Epitaxial wafer of light emitting diode and preparation method thereof

Abstract

The present invention relates to the technical field of semiconductor materials, and discloses an epitaxial wafer of a light-emitting diode and a preparation method thereof, wherein the epitaxial wafer comprises a substrate, a buffer layer, a non-doped GaN layer, an n-type semiconductor layer, a multi-quantum well layer, an electron blocking layer and a p-type semiconductor layer stacked in sequence on the substrate; wherein the n-type semiconductor layer comprises a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and a non-doped / third Si-doped gallium-containing nitride layer stacked in sequence from bottom to top. The implementation of the present invention can provide a sufficient Si doping concentration, while making the crystal quality of the n-type semiconductor layer high, the brightness of the LED device high, and the luminous efficiency high.

Description

Technical Field

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

[0002] High brightness light emitting diode, namely HB-LED (High Brightness Light Emitting Diode), is a light emitting device and a thresholdless device that spontaneously radiates and emits incoherent light through electrical injection of homogeneous pn junction or heterojunction. High brightness light emitting diode is a new solid light source with the advantages of small size, high efficiency, low power consumption, long life, convenient and safe use, strong resistance to mechanical shock and vibration, etc. It has broad application prospects in communication, transportation, outdoor large-screen display, etc., especially the breakthrough of high brightness blue light LED technology, green light LED technology and white light LED technology, which has continuously broadened the application scope of LED, and has become an electronic product with great development potential in this century.

[0003] The intrinsic conductivity of GaN crystal is low. By effectively doping to improve the conductivity of GaN, electrons can be continuously generated to participate in the radiative recombination in the active area when current is injected. The doping element is generally required to be close to the atomic radius of GaN and still maintain a certain stability at the growth temperature. In MOCVD epitaxial growth of GaN, the most commonly used n-type doping element is Si, and the doping source is SiH4.

[0004] In the current GaN epitaxial layer structure, the n-type GaN layer is usually a bulk structure. The controversy of this structure is that GaN will be doped with Si, and the crystal integrity of the GaN material will decrease with the incorporation of Si atoms, and the secondary diffusion of Si atoms will also increase with the increase of Si doping, resulting in a decrease in the crystal quality of the n-type GaN layer. On the other hand, if the n-type GaN doping concentration is low, the high-resistance n-GaN will affect the injection of electrons into the active area and increase Joule heat, affecting the reliability of the device. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an epitaxial wafer of a light emitting diode and a preparation method thereof, which can provide sufficient Si doping concentration, while making the crystal quality of the n-type semiconductor layer high, the brightness of the LED device high, and the luminous efficiency high.

[0006] In order to solve the above technical problems, the present invention provides, in a first aspect, an epitaxial wafer of a light-emitting diode, comprising a substrate, a buffer layer, a non-doped GaN layer, an n-type semiconductor layer, a multi-quantum well layer, an electron blocking layer and a p-type semiconductor layer sequentially stacked on the substrate;

[0007] The n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and an undoped / third Si-doped gallium-containing nitride layer stacked sequentially from bottom to top.

[0008] As an improvement of the above solution, the doping concentration of C in the C-Si co-doped gallium-containing nitride layer is 5×10 16 atoms / cm 3 ~5×10 17 atoms / cm 3 , the doping concentration of Si is 5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 ;

[0009] The thickness of the C-Si co-doped gallium-containing nitride layer is 0.1 μm to 2 μm.

[0010] As an improvement of the above solution, the first Si-doped / second Si-doped gallium-containing nitride layer is a superlattice structure formed by alternating first Si-doped gallium-containing nitride layers and second Si-doped gallium-containing nitride layers from bottom to top, and the number of alternating periods is 1 to 10.

[0011] As an improvement of the above solution, the doping concentration of Si in the first Si-doped gallium-containing nitride layer is X1, and the doping concentration of Si in the second Si-doped gallium-containing nitride layer is X2, satisfying X1>X2.

[0012] As an improvement of the above scheme, X1=(1.01~5)X2;

[0013] X1=5.05×10 18 atoms / cm 3 ~5.05×10 19 atoms / cm 3 , X2=5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 .

[0014] As an improvement of the above solution, the thickness of the first Si-doped / second Si-doped gallium-containing nitride layer is 0.5 μm to 3 μm;

[0015] The thickness ratio of the first Si-doped gallium-containing nitride layer to the second Si-doped gallium-containing nitride layer is 1:(1-5).

[0016] As an improvement of the above solution, the undoped / third Si-doped gallium-containing nitride layer is a superlattice structure formed by alternately stacking undoped gallium-containing nitride layers and third Si-doped gallium-containing nitride layers from bottom to top, and the number of alternating periods is 1 to 10.

[0017] As an improvement of the above solution, the doping concentration of Si in the third Si-doped gallium-containing nitride layer is X3, where X3=5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 ;

[0018] The thickness of the non-doped / third Si-doped gallium-containing nitride layer is 0.1 μm to 1 μm;

[0019] The thickness ratio of the non-doped gallium-containing nitride layer to the third Si-doped gallium-containing nitride layer is 1:(1-5).

[0020] As an improvement of the above scheme, the growth temperature of the C-Si co-doped gallium-containing nitride layer is 1000°C~1200°C, the growth pressure is 50torr~300torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1~20):(1~10);

[0021] The growth temperature of the first Si-doped / second Si-doped gallium-containing nitride layer is 1000° C.~1200° C., the growth pressure is 50torr~300torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1~20):(1~10).

[0022] The growth temperature of the non-doped / third Si-doped gallium-containing nitride layer is 1000° C. to 1200° C., the growth pressure is 50 torr to 300 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1-20):(1-10).

[0023] The second aspect of the present invention also provides a method for preparing an epitaxial wafer of a light emitting diode, comprising:

[0024] providing a substrate;

[0025] depositing a buffer layer on the substrate;

[0026] depositing a non-doped GaN layer on the buffer layer;

[0027] depositing an n-type semiconductor layer on the undoped GaN layer;

[0028] depositing a multi-quantum well layer on the n-type semiconductor layer;

[0029] depositing an electron blocking layer on the multiple quantum well layer;

[0030] depositing a p-type semiconductor layer on the electron blocking layer;

[0031] The n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and an undoped / third Si-doped gallium-containing nitride layer stacked sequentially from bottom to top.

[0032] The implementation of the present invention has the following beneficial effects:

[0033] The n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer, and an undoped / third Si-doped gallium-containing nitride layer stacked in sequence from bottom to top, which can provide sufficient electrons for the n-type GaN layer to emit light for the LED, and at the same time help to reduce line defects, improve the crystal quality of the n-type semiconductor layer, reduce the resistivity of the n-type GaN layer, alleviate the current blocking effect, reduce the operating voltage, enhance the injection efficiency of electrons into the multi-quantum well layer, and improve the luminous efficiency of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : A schematic structural diagram of an epitaxial wafer of a light emitting diode in the present invention;

[0035] Figure 2 : A flow chart of the preparation of an epitaxial wafer of a light emitting diode in the present invention.

[0036] Reference numerals:

[0037] 100-substrate; 200-buffer layer; 300-non-doped GaN layer; 400-n-type semiconductor layer; 410-C-Si co-doped gallium-containing nitride layer; 420-first Si-doped / second Si-doped gallium-containing nitride layer; 421-first Si-doped gallium-containing nitride layer; 422-second Si-doped gallium-containing nitride layer; 430-non-doped / third Si-doped gallium-containing nitride layer; 431-non-doped gallium-containing nitride layer; 432-third Si-doped gallium-containing nitride layer; 500-multi-quantum well layer; 600-electron blocking layer; 700-p-type semiconductor layer. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail with specific embodiments below.

[0039] In order to solve the above problems, the present invention provides a light emitting diode epitaxial wafer in a first aspect, such as Figure 1As shown, it includes a substrate 100, and a buffer layer 200, a non-doped GaN layer 300, an n-type semiconductor layer 400, a multi-quantum well layer 500, an electron blocking layer 600 and a p-type semiconductor layer 700 are sequentially stacked on the substrate 100;

[0040] The n-type semiconductor layer 400 includes a C-Si co-doped gallium-containing nitride layer 410 , a first Si-doped / second Si-doped gallium-containing nitride layer 420 , and an undoped / third Si-doped gallium-containing nitride layer 430 stacked sequentially from bottom to top.

[0041] In the present invention, the n-type semiconductor layer 400 includes a C-Si co-doped gallium-containing nitride layer 410, a first Si-doped / second Si-doped gallium-containing nitride layer 420 and an undoped / third Si-doped gallium-containing nitride layer 430 stacked in sequence from bottom to top, which can provide sufficient electrons for the n-type GaN layer to emit light for the LED, and at the same time help to reduce line defects, improve the crystal quality of the n-type semiconductor layer 400, reduce the resistivity of the n-type semiconductor layer 400, alleviate the current blocking effect, reduce the operating voltage, enhance the injection efficiency of electrons into the multi-quantum well layer 500, and improve the luminous efficiency of the light-emitting diode.

[0042] Among them, the setting of C-Si co-doped gallium-containing nitride layer 410 can provide sufficient electrons for LED light emission, and C (carbon) doping can attract defects generated during the growth of n-type semiconductor layer 400, thereby improving the crystal quality of n-type gallium-containing nitride layer. The first Si-doped / second Si-doped gallium-containing nitride layer 420 provides sufficient Si doping, which can effectively reduce the resistivity of the n-type gallium-containing nitride layer, increase current expansion, and alleviate the current blocking effect. The undoped / third Si-doped gallium-containing nitride layer 430 can promote the release of compressive stress through stacking faults, reduce line defects, further improve crystal quality, and at the same time be beneficial to reduce reverse leakage current, improve current expansion, reduce operating voltage, enhance the injection efficiency of electrons into the multi-quantum well layer 500, and improve the luminous efficiency of the light-emitting diode.

[0043] Preferably, the gallium-nitrogen compound in the n-type semiconductor layer 400 is a combination of one or more of GaN, AlGaN, InGaN, AlGaN, AlInGaN, BGaN, BInGaN, etc. It is understandable that the gallium-containing nitride in the C-Si co-doped gallium-containing nitride layer 410, the first Si-doped / second Si-doped gallium-containing nitride layer 420, and the undoped / third Si-doped gallium-containing nitride layer 430 may be the same substance or different substances.

[0044] Preferably, the doping concentration of C in the C-Si co-doped gallium-containing nitride layer 410 is 5×10 16 atoms / cm 3~5×10 17 atoms / cm 3 , the doping concentration of Si is 5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 ; 5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 The Si doping concentration can ensure sufficient electron quantity, while 5×10 16 atoms / cm 3 ~5×10 17 atoms / cm 3 The C doping concentration can attract the crystal quality defects of the home nitride layer caused by Si doping, and obtain a C-Si co-doped gallium-containing nitride layer 410 with higher crystal quality. The C doping concentration is 5×10 16 atoms / cm 3 ,7×10 16 atoms / cm 3 ,9×10 16 atoms / cm 3 , 1×10 17 atoms / cm 3 , 3×10 17 atoms / cm 3 , 5×10 17 atoms / cm 3 , but not limited thereto; the doping concentration of Si is exemplarily 5×10 18 atoms / cm 3 ,7×10 18 atoms / cm 3 ,9×10 18 atoms / cm 3 , 1×10 19 atoms / cm 3 , 3×10 19 atoms / cm 3 , 5×10 19 atoms / cm 3 , but not limited to this.

[0045] Further, the C—Si co-doped gallium-containing nitride layer 410 has a thickness of 0.1 μm to 2 μm, and exemplary thicknesses are 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, and 2 μm, but are not limited thereto.

[0046] Preferably, the first Si-doped / second Si-doped gallium-containing nitride layer 420 is a superlattice structure formed by alternating stacking of the first Si-doped gallium-containing nitride layer 421 and the second Si-doped gallium-containing nitride layer 422 from bottom to top, and the number of alternating periods is 1 to 10, and exemplary period numbers are 1, 3, 5, 7, 9, and 10, but are not limited thereto.

[0047] It can be understood that the gallium-containing nitride of the first Si-doped gallium-containing nitride layer 421 and the second Si-doped gallium-containing nitride layer 422 in the first Si-doped / second Si-doped gallium-containing nitride layer 420 can be the same material or different materials.

[0048] Furthermore, the doping concentration of Si in the first Si-doped gallium-containing nitride layer 421 is X1, and the doping concentration of Si in the second Si-doped gallium-containing nitride layer 422 is X2, satisfying X1>X2. The resistivity of the n-type GaN layer is higher than the resistivity of the transparent electrode on the p-type GaN, so the first Si-doped / second Si-doped gallium-containing nitride layer 420 adopts a high-doping / low-doping superlattice structure, wherein sufficient Si doping in the high-doped gallium-containing nitride layer can effectively reduce the resistivity of the n-type GaN layer, and Si doping in the low-doped gallium-containing nitride layer increases current expansion, alleviates the current blocking effect, and thereby reduces the operating voltage of the LED device and improves the luminous efficiency. More preferably, X1=(1.01~5)X2.

[0049] In some specific and preferred embodiments, X1=5.05×10 18 atoms / cm 3 ~5.05×10 19 atoms / cm 3 , X2=5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 , X1 is 5.05×10 18 atoms / cm 3 , 5.1×10 18 atoms / cm 3 , 7.1×10 18 atoms / cm 3 , 9.1×10 18 atoms / cm 3 , 1.1×10 19 atoms / cm 3 , 3.1×10 19 atoms / cm 3 5.05×10 19 atoms / cm3 , but not limited thereto; X2 is exemplarily 5×10 18 atoms / cm 3 ,7×10 18 atoms / cm 3 ,9×10 18 atoms / cm 3 , 1×10 19 atoms / cm 3 , 3×10 19 atoms / cm 3 , 5×10 19 atoms / cm 3 , but not limited to this.

[0050] Preferably, the first Si-doped / second Si-doped gallium-containing nitride layer 420 has a thickness of 0.5 μm to 3 μm, and exemplary thicknesses are 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, and 3 μm, but are not limited thereto.

[0051] Further, the thickness ratio of the first Si-doped gallium-containing nitride layer 421 to the second Si-doped gallium-containing nitride layer 422 is 1:(1-5), exemplarily 1:1, 1:2, 1:3, 1:4, 1:5, but not limited thereto.

[0052] Preferably, the non-doped / third Si-doped gallium-containing nitride layer 430 is a superlattice structure formed by alternately stacking non-doped gallium-containing nitride layers 431 and third Si-doped gallium-containing nitride layers 432 from bottom to top, with an alternating period number of 1 to 10, and exemplary period numbers are 1, 3, 5, 7, 9, and 10, but not limited thereto. Among them, the non-doped gallium-containing nitride layer 431 is not doped with Si impurities, and the compressive stress will be released through stacking faults, line defects will be reduced, the crystal quality of the non-doped / third Si-doped gallium-containing nitride layer 430 will be improved, and the reverse leakage current will be reduced. The third Si-doped gallium-containing nitride layer 432 can further improve the current expansion, reduce the operating voltage, enhance the injection efficiency of electrons into the multi-quantum well layer 500, and improve the luminous efficiency of the light-emitting diode.

[0053] It can be understood that the gallium-containing nitride in the undoped gallium-containing nitride layer 431 and the third Si-doped gallium-containing nitride layer 432 in the undoped / third Si-doped gallium-containing nitride layer 430 can be the same material or different materials.

[0054] Furthermore, the doping concentration of Si in the third Si-doped gallium-containing nitride layer 432 is X3, where X3=5×10 18 atoms / cm 3 ~5×10 19atoms / cm 3 , the exemplary doping concentration X3 is 5×10 18 atoms / cm 3 ,7×10 18 atoms / cm 3 ,9×10 18 atoms / cm 3 , 1×10 19 atoms / cm 3 , 3×10 19 atoms / cm 3 , 5×10 19 atoms / cm 3 , but not limited to this.

[0055] Further, the thickness of the undoped / third Si-doped gallium-containing nitride layer 430 is 0.1 μm-1 μm, and exemplary thicknesses are 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, and 1 μm, but not limited thereto.

[0056] Furthermore, the thickness ratio of the undoped gallium-containing nitride layer 431 to the third Si-doped gallium-containing nitride layer 432 is 1:(1-5), exemplarily 1:1, 1:2, 1:3, 1:4, 1:5, but not limited thereto.

[0057] Accordingly, the inventors have also invented a method for preparing an epitaxial wafer of a light emitting diode, such as Figure 2 As shown, including:

[0058] S01, providing a substrate 100;

[0059] Preferably, the substrate 100 can be one of a sapphire substrate, a SiO2 sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate; more preferably, it is a sapphire substrate. Sapphire is currently the most commonly used GaN-based LED substrate material. Sapphire substrates have mature preparation processes, low prices, are easy to clean and handle, and have good stability at high temperatures.

[0060] S02, depositing a buffer layer on the substrate;

[0061] Preferably, the buffer layer 200 is an AlN buffer layer. The AlN buffer layer provides a nucleation center with the same orientation as the substrate 100, releases the stress caused by the lattice mismatch between GaN and the substrate 100 and the thermal stress caused by the mismatch of thermal expansion coefficients, provides a flat nucleation surface for further growth, reduces the contact angle of its nucleation growth, and enables the island-like grown GaN grains to be connected into a surface within a smaller thickness, thereby transforming into two-dimensional epitaxial growth.

[0062] Furthermore, the buffer layer 200 is grown by PVD, and the thickness of the buffer layer 200 is 10 nm to 50 nm. Specifically, the buffer layer 200 can be deposited by using an A7 MOCVD (Metal-organic Chemical Vapor Deposition, MOCVD for short) device.

[0063] Furthermore, after the growth of the buffer layer 200 is completed, the substrate 100 coated with the buffer layer 200 can be transferred to MOCVD and pretreated in a H2 atmosphere for 1 min to 10 min at a treatment temperature of 1000°C to 1200°C, followed by nitridation treatment to improve the crystal quality of the buffer layer 200 and effectively improve the crystal quality of the subsequently deposited GaN epitaxial layer.

[0064] S03, depositing a non-doped GaN layer on the buffer layer;

[0065] Preferably, the thickness of the undoped GaN layer 300 is 1.0μm~5.0μm; more preferably 2.0μm~3.0μm. The undoped GaN layer 300 has a higher growth temperature and a lower pressure, and the prepared GaN crystal has a better quality. At the same time, as the thickness of GaN increases, the compressive stress will be released through stacking faults, line defects will be reduced, the crystal quality will be improved, and the reverse leakage will be reduced. However, increasing the thickness of the GaN layer consumes more Ga source materials, which greatly increases the epitaxial cost of the LED. Therefore, at present, LED epitaxial wafers usually grow undoped GaN of 2.0μm~3.0μm, which not only saves production costs, but also the GaN material has a higher crystal quality.

[0066] Furthermore, in MOCVD, the growth temperature of the non-doped GaN layer 300 is 1050° C. to 1200° C., and the growth pressure is 100 torr to 600 torr.

[0067] S04, depositing an n-type semiconductor layer 400 on the non-doped GaN layer 300;

[0068] The n-type semiconductor layer 400 includes a C—Si co-doped gallium-containing nitride layer 410 , a first Si-doped / second Si-doped gallium-containing nitride layer 420 , and an undoped / third Si-doped gallium-containing nitride layer 430 stacked sequentially from bottom to top.

[0069] Preferably, the growth temperature of the C-Si co-doped gallium-containing nitride layer 410 is 1000°C~1200°C, and the growth pressure is 50torr~300torr. Exemplary growth temperatures are 1000°C, 1050°C, 1100°C, 1150°C, and 1200°C, but not limited to these. Exemplary growth pressures are 50torr, 100torr, 150torr, 200torr, 250torr, and 300torr, but not limited to these.

[0070] Further, the growth atmosphere of the C-Si co-doped gallium-containing nitride layer 410 is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1~20):(1~10); exemplary flow ratios are 1:1:1, 1:1:5, 1:1:10, 1:3:1, 1:3:5, 1:3:10, 1:5:1, 1:5:5, 1:5:10, 1:10:1, 1:10:5, 1:10:10, 1:15:1, 1:15:5, 1:15:10, 1:20:1, 1:20:5, 1:20:10, but are not limited to these.

[0071] Preferably, the growth temperature of the first Si-doped / second Si-doped gallium-containing nitride layer 420 is 1000°C~1200°C, and the growth pressure is 50torr~300torr. Exemplary growth temperatures are 1000°C, 1050°C, 1100°C, 1150°C, and 1200°C, but not limited to these. Exemplary growth pressures are 50torr, 100torr, 150torr, 200torr, 250torr, and 300torr, but not limited to these.

[0072] Further, the growth atmosphere of the first Si-doped / second Si-doped gallium-containing nitride layer 420 is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1-20):(1-10). Exemplary flow ratios are 1:1:1, 1:1:5, 1:1:10, 1:3:1, 1:3:5, 1:3:10, 1:5:1, 1:5:5, 1:5:10, 1:10:1, 1:10:5, 1:10:10, 1:15:1, 1:15:5, 1:15:10, 1:20:1, 1:20:5, 1:20:10, but are not limited thereto.

[0073] Preferably, the growth temperature of the undoped / third Si-doped gallium-containing nitride layer 430 is 1000°C~1200°C, and the growth pressure is 50torr~300torr. Exemplary growth temperatures are 1000°C, 1050°C, 1100°C, 1150°C, and 1200°C, but not limited to these. Exemplary growth pressures are 50torr, 100torr, 150torr, 200torr, 250torr, and 300torr, but not limited to these.

[0074] Further, the growth atmosphere of the undoped / third Si-doped gallium-containing nitride layer 430 is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1~20):(1~10), and exemplary flow ratios are 1:1:1, 1:1:5, 1:1:10, 1:3:1, 1:3:5, 1:3:10, 1:5:1, 1:5:5, 1:5:10, 1:10:1, 1:10:5, 1:10:10, 1:15:1, 1:15:5, 1:15:10, 1:20:1, 1:20:5, 1:20:10, but not limited to these.

[0075] In the present application, by appropriately increasing the growth rate of the n-type semiconductor layer 400 and reducing the growth time, combined with the structure of the C-Si co-doped gallium-containing nitride layer 410, the first Si-doped / second Si-doped gallium-containing nitride layer 420 and the undoped / third Si-doped gallium-containing nitride layer 430, it is beneficial to further improve the crystal quality of the n-type semiconductor layer 400.

[0076] S05, depositing a multi-quantum well layer 500 on the n-type semiconductor layer 400;

[0077] Preferably, the multi-quantum well layer 500 is a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers, with a stacking period number of 5 to 20. In a single period, the In component of the InGaN quantum well layer is 0.1 to 0.5, and the thickness of the InGaN quantum well layer is 2 nm to 5 nm; the Al component of the AlGaN quantum barrier layer is 0.01 to 0.1, and the thickness of the AlGaN quantum barrier layer is 5 nm to 15 nm.

[0078] Furthermore, the growth temperature of the InGaN quantum well layer is 790° C. to 810° C., and the growth pressure is 50 torr to 300 torr; the growth temperature of the AlGaN quantum barrier layer is 800° C. to 900° C., and the growth pressure is 50 torr to 300 torr.

[0079] S06, depositing an electron blocking layer 600 on the multi-quantum well layer 500;

[0080] Preferably, the electron blocking layer 600 is an AlInGaN layer, with an Al component of 0.01-0.1 and an In component of 0.01-0.2, which can effectively limit electron overflow and reduce the blocking of holes, thereby improving the injection efficiency of holes into the multi-quantum well layer 500, reducing carrier Auger recombination, and improving the luminous efficiency of the light-emitting diode. The thickness of the electron blocking layer 600 is 10nm-40nm.

[0081] Furthermore, the growth temperature of the electron blocking layer 600 is 900° C. to 1000° C., and the growth pressure is 100 torr to 300 torr.

[0082] S07, depositing a p-type semiconductor layer 700 on the electron blocking layer 600;

[0083] Preferably, the p-type semiconductor layer 700 is a p-type GaN layer, and the doping element is Mg, and the doping concentration of Mg is 1×10 19 atoms / cm 3 ~1×10 21 atoms / cm 3 Too high a Mg doping concentration will damage the crystal quality, while a lower doping concentration will affect the hole concentration.

[0084] Furthermore, the thickness of the p-type semiconductor layer 700 is 10 nm to 50 nm.

[0085] Furthermore, the growth temperature of the p-type semiconductor layer 700 is 900° C. to 1050° C., and the growth pressure is 100 torr to 600 torr.

[0086] It should be noted that the present invention adopts the A7 MOCVD (Metal-organic Chemical Vapor Deposition, MOCVD for short) equipment to realize the epitaxial wafer growth method. High-purity H2 (hydrogen) or high-purity N2 (nitrogen) or a mixed gas of high-purity H2 and high-purity N2 is used as the carrier gas. The N source is high-purity NH3, the Al source is TMAl (trimethylaluminum), the Ga source is TMGa (trimethylgallium), the In source is TMIn (trimethylindium), the Si source is SiH4 (silane), and the Mg source is CP2Mg.

[0087] The present invention will be further described below with specific embodiments:

[0088] Example 1

[0089] This embodiment provides an epitaxial wafer of a light-emitting diode, comprising a substrate, a buffer layer, a non-doped GaN layer, an n-type semiconductor layer, a multi-quantum well layer, an electron blocking layer and a p-type semiconductor layer sequentially stacked on the substrate;

[0090] The n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and an undoped / third Si-doped gallium-containing nitride layer stacked sequentially from bottom to top.

[0091] The C-Si co-doped gallium-containing nitride layer is a C-Si co-doped GaN layer with a thickness of 1 μm and a C doping concentration of 1×10 17 atoms / cm 3 , the doping concentration of Si is 1×10 19 atoms / cm 3 ;

[0092] The first Si-doped / second Si-doped gallium-containing nitride layer is a superlattice structure formed by alternately stacking the first Si-doped GaN layer and the second Si-doped AlGaN layer from bottom to top, with a period number of 3 and a total thickness of 1.5 μm. The thickness ratio of the first Si-doped GaN layer to the second Si-doped AlGaN layer is 2:3; the Si doping concentration X1 of the first Si-doped GaN layer is 2×10 19 atoms / cm 3 , the Si doping concentration X2 in the second Si-doped AlGaN layer is 1×10 19 atoms / cm 3 ;

[0093] The non-doped / third Si-doped gallium-containing nitride layer is a superlattice structure formed by alternately stacking non-doped GaN layers and third Si-doped GaN layers from bottom to top, with an alternating period of 2 and a total thickness of 0.6 μm. The thickness ratio of the non-doped GaN layer to the third Si-doped GaN layer is 1:2, and the doping concentration X3 of Si in the third Si-doped GaN layer is 1×10 19 atoms / cm 3 .

[0094] It is prepared by the following preparation method:

[0095] S01, providing a substrate;

[0096] The substrate is a sapphire substrate.

[0097] S02, depositing a buffer layer on the substrate;

[0098] The buffer layer is an AlN buffer layer, which is grown in PVD and has a thickness of 30 nm.

[0099] After the buffer layer is grown, the substrate coated with the buffer layer can be transferred to MOCVD, pretreated in H2 atmosphere for 5 minutes at a treatment temperature of 1100°C, and then nitridation treatment is continued.

[0100] S03, depositing a non-doped GaN layer on the buffer layer;

[0101] The thickness of the non-doped GaN layer is 2.5 μm; the growth temperature is 1100° C., and the growth pressure is 150 torr.

[0102] S04, depositing an n-type semiconductor layer on the non-doped GaN layer;

[0103] The n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer, and an undoped / third Si-doped gallium-containing nitride layer stacked in sequence from bottom to top.

[0104] The growth temperature of the C-Si co-doped gallium-containing nitride layer is 1120° C., the growth pressure is 150 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:10:5.

[0105] The growth temperature of the first Si-doped / second Si-doped gallium-containing nitride layer is 1130° C., the growth pressure is 150 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:10:5;

[0106] The growth temperature of the non-doped / third Si-doped gallium-containing nitride layer is 1130° C., the growth pressure is 150 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:10:5.

[0107] S05, depositing a multi-quantum well layer on the n-type semiconductor layer;

[0108] The multi-quantum well layer is a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers, with a stacking period number of 10. In a single period, the In component of the InGaN quantum well layer is 0.15, and the thickness of the InGaN quantum well layer is 3.5 nm; the Al component of the AlGaN quantum barrier layer is 0.05, and the thickness of the AlGaN quantum barrier layer is 9.8 nm.

[0109] Furthermore, the growth temperature of the InGaN quantum well layer is 795° C., and the growth pressure is 200 torr; the growth temperature of the AlGaN quantum barrier layer is 855° C., and the growth pressure is 200 torr.

[0110] S06, depositing an electron blocking layer on the multi-quantum well layer;

[0111] The electron blocking layer is an AlInGaN layer, with an Al component of 0.05, an In component of 0.01, a thickness of 15 nm, a growth temperature of 965° C., and a growth pressure of 200 torr.

[0112] S07, depositing a p-type semiconductor layer on the electron blocking layer;

[0113] The p-type semiconductor layer is a p-type GaN layer, and the doping element is Mg, and the doping concentration of Mg is 2×10 20 atoms / cm 3 , thickness is 15nm, growth temperature is 985℃, and growth pressure is 200torr.

[0114] Examples 2 to 10 and Comparative Examples 1 to 4 were prepared according to the values ​​in Table 1 below. In the table, the unit of doping concentration is atoms / cm 3 , the unit of thickness is μm, the thickness ratio of the first Si-doped / second Si-doped gallium-containing nitride layer is the ratio of the thickness of the first Si-doped gallium-containing nitride layer to the thickness of the second Si-doped gallium-containing nitride layer; the thickness ratio of the undoped / third Si-doped gallium-containing nitride layer is the ratio of the thickness of the undoped gallium-containing nitride layer to the thickness of the third Si-doped gallium-containing nitride layer.

[0115] Table 1 Parameters of Examples 1 to 10 and Comparative Examples 1 to 4

[0116]

[0117] The epitaxial structures obtained in the embodiments and comparative examples were made into 10mil*24mil chips, and 300 LED chips were extracted respectively. The luminous brightness and luminous efficiency of the obtained chips were tested at a current of 120mA / 60mA. The luminous efficiency improvement was calculated based on comparative example 1.

[0118] The performance test results are shown in Table 2.

[0119] Table 2 Performance test results of examples and comparative examples

[0120]

[0121] From the above results, it can be seen that in the present invention, the n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and an undoped / third Si-doped gallium-containing nitride layer stacked in sequence from bottom to top, which can provide sufficient electrons for the n-type GaN layer to emit light for the LED, and at the same time help to reduce line defects, improve the crystal quality of the n-type semiconductor layer, reduce the resistivity of the n-type GaN layer, alleviate the current blocking effect, reduce the operating voltage, enhance the injection efficiency of electrons into the multi-quantum well layer, and improve the luminous efficiency of the light-emitting diode.

[0122] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An epitaxial wafer of a light emitting diode, characterized in that: It comprises a substrate, a buffer layer, a non-doped GaN layer, an n-type semiconductor layer, a multi-quantum well layer, an electron blocking layer and a p-type semiconductor layer which are sequentially stacked on the substrate; Wherein, the n-type semiconductor layer comprises a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and an undoped / third Si-doped gallium-containing nitride layer stacked in sequence from bottom to top; The doping concentration of Si in the first Si-doped gallium-containing nitride layer is X1, and the doping concentration of Si in the second Si-doped gallium-containing nitride layer is X2, satisfying X1>X2; The non-doped / third Si-doped gallium-containing nitride layer is a superlattice structure formed by alternately stacking non-doped gallium-containing nitride layers and third Si-doped gallium-containing nitride layers from bottom to top.

2. The epitaxial wafer of a light emitting diode according to claim 1, characterized in that: The doping concentration of C in the C-Si co-doped gallium-containing nitride layer is 5×10 16 atoms / cm 3 ~5×10 17 atoms / cm 3 , the doping concentration of Si is 5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 ; The thickness of the C-Si co-doped gallium-containing nitride layer is 0.1 μm to 2 μm.

3. The epitaxial wafer of a light emitting diode according to claim 1, characterized in that: The first Si-doped / second Si-doped gallium-containing nitride layer is a superlattice structure formed by alternately stacking the first Si-doped gallium-containing nitride layer and the second Si-doped gallium-containing nitride layer from bottom to top, and the number of alternating periods is 1-10.

4. The epitaxial wafer of a light emitting diode according to claim 1, characterized in that: X1=(1.01~5)X2; X1=5.05×10 18 atoms / cm 3 ~5.05×10 19 atoms / cm 3 ,X2=5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 。 5. The epitaxial wafer of a light emitting diode according to claim 3, characterized in that: The thickness of the first Si-doped / second Si-doped gallium-containing nitride layer is 0.5 μm to 3 μm; The thickness ratio of the first Si-doped gallium-containing nitride layer to the second Si-doped gallium-containing nitride layer is 1:(1-5).

6. The epitaxial wafer of a light emitting diode according to claim 1, characterized in that: The number of alternating periods of the non-doped / third Si-doped gallium-containing nitride layer is 1-10.

7. The epitaxial wafer of a light emitting diode according to claim 1, characterized in that: The doping concentration of Si in the third Si-doped gallium-containing nitride layer is X3, where X3=5×10 18 atoms / cm 3 ~5×10 19 atoms / cm 3 ; The thickness of the non-doped / third Si-doped gallium-containing nitride layer is 0.1 μm to 1 μm; The thickness ratio of the non-doped gallium-containing nitride layer to the third Si-doped gallium-containing nitride layer is 1:(1-5).

8. The epitaxial wafer of a light emitting diode according to claim 1, characterized in that: The growth temperature of the C-Si co-doped gallium-containing nitride layer is 1000° C. to 1200° C., the growth pressure is 50 torr to 300 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1-20):(1-10); The growth temperature of the first Si-doped / second Si-doped gallium-containing nitride layer is 1000° C. to 1200° C., the growth pressure is 50 torr to 300 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1-20):(1-10); The growth temperature of the non-doped / third Si-doped gallium-containing nitride layer is 1000° C. to 1200° C., the growth pressure is 50 torr to 300 torr, the growth atmosphere is N2 / H2 / NH3, and the flow ratio of N2 / H2 / NH3 is 1:(1-20):(1-10).

9. A method for preparing an epitaxial wafer of a light emitting diode as claimed in claims 1 to 8, characterized in that: include: providing a substrate; depositing a buffer layer on the substrate; depositing a non-doped GaN layer on the buffer layer; depositing an n-type semiconductor layer on the undoped GaN layer; depositing a multi-quantum well layer on the n-type semiconductor layer; depositing an electron blocking layer on the multiple quantum well layer; depositing a p-type semiconductor layer on the electron blocking layer; The n-type semiconductor layer includes a C-Si co-doped gallium-containing nitride layer, a first Si-doped / second Si-doped gallium-containing nitride layer and an undoped / third Si-doped gallium-containing nitride layer stacked sequentially from bottom to top.

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