Light-emitting diode epitaxial wafer, method for preparing same, and light-emitting diode

Abstract

The present invention discloses a light-emitting diode epitaxial wafer, a preparation method thereof, and a light-emitting diode, relating to the field of semiconductor optoelectronic devices. The epitaxial wafer sequentially includes a substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a V-pit control layer, a multi-quantum well layer, an electron blocking layer, and a P-type semiconductor layer; the V-pit control layer includes a first stepped layer, a second stepped layer, and a third stepped layer which are sequentially stacked; the first stepped layer is a periodic structure formed by alternately stacking an N-type Al w In x Ga 1‑w‑x N layer and a BN layer, the second stepped layer is a periodic structure formed by alternately stacking an N-type Al y In z Ga 1‑y‑z N layer and a B α In β Ga 1‑α‑β N layer, and the third stepped layer is a periodic structure formed by alternately stacking an N-type Al γ In δ Ga 1‑γ‑δ N layer and a Si3N4 layer. Implementing the present invention can improve the luminous efficiency of the light-emitting diode.

Description

Technical Field

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

[0002] As a typical representative of the third-generation semiconductors, gallium nitride materials have become the most promising materials in the future semiconductor field due to their large bandgap width, high electron mobility, etc. In particular, gallium nitride-based devices are widely used in electronic systems such as wireless communication and radar in the microwave and millimeter-wave frequency bands, and have very broad development prospects in the fields of optoelectronics and microelectronics.

[0003] Currently, an epitaxial structure of a substrate, a buffer layer, an n-type layer, a light-emitting layer, an electron blocking layer, and a p-type layer is usually adopted, and the main light emission source is the light-emitting layer. However, as the working current density increases accordingly, the droop effect caused by Auger recombination and carrier leakage effects will seriously affect the carrier injection efficiency of the LED, thereby further affecting the light output power. At present, it is proposed to design the structure of the electron blocking layer (EBL) and use the polarization effect to modulate the energy band structure to increase the hole injection efficiency and at the same time reduce the influence of the droop effect caused by electron leakage. However, due to the difference in the effective masses of holes and electrons, the migration abilities of holes and electrons in GaN materials are very different, and the mobility of holes is much smaller than that of electrons; adjusting the structure of the electron blocking layer often reduces the hole injection efficiency and leads to a decrease in the light emission efficiency. Summary of the Invention

[0004] 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 emission efficiency of the light-emitting diode.

[0005] To solve the above problems, the present invention discloses a light-emitting diode epitaxial wafer, which includes a substrate, a buffer layer, an undoped GaN layer, an n-type GaN layer, a V-pit control layer, a multi-quantum well layer, an electron blocking layer, and a p-type semiconductor layer sequentially stacked on the substrate; the V-pit control layer includes a first stepped layer, a second stepped layer, and a third stepped layer sequentially stacked on the n-type GaN layer;

[0006] The first stepped layer is a periodic structure formed by alternately stacking an N-type Al w In x Ga 1-w-x N layer and a BN layer, and the second stepped layer is an N-type Al y In z Ga 1-y-z N layer and a B α In β Ga 1-α-βA periodic structure formed by N alternating stacked layers, where the third stepped layer is N-type Al γ In δ Ga 1-γ-δ A periodic structure formed by alternating stacked N layers and Si3N4 layers;

[0007] Among them, 0.01 ≤ w ≤ y ≤ γ ≤ 0.1, 0.01 ≤ x ≤ z ≤ δ ≤ 0.1, α < y, z ≤ β.

[0008] As an improvement to the above technical solution, the number of periods of the first stepped layer is 5 to 10, and the N-type Al w In x Ga 1-w-x The thickness of the N layer is 3 nm to 5 nm, w is 0.01 to 0.06, x is 0.01 to 0.05, and its doping concentration is 1×10 17 cm -3 ~5×10 18 cm -3 ;

[0009] The thickness of the BN layer is 3 nm to 5 nm.

[0010] As an improvement to the above technical solution, the number of periods of the second stepped layer is 3 to 12, and the N-type Al y In z Ga 1-y-z The thickness of the N layer is 2 nm to 4 nm, y is 0.03 to 0.08, z is 0.02 to 0.07, and its doping concentration is 1×10 17 cm -3 ~5×10 18 cm -3 ;

[0011] The α In β Ga 1-α-β The thickness of the N layer is 2 nm to 4 nm, α is 0.2 to 0.6, and β is 0.03 to 0.08.

[0012] As an improvement to the above technical solution, the number of periods of the third stepped layer is 2 to 4, and the N-type Al γ In δ Ga 1-γ-δ The thickness of the N layer is 3 nm to 5 nm, γ is 0.05 to 0.09, δ is 0.04 to 0.09, and its doping concentration is 1×10 15 cm -3 ~1×10 17 cm -3 ;

[0013] The thickness of the Si3N4 layer is 3 nm to 5 nm.

[0014] As an improvement of the above technical solution, along the growth direction of the epitaxial wafer, the Al w In x Ga 1-w-x component in the N-layer shows a decreasing change, and the In component shows an increasing change. The Al y In z Ga 1-y-z component in the N-layer shows a decreasing change, and the In component shows an increasing change. The Al γ In δ Ga 1-γ-δ component in the N-layer shows a decreasing change, and the In component shows an increasing change.

[0015] As an improvement of the above technical solution, the doping concentration of the N-type Al w In x Ga 1-w-x N layer is greater than that of the N-type Al γ In δ Ga 1-γ-δ N layer;

[0016] The doping concentration of the N-type Al y In z Ga 1-y-z N layer is greater than that of the N-type Al γ In δ Ga 1-γ-δ N layer;

[0017] The doping concentration of the N-type Al w In x Ga 1-w-x N layer is the same as or different from that of the N-type Al y In z Ga 1-y-z N layer.

[0018] As an improvement of the above technical solution, along the growth direction of the epitaxial wafer, the doping concentration of the N-type Al γ In δ Ga 1-γ-δ N layer shows a decreasing change.

[0019] As an improvement of the above technical solution, the multi-quantum well layer is a periodic structure formed by alternating stacking of InGaN quantum well layers and AlGaN quantum barrier layers, and the number of periods is 6 to 12;

[0020] The thickness of the InGaN quantum well layer is 2 nm to 5 nm, and the proportion of the In component is 0.15 to 0.25;

[0021] The thickness of the AlGaN quantum barrier layer is 5 nm to 15 nm, and the Al component ratio is 0.01 to 0.1.

[0022] Correspondingly, the present invention also discloses a method for preparing a light-emitting diode epitaxial wafer for preparing the above-mentioned light-emitting diode epitaxial wafer, which includes:

[0023] Providing a substrate, and sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, a V-pit control layer, a multi-quantum well layer, an electron blocking layer, and a P-type semiconductor layer on the substrate; the V-pit control layer includes a first step layer, a second step layer, and a third step layer sequentially stacked on the N-type GaN layer;

[0024] The first step layer is a periodic structure formed by alternately stacking an N-type Al w In x Ga 1-w-x N layer and a BN layer, the second step layer is a periodic structure formed by alternately stacking an N-type Al y In z Ga 1-y-z N layer and a B α In β Ga 1-α-β N layer, and the third step layer is a periodic structure formed by alternately stacking an N-type Al γ In δ Ga 1-γ-δ N layer and a Si3N4 layer;

[0025] Wherein, 0.01 ≤ w ≤ y ≤ γ ≤ 0.1, 0.01 ≤ x ≤ z ≤ δ ≤ 0.1, α < y, z ≤ β;

[0026] Wherein, the growth temperature of the V-pit control layer is 850 °C to 1050 °C, and the growth pressure is 100 torr to 300 torr.

[0027] Correspondingly, the present invention also discloses a light-emitting diode, which includes the above-mentioned light-emitting diode epitaxial wafer.

[0028] Implementing the present invention has the following beneficial effects:

[0029] In the light-emitting diode epitaxial wafer of the present invention, a V-pit control layer is provided between the N-type GaN layer and the multi-quantum well layer, which includes a first step layer, a second step layer, and a third step layer sequentially stacked; the first step layer is a periodic structure formed by alternately stacking an N-type Al w In x Ga 1-w-x N layer and a BN layer, the second step layer is a periodic structure formed by alternately stacking an N-type Al y In z Ga 1-y-z N layer and a Bα In β Ga 1-α-β A periodic structure formed by alternating stacking of N layers, and the third ladder layer is an N-type Al γ In δ Ga 1-γ-δ A periodic structure formed by alternating stacking of N layers and Si3N4 layers; and 0.01 ≤ w ≤ y ≤ γ ≤ 0.1, 0.01 ≤ x ≤ z ≤ δ ≤ 0.1, α < y, z ≤ β. In the above epitaxial wafer, the BN layer in the first ladder layer has a higher energy band, which can reduce the flow of electrons into the multi-quantum well layer and reduce the overflow of excessive electrons. At the same time, the BN layer and the N-type Al w In x Ga 1-w-x The periodic structure formed by alternating stacking of N layers can continuously release the compressive stress at the bottom layer, improve the crystal quality, and reduce the generation of defects. The B α In β Ga 1-α-β The B / In-doped energy band in the N layer in the second ladder layer promotes the flow of effectively recombined electrons into the multi-quantum well layer, enhances the electron injection efficiency, and reduces the working voltage. In addition, the N-type Al y In z Ga 1-y-z The N layer and the B α In β Ga 1-α-β The N layer has a small lattice difference, which can further release the compressive stress and improve the crystal quality. The periodically grown Si3N4 layer in the third ladder layer can continuously and effectively block the extension of defects, thereby controlling the generation of V-shaped pits, reducing the density and depth of V-shaped pits, and thus weakening the Efficiency Droop effect. In addition, N-type doping is introduced in the first ladder layer, the second ladder layer, and the third ladder layer, which can increase the current spreading ability and reduce the resistivity. The n-type doping concentration in the third ladder layer is relatively low to prevent the n-type doping from extending to the light-emitting layer and the P-type layer, reducing the non-effective recombination and the crystal quality of the light-emitting layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of a light-emitting diode epitaxial wafer in an embodiment of the present invention;

[0031] Figure 2 is a flowchart of a method for manufacturing a light-emitting diode epitaxial wafer in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below.

[0033] Refer to Figure 1, the present invention discloses a light-emitting diode epitaxial wafer, which includes a substrate 100, a buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a V-pit control layer 500, a multi-quantum well layer 600, an electron blocking layer 700, and a P-type semiconductor layer 800 that are sequentially stacked on the substrate 100. Among them, the V-pit control layer 500 includes a first stepped layer 510, a second stepped layer 520, and a third stepped layer 530 that are sequentially stacked on the N-type GaN layer 400. The first stepped layer 510 is a periodic structure formed by alternately stacking an N-type Al w In x Ga 1-w-x N layer 511 and a BN layer 512. The second stepped layer 520 is a periodic structure formed by alternately stacking an N-type Al y In z Ga 1-y-z N layer 521 and a B α In β Ga 1-α-β N layer 522. The third stepped layer 530 is a periodic structure formed by alternately stacking an N-type Al γ In δ Ga 1-γ-δ N layer 531 and a Si3N4 layer 532; and 0.01 ≤ w ≤ y ≤ γ ≤ 0.1, 0.01 ≤ x ≤ z ≤ δ ≤ 0.1, α < y, z ≤ β. Based on the above structure, the number and speed of electrons entering the multi-quantum well layer can be modulated, electron leakage can be reduced, and the efficiency droop effect can be weakened. At the same time, the accumulation of compressive stress can be effectively reduced, the recombination efficiency of electrons and holes in the multi-quantum well layer can be optimized, and the light-emitting efficiency can be improved.

[0034] Among them, the number of periods of the first stepped layer 510 is 3 to 10, preferably 5 to 10, and more preferably 6 to 9. The thickness of the N-type Al w In x Ga 1-w-x N layer 511 is 2 nm to 5 nm, preferably 3 nm to 5 nm, and more preferably 3.5 nm to 5 nm. Among them, the proportion of the Al component in the N-type Al w In x Ga 1-w-x N layer 511 (i.e., w) is 0.01 to 0.07, preferably 0.01 to 0.06, and more preferably 0.01 to 0.04. The proportion of the In component in the N-type Al w In x Ga 1-w-x N layer 511 (i.e., x) is 0.02 to 0.1, preferably 0.03 to 0.08, and more preferably 0.03 to 0.05. The N-type Al w In x Ga 1-w-xThe doping concentration of Si in the N-layer 511 is 1×10 17 cm -3 ~5×10 18 cm -3 ; preferably 1×10 18 cm -3 ~5×10 18 cm -3 。

[0035] Among them, the thickness of the BN layer is 2 nm to 5 nm, preferably 3 nm to 5 nm, more preferably 3.5 nm to 5 nm.

[0036] Among them, the number of periods of the second step layer 520 is 3 to 15, preferably 3 to 12, more preferably 4 to 10. Among them, N-type Al y In z Ga 1-y-z The thickness of the N-layer 521 is 2 nm to 5 nm, preferably 2 nm to 4 nm. N-type Al y In z Ga 1-y-z The proportion of the Al component (i.e., y) in the N-layer 521 is 0.02 to 0.08, preferably 0.03 to 0.08, more preferably 0.04 to 0.07. N-type Al y In z Ga 1-y-z The proportion of the In component (i.e., z) in the N-layer 521 is 0.02 to 0.08, preferably 0.02 to 0.07. N-type Al y In z Ga 1-y-z The doping concentration of Si in the N-layer 521 is 1×10 17 cm -3 ~5×10 18 cm -3 ; preferably 1×10 18 cm -3 ~5×10 18 cm -3 。

[0037] Among them, B α In β Ga 1-α-β The thickness of the N-layer 522 is 2 nm to 5 nm, preferably 2 nm to 4 nm. B α In β Ga 1-α-β The proportion of the B component (i.e., α) in the N-layer 522 is 0.15 to 0.65, preferably 0.2 to 0.6, more preferably 0.2 to 0.3. B α In β Ga 1-α-βThe proportion of In component in the N-layer 522 (i.e., β) is 0.03 to 0.1, preferably 0.03 to 0.08.

[0038] Among them, the number of periods of the third ladder layer 530 is 2 to 8, preferably 2 to 4. Among them, N-type Al γ In δ Ga 1-γ-δ The thickness of the N-layer 531 is 2 nm to 5 nm, preferably 3 nm to 5 nm. N-type Al γ In δ Ga 1-γ-δ The proportion of Al component in the N-layer 531 (i.e., γ) is 0.05 to 0.1, preferably 0.05 to 0.09. N-type Al γ In δ Ga 1-γ-δ The proportion of In component in the N-layer 531 (i.e., δ) is 0.04 to 0.1, preferably 0.04 to 0.09, more preferably 0.05 to 0.09. N-type Al γ In δ Ga 1-γ-δ The Si doping concentration in the N-layer 531 is 1×10 15 cm -3 ~5×10 17 cm -3 ,preferably 1×10 15 cm -3 ~1×10 17 cm -3 。

[0039] Among them, the thickness of the Si3N4 layer 532 is 2 nm to 5 nm, preferably 3 nm to 5 nm.

[0040] Preferably, in some embodiments of the present invention, w < y < γ, x < z < δ, α < y, z < β. Based on the control of the above components, the luminous efficiency can be further improved.

[0041] Preferably, in some embodiments of the present invention, along the epitaxial wafer growth direction, N-type Al w In x Ga 1-w-x In the N-layer 511, the Al component shows a decreasing change and the In component shows an increasing change. N-type Al y In z Ga 1-y-z In the N-layer 521, the Al component shows a decreasing change and the In component shows an increasing change. N-type Al γ In δ Ga 1-γ-δThe Al component in the N-layer 531 shows a decreasing change, and the In component shows an increasing change. Based on this component control, not only can the compressive stress be better released, the luminous efficiency be improved, but also electron traps are formed, the migration speed of electrons is reduced, and the Efficiency Droop effect is further weakened. It should be noted that when the technical solution of gradually changing the In component and the Al component is adopted, the proportion of the Al component and the In component in each layer and the like all refer to the average proportion in that layer.

[0042] Preferably, in some embodiments of the present invention, N-type Al w In x Ga 1-w-x The doping concentration of the N-layer 511 is greater than that of N-type Al γ In δ Ga 1-γ-δ The doping concentration of the N-layer 531; N-type Al y In z Ga 1-y-z The doping concentration of the N-layer 521 is greater than that of the said N-type Al γ In δ Ga 1-γ-δ The doping concentration of the N-layer 531; N-type Al w In x Ga 1-w-x The doping concentration of the N-layer 511 and N-type Al y In z Ga 1-y-z The doping concentration of the N-layer 521 is the same or different. Based on the above control, while improving the current spreading ability, excessive redundant electrons can be prevented from entering the multiple quantum well layer 600, the luminous efficiency is improved, and the Efficiency Droop effect is weakened. More preferably, N-type Al w In x Ga 1-w-x The doping concentration of the N-layer 511 and N-type Al y In z Ga 1-y-z The doping concentration of the N-layer 521 is the same.

[0043] Preferably, in some embodiments of the present invention, along the epitaxial wafer growth direction, N-type Al γ In δ Ga 1-γ-δ The doping concentration of the N-layer 531 shows a decreasing change.

[0044] Among them, the multiple quantum well layer 600 can be an InGaN-GaN type multiple quantum well layer common in the art, but is not limited thereto. Preferably, in some embodiments of the present invention, the multiple quantum well layer 600 is a periodic structure formed by alternately laminating an InGaN quantum well layer 610 and an AlGaN quantum barrier layer 620, and the number of periods is 6 to 12. The V-groove control layer 500 of the present invention greatly weakens the compressive stress from the bottom layer and blocks the extension of defects, so that the multiple quantum well layer 600 can adopt an InGaN-AlGaN structure with a large lattice difference, improving the confinement ability of electrons and the light emission efficiency. Specifically, the thickness of the InGaN quantum well layer 610 is 2 nm to 5 nm, and the In component ratio is 0.15 to 0.25; the thickness of the AlGaN quantum barrier layer 620 is 5 nm to 15 nm, and the Al component ratio is 0.01 to 0.1.

[0045] Among them, the substrate 100 is a sapphire substrate, a silicon substrate or a carbonized substrate, but is not limited thereto.

[0046] Among them, 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.

[0047] Among them, the thickness of the undoped GaN layer 300 is 1 μm to 3 μm. The thickness of the N-type GaN layer 400 is 1 μm to 3 μm, and its Si doping concentration is 5×10 18 cm -3 ~5×10 19 cm -3 。

[0048] Among them, the electron blocking layer 700 is an AlGaN layer, the Al component ratio of which is 0.05 to 0.2, and the thickness is 10 nm to 40 nm, but is not limited thereto.

[0049] Among them, the P-type semiconductor layer 800 is a P-type GaN layer, the thickness of which is 100 nm to 500 nm, and its Mg doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 。

[0050] Correspondingly, referring to Figure 2 , the present invention also provides a method for preparing a light-emitting diode epitaxial wafer for preparing the above-mentioned light-emitting diode epitaxial wafer, which specifically includes the following steps:

[0051] S1: Provide a substrate;

[0052] S2: Grow a buffer layer, an undoped GaN layer, an N-type GaN layer, a V-pit control layer, a multi-quantum well layer, an electron blocking layer, and a P-type semiconductor layer on the substrate in sequence;

[0053] Preferably, in some embodiments of the present invention, step S2 includes:

[0054] S21: Grow a buffer layer on the substrate;

[0055] Among them, in one embodiment of the present invention, an AlN layer is grown by PVD as the buffer layer.

[0056] S22: Grow an undoped GaN layer on the buffer layer;

[0057] Among them, in one embodiment of the present invention, the undoped GaN layer is grown by MOCVD. Its growth temperature is 1050°C to 1200°C, and the growth pressure is 100 torr to 500 torr.

[0058] S23: Grow an N-type GaN layer on the undoped GaN layer;

[0059] Among them, in one embodiment of the present invention, the N-type GaN layer is grown by MOCVD, and its growth temperature is 1050°C to 1200°C, and the growth pressure is 100 torr to 500 torr.

[0060] S24: Grow a V-pit control layer on the N-type GaN layer;

[0061] Specifically, step S24 includes:

[0062] S241: Grow a first stepped layer on the N-type GaN layer;

[0063] Among them, in one embodiment of the present invention, an N-type Al w In x Ga 1-w-x N layer and a BN layer are grown periodically by MOCVD until the first stepped layer is obtained. Its growth temperature is 850°C to 1050°C, and the growth pressure is 100 torr to 300 torr.

[0064] S242: Grow a second stepped layer on the first stepped layer;

[0065] Among them, in one embodiment of the present invention, an N-type Al y In z Ga 1-y-z N layer and B α In β Ga 1-α-βThe N layers are grown until the second step layer is obtained. The growth temperature is 850°C to 1050°C, and the growth pressure is 100 torr to 300 torr.

[0066] S243: The third step layer is grown on the second step layer to obtain the V pit control layer;

[0067] Among them, in one embodiment of the present invention, the N-type Al γ In δ Ga 1-γ-δ N layers and Si3N4 layers are grown until the third step layer is obtained. The growth temperature is 850°C to 1050°C, and the growth pressure is 100 torr to 300 torr.

[0068] S25: The multiple quantum well layer is grown on the V pit control layer;

[0069] Among them, in one embodiment of the present invention, the InGaN quantum well layer and the AlGaN quantum barrier layer are periodically grown on the V pit control layer by MOCVD until the multiple quantum well layer is obtained. Among them, the growth temperature of the InGaN quantum well layer is 760°C to 820°C, and the growth pressure is 100 torr to 300 torr. The growth temperature of the AlGaN quantum barrier layer is 800°C to 950°C, and the growth pressure is 100 torr to 300 torr.

[0070] S26: The electron blocking layer is grown on the multiple quantum well layer;

[0071] Among them, in one embodiment of the present invention, the AlGaN layer is grown by MOCVD as the electron blocking layer, and its growth temperature is 900°C to 1000°C, and the growth pressure is 100 torr to 300 torr.

[0072] S27: The P-type semiconductor layer is grown on the electron blocking layer;

[0073] Specifically, in one embodiment of the present invention, the P-type GaN layer is grown by MOCVD as the P-type semiconductor layer, and its growth temperature is 900°C to 1050°C, and the growth pressure is 100 torr to 500 torr.

[0074] The present invention will be further described below with specific embodiments:

[0075] Example 1

[0076] Reference Figure 1, this embodiment provides a light-emitting diode epitaxial wafer, which includes a substrate 100, a buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a V-pit control layer 500, a multi-quantum well layer 600, an electron blocking layer 700, and a P-type semiconductor layer 800 that are sequentially stacked on the substrate 100.

[0077] Among them, the substrate 100 is a sapphire substrate, and the buffer layer 200 is an AlN layer with a thickness of 40 nm. The thickness of the undoped GaN layer 300 is 1.5 μm. The doping concentration of the N-type GaN layer 400 is 8×10 18 cm -3 , and its thickness is 2.5 μm.

[0078] Among them, the V-pit control layer 500 includes a first stepped layer 510, a second stepped layer 520, and a third stepped layer 530 that are sequentially stacked on the N-type GaN layer 400; the first stepped layer 510 is a periodic structure formed by alternately stacking an N-type Al w In x Ga 1-w-x N layer 511 (w = 0.03, x = 0.03) and a BN layer, with 8 periods. The Si doping concentration in the N-type Al w In x Ga 1-w-x N layer 511 is 4×10 17 cm -3 , the thickness is 4 nm, and the thickness of the BN layer 512 is 4 nm. The second stepped layer 520 is a periodic structure formed by alternately stacking an N-type Al y In z Ga 1-y-z N layer 521 (y = 0.05, z = 0.04) and a B α In β Ga 1-α-β N layer 522 (α = 0.35, β = 0.06), with 10 periods. The Si doping concentration in the N-type Al y In z Ga 1-y-z N layer 521 is 6×10 17 cm -3 , the thickness is 3 nm, and the thickness of the B α In β Ga 1-α-β N layer 522 is 3 nm. The third stepped layer 530 is a periodic structure formed by alternately stacking an N-type Al γ In δ Ga 1-γ-δ N layer 531 (γ = 0.08, δ = 0.08) and a Si3N4 layer, with 3 periods. The N-type Al γ In δ Ga1-γ-δ The Si doping concentration in the N-layer 531 is 4×10 17 cm -3 , with a thickness of 4 nm, and the thickness of the Si3N4 layer is 4 nm. Along the growth direction of the epitaxial wafer, the Al composition, In composition, and Si doping concentration in the N-type Al w In x Ga 1-w-x N-layer 511 are all maintained constant. The Al composition, In composition, and Si doping concentration in the N-type Al y In z Ga 1-y-z N-layer 521 are all maintained constant. The Al composition, In composition, and Si doping concentration in the N-type Al γ In δ Ga 1-γ-δ N-layer 531 are all maintained constant.

[0079] Among them, the multi-quantum well layer 600 is a periodic structure formed by alternately stacking InGaN quantum well layers 610 and AlGaN quantum barrier layers 620, with a period number of 10. Among them, the In composition ratio of the InGaN quantum well layer 610 is 0.22, the thickness is 3.5 nm, the Al composition ratio of the AlGaN quantum barrier layer 620 is 0.08, and its thickness is 10 nm.

[0080] Among them, the electron blocking layer 700 is an AlGaN layer, with an Al composition ratio of 0.18 and a thickness of 35 nm. The P-type semiconductor layer 800 is a P-type GaN layer, with an Mg doping concentration of 2×10 20 cm -3 , and the thickness is 220 nm.

[0081] The method for preparing the light-emitting diode epitaxial wafer in this embodiment includes the following steps:

[0082] (1) Provide a substrate.

[0083] (2) Grow a buffer layer on the substrate;

[0084] Among them, grow an AlN layer by PVD as the buffer layer;

[0085] (3) Grow an undoped GaN layer on the buffer layer;

[0086] Among them, grow the undoped GaN layer by MOCVD. Its growth temperature is 1100 °C, and the growth pressure is 150 torr.

[0087] (4) Grow an N-type GaN layer on the undoped GaN layer;

[0088] Among them, an N-type GaN layer is grown by MOCVD, with a growth temperature of 1120 °C and a growth pressure of 100 torr.

[0089] (5) Grow a first stepped layer on the N-type semiconductor layer;

[0090] Among them, an N-type Al w In x Ga 1-w-x N layer and a BN layer are grown periodically by MOCVD until the first stepped layer is obtained. The growth temperature of both is 900 °C, and the growth pressure is 200 torr.

[0091] (6) Grow a second stepped layer on the first stepped layer;

[0092] Among them, an N-type Al y In z Ga 1-y-z N layer and B α In β Ga 1-α-β N layers are grown periodically by MOCVD until the second stepped layer is obtained. The growth temperature is 950 °C, and the growth pressure is 200 torr.

[0093] (7) Grow a third stepped layer on the second stepped layer to obtain a V-pit control layer;

[0094] Among them, an N-type Al γ In δ Ga 1-γ-δ N layer and a Si3N4 layer are grown periodically by MOCVD until the third stepped layer is obtained. The growth temperature is 1020 °C, and the growth pressure is 200 torr.

[0095] (8) Grow a multi-quantum well layer on the V-pit control layer;

[0096] Among them, an InGaN quantum well layer and an AlGaN quantum barrier layer are grown periodically on the V-pit control layer by MOCVD until the multi-quantum well layer is obtained. Among them, the growth temperature of the InGaN quantum well layer is 780 °C, and the growth pressure is 200 torr. The growth temperature of the AlGaN quantum barrier layer is 930 °C, and the growth pressure is 200 torr.

[0097] (9) Grow an electron blocking layer on the multi-quantum well layer;

[0098] Among them, an AlGaN layer is grown by MOCVD as the electron blocking layer, with a growth temperature of 980 °C and a growth pressure of 180 torr.

[0099] (10) Grow a P-type semiconductor layer on the electron blocking layer;

[0100] Specifically, a P-type GaN layer is grown by MOCVD. As the P-type semiconductor layer, its growth temperature is 1020 °C and the growth pressure is 300 torr.

[0101] Example 2

[0102] This example provides a light-emitting diode epitaxial wafer, which is different from Example 1 in that:

[0103] Along the growth direction of the epitaxial wafer, the Al component in the N-type Al w In x Ga 1-w-x N layer 511 shows a decreasing change in the Al component and an increasing change in the In component. The N-type Al y In z Ga 1-y-z N layer 521 shows a decreasing change in the Al component and an increasing change in the In component. The N-type Al γ In δ Ga 1-γ-δ N layer 531 shows a decreasing change in the Al component and an increasing change in the In component.

[0104] The rest are the same as those in Example 1.

[0105] Example 3

[0106] This example provides a light-emitting diode epitaxial wafer, which is different from Example 2 in that:

[0107] The Si doping concentration in the N-type Al w In x Ga 1-w-x N layer 511 is 1×10 18 cm -3 , and the Si doping concentration in the N-type Al y In z Ga 1-y-z N layer 521 is 1×10 18 cm -3 , and the Si doping concentration in the N-type Al γ In δ Ga 1-γ-δ N layer 531 is 5×10 16 cm -3 .

[0108] The rest are the same as those in Example 2.

[0109] Example 4

[0110] This example provides a light-emitting diode epitaxial wafer, which is different from Example 3 in that:

[0111] Along the growth direction of the epitaxial wafer, the N-type Alγ In δ Ga 1-γ-δ The doping concentration of the N layer 531 shows a decreasing change, and the rest is the same as that of Example 1.

[0112] Comparative Example 1

[0113] This comparative example provides a light-emitting diode epitaxial wafer, which is different from that of Example 1 in that:

[0114] It does not include the V-groove control layer. Correspondingly, the preparation method does not include the step of preparing this layer either.

[0115] The rest is the same as that of Example 1.

[0116] The light-emitting diode epitaxial wafers obtained in Examples 1 to 4 and Comparative Example 1 were tested, and based on the data of Comparative Example 1, the light emission efficiency improvement rate was calculated.

[0117] The specific results are shown in the following table:

[0118]

[0119]

[0120] The above are the preferred embodiments of the invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that, It includes a substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a V-pit control layer, a multi-quantum well layer, an electron blocking layer, and a P-type semiconductor layer that are sequentially stacked on the substrate; the V-pit control layer includes a first stepped layer, a second stepped layer, and a third stepped layer that are sequentially stacked on the N-type GaN layer. The first stepped layer is a periodic structure formed by alternating N-type Al w In x Ga 1-w-x N layers and BN layers, the second stepped layer is a periodic structure formed by alternating N-type Al y In z Ga 1-y-z N layers and B α In β Ga 1-α-β N layers, and the third stepped layer is a periodic structure formed by alternating N-type Al γ In δ Ga 1-γ-δ N layers and Si3N4 layers; Wherein, 0.01 ≤ w ≤ y ≤ γ ≤ 0.1, 0.01 ≤ x ≤ z ≤ δ ≤ 0.1, α < y, z ≤ β.

2. The light-emitting diode epitaxial wafer according to claim 1, wherein The number of periods of the first ladder layer is 5 to 10, and the N-type Al w In x Ga 1-w-x N layer has a thickness of 3 nm to 5 nm, w is 0.01 to 0.06, x is 0.01 to 0.05, and its doping concentration is 1×10 17 cm -3 ~5×10 18 cm -3 ; The thickness of the BN layer is 3 nm to 5 nm.

3. The light-emitting diode epitaxial wafer according to claim 1, characterized in that, The number of periods of the second ladder layer is 3 to 12, and the N-type Al y In z Ga 1-y-z The thickness of the N layer is 2 nm to 4 nm, y is 0.03 to 0.08, z is 0.02 to 0.07, and its doping concentration is 1×10 17 cm -3 ~5×10 18 cm -3 ; The said B α In β Ga 1-α-β The thickness of the N layer is 2 nm to 4 nm, α is 0.2 to 0.6, and β is 0.03 to 0.

08.

4. The light-emitting diode epitaxial wafer according to claim 1, characterized in that, The number of periods of the third ladder layer is 2 to 4, and the N-type Al γ In δ Ga 1-γ-δ The thickness of the N layer is 3 nm to 5 nm, γ is 0.05 to 0.09, δ is 0.04 to 0.09, and its doping concentration is 1×10 15 cm -3 ~1×10 17 cm -3 ; The thickness of the Si3N4 layer is 3 nm to 5 nm.

5. The light-emitting diode epitaxial wafer according to any one of claims 1 to 4, characterized in that Along the growth direction of the epitaxial wafer, the Al in the N-type Al w In x Ga 1-w-x N layer shows a decreasing change in the Al component and an increasing change in the In component. The Al in the N-type Al y In z Ga 1-y-z N layer shows a decreasing change in the Al component and an increasing change in the In component. The Al in the N-type Al γ In δ Ga 1-γ-δ N layer shows a decreasing change in the Al component and an increasing change in the In component.

6. The light-emitting diode epitaxial wafer according to any one of claims 1 to 4, wherein The N-type Al w In x Ga 1-w- x The doping concentration of the N-type Al γ In δ Ga 1-γ-δ N layer is greater than the doping concentration of the N-type Al The N-type Al y In z Ga 1-y-z doping concentration of the N layer is greater than that of the N-type Al γ In δ Ga 1-γ-δ N layer; The doping concentration of the N-type Al w In x Ga 1-w-x N layer is the same as or different from the doping concentration of the N-type Al y In z Ga 1-y-z N layer.

7. The light-emitting diode epitaxial wafer according to any one of claims 1 to 4, characterized in that, Along the growth direction of the epitaxial wafer, the doping concentration of the N-type Al γ In δ Ga 1-γ-δ N layer decreases gradually.

8. The light-emitting diode epitaxial wafer according to any one of claims 1 to 4, characterized in that The multi-quantum well layer is a periodic structure formed by alternately stacking InGaN quantum well layers and AlGaN quantum barrier layers, and the number of periods is 6 to 12. The thickness of the InGaN quantum well layer is 2 nm to 5 nm, and the In component ratio is 0.15 to 0.

25. The thickness of the AlGaN quantum barrier layer is 5 nm to 15 nm, and the Al component ratio is 0.01 to 0.

1.

9. A method for preparing a light-emitting diode epitaxial wafer, which is used to prepare the light-emitting diode epitaxial wafer according to any one of claims 1 to 8, characterized in that, It includes: Providing a substrate, and sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, a V-pit control layer, a multi-quantum well layer, an electron blocking layer, and a P-type semiconductor layer on the substrate; the V-pit control layer includes a first stepped layer, a second stepped layer, and a third stepped layer that are sequentially stacked on the N-type GaN layer. The first stepped layer is a periodic structure formed by alternately stacking N-type Al w In x Ga 1-w-x N layers and BN layers, the second stepped layer is a periodic structure formed by alternately stacking N-type Al y In z Ga 1-y-z N layers and B α In β Ga 1-α-β N layers, and the third stepped layer is a periodic structure formed by alternately stacking N-type Al γ In δ Ga 1-γ-δ N layers and Si3N4 layers; Wherein, 0.01 ≤ w ≤ y ≤ γ ≤ 0.1, 0.01 ≤ x ≤ z ≤ δ ≤ 0.1, α < y, z ≤ β; Wherein, the growth temperature of the V-pit control layer is 850 °C to 1050 °C, and the growth pressure is 100 torr to 300 torr.

10. A light-emitting diode, characterized in that, It includes a light-emitting diode epitaxial wafer as described in any one of claims 1 to 8.

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