Light-emitting diode epitaxial wafer and preparation method thereof, and light-emitting diode

Abstract

The present invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and a light-emitting diode, and relates to the field of semiconductor optoelectronic devices. The light-emitting diode epitaxial wafer includes a substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer, and a P-type GaN layer in sequence; the multi-quantum well layer includes a first multi-quantum well layer, a final well layer, and a final barrier layer in sequence, the first multi-quantum well layer includes a quantum well layer and a quantum barrier layer, and the final barrier layer includes an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer, and a second boron-containing nitride layer in sequence; the superlattice layer includes an AlGaN layer and a Mg-doped GaN layer that are alternately stacked; the first boron-containing nitride layer and the second boron-containing nitride layer are BGaN layers and / or BInGaN layers, both of which are doped with Mg, and their Mg doping concentration is greater than the doping concentration of the Mg-doped GaN layer. The implementation of the present invention can improve the luminous efficiency of the light-emitting diode.

Description

Technical Field

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

[0002] The general structure of GaN-based light-emitting diode epitaxial wafers is: substrate, buffer layer, N-type GaN layer, InGaN-GaN multi-quantum well layer, electron blocking layer and P-type GaN layer stacked from bottom to top. Since the concentrations of electrons and holes in the multi-quantum well layer are different, and the mobility of the two is also quite different, it is easy for electrons to leak from the multi-quantum well layer and enter the P-type GaN layer. Its energy is eventually converted into heat energy, causing carrier loss and reducing luminous efficiency. In addition, the electron blocking layer not only blocks electrons, but also reduces the efficiency of hole injection into the multi-quantum well layer. Both of these reduce the 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 a light emitting diode epitaxial wafer and a preparation method thereof, which can improve the light emitting efficiency of the light emitting diode.

[0004] In order to solve the above problems, the present invention discloses a light-emitting diode epitaxial wafer, which comprises a substrate, a buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially stacked on the substrate;

[0005] The multi-quantum well layer comprises a first multi-quantum well layer, a final well layer and a final barrier layer sequentially stacked on the N-type GaN layer, the first multi-quantum well layer is a periodic structure formed by alternating stacking of quantum well layers and quantum barrier layers, the quantum well layer and the final well layer are both InGaN quantum well layers, and the quantum barrier layer is a GaN quantum barrier layer;

[0006] The final barrier layer comprises an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer and a second boron-containing nitride layer which are sequentially stacked on the final well layer;

[0007] The superlattice layer includes an AlGaN layer and a Mg-doped GaN layer stacked alternately;

[0008] The first boron-containing nitride layer and the second boron-containing nitride layer are BGaN layers and / or BInGaN layers. Both the first boron-containing nitride layer and the second boron-containing nitride layer are doped with Mg, and their Mg doping concentrations are greater than the Mg doping concentration of the Mg-doped GaN layer.

[0009] As an improvement of the above technical solution, the bandgap width of the first boron-containing nitride layer is greater than the bandgap width of the second boron-containing nitride layer.

[0010] As an improvement of the above technical solution, along the growth direction of the light-emitting diode epitaxial wafer, the proportion of Al component in the AlInGaN layer gradually increases, and the proportion of In component gradually decreases.

[0011] As an improvement of the above technical solution, the number of periods of the superlattice layer is ≥3;

[0012] The thickness ratio of the AlGaN layer to the Mg-doped GaN layer is 1:1 to 1:8;

[0013] The Al component ratio in the AlGaN layer is ≤0.15.

[0014] As an improvement of the above technical solution, the thickness of the AlN layer is ≤5 nm.

[0015] As an improvement of the above technical solution, the ratio of the thickness of the first boron-containing nitride layer to the thickness of the second boron-containing nitride layer is 1:2-1:6.

[0016] As an improvement of the above technical solution, the Al component ratio in the AlInGaN layer is 0.01-0.1, the In component ratio is 0.03-0.1, and the thickness is 1nm-3nm;

[0017] The number of periods of the superlattice layer is 4-10, and its thickness is 10nm-50nm. The Al component ratio in the AlGaN layer is 0.01-0.1; the Mg doping concentration in the Mg-doped GaN layer is 1×10 18 cm -3 ~1×10 19 cm -3 ;

[0018] The thickness of the AlN layer is 0.5 nm to 4.5 nm;

[0019] The B component ratio in the first boron-containing nitride layer is 0.05-0.15, the thickness is 3nm-25nm, and the Mg doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 ;

[0020] The B component ratio in the second boron-containing nitride layer is 0.01-0.1, the thickness is 10 nm-70 nm, and the Mg doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 .

[0021] Correspondingly, the present invention also discloses a method for preparing a light emitting diode epitaxial wafer, which is used to prepare the above-mentioned light emitting diode epitaxial wafer, and comprises:

[0022] Providing a substrate, and sequentially growing a buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer, and a P-type GaN layer on the substrate;

[0023] The multi-quantum well layer comprises a first multi-quantum well layer, a final well layer and a final barrier layer sequentially stacked on the N-type GaN layer, the first multi-quantum well layer is a periodic structure formed by alternating stacking of quantum well layers and quantum barrier layers, the quantum well layer and the final well layer are both InGaN quantum well layers, and the quantum barrier layer is a GaN quantum barrier layer;

[0024] The final barrier layer comprises an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer and a second boron-containing nitride layer which are sequentially stacked on the final well layer;

[0025] The superlattice layer includes an AlGaN layer and a Mg-doped GaN layer stacked alternately;

[0026] The first boron-containing nitride layer and the second boron-containing nitride layer are both BGaN layers and / or BInGaN layers. The first boron-containing nitride layer and the second boron-containing nitride layer are both doped with Mg, and their Mg doping concentrations are greater than the Mg doping concentration of the Mg-doped GaN layer.

[0027] As an improvement of the above technical solution, the growth temperature of the AlInGaN layer is 800° C. to 1000° C., and the growth pressure is 50 torr to 500 torr;

[0028] The growth temperature of the superlattice layer is 800° C. to 1000° C., and the growth pressure is 50 torr to 500 torr;

[0029] The growth temperature of the AlN layer is 650° C. to 800° C., and the growth pressure is 50 torr to 500 torr;

[0030] The growth temperature of the first boron nitride layer is 1000° C. to 1100° C., and the growth pressure is 50 torr to 500 torr;

[0031] The growth temperature of the second boron nitride layer is 900° C. to 1050° C., and the growth pressure is 50 torr to 500 torr.

[0032] Correspondingly, the present invention also discloses a light emitting diode, which comprises the light emitting diode epitaxial wafer mentioned above.

[0033] The implementation of the present invention has the following beneficial effects:

[0034] In the light-emitting diode epitaxial wafer of one embodiment of the present invention, the AlInGaN layer, the superlattice layer, the AlN layer, the first boron-containing nitride layer and the second boron-containing nitride layer stacked in sequence on the final well layer are used as the final barrier layer. Among them, the AlInGaN layer introduces the In component, which reduces the lattice mismatch between the final well layer and the final barrier layer, weakens the piezoelectric polarization effect, and improves the recombination efficiency of electrons and holes in the multi-quantum well layer. The superlattice layer includes an AlGaN layer and a Mg-doped GaN layer stacked alternately. The AlGaN layer can improve the potential barrier of the final barrier layer and reduce the probability of electrons overflowing the multi-quantum well layer. The Mg-doped GaN layer can improve the hole injection efficiency. Moreover, by adopting a superlattice structure, the strong polarization effect generated by the AlGaN material can be weakened, and the recombination efficiency of electrons and holes in the multi-quantum well layer can be improved. Boron is introduced into the first boron-containing nitride layer and the second boron-containing nitride layer, which increases the potential barrier and further reduces the probability of electron overflow. In addition, the first boron-containing nitride layer and the second boron-containing nitride layer are doped with Mg. Since boron can reduce the activation energy of Mg, the concentration of effective holes in the first boron-containing nitride layer and the second boron-containing nitride layer is increased. Therefore, based on the light-emitting diode epitaxial wafer of this embodiment, electron overflow can be reduced, the efficiency of hole injection into the multi-quantum well layer can be improved, thereby increasing the recombination probability of electrons and holes in the multi-quantum well layer and improving the luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of a light emitting diode epitaxial wafer in one embodiment of the present invention;

[0036] Figure 2 is a schematic structural diagram of a superlattice layer in one embodiment of the present invention;

[0037] Figure 3 It is a flow chart of a method for preparing a light emitting diode epitaxial wafer in one embodiment of the present invention. DETAILED DESCRIPTION

[0038] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation or embodiment, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0040] See also Figure 1 , Figure 2As a first aspect of the present invention, the present invention discloses a light emitting diode epitaxial wafer, which includes a substrate 100, a buffer layer 200, a non-doped GaN layer 300, an N-type GaN layer 400, a multi-quantum well layer 500, an electron blocking layer 600 and a P-type GaN layer 700 sequentially stacked on the substrate 100. Among them, the multi-quantum well layer 500 includes a first multi-quantum well layer 510, a final well layer 520 and a final barrier layer 530 sequentially stacked on the N-type GaN layer 400; the first multi-quantum well layer 510 is a periodic structure composed of quantum well layers 511 and quantum barrier layers 512 alternately stacked. The final barrier layer 530 includes an AlInGaN layer 531, a superlattice layer 532, an AlN layer 533, a first boron-containing nitride layer 534, and a second boron-containing nitride layer 535 sequentially stacked on the final well layer 520; the superlattice layer 532 includes an AlGaN layer 5321 and a Mg-doped GaN layer 5322 alternately stacked; the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both BGaN layers and / or BInGaN layers, and the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both doped with Mg, and their Mg doping concentrations are both greater than the Mg doping concentration of the Mg-doped GaN layer 5322. Specifically, the AlInGaN layer 531 introduces an In component, which reduces the lattice mismatch between the final well layer 520 and the final barrier layer 530, weakens the piezoelectric polarization effect, and improves the recombination efficiency of electrons and holes in the multi-quantum well layer 500. The AlGaN layer 5321 can improve the potential barrier of the last barrier layer 530 and reduce the probability of electrons overflowing the multi-quantum well layer 500. The Mg-doped GaN layer 5322 can improve the hole injection efficiency. Moreover, the strong polarization effect generated by the AlGaN material can be weakened by adopting a superlattice structure, thereby improving the recombination efficiency of electrons and holes in the multi-quantum well layer 500. Boron is introduced into the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535, thereby improving the potential barrier and further reducing the probability of electron overflow. Moreover, the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both doped with Mg. Since boron can reduce the activation energy of Mg, the concentration of effective holes in the first boron-containing nitride layer and the second boron-containing nitride layer is improved. Therefore, based on the light-emitting diode epitaxial wafer of this embodiment, electron overflow can be reduced, the efficiency of hole injection into the multi-quantum well layer 500 can be improved, thereby improving the recombination probability of electrons and holes in the multi-quantum well layer 500 and improving the luminous efficiency.

[0041] Specifically, in some embodiments, the Al component ratio in the AlInGaN layer 531 is 0.01-0.15, exemplarily 0.03, 0.05, 0.07, 0.09, 0.11 or 0.13, but not limited thereto, preferably 0.01-0.1.

[0042] Specifically, in some embodiments, the In component ratio in the AlInGaN layer 531 is 0.01-0.2, exemplarily 0.03, 0.05, 0.07, 0.09, 0.11, 0.13, 0.15, 0.17 or 0.19, but not limited thereto, preferably 0.03-0.1.

[0043] Specifically, in some embodiments, the thickness of the AlInGaN layer 531 is 0.5 nm to 5 nm, exemplarily 0.8 nm, 1.5 nm, 2.2 nm, 2.9 nm, 3.6 nm or 4.3 nm, but not limited thereto, preferably 1 nm to 3 nm.

[0044] Specifically, in some embodiments, the period number of the superlattice layer 532 is ≥ 3 to weaken the polarization effect. More specifically, the period number of the superlattice is 3 to 10, exemplarily 4, 5, 6, 7 or 8, but not limited thereto. Preferably, it is 4 to 10.

[0045] Specifically, in some embodiments, the thickness of the superlattice layer 532 is 5 nm to 60 nm, illustratively 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm or 55 nm, but not limited thereto, preferably 10 nm to 50 nm.

[0046] Specifically, in some embodiments, the Al component ratio in the AlGaN layer 5321 is 0.01-0.2, and exemplary ratios are 0.03, 0.07, 0.11, 0.15 or 0.19, but not limited thereto.

[0047] Specifically, in some embodiments, the thickness ratio of the AlGaN layer 5321 to the Mg-doped GaN layer 5322 is 1:(1-10), exemplarily 1:3, 1:5, 1:7 or 1:9, but not limited thereto.

[0048] Specifically, in some embodiments, the Mg doping concentration in the Mg-doped GaN layer 5322 is 1×10 18 cm -3 ~5×10 19 cm -3 , exemplarily 3×10 18 cm -3 , 5×10 18 cm -3 ,7×10 18 cm -3 , 1×10 19 cm -3 or 3×10 19 cm -3 , but not limited to this. Preferably 1×1018 cm -3 ~1×10 19 cm -3 .

[0049] Specifically, in some embodiments, the thickness of the AlN layer 533 is ≤5 nm, so that holes tunnel through the layer to avoid affecting hole injection. More specifically, the thickness of the AlN layer 533 is 0.5 nm to 5 nm, exemplarily 0.8 nm, 1.5 nm, 2.3 nm, 3.1 nm, 3.6 nm or 4.2 nm, but not limited thereto. Preferably, the thickness of the AlN layer 533 is 0.5 nm to 4.5 nm.

[0050] Specifically, in some embodiments, the B component in the first boron-containing nitride layer 534 has a ratio of 0.05 to 0.2, exemplarily 0.08, 0.11, 0.13, 0.15 or 0.17, but not limited thereto, preferably 0.05 to 0.15.

[0051] Specifically, in some embodiments, the thickness of the first boron-containing nitride layer 534 is 1 nm to 30 nm, illustratively 5 nm, 10 nm, 15 nm, 20 nm or 25 nm, but not limited thereto, preferably 3 nm to 25 nm.

[0052] Specifically, the first boron-containing nitride layer 534 is doped with Mg, and the Mg doping concentration is greater than the Mg doping concentration of the Mg-doped GaN layer 5322. Based on this embodiment, more effective holes can be obtained to improve the luminous efficiency. Specifically, the Mg doping concentration of the first boron-containing nitride layer 534 is 5×10 18 cm -3 ~1×10 21 cm -3 , exemplarily 7×10 18 cm -3 , 1×10 19 cm -3 , 4×10 19 cm -3 , 8×10 19 cm -3 , 3×10 20 cm -3 ,7×10 20 cm -3 , but not limited to this. Preferably 1×10 19 cm -3 ~1×10 21 cm -3 .

[0053] Specifically, in some embodiments, the B component in the second boron-containing nitride layer 535 has a ratio of 0.01 to 0.15, exemplarily 0.03, 0.04, 0.08, 0.11, 0.13 or 0.14, but not limited thereto, preferably 0.01 to 0.1.

[0054] Specifically, in some embodiments, the thickness of the second boron-containing nitride layer 535 is 5 nm to 80 nm, illustratively 8 nm, 20 nm, 32 nm, 44 nm, 56 nm, 68 nm or 75 nm, but not limited thereto, preferably 10 nm to 70 nm.

[0055] Specifically, the second boron-containing nitride layer 535 is doped with Mg, and the Mg doping concentration is greater than the Mg doping concentration of the Mg-doped GaN layer 5322. Based on this embodiment, more effective holes can be obtained to improve the luminous efficiency. Specifically, the Mg doping concentration of the second boron-containing nitride layer 535 is 5×10 18 cm -3 ~1×10 21 cm -3 , exemplarily 7×10 18 cm -3 , 1×10 19 cm -3 , 4×10 19 cm -3 , 8×10 19 cm -3 , 3×10 20 cm -3 ,7×10 20 cm -3 , but not limited to this. Preferably 1×10 19 cm -3 ~1×10 21 cm -3 .

[0056] Specifically, in some embodiments, the substrate 100 is a sapphire substrate, a silicon substrate or a silicon carbide substrate, but is not limited thereto. Preferably, it is a sapphire substrate.

[0057] Specifically, in some embodiments, the buffer layer 200 is an AlN layer or an AlGaN layer, but is not limited thereto. Preferably, it is an AlN layer. The thickness of the buffer layer 200 is 20 nm to 80 nm.

[0058] Specifically, in some embodiments, the thickness of the undoped GaN layer 300 is 1 μm to 3 μm.

[0059] Specifically, in some embodiments, the N-type doping (Si) concentration in the N-type GaN layer 400 is 5×10 18cm -3 ~5×10 19 cm -3 , thickness is 1μm~5μm.

[0060] Specifically, in some embodiments, the quantum well layer 511 and the end well layer 520 are both InGaN quantum well layers, the In component ratio of the InGaN quantum well layer is 0.15-0.35, and the thickness is 2nm-5nm. The quantum barrier layer 512 is a GaN quantum barrier layer, and the thickness of the quantum barrier layer 512 is 5nm-15nm. The number of periods of the first multi-quantum well layer is 3-15.

[0061] Specifically, in some embodiments, the electron blocking layer 600 is an AlGaN layer or an AlInGaN layer, but is not limited thereto. Preferably, it is an AlInGaN layer, wherein the Al component ratio is 0.01-0.1, the In component ratio is 0.02-0.2, and the thickness is 10nm-40nm.

[0062] Specifically, in some embodiments, the Mg doping concentration in the P-type GaN layer 700 is 1×10 19 cm -3 ~1×10 21 cm -3 , and its thickness is 50nm~200nm.

[0063] It should be noted that the light emitting diode epitaxial wafer in the present invention may also include a stress release layer, a P-type contact layer, etc. commonly used in the art, but is not limited thereto.

[0064] Preferably, in some embodiments, the bandgap width of the first boron-containing nitride layer 534 is greater than the bandgap width of the second boron-containing nitride layer 535. Based on this structure, not only the probability of electrons overflowing the multi-quantum well layer 500 can be further reduced, but also the hole injection efficiency can be improved, and the luminescence efficiency can be improved. Specifically, the control of the bandgap width can be achieved by controlling the B component. For example, when the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both BGaN layers, the proportion of the B component in the first boron-containing nitride layer 534 is controlled to be greater than the proportion of the B component in the second boron-containing nitride layer 535, so that the bandgap width of the first boron-containing nitride layer 534 is greater than the bandgap width of the second boron-containing nitride layer 535. Similarly, the bandgap width can also be controlled by controlling the specific components of the two. For example, the first boron-containing nitride layer 534 can be a BGaN layer, and the second boron-containing nitride layer 535 can be a BInGaN layer. In this way, even if the proportion of B components in the two is the same, the bandgap width of the first boron-containing nitride layer 534 can be greater than the bandgap width of the second boron-containing nitride layer 535.

[0065] Preferably, in some embodiments, along the growth direction of the light-emitting diode epitaxial wafer, the Al component ratio in the AlInGaN layer 531 gradually increases, and the In component ratio gradually decreases. Based on this change in composition, the lattice mismatch between the final well layer 520 and the final barrier layer 530 can be further reduced, the polarization effect can be weakened, and the luminous efficiency can be improved.

[0066] Preferably, in some embodiments, the thickness ratio of the AlGaN layer 5321 to the Mg-doped GaN layer 5322 is 1:1-1:8; and the Al component ratio in the AlGaN layer 5321 is ≤0.15. By controlling the Al component ratio and thickness in the AlGaN layer 5321, the blocking of electrons can be further improved, the polarization effect can be weakened, and the luminous efficiency can be improved. More preferably, the Al component ratio in the AlGaN layer 5321 is 0.01-0.15, and further preferably 0.01-0.1.

[0067] Preferably, in some embodiments, the ratio of the thickness of the first boron-containing nitride layer 534 to the thickness of the second boron-containing nitride layer 535 is 1:(2-6). Based on this thickness ratio, the hole injection efficiency can be further improved, and the luminous efficiency can be improved.

[0068] See also Figure 3 As a second aspect of the present invention, the present invention also provides a method for preparing a light-emitting diode epitaxial wafer, which is used to prepare the above-mentioned light-emitting diode epitaxial wafer, and specifically comprises the following steps:

[0069] S1: providing a substrate;

[0070] S2: sequentially growing a buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer on the substrate;

[0071] The multi-quantum well layer 500 includes a first multi-quantum well layer 510, a final well layer 520 and a final barrier layer 530 sequentially stacked on the N-type GaN layer 400; the first multi-quantum well layer 510 is a periodic structure composed of quantum well layers 511 and quantum barrier layers 512 alternately stacked. The final barrier layer 530 includes an AlInGaN layer 531, a superlattice layer 532, an AlN layer 533, a first boron-containing nitride layer 534, and a second boron-containing nitride layer 535 sequentially stacked on the final well layer 520; the superlattice layer 532 includes an AlGaN layer 5321 and a Mg-doped GaN layer 5322 alternately stacked; the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both BGaN layers and / or BInGaN layers, and the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both doped with Mg, and their Mg doping concentrations are both greater than the Mg doping concentration of the Mg-doped GaN layer 5322. Specifically, the AlInGaN layer 531 introduces an In component, which reduces the lattice mismatch between the final well layer 520 and the final barrier layer 530, weakens the piezoelectric polarization effect, and improves the recombination efficiency of electrons and holes in the multi-quantum well layer 500. The AlGaN layer 5321 can improve the potential barrier of the last barrier layer 530 and reduce the probability of electrons overflowing the multi-quantum well layer 500. The Mg-doped GaN layer 5322 can improve the hole injection efficiency. Moreover, the strong polarization effect generated by the AlGaN material can be weakened by adopting a superlattice structure, thereby improving the recombination efficiency of electrons and holes in the multi-quantum well layer 500. Boron is introduced into the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535, thereby improving the potential barrier and further reducing the probability of electron overflow. Moreover, the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both doped with Mg. Since boron can reduce the activation energy of Mg, the concentration of effective holes in the first boron-containing nitride layer and the second boron-containing nitride layer is improved. Therefore, the light-emitting diode epitaxial wafer prepared by the method for preparing the light-emitting diode epitaxial wafer of this embodiment can reduce electron overflow and improve the efficiency of hole injection into the multi-quantum well layer 500, thereby improving the recombination probability of electrons and holes in the multi-quantum well layer 500 and improving the luminescence efficiency.

[0072] Specifically, in some embodiments, step S2 includes:

[0073] S21: growing a buffer layer on the substrate;

[0074] The buffer layer may be grown by PVD, MOCVD, MBE or VPE, but is not limited thereto.

[0075] Preferably, in some embodiments, an AlN layer is grown by PVD to serve as a buffer layer.

[0076] S22: growing a non-doped GaN layer on the buffer layer;

[0077] The non-doped GaN layer may be grown by PVD, MOCVD, MBE or VPE, but is not limited thereto.

[0078] Preferably, in some embodiments, the non-doped GaN layer is grown by MOCVD at a growth temperature of 1100° C. to 1150° C. and a growth pressure of 100 torr to 500 torr.

[0079] S23: growing an N-type GaN layer on the non-doped GaN layer;

[0080] The N-type GaN layer may be grown by MOCVD, MBE or VPE, but is not limited thereto.

[0081] Preferably, in some embodiments, the N-type GaN layer is grown by MOCVD; the growth temperature is 1100° C. to 1150° C., and the growth pressure is 100 torr to 500 torr.

[0082] S24: growing a multi-quantum well layer on the N-type GaN layer;

[0083] Specifically, in some embodiments, step S24 includes the following steps:

[0084] S241: growing a first multi-quantum well layer on the N-type GaN layer;

[0085] Specifically, in some embodiments, a quantum well layer and a quantum barrier layer are periodically grown on an N-type GaN layer by MOCVD until a multi-quantum well layer is obtained. The growth temperature of the quantum well layer is 740°C to 820°C, and the growth pressure is 100 torr to 300 torr. The growth temperature of the quantum barrier layer is 850°C to 950°C, and the growth pressure is 100 torr to 300 torr.

[0086] S242: growing a final well layer on the first multi-quantum well layer;

[0087] The InGaN quantum well layer may be grown by MOCVD, MBE or VPE as the final well layer, but is not limited thereto.

[0088] Preferably, in some embodiments, an InGaN quantum well layer is grown by MOCVD as the final well layer; the growth temperature is 740° C. to 820° C., and the growth pressure is 100 torr to 300 torr.

[0089] S243: growing a final barrier layer on the final well layer to obtain a multi-quantum well layer;

[0090] Specifically, in some embodiments, an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer, and a second boron-containing nitride layer are sequentially grown on the final well layer by MOCVD to form a final barrier layer.

[0091] More specifically, the growth temperature of the AlInGaN layer is 800℃~1000℃, and the growth pressure is 50torr~500torr; the growth temperature of the superlattice layer is 800℃~1000℃, and the growth pressure is 50torr~500torr; the growth temperature of the AlN layer is 650℃~800℃, and the growth pressure is 50torr~500torr; the growth temperature of the first boron-containing nitride layer is 1000℃~1100℃, and the growth pressure is 50torr~500torr; the growth temperature of the second boron-containing nitride layer is 900℃~1050℃, and the growth pressure is 50torr~500torr.

[0092] S25: growing an electron blocking layer on the multi-quantum well layer;

[0093] Herein, an AlGaN layer or an AlInGaN layer may be grown by MOCVD, MBE or VPE as the electron blocking layer, but is not limited thereto.

[0094] Preferably, in some embodiments, an AlInGaN layer is grown by MOCVD as an electron blocking layer, and the growth temperature thereof is 800° C. to 1000° C. and the growth pressure is 50 torr to 500 torr.

[0095] S26: growing a P-type GaN layer on the electron blocking layer;

[0096] The P-type GaN layer may be grown by MOCVD, MBE or VPE, but is not limited thereto.

[0097] Preferably, in some embodiments, the P-type GaN layer is grown by MOCVD, and the growth temperature is 900° C. to 1050° C. and the growth pressure is 100 torr to 500 torr.

[0098] As a third aspect of the present invention, the present invention discloses a light-emitting diode, which includes the light-emitting diode epitaxial wafer described above. The light-emitting diode epitaxial wafer includes a substrate 100, a buffer layer 200, a non-doped GaN layer 300, an N-type GaN layer 400, a multi-quantum well layer 500, an electron blocking layer 600, and a P-type GaN layer 700, which are sequentially stacked on the substrate 100. Among them, the multi-quantum well layer 500 includes a first multi-quantum well layer 510, a final well layer 520, and a final barrier layer 530, which are sequentially stacked on the N-type GaN layer 400; the first multi-quantum well layer 510 is a periodic structure composed of quantum well layers 511 and quantum barrier layers 512 alternately stacked. The final barrier layer 530 includes an AlInGaN layer 531, a superlattice layer 532, an AlN layer 533, a first boron-containing nitride layer 534, and a second boron-containing nitride layer 535 sequentially stacked on the final well layer 520; the superlattice layer 532 includes an AlGaN layer 5321 and a Mg-doped GaN layer 5322 alternately stacked; the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are BGaN layers and / or BInGaN layers, and the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both doped with Mg, and the doping concentration is greater than the Mg doping concentration of the Mg-doped GaN layer 5322. Specifically, the AlInGaN layer 531 introduces an In component, which reduces the lattice mismatch between the final well layer 520 and the final barrier layer 530, weakens the piezoelectric polarization effect, and improves the recombination efficiency of electrons and holes in the multi-quantum well layer 500. The AlGaN layer 5321 can improve the potential barrier of the last barrier layer 530 and reduce the probability of electrons overflowing the multi-quantum well layer 500. The Mg-doped GaN layer 5322 can improve the hole injection efficiency. Moreover, the strong polarization effect generated by the AlGaN material can be weakened by adopting a superlattice structure, thereby improving the recombination efficiency of electrons and holes in the multi-quantum well layer 500. Boron is introduced into the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535, thereby improving the potential barrier and further reducing the probability of electron overflow. Moreover, the first boron-containing nitride layer 534 and the second boron-containing nitride layer 535 are both doped with Mg. Since boron can reduce the activation energy of Mg, the concentration of effective holes in the first boron-containing nitride layer and the second boron-containing nitride layer is improved. Therefore, based on the last barrier layer 530 of this embodiment, electron overflow can be reduced, the efficiency of hole injection into the multi-quantum well layer 500 can be improved, thereby improving the recombination probability of electrons and holes in the multi-quantum well layer 500 and improving the luminous efficiency of the light-emitting diode.

[0099] The present invention will be further described below with specific embodiments:

[0100] Example 1

[0101] This embodiment provides a light emitting diode epitaxial wafer, which includes a substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer stacked in sequence on the substrate.

[0102] The substrate is a sapphire substrate, the buffer layer is an AlN layer with a thickness of 30 nm, the thickness of the undoped GaN layer is 2 μm, and the doping element of the N-type GaN layer is Si with a doping concentration of 8×10 18 cm -3 , and its thickness is 2.5μm.

[0103] The multi-quantum well layer includes a first multi-quantum well layer, a final well layer and a final barrier layer stacked sequentially on the N-type GaN layer. The first multi-quantum well layer is a periodic structure with 9 periods. Each period includes a quantum well layer and a quantum barrier layer stacked sequentially. The quantum well layer is In 0.18 Ga 0.82 N layer, with a thickness of 3nm; the quantum barrier layer is GaN layer, with a thickness of 10nm. The final well layer is In 0.18 Ga 0.82 N layer, with a thickness of 3nm; the final barrier layer includes an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer, and a second boron-containing nitride layer stacked in sequence on the final well layer. The Al component ratio in the AlInGaN layer is 0.05, the In component ratio is 0.08, and both are maintained constant. The thickness of the AlInGaN layer is 2nm. The number of periods of the superlattice layer is 6, with a total thickness of 40nm. Each period includes a stacked AlGaN layer and a Mg-doped GaN layer, and the thickness ratio of the two is 1:10. The Al component ratio in the AlGaN layer is 0.18, and the Mg doping concentration in the Mg-doped GaN layer is 8×10 18 cm -3 The thickness of the AlN layer is 3 nm. The first boron nitride layer is a Mg-doped BGaN layer, in which the B component ratio is 0.05 and the Mg doping concentration is 2×10 19 cm -3 , with a thickness of 5 nm. The second boron nitride layer is a Mg-doped BGaN layer, with a B component ratio of 0.05 and a Mg doping concentration of 2×10 19 cm -3 , thickness is 50nm.

[0104] The electron blocking layer is an AlInGaN layer, in which the Al component accounts for 0.03, the In component accounts for 0.05, and the thickness is 30nm. The Mg doping concentration in the P-type GaN layer is 3×10 20 cm -3 , and its thickness is 100nm.

[0105] The method for preparing the light emitting diode epitaxial wafer in this embodiment comprises the following steps:

[0106] (1) Providing a substrate.

[0107] (2) growing a buffer layer on the substrate;

[0108] Among them, an AlN layer is grown by PVD as a buffer layer;

[0109] (3) growing a non-doped GaN layer on the buffer layer;

[0110] The non-doped GaN layer is grown by MOCVD at a growth temperature of 1120° C. and a growth pressure of 200 torr.

[0111] (4) growing an N-type GaN layer on the undoped GaN layer;

[0112] The N-type GaN layer is grown by MOCVD at a growth temperature of 1140° C. and a growth pressure of 300 torr.

[0113] (5) growing a first multi-quantum well layer on the N-type GaN layer;

[0114] Specifically, quantum well layers and quantum barrier layers are periodically grown on the N-type GaN layer by MOCVD until a first multi-quantum well layer is obtained, wherein the growth temperature of the quantum well layer is 780°C and the growth pressure is 200 torr; the growth temperature of the quantum barrier layer is 880°C and the growth pressure is 200 torr.

[0115] (6) growing a final well layer on the first multi-quantum well layer;

[0116] Specifically, in In 0.18 Ga 0.82 The N layer is used as the end well layer; its growth temperature is 780°C and its growth pressure is 200 torr.

[0117] (7) growing a final barrier layer on the final well layer;

[0118] Specifically, an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer and a second boron-containing nitride layer are grown in sequence by MOCVD to obtain a final barrier layer.

[0119] Among them, the growth temperature of the AlInGaN layer is 900°C, and the growth pressure is 200torr; the growth temperature of the superlattice layer is 920°C, and the growth pressure is 200torr; the growth temperature of the AlN layer is 720°C, and the growth pressure is 200torr; the growth temperature of the first boron-containing nitride layer is 1020°C, and the growth pressure is 200torr; the growth temperature of the second boron-containing nitride layer is 1020°C, and the growth pressure is 200torr.

[0120] (8) growing an electron blocking layer on the final barrier layer;

[0121] Specifically, an AlInGaN layer is grown by MOCVD as an electron blocking layer at a growth temperature of 820° C. and a growth pressure of 400 torr.

[0122] (9) Growing a P-type GaN layer on the electron blocking layer;

[0123] Specifically, the P-type GaN layer is grown by MOCVD at a growth temperature of 920° C. and a growth pressure of 300 torr.

[0124] Example 2

[0125] This embodiment provides a light emitting diode epitaxial wafer, which is different from the embodiment 1 in that:

[0126] The second boron nitride layer is a Mg-doped BInGaN layer, in which the B component accounts for 0.05, the In component accounts for 0.03, and the Mg doping concentration is 2×10 19 cm -3 , thickness is 50nm.

[0127] The rest are the same as in Example 1.

[0128] Example 3

[0129] This embodiment provides a light emitting diode epitaxial wafer, which is different from the embodiment 2 in that:

[0130] The thickness of the first boron-containing nitride layer is 10 nm, and the thickness of the second boron-containing nitride layer is 45 nm.

[0131] The rest is the same as Example 2.

[0132] Example 4

[0133] This embodiment provides a light emitting diode epitaxial wafer, which is different from the embodiment 3 in that:

[0134] Along the growth direction of the light-emitting diode epitaxial wafer, the proportion of Al component in the AlInGaN layer gradually increases, specifically from 0.01 to 0.08; the proportion of In component gradually decreases, specifically from 0.1 to 0.05.

[0135] The rest is the same as Example 3.

[0136] Example 5

[0137] This embodiment provides a light emitting diode epitaxial wafer, which is different from the embodiment 4 in that:

[0138] The thickness ratio of the AlGaN layer to the Mg-doped GaN layer is 1:6; the Al component accounts for 0.12 in the AlGaN layer.

[0139] The rest is the same as Example 4.

[0140] Comparative Example 1

[0141] This comparative example provides a light emitting diode epitaxial wafer, which differs from Example 1 in that:

[0142] The final barrier layer is a GaN layer with a thickness of 10 nm.

[0143] In this comparative example, the growth conditions of the final barrier layer are the same as the growth conditions of the quantum barrier layer in Example 1.

[0144] The rest are the same as in Example 1.

[0145] The light emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Example 1 were tested in the following manner:

[0146] The epitaxial wafer was made into a 10 mil×24 mil chip, and its brightness was tested at 120 mA. The brightness improvement rate was calculated based on the data of comparative example 1.

[0147] Specifically, the brightness improvement rate=(brightness of each embodiment−brightness of comparative example 1) / brightness of comparative example 1.

[0148] The specific results are shown in the following table:

[0149]

[0150] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A light emitting diode epitaxial wafer, characterized in that: It comprises a substrate, a buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially stacked on the substrate; The multi-quantum well layer comprises a first multi-quantum well layer, a final well layer and a final barrier layer sequentially stacked on the N-type GaN layer, the first multi-quantum well layer is a periodic structure formed by alternating stacking of quantum well layers and quantum barrier layers, the quantum well layer and the final well layer are both InGaN quantum well layers, and the quantum barrier layer is a GaN quantum barrier layer; The final barrier layer comprises an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer and a second boron-containing nitride layer which are sequentially stacked on the final well layer; The superlattice layer includes an AlGaN layer and a Mg-doped GaN layer stacked alternately; The first boron-containing nitride layer and the second boron-containing nitride layer are BGaN layers and / or BInGaN layers. Both the first boron-containing nitride layer and the second boron-containing nitride layer are doped with Mg, and their Mg doping concentrations are greater than the Mg doping concentration of the Mg-doped GaN layer.

2. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The bandgap of the first boron-containing nitride layer is greater than the bandgap of the second boron-containing nitride layer.

3. The light emitting diode epitaxial wafer according to claim 1, characterized in that: Along the growth direction of the light-emitting diode epitaxial wafer, the proportion of Al component in the AlInGaN layer gradually increases, and the proportion of In component gradually decreases.

4. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The period number of the superlattice layer is ≥3; The thickness ratio of the AlGaN layer to the Mg-doped GaN layer is 1:1 to 1:8; The Al component ratio in the AlGaN layer is ≤0.

15.

5. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the AlN layer is ≤5 nm.

6. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The ratio of the thickness of the first boron-containing nitride layer to the thickness of the second boron-containing nitride layer is 1:2-1:

6.

7. The light emitting diode epitaxial wafer according to any one of claims 1 to 6, characterized in that: The AlInGaN layer has an Al component ratio of 0.01-0.1, an In component ratio of 0.03-0.1, and a thickness of 1nm-3nm; The number of periods of the superlattice layer is 4-10, and its thickness is 10nm-50nm. The Al component ratio in the AlGaN layer is 0.01-0.1; the Mg doping concentration in the Mg-doped GaN layer is 1×10 18 cm -3 ~1×10 19 cm -3 ; The thickness of the AlN layer is 0.5 nm to 4.5 nm; The B component ratio in the first boron-containing nitride layer is 0.05-0.15, the thickness is 3nm-25nm, and the Mg doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 ; The B component ratio in the second boron-containing nitride layer is 0.01-0.1, the thickness is 10 nm-70 nm, and the Mg doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 .

8. A method for preparing a light emitting diode epitaxial wafer, for preparing the light emitting diode epitaxial wafer according to any one of claims 1 to 7, characterized in that: include: Providing a substrate, and sequentially growing a buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer, and a P-type GaN layer on the substrate; The multi-quantum well layer comprises a first multi-quantum well layer, a final well layer and a final barrier layer sequentially stacked on the N-type GaN layer, the first multi-quantum well layer is a periodic structure formed by alternating stacking of quantum well layers and quantum barrier layers, the quantum well layer and the final well layer are both InGaN quantum well layers, and the quantum barrier layer is a GaN quantum barrier layer; The final barrier layer comprises an AlInGaN layer, a superlattice layer, an AlN layer, a first boron-containing nitride layer and a second boron-containing nitride layer which are sequentially stacked on the final well layer; The superlattice layer includes an AlGaN layer and a Mg-doped GaN layer stacked alternately; The first boron-containing nitride layer and the second boron-containing nitride layer are both BGaN layers and / or BInGaN layers. The first boron-containing nitride layer and the second boron-containing nitride layer are both doped with Mg, and their Mg doping concentrations are greater than the Mg doping concentration of the Mg-doped GaN layer.

9. The method for preparing a light emitting diode epitaxial wafer according to claim 8, characterized in that: The growth temperature of the AlInGaN layer is 800° C. to 1000° C., and the growth pressure is 50 torr to 500 torr; The growth temperature of the superlattice layer is 800° C. to 1000° C., and the growth pressure is 50 torr to 500 torr; The growth temperature of the AlN layer is 650° C. to 800° C., and the growth pressure is 50 torr to 500 torr; The growth temperature of the first boron nitride layer is 1000° C. to 1100° C., and the growth pressure is 50 torr to 500 torr; The growth temperature of the second boron nitride layer is 900° C. to 1050° C., and the growth pressure is 50 torr to 500 torr.

10. A light emitting diode, characterized in that: It comprises the light emitting diode epitaxial wafer as described in any one of claims 1 to 7.

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