first stacked structure 410 to be lower, can weaken the overall stress of the p-type contact layer 40.

[0055] For example, the second sublayer 402 of the first stacked structure 410 is In 0.03 Ga 0.97 N layers, i.e., m = 0.03; the second sublayer 402 of the second stacked structure 420 is In. 0.05 Ga 0.95 N layers, i.e., m = 0.05. At this time, the In component content of the second sublayer 402 of the first stacked structure 410 is less than the In component content of the second sublayer 402 of the second stacked structure 420.

[0056] For example, the second sublayer 402 of the first stacked structure 410 is In 0.05 Ga 0.95 N layers, i.e., m = 0.05; the second sublayer 402 of the second stacked structure 420 is In. 0.05 Ga 0.95 N layers, i.e., m = 0.05. At this time, the In content of the second sublayer 402 of the first stacked structure 410 is equal to the In content of the second sublayer 402 of the second stacked structure 420.

[0057] Optionally, such as Figure 1As shown, the light emitting diode may further include a substrate 10, which is a base for carrying an epitaxial layer, and an n-type layer 20, a multiple quantum well layer 30 and a p-type layer are sequentially stacked on the substrate 10.

[0058] For example, the substrate is a sapphire substrate, a silicon substrate or a silicon carbide substrate. The substrate may be a flat substrate or a patterned substrate.

[0059] By way of example, in the embodiment of the present disclosure, the substrate is a sapphire substrate. Sapphire substrate is a commonly used substrate with mature technology and low cost. Specifically, it may be a patterned sapphire substrate or a flat sapphire substrate.

[0060] Optionally, the n-type layer 20 may be an n-type GaN layer. The thickness of the n-type layer 20 is 0.5 μm to 3 μm.

[0061] Wherein, the dopant of the n-type layer 20 is silane, and the doping concentration of silane may be 1×10 18 cm -3 to 1×10 19 cm -3 .

[0062] Optionally, the multiple quantum well layer 30 may include 8 to 15 periods of quantum well layers 31 and quantum barrier layers 32.

[0063] Wherein, the quantum well layer may include In x Ga 1-x N layer, where 0.2<x<0.5. And the thickness of each quantum well layer may be 2 nm to 5 nm.

[0064] For example, the content of In component in each quantum well layer is equal, which is better for industrial mass production.

[0065] Wherein, the quantum barrier layer 32 may include a GaN layer, and the thickness of each quantum barrier layer 32 may be 8 nm to 20 nm.

[0066] Optionally, the p-type layer further includes a low-temperature p-type AlGaN layer 41, a p-type electron blocking layer 42 and a high-temperature p-type GaN layer 43, and the low-temperature p-type AlGaN layer 41, the p-type electron blocking layer 42, the high-temperature p-type GaN layer 43 and the p-type contact layer 40 are sequentially stacked on the multiple quantum well layer 30.

[0067] For example, the p-type electron blocking layer 42 may be p-type Al k Ga 1-k N layer, where 0.2<k<0.5, and the thickness of the p-type electron blocking layer 42 may be 20 nm to 100 nm.

[0068] If the p-type electron blocking layer 42 is too thin, it will reduce the blocking effect on electrons; if the p-type electron blocking layer 42 is too thick, it will increase the absorption of light by the p-type electron blocking layer 42, thereby reducing the luminous efficiency of the LED.

[0069] In this embodiment, both the low-temperature p-type AlGaN layer 41 and the high-temperature p-type GaN layer 43 are Mg-doped.

[0070] The Mg doping concentration of the low-temperature p-type AlGaN layer 41 is 5 × 10⁻⁶. 19 cm -3 Up to 1×10 21 cm -3 The Mg doping concentration of the high-temperature p-type GaN layer 43 is 5 × 10⁻⁶. 19 cm -3 Up to 1×10 21 cm -3 .

[0071] The thickness of the low-temperature p-type AlGaN layer 41 can be from 50 nm to 100 nm. For example, the thickness of the low-temperature p-type AlGaN layer 41 can be 80 nm.

[0072] The thickness of the high-temperature p-type GaN layer 43 can be from 100nm to 200nm. For example, the thickness of the high-temperature p-type GaN layer 43 can be 150nm.

[0073] Optionally, the thickness of the p-type contact layer 40 can be from 10 nm to 50 nm. As an example, in this embodiment of the present disclosure, the thickness of the p-type contact layer 40 is 20 nm.

[0074] If the thickness of the p-type contact layer 40 is too thin, it will affect the current contact between the epitaxial layer and the electrode. If the thickness of the p-type contact layer 40 is too thick, it will increase the absorption of light by the p-type contact layer 40, thereby reducing the luminous efficiency of the LED.

[0075] Optionally, such as Figure 1 As shown, a buffer layer 51, a nucleation layer 52, and an undoped GaN layer 53 are also included between the substrate and the n-type layer 20. The buffer layer 51, the nucleation layer 52, and the undoped GaN layer 53 are stacked sequentially on the substrate.

[0076] In this embodiment of the disclosure, the buffer layer 51 may be an AlN layer, which is an AlN layer grown at a temperature between 400°C and 800°C.

[0077] The thickness of the buffer layer 51 can be from 10 nm to 50 nm. For example, the thickness of the buffer layer 51 can be 20 nm.

[0078] By setting the thickness of the buffer layer 51 within the above-mentioned range, it is possible to avoid the buffer layer 51 being too thin, which would reduce the crystal quality of the epitaxial layer grown on the thinner buffer layer 51; it is also possible to avoid the buffer layer 51 being too thick, which would increase the absorption of light by the buffer layer 51, thereby reducing the luminous efficiency of the light-emitting diode.

[0079] Optionally, the nucleation layer 52 can be a three-dimensional GaN nucleation layer 52.

[0080] For example, the growth thickness of the three-dimensional GaN nucleation layer 52 can be from 0.3 μm to 0.5 μm.

[0081] In this embodiment of the present disclosure, an undoped GaN layer 53 is also grown between the three-dimensional GaN nucleation layer 52 and the n-type layer 20. Compared with the substrate, since the crystal structure of the undoped GaN layer 53 is similar to that of the n-type layer 20, the crystal quality of the subsequent epitaxial layer can be improved by setting the undoped GaN layer 53 as a transition layer.

[0082] The thickness of the undoped GaN layer 53 is 0.5 μm to 3 μm. For example, the thickness of the undoped GaN layer 53 is 2 μm.

[0083] By setting the thickness of the undoped GaN layer 53 within the above range, it is possible to avoid the undoped GaN layer 53 being too thin, thus failing to play a transition role and reducing the crystal quality of the grown epitaxial layer; it is also possible to avoid the undoped GaN layer 53 being too thick, which would increase the absorption of light by the undoped GaN layer 53, thereby reducing the luminous efficiency of the light-emitting diode.

[0084] Figure 2 This is a flowchart illustrating a method for fabricating a light-emitting diode (LED) according to an embodiment of this disclosure. This method is used to fabricate... Figure 1 The light-emitting diode shown. For example... Figure 2 As shown, the preparation method includes:

[0085] S11: Provide a substrate.

[0086] S12: Forming an n-type layer, a multiple quantum well layer, and a p-type layer on the substrate.

[0087] The p-type layer includes a p-type contact layer located on the multi-quantum-well layer; the p-type contact layer includes multiple stacked structures, each stacked structure including a first sub-layer and a second sub-layer, the first sub-layer being an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer being an InGaN layer doped with Mg and In but not doped with Al.

[0088] The p-type contact layer of the light-emitting diode prepared by this method includes multiple stacked structures, and each stacked structure includes a first sub-layer and a second sub-layer stacked sequentially. The first sub-layer is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer is an InGaN layer doped with Mg and In but not doped with Al.

[0089] The co-doping of Mg, Al, and In leads to Mg and In atoms existing as impurities in the p-type contact layer, forming lattice defects. This results in high-magnification surface defects on the epitaxial wafer surface under an electron microscope, reducing the reliability of the LED. Furthermore, the highly reactive nature of Al atoms allows them to readily combine with N atoms released from NH3, further reducing the effective doping efficiency of Mg and In atoms, significantly decreasing the hole concentration, and consequently increasing the operating voltage of the LED.

[0090] In this embodiment, Mg, Al, and In are incorporated into the p-type contact layer in a separate manner; that is, Al is incorporated without Mg and In, and Mg and In are incorporated without Al during growth. Therefore, the Mg doping efficiency is effectively improved, the dislocation density of the p-type contact layer is reduced, and the self-compensation of Mg acceptors is further reduced, thereby significantly increasing the hole concentration in the material and lowering the operating voltage of the light-emitting diode.

[0091] Furthermore, when Al is doped but not Mg and In, the pre-reaction generated during the decomposition of Al and NH3 can be reduced by adjusting the Al-doped growth conditions, such as using low-pressure growth and reducing the NH3 flow rate during Al doping. This avoids reducing the effective doping efficiency of Mg and In atoms, improves the problem of reduced hole concentration, and prevents the operating voltage of the light-emitting diode from increasing.

[0092] For example, when Al is doped but Mg and In are not, the pressure inside the reaction chamber is controlled to a low-pressure environment of 50 to 150 torr, while the NH3 flow rate is reduced to 5 L / min to 50 L / min. Under these growth conditions, the pre-reactions generated during the decomposition of Al and NH3 can be effectively reduced, thereby avoiding a decrease in the effective incorporation efficiency of Mg and In atoms.

[0093] In step S11, the substrate is a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The substrate can be a flat substrate or a patterned substrate.

[0094] As an example, in this embodiment of the disclosure, the substrate is a sapphire substrate. Sapphire substrates are a commonly used substrate, with mature technology and low cost. Specifically, it can be a patterned sapphire substrate or a flat sapphire substrate.

[0095] In step S11, the sapphire substrate can be subjected to high-temperature cleaning treatment in a hydrogen atmosphere at 1000°C to 1200°C for 5 to 20 minutes, and then subjected to nitriding treatment.

[0096] In step S11, the sapphire substrate can be pretreated by placing it in an MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber and baking it for 12 to 18 minutes. As an example, in this embodiment of the present disclosure, the sapphire substrate is baked for 15 minutes.

[0097] Specifically, the baking temperature can be from 1000°C to 1200°C, and the pressure in the MOCVD reaction chamber during baking can be from 100 mbar to 200 mbar.

[0098] The following steps may also be included before step S12:

[0099] The first step is to grow a buffer layer on the substrate.

[0100] Specifically, an AlN layer is deposited on a sapphire substrate using a physical vapor deposition (PVD) device via magnetron sputtering to obtain a buffer layer.

[0101] The growth temperature in the PVD equipment is 400℃ to 800℃, the sputtering power is 3000W to 5000W, the pressure is 2mtorr to 20mtorr, and the AlN layer deposition thickness is 10nm to 50nm.

[0102] The second step involves placing the substrate coated with the buffer layer into the MOCVD system to grow the nucleation layer. The MOCVD reaction chamber temperature is 950℃ to 1080℃, the reaction chamber pressure is controlled at 300 torr to 500 torr, and the nucleation layer thickness is 0.3 μm to 0.5 μm under a mixed atmosphere of nitrogen, hydrogen, and ammonia.

[0103] The third step is to grow an undoped GaN layer on the nucleation layer.

[0104] In this embodiment, an undoped GaN layer is grown between the nucleation layer and the n-type layer. Compared to the substrate, since the crystal structure of the undoped GaN layer is similar to that of the n-type layer, setting the undoped GaN layer as a transition layer can improve the crystal quality of the subsequent epitaxial layer.

[0105] The thickness of the undoped GaN layer is 0.5 μm to 3 μm. For example, the thickness of the undoped GaN layer is 2 μm.

[0106] Specifically, an undoped GaN buffer recovery layer is grown by MOCVD. In the MOCVD system, an undoped GaN layer with a thickness of 0.5 μm to 3 μm is grown under an environment where the temperature is adjusted to 1000°C to 1150°C and the growth pressure is 100 Torr to 300 Torr.

[0107] Step S12 may include the following steps:

[0108] In the first step, an n-type layer is grown on the undoped GaN layer.

[0109] Optionally, the n-type layer may be an n-type GaN layer. The thickness of the n-type layer is 0.5 μm to 3 μm. Wherein, the dopant of the n-type layer is silane.

[0110] Specifically, in the MOCVD system, an n-type doped GaN layer with a thickness of 0.5 μm to 3 μm is grown under an environment where the temperature is adjusted to 1000°C to 1150°C and the growth pressure is 100 Torr to 300 Torr, and the Si doping concentration of the n-type GaN layer is 1×10 18 cm -3 to 1×10 19 cm -3 .

[0111] In the second step, a multiple quantum well layer is grown on the n-type GaN layer.

[0112] Wherein, the multiple quantum well layer comprises 8 to 15 cycles of quantum well layers and quantum barrier layers.

[0113] Wherein, the quantum well layer may comprise In x Ga 1-x N layer, where 0.2 < x < 0.5. And the thickness of each quantum well layer may be 2 nm to 5 nm.

[0114] Exemplarily, the content of In component in each quantum well layer is equal, which is better for industrial mass production.

[0115] The preparation process of each quantum well layer may include: under the growth condition of pure nitrogen atmosphere, controlling the growth temperature at 700°C to 850°C, controlling the growth pressure at 200 torr to 500 torr, and growing an In x Ga 1-x N layer with a thickness of 2 nm to 5 nm.

[0116] The preparation process of each quantum barrier layer may include: in a mixed atmosphere of nitrogen and hydrogen, controlling the growth temperature at 800°C to 960°C, controlling the growth pressure at 100 torr to 300 torr, and growing a GaN layer with a thickness of 8 nm to 20 nm

[0117] In the third step, a p-type layer is grown on the multiple quantum well layer.

[0118] wherein, the p-type layer comprises a low-temperature p-type AlGaN layer, a p-type electron blocking layer, a high-temperature p-type GaN layer and a p-type contact layer sequentially stacked on the multiple quantum well layer.

[0119] Illustratively, the p-type electron blocking layer may be p-type Al k Ga 1-k N (0.1<k<0.5) layer, and the thickness of the p-type electron blocking layer may be 20 nm to 100 nm.

[0120] If the thickness of the p-type electron blocking layer is too thin, the electron blocking effect will be reduced; if the thickness of the p-type electron blocking layer is too thick, the absorption of light by the p-type electron blocking layer will be increased, thereby resulting in a decrease in the luminous efficiency of the LED.

[0121] In the embodiments of the present disclosure, both the low-temperature p-type AlGaN layer and the high-temperature p-type GaN layer are doped with Mg.

[0122] Illustratively, the low-temperature p-type AlGaN layer comprises Al w Ga 1-w N layer, where 0.1<w<0.3.

[0123] The Mg doping concentration of the low-temperature p-type AlGaN layer is 5×10 19 cm -3 to 1×10 21 cm -3 , and the Mg doping concentration of the high-temperature p-type GaN layer is 5×10 19 cm -3 to 1×10 21 cm -3 .

[0124] wherein, the thickness of the low-temperature p-type AlGaN layer may be 50 nm to 100 nm, for example, the thickness of the low-temperature p-type AlGaN layer may be 80 nm.

[0125] wherein, the thickness of the high-temperature p-type GaN layer may be 100 nm to 200 nm, for example, the thickness of the high-temperature p-type GaN layer may be 150 nm.

[0126] When growing the low-temperature p-type AlGaN layer, the growth temperature is adjusted to 700°C to 800°C, and the low-temperature p-type AlGaN layer is grown under an environment with a growth pressure of 200 Torr to 500 Torr, with a thickness of 50 nm to 100 nm.

[0127] wherein, the Mg doping concentration of the low-temperature p-type AlGaN layer is 5×10 19 cm -3 to 1×10 21 cm-3 .

[0128] When growing the p-type electron blocking layer, adjust the growth temperature to 800°C to 1000°C and the growth pressure to an environment of 100 Torr to 300 Torr, and the p-type electron blocking layer may be Al k Ga 1-k N layer, wherein 0.2<k<0.5, and the thickness is 20 nm to 100 nm.

[0129] When growing the high-temperature p-type GaN layer, control the growth pressure in an environment of 200 Torr to 600 Torr, the growth temperature is 800°C to 1000°C, the p-type GaN layer with a growth thickness of 100 nm to 200 nm, and the Mg doping concentration is 5×10 19 cm -3 to 1×10 21 cm -3 .

[0130] Wherein, the p-type contact layer may comprise two stacked stacked structures, and the two stacked structures comprise a stacked first stacked structure and a stacked second stacked structure.

[0131] Optionally, the Al component content of the first sub-layer of the first stacked structure is greater than the Al component content of the first sub-layer of the second stacked structure.

[0132] In the embodiments of the present disclosure, controlling the Al component content of the first sub-layer of the first stacked structure may control the pressure of the reaction chamber to be 75 Torr to 150 Torr, and the growth atmosphere is a pure nitrogen atmosphere, so that the first sub-layer grows in a low-pressure environment. The actual Al component content in the p-type AlGaN material is far less than the Al component content in the gas phase. This is because Al atoms are very reactive, and a parasitic reaction already occurs with N atoms during mass transport, so that the number of Al atoms diffused to the surface to participate in material growth is greatly reduced, resulting in that the Al component content in the final AlGaN material is less than the Al component content in the gas phase. Therefore, low-pressure growth is conducive to the growth of AlGaN. On the one hand, the flow rate of the organic source increases, and the growth rate increases; on the other hand, it is also conducive to the incorporation of Al into the growth. Therefore, a low-pressure environment is conducive to the effective incorporation of Al atoms, and reduces the non-radiative recombination caused by lattice defects formed by Al atoms existing as impurities.

[0133] Exemplarily, the first sub-layer of the first stacked structure comprises Al w Ga 1-w N layer, wherein 0<w<0.3.

[0134] As an example, in the embodiments of the present disclosure, the first sub-layer of the first stacked structure comprises Al 0.1 Ga 0.9N layers, i.e., w = 0.1.

[0135] For example, the first sublayer of the second stacked structure includes Al y Ga 1-y N layers, where 0 < y < 0.1.

[0136] As an example, in an embodiment of this disclosure, the first sublayer of the second stacked structure includes Al. 0.05 Ga 0.95 N layers, i.e., y = 0.05.

[0137] Optionally, the Mg doping concentration of the second sublayer of the first stacked structure is less than the Mg doping concentration of the second sublayer of the second stacked structure.

[0138] Optionally, the Mg doping concentration of the second sublayer of the first stacked structure is 1×10⁻⁶. 19 cm -3 Up to 1×10 21 cm -3 .

[0139] For example, the Mg doping concentration of the second sublayer of the first stacked structure is 5 × 10⁻⁶. 19 cm -3 .

[0140] Optionally, the Mg doping concentration of the second sublayer of the second stacked structure is 1×10⁻⁶. 20 cm -3 Up to 1×10 22 cm -3 .

[0141] For example, the Mg doping concentration of the second sublayer of the second stacked structure is 5 × 10⁻⁶. 21 cm -3 .

[0142] In this embodiment of the disclosure, the second sub-layer of the stacked structure includes In m Ga 1-m N layers. The In content of the second sublayer of the first stacked structure is less than or equal to the In content of the second sublayer of the second stacked structure.

[0143] Since temperature affects the doping efficiency of the In component, controlling the growth temperature of the second sublayer of the second stacked structure to be lower than that of the second sublayer of the first stacked structure can achieve the goal of having a lower In component content in the second sublayer of the first stacked structure than in the second sublayer of the second stacked structure.

[0144] For example, the second sublayer of the first stacked structure is In 0.03 Ga 0.97N layers, i.e., m = 0.03; the second sublayer of the second stacked structure is In. 0.05 Ga 0.95 N layers, i.e., m = 0.05. At this time, the In component content of the second sublayer of the first stacked structure is less than the In component content of the second sublayer of the second stacked structure.

[0145] For example, the second sublayer of the first stacked structure is In 0.05 Ga 0.95 N layers, i.e., m = 0.05; the second sublayer of the second stacked structure is In. 0.05 Ga 0.95 N layers, i.e., m = 0.05. At this time, the In component content of the second sublayer of the first stacked structure is equal to the In component content of the second sublayer of the second stacked structure.

[0146] Optionally, during the growth of the first stacked structure, the Mg doping concentration of the second sublayer of the first stacked structure is controlled to be 1×10⁻⁶. 19 cm -3 Up to 1×10 21 cm -3 During the growth of the second stacked structure, the Mg doping concentration of the second sublayer of the second stacked structure is controlled to be 1×10⁻⁶. 20 cm -3 Up to 1×10 22 cm -3 .

[0147] In this embodiment of the disclosure, growing the first stacked structure may include:

[0148] First, the growth pressure is controlled at 75 to 100 torr, the growth speed is controlled at 1200 ± 100 rpm, the growth temperature is controlled at 960 ± 50℃, and the growth atmosphere is controlled as a mixture of nitrogen and ammonia, with the nitrogen to ammonia ratio preferably 5:1. The first sublayer with a thickness of 1 nm to 5 nm is grown.

[0149] Then, the growth pressure was controlled at 200 torr to 500 torr, the growth speed at 1200 ± 100 rpm, the growth temperature at 930 ± 50℃, and the growth atmosphere was a mixture of nitrogen, hydrogen, and ammonia with a nitrogen:hydrogen:ammonia ratio of 6:1:3. The concentration of Mg doping was 5 × 10⁻⁶. 19 cm -3 A second sublayer with a thickness of 2 nm to 10 nm is grown to obtain the first stacked structure.

[0150] Growing a second layered structure may include:

[0151] First, the growth pressure was controlled at 75 to 100 torr, the growth speed at 1200 ± 100 rpm, the growth temperature at 950 ± 50℃, and the growth atmosphere was a mixture of nitrogen and ammonia with a nitrogen to ammonia ratio of 5:1. The first sublayer with a growth thickness of 1 nm to 10 nm was grown.

[0152] Then, the growth pressure was controlled at 200 torr to 500 torr, the growth speed was preferably 1200±100 rpm, the growth temperature was 910±50℃, and the growth atmosphere was a mixture of nitrogen, hydrogen, and ammonia with a nitrogen:hydrogen:ammonia ratio of 6:1:3. The concentration of Mg doping was 5×10⁻⁶. 21 cm -3 A second sublayer with a thickness of 1 nm to 20 nm is grown to obtain a second stacked structure.

[0153] Optionally, when growing the second sublayer of the first and second stacked structures, hydrogen is controlled to account for 60% to 80% of the total volume of the mixed atmosphere in the growth atmosphere. Heavy hydrogen doping growth is beneficial for the effective doping of Mg atoms. Hydrogen atoms are small and have a fast migration rate, which can accelerate the bonding between Ga atoms and the N source, further promoting the two-dimensional growth of GaN, allowing more Mg atoms to be effectively incorporated, and also making the surface of p-type GaN smoother.

[0154] After step S12, the preparation method may further include annealing the light-emitting diode.

[0155] After epitaxial growth is completed, the temperature of the reaction chamber is lowered to 650°C to 850°C and annealed in an N2 atmosphere for 5 to 15 minutes. Then, it is gradually lowered to room temperature. Subsequently, the chip is fabricated through cleaning, deposition, photolithography and etching processes.

[0156] In specific implementation, embodiments of this disclosure may use high-purity H2 and / or N2 as carrier gas, TEGa or TMGa as Ga source, TMIn as In source, SiH4 as n-type dopant, TMAl as aluminum source, ammonia as N source, and Cp2Mg as p-type dopant.

[0157] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A light-emitting diode, characterized in that, The light-emitting diode includes an n-type layer (20), a multi-quantum well layer (30), and a p-type layer stacked sequentially. The p-type layer includes a p-type contact layer (40) located on the multi-quantum well layer (30). The p-type contact layer (40) includes multiple stacked structures, including a first sub-layer (401) and a second sub-layer (402). The first sub-layer (401) is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer (402) is an InGaN layer doped with Mg and In but not doped with Al.

2. The light-emitting diode according to claim 1, characterized in that, The p-type contact layer (40) comprises two stacked structures.

3. The light-emitting diode according to claim 2, characterized in that, The two stacked structures include a first stacked structure (410) and a second stacked structure (420) stacked together; The content of Al component in the first sublayer (401) of the first stacked structure (410) is greater than the content of Al component in the first sublayer (401) of the second stacked structure (420).

4. The light-emitting diode according to claim 3, characterized in that, The first sub-layer (401) of the first stack structure (410) is Al w Ga 1-w N layer, wherein 0 < w < 0.3, the first sub-layer (401) of the second stack structure (420) is Al y Ga 1-y N layer, wherein 0 < y < 0.

1.

5. The light-emitting diode according to claim 2, characterized in that, The two stacked structures include a first stacked structure (410) and a second stacked structure (420) stacked together; The Mg doping concentration of the second sublayer (402) of the first stacked structure (410) is less than the Mg doping concentration of the second sublayer (402) of the second stacked structure (420).

6. The light-emitting diode according to claim 5, characterized in that, The Mg doping concentration of the second sub-layer (402) of the first stacked structure (410) is 1 x 10 19 cm -3 to 1 x 10 21 cm -3 ; The Mg doping concentration of the second sub-layer (402) of the second stack structure (420) is 1 x 10 20 cm -3 to 1 x 10 22 cm -3 .

7. The light-emitting diode according to claim 2, characterized in that, The two stacked structures include a first stacked structure (410) and a second stacked structure (420) stacked together; The content of In component in the second sublayer (402) of the first stacked structure (410) is less than or equal to the content of In component in the second sublayer (402) of the second stacked structure (420).

8. A method for fabricating a light-emitting diode, characterized in that, The preparation method includes: Provide a substrate; An n-type layer, a multiple quantum well layer, and a p-type layer are formed on the substrate. The p-type layer includes a p-type contact layer located on the multiple quantum well layer. The p-type contact layer includes multiple stacked structures, each stacked structure including a first sub-layer and a second sub-layer. The first sub-layer is an AlGaN layer doped with Al but not doped with Mg and In, and the second sub-layer is an InGaN layer doped with Mg and In but not doped with Al.

9. The preparation method according to claim 8, characterized in that, The p-type contact layer includes a first stacked structure, and growing the first stacked structure includes: The growth pressure was controlled at 75 to 100 torr, the growth speed at 1200 ± 100 rpm, the growth temperature at 960 ± 50℃, and the growth atmosphere was controlled as a mixture of nitrogen and ammonia to grow the first sublayer. The growth pressure is controlled to be 200 to 500 torr, the growth rotation speed is 1200±100 rpm, the growth temperature is 930±50℃, the growth atmosphere is a mixed gas of nitrogen, hydrogen and ammonia, the Mg-doped concentration is 5×10 19 cm -3 The second sub-layer is grown on the first sub-layer to obtain the first laminated structure.

10. The preparation method according to claim 9, characterized in that, The p-type contact layer further includes a second stacked structure stacked on the first stacked structure, and growing the second stacked structure includes: The growth pressure was controlled at 75 to 100 torr, the growth speed at 1200 ± 100 rpm, the growth temperature at 950 ± 50℃, and the growth atmosphere was a mixture of nitrogen and ammonia to grow the first sublayer. The growth pressure was controlled at 200 torr to 500 torr, the growth speed at 1200 ± 100 rpm, the growth temperature at 910 ± 50℃, and the growth atmosphere was a mixture of nitrogen, hydrogen, and ammonia. The concentration of Mg doping was 5 × 10⁻⁶. 21 cm -3 A second sublayer is grown on the first sublayer to obtain the second stacked structure.

Images