Epitaxial structure of light emitting diode and preparation method thereof, light emitting diode

Abstract

The present invention discloses an epitaxial structure of a light-emitting diode, a preparation method thereof, and a light-emitting diode, relating to the field of semiconductor optoelectronic devices. The epitaxial structure of the light-emitting diode includes a substrate and a buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a P-GaN layer, and a P-type contact layer that are sequentially stacked on the substrate; wherein, the P-GaN layer is an O, Be co-doped GaN layer, the doping concentration of O is 5×10<supgt;18< / supgt>-5×10<supgt;19< / supgt> atom / cm<supgt;3< / supgt>, and the doping concentration of Be is 1×10<supgt;19< / supgt>-1×10<supgt;20< / supgt> atom / cm<supgt;3. Implementing the present invention can improve the light-emitting efficiency of the light-emitting diode.

Description

Technical Field

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

[0002] In a light-emitting diode, the P-type semiconductor layer (such as P-GaN, P-AlGaN, etc.) provides holes, and the N-type semiconductor layer (such as N-GaN, N-AlGaN, etc.) provides electrons. The two converge in the multi-quantum well layer to achieve light emission. However, due to the fast movement of electrons and the slow movement of holes, the probability of recombination between the two is low. A common method is to increase the concentration of dopants (usually Mg) in the P-type semiconductor layer to provide more holes. However, as the magnesium doping concentration continues to increase, the hole concentration begins to decrease after it increases to a certain level. This is because when heavily doped with Mg, there are a large number of nitrogen vacancies and magnesium gaps in the P-type semiconductor layer, which will greatly reduce the doping efficiency and affect the final luminous efficiency of the light-emitting diode. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an epitaxial structure of a light emitting diode and a preparation method thereof, which can effectively improve the light emitting efficiency of the light emitting diode.

[0004] Another technical problem to be solved by the present invention is to provide a light emitting diode with high light emitting efficiency.

[0005] In order to solve the above problems, the present invention discloses an epitaxial structure of a light emitting diode, which comprises a substrate and a buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a P-GaN layer and a P-type contact layer sequentially stacked on the substrate;

[0006] The P-GaN layer is an O and Be co-doped GaN layer, and the O doping concentration is 5×10 18 -5×10 19 atom / cm 3 , the doping concentration of Be is 1×10 19 -1×10 20 atom / cm 3 .

[0007] As an improvement of the above technical solution, the P-GaN layer includes a first P-GaN layer and a second P-GaN layer sequentially stacked on the multi-quantum well layer, the first P-GaN layer is an undoped P-GaN layer or a Be-doped GaN layer, and the second P-GaN layer is an O and Be co-doped GaN layer;

[0008] The doping concentration of Be in the first P-GaN layer is less than the doping concentration of Be in the second P-GaN layer.

[0009] As an improvement of the above technical solution, the first P-GaN layer is a Be-doped GaN layer, and the Be doping concentration is 1×10 18 -1×10 19 atom / cm 3 ;

[0010] The doping concentration of O in the second P-GaN layer is 5×10 18 -1×10 19 atom / cm 3 , the doping concentration of Be is 1×10 19 -8×10 19 atom / cm 3 .

[0011] As an improvement of the above technical solution, the thickness of the first P-GaN layer is 3-20 nm, and the thickness of the second P-GaN layer is 5-40 nm.

[0012] As an improvement of the above technical solution, the P-GaN layer includes a first P-GaN layer, a second P-GaN layer and a third P-GaN layer which are sequentially stacked on the multi-quantum well layer;

[0013] The first P-GaN layer is an undoped P-GaN layer or a Be-doped GaN layer, the second P-GaN layer is an O and Be co-doped GaN layer, and the third P-GaN layer is a Mg-doped GaN layer;

[0014] The doping concentration of Be in the first P-GaN layer is less than the doping concentration of Be in the second P-GaN layer and less than the doping concentration of Mg in the third P-GaN layer.

[0015] The first P-GaN layer is a Be-doped GaN layer, and the Be doping concentration is 1×10 18 -1×10 19 atom / cm 3 ;

[0016] The doping concentration of O in the second P-GaN layer is 8×10 18 -5×10 19 atom / cm 3 , the doping concentration of Be is 1×10 19 -6×10 19 atom / cm 3 ;

[0017] The doping concentration of Mg in the third P-GaN layer is 1×10 19 -5×10 20 atom / cm 3;

[0018] The thickness of the first P-GaN layer is 3-20 nm, the thickness of the second P-GaN layer is 5-25 nm, and the thickness of the third P-GaN layer is 5-35 nm.

[0019] Correspondingly, the present invention also discloses a method for preparing an epitaxial structure of a light emitting diode, which is used to prepare the epitaxial structure of the light emitting diode, and comprises:

[0020] Providing a substrate, and sequentially growing a buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a P-GaN layer and a P-type contact layer on the substrate;

[0021] The P-GaN layer is an O and Be co-doped GaN layer, and the O doping concentration is 5×10 18 -5×10 19 atom / cm 3 , the doping concentration of Be is 1×10 19 -1×10 20 atom / cm 3 .

[0022] As an improvement of the above technical solution, the P-GaN layer is grown in a nitrogen atmosphere, with a growth temperature of 900-1100° C. and a growth pressure of 150-250 torr.

[0023] As an improvement of the above technical solution, it includes:

[0024] Providing a substrate, and sequentially growing an AlN buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a first P-GaN layer, a second P-GaN layer, a third P-GaN layer and a P-type contact layer on the substrate; the first P-GaN layer is an undoped P-GaN layer or a Be-doped GaN layer, the second P-GaN layer is an O and Be co-doped GaN layer, and the third P-GaN layer is a Mg-doped GaN layer;

[0025] The first P-GaN layer is grown in a hydrogen atmosphere at a growth temperature of 900-1100° C. and a growth pressure of 150-250 torr;

[0026] The second P-GaN layer is grown in a nitrogen atmosphere at a growth temperature of 900-1100° C. and a growth pressure of 150-250 torr;

[0027] The third P-GaN layer is grown in a nitrogen and / or hydrogen atmosphere at a growth temperature of 900-1100° C. and a growth pressure of 150-250 torr.

[0028] Correspondingly, the present invention also discloses a light emitting diode, which includes the epitaxial structure of the light emitting diode mentioned above.

[0029] The implementation of the present invention has the following beneficial effects:

[0030] 1. The epitaxial structure of the light-emitting diode of the present invention uses an O- and Be-doped GaN layer as a P-GaN layer. O doping reduces nitrogen vacancies, improves the Be doping efficiency, and further increases the hole concentration of the P-GaN layer, thereby improving the luminous efficiency of the light-emitting diode.

[0031] 2. The epitaxial structure of the light-emitting diode of the present invention divides the P-GaN layer into a first P-GaN layer doped with Be (or not doped) and a second P-GaN layer co-doped with O and Be. Among them, the Be in the first P-GaN layer has a smaller atomic radius, which is more conducive to filling the dislocations extending from the multi-quantum well layer, reducing the number of electrons from the multi-quantum well layer entering the P-GaN layer, and improving the problem of invalid recombination caused by electrons entering the P-GaN layer. Furthermore, the O introduced into the second P-GaN layer improves the doping efficiency of Be. The combination of the two effectively improves the luminous efficiency of the light-emitting diode.

[0032] 3. The epitaxial structure of the light-emitting diode of the present invention divides the P-GaN layer into a first P-GaN layer doped with Be (or not doped), a second P-GaN layer co-doped with O and Be, and a third P-GaN layer doped with Mg. Among them, the first P-GaN layer blocks the extension of dislocations. The O in the second P-GaN layer can improve the problem that the doping efficiency decreases when the magnesium doping concentration of the third P-GaN layer is high due to nitrogen vacancies and magnesium gaps, and can increase the hole concentration of the third P-GaN layer with a high Mg doping concentration. At the same time, based on the control of the concentration of doping elements in the first P-GaN layer, the second P-GaN layer, and the third P-GaN layer, the resistivity can be gradually reduced along the epitaxial growth direction, and then the P-type contact layer heavily doped with Mg can be used in the later stage to improve the lateral expansion ability of the P-type current. When the current enters the P-type from the P electrode, it can be expanded laterally along the P-type to the greatest extent, and then enter the multi-quantum well layer, which can increase the hole concentration of the quantum well that finally enters the effective light-emitting area, improve the luminous efficiency and the antistatic ability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of an epitaxial structure of a light emitting diode in one embodiment of the present invention;

[0034] Figure 2 is a schematic structural diagram of an epitaxial structure of a light emitting diode in another embodiment of the present invention;

[0035] Figure 3is a structural schematic diagram of an epitaxial structure of a light emitting diode in another embodiment of the present invention;

[0036] Figure 4 It is a flow chart of a method for preparing an epitaxial structure of a light emitting diode in one embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0038] refer to Figure 1 The present invention discloses an epitaxial structure of a light-emitting diode, comprising a substrate 1 and a buffer layer 2, a U-GaN layer 3, an N-GaN layer 4, a multi-quantum well layer 5, a P-GaN layer 6 and a P-type contact layer 7 sequentially stacked on the substrate 1. The P-GaN layer is an O and Be co-doped GaN layer. After O is doped into the GaN layer, it will occupy the original nitrogen vacancies in GaN to form oxygen-substituted nitrogen vacancies, thereby improving the compensation effect of nitrogen vacancies on hole carriers in GaN, increasing the doping concentration of Be, and improving the luminous efficiency of the light-emitting diode. Be and Mg belong to the same group of elements, and their doping will produce a certain concentration of holes in the P-GaN layer 6. At the same time, since the atomic radius of Be is smaller than that of Mg, it can better fill the dislocations extending from the multi-quantum well layer 5, reduce the number of electrons entering the P-GaN layer 6 and the P-type contact layer 7 from the multi-quantum well layer 5, and improve the performance of the device.

[0039] The doping concentration of O in the P-GaN layer 6 is 5×10 18 -5×10 19 atom / cm 3 , when the O doping concentration is less than 5×10 18 atom / cm 3 When the O doping concentration is greater than 5×10 19 atom / cm 3 When O is added to the P-GaN layer 6, it will not only form oxygen to replace nitrogen vacancies, but also replace the original N in GaN, forming a partial electronic semiconductor, reducing the amount of hole generation, and reducing the luminous efficiency of the light-emitting diode. For example, the doping concentration of O in the P-GaN layer 6 is: 6×10 18 atom / cm 3 , 8×10 18 atom / cm 3 , 1×10 19 atom / cm 3 , 2×10 19 atom / cm 3 , 3×10 19 atom / cm3 or 4×10 19 atom / cm 3 , but not limited to this.

[0040] The doping concentration of Be in the P-GaN layer 6 is 1×10 19 -1×10 20 atom / cm 3 , when the Be doping concentration is less than 1×10 19 atom / cm 3 When the hole concentration in the P-GaN layer 6 is low, it is difficult to effectively improve the luminous efficiency; when the Be doping concentration is greater than 1×10 20 atom / cm 3 When the effective doping concentration begins to decrease, the hole concentration entering the multi-quantum well layer 5 is reduced, and the luminous efficiency is reduced. In addition, a higher doping concentration will also weaken the lateral expansion of the current in the P-GaN layer 6, reducing the luminous efficiency and antistatic ability. For example, the doping concentration of Be in the P-GaN layer 6 is 2×10 19 atom / cm 3 , 3.5×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6.5×10 19 atom / cm 3 , 8×10 19 atom / cm 3 or 9.5×10 19 atom / cm 3 , but not limited to this.

[0041] Wherein, the thickness of the P-GaN layer 6 is 10-80nm. When the thickness is less than 10nm, the P-GaN layer 6 can provide too few holes, reducing the luminous efficiency. When the thickness is greater than 80nm, it will absorb more light, reducing the luminous efficiency. Exemplarily, the thickness of the P-GaN layer 6 is 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm or 75nm.

[0042] Preferably, reference Figure 2In one embodiment of the present invention, the P-GaN layer 6 includes a first P-GaN layer 61 and a second P-GaN layer 62 stacked on the multi-quantum well layer 5. Among them, the first P-GaN layer 61 is an undoped P-GaN layer or a Be-doped GaN layer, and the second P-GaN layer 62 is an O and Be co-doped GaN layer; and the doping concentration of Be in the first P-GaN layer 61 is less than the doping concentration of Be in the second P-GaN layer 62. Based on the above configuration, on the one hand, the first P-GaN layer 61 can better block the dislocations extending from the multi-quantum well layer 5, and improve the crystal quality of the second P-GaN layer 62 and the P-type contact layer. On the other hand, a high resistivity-low resistivity structure is formed in the growth direction of the epitaxial structure, which enhances the current expansion capability and further improves the luminous efficiency and antistatic capability.

[0043] Preferably, the first P-GaN layer 61 is a Be-doped GaN layer, and the Be doping concentration is 1×10 18 -1×10 19 atom / cm 3 For example, the doping concentration of Be is 2×10 18 atom / cm 3 , 3×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ,7×10 18 atom / cm 3 , 8×10 18 atom / cm 3 or 9.5×10 18 atom / cm 3 , but not limited to this.

[0044] The O doping concentration in the second P-GaN layer 62 is 5×10 18 -1×10 19 atom / cm 3 , exemplarily 6×10 18 atom / cm 3 ,7×10 18 atom / cm 3 , 8×10 18 atom / cm 3 or 9×10 18 atom / cm 3 , but not limited thereto. The doping concentration of Be in the second P-GaN layer 62 is 1×10 19 -8×10 19 atom / cm 3 , exemplarily 2×10 19 atom / cm3 , 3×10 19 atom / cm 3 , 4×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 or 7×10 19 atom / cm 3 It should be noted that, by introducing the first P-GaN layer 61, the requirement for the hole concentration of the second P-GaN layer 62 can be reduced, thereby reducing the doping concentration of O and Be, reducing the doping difficulty, and reducing the preparation cost of the epitaxial structure.

[0045] The thickness of the first P-GaN layer 61 is 3-20 nm, and is exemplarily 5 nm, 8 nm, 11 nm, 14 nm, 17 nm, or 19 nm. The thickness of the second P-GaN layer 62 is 5-40 nm, and is exemplarily 9 nm, 13 nm, 17 nm, 21 nm, 25 nm, 30 nm, 34 nm, or 38 nm, but is not limited thereto.

[0046] Preferably, reference Figure 3 In another embodiment of the present invention, the P-GaN layer 6 includes a first P-GaN layer 61, a second P-GaN layer 62 and a third P-GaN layer 63 stacked on the multi-quantum well layer 5. The first P-GaN layer 61 is an undoped P-GaN layer or a Be-doped GaN layer, the second P-GaN layer 62 is an O and Be co-doped GaN layer, and the third P-GaN layer 63 is a Mg-doped GaN layer; and the doping concentration of Be in the first P-GaN layer 61 is less than the doping concentration of Be in the second P-GaN layer 62 and less than the doping concentration of Mg in the third P-GaN layer 63. Based on the above configuration, on the one hand, the first P-GaN layer 61 can better block the dislocations extending from the multi-quantum well layer 5, and improve the crystal quality of the second P-GaN layer 62, the third P-GaN layer 63 and the P-type contact layer 7. Secondly, the nitrogen vacancies in the second P-GaN layer 62 are eliminated by doping with O, and the second P-GaN layer 62 is used as a transition, which also reduces the nitrogen vacancies in the third P-GaN layer 63 to a certain extent, increases the doping concentration of Mg, and increases the hole concentration. Thirdly, a structure of high resistivity-medium resistivity-small resistivity is formed in the growth direction of the epitaxial structure, which enhances the current expansion capability and further improves the luminous efficiency and antistatic capability.

[0047] Preferably, the first P-GaN layer 61 is a Be-doped GaN layer, and the Be doping concentration is 1×10 18 -1×1019 atom / cm 3 For example, the doping concentration of Be is 2×10 18 atom / cm 3 , 3×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ,7×10 18 atom / cm 3 , 8×10 18 atom / cm 3 or 9.5×10 18 atom / cm 3 , but not limited to this.

[0048] The O doping concentration in the second P-GaN layer 62 is 8×10 18 -5×10 19 atom / cm 3 , exemplarily 9×10 18 atom / cm 3 , 1×10 19 atom / cm 3 , 2×10 19 atom / cm 3 , 3×10 19 atom / cm 3 or 4×10 19 atom / cm 3 , but not limited thereto. The doping concentration of Be in the second P-GaN layer 62 is 1×10 19 -6×10 19 atom / cm 3 , exemplarily 2×10 19 atom / cm 3 , 3×10 19 atom / cm 3 , 4×10 19 atom / cm 3 or 5×10 19 atom / cm 3 , but not limited thereto. The doping concentration of Mg in the third P-GaN layer is 1×10 19 -5×10 20 atom / cm 3 , exemplarily 1.5×10 19 atom / cm 3 , 3×10 19 atom / cm 3 , 4.5×10 19atom / cm 3 , 6×10 19 atom / cm 3 , 7.5×10 19 atom / cm 3 or 9×10 19 atom / cm 3 , but not limited to this.

[0049] The thickness of the first P-GaN layer 61 is 3-20 nm, and is exemplarily 5 nm, 8 nm, 11 nm, 14 nm, 17 nm, or 19 nm. The thickness of the second P-GaN layer 62 is 5-25 nm, and is exemplarily 7 nm, 10 nm, 13 nm, 16 nm, 19 nm, 22 nm, or 24 nm, but is not limited thereto. The thickness of the third P-GaN layer 63 is 5-35 nm, and is exemplarily 8 nm, 11 nm, 14 nm, 17 nm, 20 nm, 23 nm, 26 nm, 29 nm, or 32 nm, but is not limited thereto.

[0050] The substrate 1 may be a sapphire substrate, a silicon substrate, or a silicon carbide substrate, but is not limited thereto.

[0051] The buffer layer 2 may be an AlN layer, a GaN layer or an AlGaN layer, but is not limited thereto. Preferably, it is an AlGaN layer. The thickness of the buffer layer 2 is 10-50 nm. Exemplary thicknesses are 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 10 nm or 45 nm, but are not limited thereto.

[0052] The thickness of the U-GaN layer 3 is 1-4 μm, exemplarily 1.4 μm, 1.8 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3.2 μm, 3.5 μm or 3.8 μm, but not limited thereto.

[0053] The doping element of the N-GaN layer 4 is Si, but not limited thereto. The doping concentration of the N-GaN layer 4 is 4×10 18 -1×10 19 atom / cm 3 , and its thickness is 1-3 μm, and exemplary ones are 1.3 μm, 1.6 μm, 1.9 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm or 2.9 μm, but not limited thereto.

[0054] The multi-quantum well layer 5 is a periodic structure formed by multiple InGaN well layers and multiple GaN barrier layers, and the number of periods is 9 to 11. Specifically, the thickness of a single InGaN well layer is 2 to 5 nm, and the thickness of a single GaN barrier layer is 5 to 15 nm.

[0055] The P-type contact layer 7 is a heavily Mg-doped GaN layer, and its Mg doping concentration is 1×10 20 -8×10 20 atom / cm 3 , the thickness of the P-type contact layer 7 is 5-10 nm.

[0056] Accordingly, reference Figure 4 The present invention also discloses a method for preparing an epitaxial structure of a light emitting diode, which is used to prepare the epitaxial structure of the light emitting diode, and comprises the following steps:

[0057] S1: providing a substrate;

[0058] Specifically, the substrate is a sapphire substrate, a silicon substrate, or a silicon carbide substrate, but is not limited thereto. Preferably, it is a patterned sapphire substrate.

[0059] S2: sequentially growing a buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a P-GaN layer and a P-type contact layer on the substrate;

[0060] Specifically, S2 includes:

[0061] S21: growing a buffer layer on the substrate;

[0062] The buffer layer may be formed by PVD or MOCVD. Preferably, in one embodiment of the present invention, an AlGaN layer is grown by MOCVD as the buffer layer. The specific growth conditions are: growth temperature 770-840° C., growth pressure 100-200 torr.

[0063] S22: growing a U-GaN layer on the buffer layer;

[0064] In one embodiment of the present invention, U-GaN layers are sequentially grown in MOCVD, with specific growth conditions of: growth temperature of 1070-1220° C. and growth pressure of 150-250 torr.

[0065] S23: growing an N-GaN layer on the U-GaN layer;

[0066] Specifically, in one embodiment of the present invention, an N-GaN layer is grown in MOCVD, and specific growth conditions are: a growth temperature of 1050° C.-1150° C., and a growth pressure of 100-300 torr.

[0067] S24: growing a multi-quantum well layer on the N-GaN layer;

[0068] In one embodiment of the present invention, a multi-quantum well layer is grown in MOCVD. Specifically, an InGaN well layer and a GaN barrier layer are alternately grown on an N-GaN layer, and repeated for 9-11 cycles to obtain a multi-quantum well layer. The growth temperature of the InGaN well layer is 700-800°C, and the growth temperature of the GaN barrier layer is 800-900°C.

[0069] S25: growing a P-GaN layer on the multi-quantum well layer;

[0070] In one embodiment of the present invention, a P-GaN layer is grown in MOCVD at a growth temperature of 900-1100°C and a growth pressure of 150-250 torr. During the growth process, TMGa or TEGa is used as a Ga source, and NH 3 As the N source, di-tert-butylberyllium as the Be source, and oxygen as the O source.

[0071] Preferably, in one embodiment of the present invention, S25 includes:

[0072] S251: Growing the first P-GaN layer on the multi-quantum well layer

[0073] In one embodiment of the present invention, the first P-GaN layer is grown in MOCVD at a growth temperature of 900-1100°C and a growth pressure of 150-250 torr. During the growth process, TMGa or TEGa is used as a Ga source, and NH 3 As the N source, di-tert-butylberyllium was used as the Be source.

[0074] The growth atmosphere of the first P-GaN layer is hydrogen. Firstly, the hydrogen atmosphere can promote the lateral growth of the first GaN layer 251, which is more conducive to filling defects. Secondly, the high-energy active state of hydrogen can accelerate the decomposition of GaN with more defects and retain high-crystalline quality GaN.

[0075] S252: growing a second P-GaN layer on the first P-GaN layer;

[0076] In one embodiment of the present invention, the second P-GaN layer is grown in MOCVD at a growth temperature of 900-1100°C and a growth pressure of 150-250 torr. During the growth process, TMGa or TEGa is used as a Ga source, and NH 3 As an N source, di-tert-butyl beryllium as a Be source, and oxygen as an O source. The growth atmosphere of the second P-GaN layer is nitrogen.

[0077] Preferably, in another embodiment of the present invention, S25 includes:

[0078] S251: Growing the first P-GaN layer on the multi-quantum well layer

[0079] In one embodiment of the present invention, the first P-GaN layer is grown in MOCVD at a growth temperature of 900-1100°C, a growth pressure of 150-250 torr, and a growth atmosphere of hydrogen. During the growth process, TMGa or TEGa is used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium was used as the Be source.

[0080] S252: growing a second P-GaN layer on the first P-GaN layer;

[0081] In one embodiment of the present invention, the second P-GaN layer is grown in MOCVD at a growth temperature of 900-1100°C, a growth pressure of 150-250 torr, and a growth atmosphere of nitrogen. During the growth process, TMGa or TEGa is used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium as the Be source, and oxygen as the O source.

[0082] S253: growing a third P-GaN layer on the second P-GaN layer;

[0083] In one embodiment of the present invention, the third P-GaN layer is grown in MOCVD at a growth temperature of 900-1100°C and a growth pressure of 150-250 torr. During the growth process, TMGa or TEGa is used as the Ga source, and NH 3 As the N source, bismuth magnesium was used as the Mg source.

[0084] Specifically, the growth atmosphere of the third P-GaN layer is hydrogen and / or nitrogen, preferably hydrogen and nitrogen. By introducing nitrogen, the formation of Mg-H bonds can be reduced, the activation efficiency of Mg can be improved, and the hole concentration of the third P-GaN layer can be increased. Specifically, the volume ratio of hydrogen to nitrogen is (1.5-4):1.

[0085] S26: growing a P-type contact layer on the P-GaN layer;

[0086] In one embodiment of the present invention, a heavily Mg-doped GaN layer is grown in MOCVD as a P-type contact layer, and the specific growth conditions are: a growth temperature of 850-1000° C. and a growth pressure of 100-200 torr.

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

[0088] Example 1

[0089] This embodiment provides an epitaxial structure of a light emitting diode. Figure 1 The structure comprises a substrate 1 and a buffer layer 2, a U-GaN layer 3, an N-GaN layer 4, a multi-quantum well layer 5, a P-GaN layer 6 and a P-type contact layer sequentially grown on the substrate 1. The P-GaN layer 6 is an O and Be co-doped GaN layer, and the O doping concentration is 1.5×10 19 atom / cm 3 , the doping concentration of Be is 6×10 19 atom / cm 3 , the thickness of the P-GaN layer is 30nm.

[0090] The substrate 1 is a sapphire substrate, the buffer layer 2 is an AlGaN layer with a thickness of 12 nm, the thickness of the U-GaN layer 3 is 1.2 μm, and the doping concentration of Si in the N-GaN layer 4 is 5.2×10 18 atom / cm 3 , and its thickness is 1.8μm.

[0091] The multi-quantum well layer 5 is a periodic structure with a period number of 10 formed by multiple InGaN well layers and multiple GaN barrier layers. The thickness of a single InGaN well layer is 3.2 nm, and the thickness of a single GaN barrier layer is 10.2 nm. The P-type contact layer is a heavily Mg-doped GaN layer, and the Mg doping concentration is 5.9×10 20 atom / cm 3 , with a thickness of 6nm.

[0092] The method for preparing the epitaxial structure of a light emitting diode in this embodiment comprises the following steps:

[0093] (1) providing a substrate;

[0094] (2) growing a buffer layer on the substrate;

[0095] Specifically, an AlGaN layer is grown by MOCVD as a buffer layer, and the growth temperature is 780° C. and the growth pressure is 120 torr.

[0096] (3) growing a U-GaN layer on the buffer layer;

[0097] Specifically, the U-GaN layer is grown in MOCVD at a growth temperature of 1200° C. and a growth pressure of 200 torr.

[0098] (4) growing an N-GaN layer on the U-GaN layer;

[0099] Specifically, the N-GaN layer is grown in MOCVD at a growth temperature of 1120° C. and a growth pressure of 200 torr.

[0100] (5) growing a multi-quantum well layer on the N-GaN layer;

[0101] Specifically, InGaN well layers and GaN barrier layers are periodically grown in MOCVD as multi-quantum well layers, wherein the growth temperature of the InGaN well layers is 790° C. and the growth pressure is 200 torr; the growth temperature of the GaN barrier layers is 880° C. and the growth pressure is 200 torr.

[0102] (6) growing a P-GaN layer on the multi-quantum well layer;

[0103] Specifically, the P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of nitrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium as the Be source, and oxygen as the O source.

[0104] (7) growing a P-type contact layer on the P-GaN layer;

[0105] Specifically, the P-type contact layer is grown in MOCVD at a growth temperature of 900° C. and a growth pressure of 200 torr.

[0106] Example 2

[0107] This embodiment provides an epitaxial structure of a light emitting diode. Figure 2 , which includes a substrate 1 and a buffer layer 2, a U-GaN layer 3, an N-GaN layer 4, a multi-quantum well layer 5, a P-GaN layer 6 and a P-type contact layer sequentially grown on the substrate 1. The P-GaN layer 6 includes a first P-GaN layer 61 and a second P-GaN layer 62 sequentially stacked on the multi-quantum well layer 5. The first P-GaN layer 61 is a Be-doped GaN layer with a Be doping concentration of 8×10 18 atom / cm 3 The thickness of the first P-GaN layer is 5 nm; the second P-GaN layer 62 is an O and Be co-doped GaN layer, and the O doping concentration is 9×10 18 atom / cm 3 , the doping concentration of Be is 4×10 19 atom / cm 3 , the thickness of the second P-GaN layer 62 is 20 nm.

[0108] The substrate 1 is a sapphire substrate, the buffer layer 2 is an AlGaN layer with a thickness of 12 nm, the thickness of the U-GaN layer 3 is 1.2 μm, and the doping concentration of Si in the N-GaN layer 4 is 5.2×10 18 atom / cm 3 , and its thickness is 1.8μm.

[0109] The multi-quantum well layer 5 is a periodic structure with a period number of 10 formed by multiple InGaN well layers and multiple GaN barrier layers. The thickness of a single InGaN well layer is 3.2 nm, and the thickness of a single GaN barrier layer is 10.2 nm. The P-type contact layer is a heavily Mg-doped GaN layer, and the Mg doping concentration is 5.9×10 20 atom / cm 3 , with a thickness of 6nm.

[0110] The method for preparing the epitaxial structure of a light emitting diode in this embodiment comprises the following steps:

[0111] (1) providing a substrate;

[0112] (2) growing a buffer layer on the substrate;

[0113] Specifically, an AlGaN layer is grown by MOCVD as a buffer layer, and the growth temperature is 780° C. and the growth pressure is 120 torr.

[0114] (3) growing a U-GaN layer on the buffer layer;

[0115] Specifically, the U-GaN layer is grown in MOCVD at a growth temperature of 1200° C. and a growth pressure of 200 torr.

[0116] (4) growing an N-GaN layer on the U-GaN layer;

[0117] Specifically, the N-GaN layer is grown in MOCVD at a growth temperature of 1120° C. and a growth pressure of 200 torr.

[0118] (5) growing a multi-quantum well layer on the N-GaN layer;

[0119] Specifically, InGaN well layers and GaN barrier layers are periodically grown in MOCVD as multi-quantum well layers, wherein the growth temperature of the InGaN well layers is 790° C. and the growth pressure is 200 torr; the growth temperature of the GaN barrier layers is 880° C. and the growth pressure is 200 torr.

[0120] (6) growing a first P-GaN layer on the multi-quantum well layer;

[0121] Specifically, the first P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of hydrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium was used as the Be source.

[0122] (7) growing a second P-GaN layer on the first P-GaN layer;

[0123] Specifically, the second P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of nitrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium as the Be source, and oxygen as the O source.

[0124] (8) growing a P-type contact layer on the second P-GaN layer;

[0125] Specifically, the P-type contact layer is grown in MOCVD at a growth temperature of 900° C. and a growth pressure of 200 torr.

[0126] Example 3

[0127] This embodiment provides an epitaxial structure of a light emitting diode. Figure 3 , which includes a substrate 1 and a buffer layer 2, a U-GaN layer 3, an N-GaN layer 4, a multi-quantum well layer 5, a P-GaN layer 6 and a P-type contact layer sequentially grown on the substrate 1. Among them, the P-GaN layer 6 includes a first P-GaN layer 61, a second P-GaN layer 62 and a third P-GaN layer sequentially stacked on the multi-quantum well layer 5, and the first P-GaN layer 61 is a Be-doped GaN layer with a Be doping concentration of 8×10 18 atom / cm 3 The thickness of the first P-GaN layer is 5 nm; the second P-GaN layer 62 is an O and Be co-doped GaN layer, and the O doping concentration is 3×10 19 atom / cm 3 , the doping concentration of Be is 7×10 19 atom / cm 3 The thickness of the second P-GaN layer 62 is 8 nm. The third P-GaN layer 63 is a Mg-doped GaN layer with a Mg doping concentration of 7×10 19 atom / cm 3 , the thickness of the third P-GaN layer 63 is 10 nm.

[0128] The substrate 1 is a sapphire substrate, the buffer layer 2 is an AlGaN layer with a thickness of 12 nm, the thickness of the U-GaN layer 3 is 1.2 μm, and the doping concentration of Si in the N-GaN layer 4 is 5.2×10 18 atom / cm 3 , and its thickness is 1.8μm.

[0129] The multi-quantum well layer 5 is a periodic structure with a period number of 10 formed by multiple InGaN well layers and multiple GaN barrier layers. The thickness of a single InGaN well layer is 3.2 nm, and the thickness of a single GaN barrier layer is 10.2 nm. The P-type contact layer is a heavily Mg-doped GaN layer, and the Mg doping concentration is 5.9×10 20 atom / cm 3 , with a thickness of 6nm.

[0130] The method for preparing the epitaxial structure of a light emitting diode in this embodiment comprises the following steps:

[0131] (1) providing a substrate;

[0132] (2) growing a buffer layer on the substrate;

[0133] Specifically, an AlGaN layer is grown by MOCVD as a buffer layer, and the growth temperature is 780° C. and the growth pressure is 120 torr.

[0134] (3) growing a U-GaN layer on the buffer layer;

[0135] Specifically, the U-GaN layer is grown in MOCVD at a growth temperature of 1200° C. and a growth pressure of 200 torr.

[0136] (4) growing an N-GaN layer on the U-GaN layer;

[0137] Specifically, the N-GaN layer is grown in MOCVD at a growth temperature of 1120° C. and a growth pressure of 200 torr.

[0138] (5) growing a multi-quantum well layer on the N-GaN layer;

[0139] Specifically, InGaN well layers and GaN barrier layers are periodically grown in MOCVD as multi-quantum well layers, wherein the growth temperature of the InGaN well layers is 790° C. and the growth pressure is 200 torr; the growth temperature of the GaN barrier layers is 880° C. and the growth pressure is 200 torr.

[0140] (6) growing a first P-GaN layer on the multi-quantum well layer;

[0141] Specifically, the first P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of hydrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium was used as the Be source.

[0142] (7) growing a second P-GaN layer on the first P-GaN layer;

[0143] Specifically, the second P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of nitrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium as the Be source, and oxygen as the O source.

[0144] (8) growing a third P-GaN layer on the second P-GaN layer;

[0145] Specifically, the third P-GaN layer is grown in MOCVD at a growth temperature of 1000° C., a growth pressure of 200 torr, and a growth atmosphere of a mixture of nitrogen and hydrogen (H 2 :N 2 =3:1, volume ratio). During the growth process, TMGa was used as Ga source, NH 3 As the N source, bismuth magnesium was used as the Mg source.

[0146] (9) growing a P-type contact layer on the second P-GaN layer;

[0147] Specifically, the P-type contact layer is grown in MOCVD at a growth temperature of 900° C. and a growth pressure of 200 torr.

[0148] Example 4

[0149] This embodiment provides an epitaxial structure of a light emitting diode. Figure 3 , which includes a substrate 1 and a buffer layer 2, a U-GaN layer 3, an N-GaN layer 4, a multi-quantum well layer 5, a P-GaN layer 6 and a P-type contact layer sequentially grown on the substrate 1. Among them, the P-GaN layer 6 includes a first P-GaN layer 61, a second P-GaN layer 62 and a third P-GaN layer sequentially stacked on the multi-quantum well layer 5, and the first P-GaN layer 61 is a Be-doped GaN layer with a Be doping concentration of 8×10 18 atom / cm 3 The thickness of the first P-GaN layer is 5 nm; the second P-GaN layer 62 is an O and Be co-doped GaN layer, and the O doping concentration is 3×10 19 atom / cm 3 , the doping concentration of Be is 2.5×10 19 atom / cm 3 The thickness of the second P-GaN layer 62 is 8 nm. The third P-GaN layer 63 is a Mg-doped GaN layer with a Mg doping concentration of 7×10 19 atom / cm 3 , the thickness of the third P-GaN layer 63 is 10 nm.

[0150] The substrate 1 is a sapphire substrate, the buffer layer 2 is an AlGaN layer with a thickness of 12 nm, the thickness of the U-GaN layer 3 is 1.2 μm, and the doping concentration of Si in the N-GaN layer 4 is 5.2×10 18 atom / cm 3 , and its thickness is 1.8μm.

[0151] The multi-quantum well layer 5 is a periodic structure with a period number of 10 formed by multiple InGaN well layers and multiple GaN barrier layers. The thickness of a single InGaN well layer is 3.2 nm, and the thickness of a single GaN barrier layer is 10.2 nm. The P-type contact layer is a heavily Mg-doped GaN layer, and the Mg doping concentration is 5.9×10 20 atom / cm 3 , with a thickness of 6nm.

[0152] The method for preparing the epitaxial structure of a light emitting diode in this embodiment comprises the following steps:

[0153] (1) providing a substrate;

[0154] (2) growing a buffer layer on the substrate;

[0155] Specifically, an AlGaN layer is grown by MOCVD as a buffer layer, and the growth temperature is 780° C. and the growth pressure is 120 torr.

[0156] (3) growing a U-GaN layer on the buffer layer;

[0157] Specifically, the U-GaN layer is grown in MOCVD at a growth temperature of 1200° C. and a growth pressure of 200 torr.

[0158] (4) growing an N-GaN layer on the U-GaN layer;

[0159] Specifically, the N-GaN layer is grown in MOCVD at a growth temperature of 1120° C. and a growth pressure of 200 torr.

[0160] (5) growing a multi-quantum well layer on the N-GaN layer;

[0161] Specifically, InGaN well layers and GaN barrier layers are periodically grown in MOCVD as multi-quantum well layers, wherein the growth temperature of the InGaN well layers is 790° C. and the growth pressure is 200 torr; the growth temperature of the GaN barrier layers is 880° C. and the growth pressure is 200 torr.

[0162] (6) growing a first P-GaN layer on the multi-quantum well layer;

[0163] Specifically, the first P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of hydrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium was used as the Be source.

[0164] (7) growing a second P-GaN layer on the first P-GaN layer;

[0165] Specifically, the second P-GaN layer was grown in MOCVD at a growth temperature of 1000°C, a growth pressure of 200 torr, and a growth atmosphere of nitrogen. During the growth process, TMGa was used as the Ga source, and NH 3 As the N source, di-tert-butylberyllium as the Be source, and oxygen as the O source.

[0166] (8) growing a third P-GaN layer on the second P-GaN layer;

[0167] Specifically, the third P-GaN layer is grown in MOCVD at a growth temperature of 1000° C., a growth pressure of 200 torr, and a growth atmosphere of a mixture of nitrogen and hydrogen (H 2 :N 2 =3:1, volume ratio). During the growth process, TMGa was used as Ga source, NH 3 As the N source, bismuth magnesium was used as the Mg source.

[0168] (9) growing a P-type contact layer on the second P-GaN layer;

[0169] Specifically, the P-type contact layer is grown in MOCVD at a growth temperature of 900° C. and a growth pressure of 200 torr.

[0170] Comparative Example 1

[0171] The difference between this comparative example and Example 1 is:

[0172] 1. An electron blocking layer (AlGaN layer) is provided between the multi-quantum well layer and the P-GaN layer. The thickness of the layer is 80 nm. The layer is grown by MOCVD at a growth temperature of 950° C. and a growth pressure of 100 torr.

[0173] 2. The doping element in the P-GaN layer is Mg, and the doping concentration is 8.5×10 18 cm -3 .

[0174] The rest are the same as in Example 1.

[0175] Comparative Example 2

[0176] The difference between this comparative example and Example 1 is that the doping concentration of O in the P-GaN layer 6 is 8×10 19 atom / cm 3 , the rest are the same as in Example 1.

[0177] Comparative Example 3

[0178] The difference between this comparative example and Example 1 is that the doping concentration of O in the P-GaN layer 6 is 4×10 18 atom / cm 3 , the rest are the same as in Example 1.

[0179] Comparative Example 4

[0180] The difference between this comparative example and Example 1 is that O doping is not provided in the P-GaN layer 6 , and the rest is the same as Example 1.

[0181] Comparative Example 5

[0182] The difference between this comparative example and Example 1 is that Mg doping is used in the P-GaN layer 6 instead of Be doping, and the rest is the same as Example 1.

[0183] The epitaxial wafers obtained in Examples 1-4 and Comparative Examples 1-5 were processed into 10×24mil LED chips with a vertical structure, and their antistatic ability and luminous brightness were tested;

[0184] The specific test method of the chip is:

[0185] (1) Antistatic performance test: The antistatic performance of the base chip is tested using an electrostatic meter under the HBM (Human Body Model) model to test the pass rate of the chip that can withstand reverse 6000V static electricity;

[0186] (2) Brightness: When the current is 120 mA, the luminous intensity of the chip is tested;

[0187] The specific test results are shown in the following table:

[0188]

[0189]

[0190] It can be seen from the table that when the traditional electron blocking layer + P-GaN layer (doped with Mg) in Comparative Example 1 is changed to the O, Be co-doped P-GaN layer of the present invention, the brightness and antistatic ability are effectively improved.

[0191] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. An epitaxial structure of a light emitting diode, characterized in that: It comprises a substrate and a buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a P-GaN layer and a P-type contact layer which are sequentially stacked on the substrate; The P-GaN layer includes a first P-GaN layer and a second P-GaN layer sequentially stacked on the multi-quantum well layer, the first P-GaN layer is an undoped P-GaN layer or a Be-doped GaN layer, and the second P-GaN layer is an O and Be co-doped GaN layer; The doping concentration of Be in the first P-GaN layer is less than the doping concentration of Be in the second P-GaN layer.

2. The epitaxial structure of a light emitting diode according to claim 1, characterized in that: The first P-GaN layer is a Be-doped GaN layer, and the Be doping concentration is 1×10 18 -1×10 19 atom / cm 3 ; The doping concentration of O in the second P-GaN layer is 5×10 18 -1×10 19 atom / cm 3 , the doping concentration of Be is 1×10 19 -8×10 19 atom / cm 3 .

3. The epitaxial structure of a light emitting diode according to claim 1 or 2, characterized in that: The thickness of the first P-GaN layer is 3-20 nm, and the thickness of the second P-GaN layer is 5-40 nm.

4. A method for preparing an epitaxial structure of a light emitting diode, for preparing the epitaxial structure of a light emitting diode as claimed in any one of claims 1 to 3, characterized in that: include: Providing a substrate, and sequentially growing a buffer layer, a U-GaN layer, an N-GaN layer, a multi-quantum well layer, a P-GaN layer and a P-type contact layer on the substrate; The P-GaN layer includes a first P-GaN layer and a second P-GaN layer sequentially stacked on the multi-quantum well layer, the first P-GaN layer is an undoped P-GaN layer or a Be-doped GaN layer, and the second P-GaN layer is an O and Be co-doped GaN layer; The doping concentration of Be in the first P-GaN layer is less than the doping concentration of Be in the second P-GaN layer.

5. The method for preparing the epitaxial structure of a light emitting diode according to claim 4, characterized in that: The P-GaN layer is grown in a nitrogen atmosphere at a growth temperature of 900-1100° C. and a growth pressure of 150-250 torr.

6. A light emitting diode, characterized in that: It comprises the epitaxial structure of the light emitting diode as claimed in any one of claims 1 to 3.

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