Light emitting diode for improving electron leakage and preparation method thereof

Abstract

The invention provides a light-emitting diode for improving electron leakage and a preparation method thereof. The light-emitting diode comprises an n-type layer, a multi-quantum well layer, an electron blocking layer and a p-type layer which are stacked in sequence, the electron blocking layer comprises a first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer which are sequentially stacked on the multi-quantum well layer, and the Al component content of the first p-type AlGaN layer and the Al component content of the third p-type AlGaN layer are both larger than the Al component content of the second p-type AlGaN layer. The problem that a large number of electrons are leaked to the p-type layer can be solved, and the light-emitting effect of the light-emitting diode is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light emitting diode with improved electron leakage and a preparation method thereof. Background Art

[0002] Light Emitting Diode (LED) is an extremely influential new product in the optoelectronics industry. It has the characteristics of small size, long service life, rich colors and low energy consumption. It is widely used in lighting, display screens, signal lights, backlight sources, toys and other fields.

[0003] In the related art, a light-emitting diode generally includes an n-type layer, a multi-quantum well layer, and a p-type layer. Since the electron transmission speed is much faster than the hole transmission speed, when a large number of electrons are injected from the n-type layer into the active region, there are not enough holes to recombine with them, resulting in a large number of electrons leaking to the p-type layer.

[0004] However, a large amount of electrons leaking into the p-type layer will reduce the recombination efficiency of the light-emitting diode and affect the light-emitting effect of the light-emitting diode. Summary of the invention

[0005] The embodiments of the present disclosure provide a light-emitting diode with improved electron leakage and a method for manufacturing the same, which can improve the problem of a large amount of electrons leaking into the p-type layer and enhance the light-emitting effect of the light-emitting diode. The technical solution is as follows:

[0006] On the one hand, an embodiment of the present disclosure provides an external light-emitting diode, which includes an n-type layer, a multi-quantum well layer, an electron blocking layer and a p-type layer stacked in sequence; the electron blocking layer includes a first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer stacked in sequence on the multi-quantum well layer, and the Al component content of the first p-type AlGaN layer and the third p-type AlGaN layer are both greater than the Al component content of the second p-type AlGaN layer.

[0007] In one implementation of the embodiment of the present disclosure, the Al / Ga component content ratio of the first p-type AlGaN layer is equal to the Al / Ga component content ratio of the third p-type AlGaN layer, and the Al / Ga component content ratio of the first p-type AlGaN layer is 1.5 to 9.

[0008] In another implementation of the embodiment of the present disclosure, the Al / Ga component content ratio of the second p-type AlGaN layer is 1 to 2.3.

[0009] In another implementation of the embodiment of the present disclosure, the thicknesses of the first p-type AlGaN layer, the second p-type AlGaN layer and the third p-type AlGaN layer are the same; the thickness of the first p-type AlGaN layer is greater than the thickness of the first AlN layer, and the thickness of the second AlN layer is less than or equal to the thickness of the first AlN layer.

[0010] In another implementation of the embodiment of the present disclosure, the thickness of the first p-type AlGaN layer is 7 nm to 10 nm; the thickness of the first AlN layer is 3 nm to 6 nm, and the thickness of the second AlN layer is less than or equal to 3 nm.

[0011] In another implementation of the embodiment of the present disclosure, the electron concentration of the p-type layer is less than or equal to 10 12 atoms / cm 3 .

[0012] On the other hand, an embodiment of the present disclosure provides a method for preparing a light-emitting diode, the method comprising: providing a substrate; forming an n-type layer on the substrate; forming a multi-quantum well layer on the n-type layer; sequentially forming a first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer on the multi-quantum well layer to form an electron blocking layer, the Al component contents of the first p-type AlGaN layer and the third p-type AlGaN layer being greater than the Al component content of the second p-type AlGaN layer; and forming a p-type layer on the electron blocking layer.

[0013] In another implementation of the embodiment of the present disclosure, a first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer are sequentially formed on the multi-quantum well layer, including: raising the temperature in the reaction chamber to 900°C to 1500°C, and controlling the pressure in the reaction chamber to 80mbar to 120mbar; introducing TMAl, NH3, and H2 into the reaction chamber to grow a first AlN layer with a thickness; introducing TMAl, TEGa, Cp2Mg, NH3 and H2 into the reaction chamber to grow a first p-type AlGaN layer; introducing TMAl, TEGa, Cp2Mg, NH3 and H2 into the reaction chamber to grow a second p-type AlGaN layer; introducing TMAl, TEGa, Cp2Mg, NH3 and H2 into the reaction chamber to grow a third p-type AlGaN layer; introducing TMAl, NH3 and H2 into the reaction chamber to grow a second AlN layer with a thickness.

[0014] In another implementation of the embodiment of the present disclosure, the Al / Ga component content ratios of the grown first p-type AlGaN layer and the third p-type AlGaN layer are the same, and the Al / Ga component content ratio of the first p-type AlGaN layer is 1.5 to 9; the Al / Ga component content ratio of the grown second p-type AlGaN layer is 1 to 2.3.

[0015] In another implementation of the embodiment of the present disclosure, the thicknesses of the grown first p-type AlGaN layer, second p-type AlGaN layer and third p-type AlGaN layer are the same; the thickness of the first p-type AlGaN layer is greater than the thickness of the first AlN layer, and the thickness of the second AlN layer is less than or equal to the thickness of the first AlN layer.

[0016] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0017] The electron blocking layer of the light-emitting diode provided in the embodiment of the present disclosure includes a first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer stacked in sequence. The Al component content of the first p-type AlGaN layer and the third p-type AlGaN layer is greater than the Al component content of the second p-type AlGaN layer. In this way, a structural layer composed of AlN, high Al component AlGaN, low Al component AlGaN, high Al component AlGaN and AlN is formed.

[0018] From the perspective of energy band, from AlN, high Al component AlGaN to low Al component AlGaN, the bandgap width of the film layer first gradually narrows from wide to narrow. This is to increase the conduction band potential height from the last quantum barrier in the multi-quantum well layer to the electron blocking layer. The increase in the conduction band potential barrier can effectively block electrons from being injected upward into the p-type layer. From low Al component AlGaN, high Al component AlGaN to AlN, the bandgap width of the film layer gradually widens in order to reduce the potential height of the valence band. Reducing the valence band potential barrier is conducive to the downward injection of holes into the multi-quantum well layer and recombination with electrons, thereby improving the luminescence effect of the light-emitting diode.

[0019] At the same time, due to the polarization effect of the transition from AlN to AlGaN, the polarization effect will cause the barrier height of the AlN layer on both sides of the electron blocking layer to achieve a sudden change. This can improve the effective potential height of the conduction band electrons, thereby more effectively preventing the leakage of electrons from the multi-quantum well layer; and also reduce the effective potential height of the valence band holes, making it easier for holes to migrate to the multi-quantum well layer, thereby improving the problem of a large number of electrons leaking to the p-type layer and improving the luminescence effect of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 is a structural schematic diagram of a light emitting diode provided by an embodiment of the present disclosure;

[0022] Figure 2 is a schematic diagram of a bandgap width of an electron blocking layer provided by an embodiment of the present disclosure;

[0023] Figure 3 is a schematic diagram of the electron concentration of each film layer in a light-emitting diode provided by an embodiment of the present disclosure;

[0024] Figure 4 It is a flow chart of a method for preparing a light emitting diode provided in an embodiment of the present disclosure.

[0025] The descriptions of the marks in the figure are as follows:

[0026] 10. Substrate;

[0027] 20. Buffer layer;

[0028] 30. n-type layer;

[0029] 40. Multiple quantum well layer;

[0030] 50. electron blocking layer; 51. first AlN layer; 52. first p-type AlGaN layer; 53. second p-type AlGaN layer; 54. third p-type AlGaN layer; 55. second AlN layer;

[0031] 60. p-type layer. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0033] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] Figure 1 Schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 1 As shown, the light emitting diode includes an n-type layer 30, a multi-quantum well layer 40, an electron blocking layer 50 and a p-type layer 60 which are stacked in sequence.

[0035] like Figure 1 As shown, the electron blocking layer 50 includes a first AlN layer 51 , a first p-type AlGaN layer 52 , a second p-type AlGaN layer 53 , a third p-type AlGaN layer 54 and a second AlN layer 55 which are sequentially stacked on the multi-quantum well layer 40 .

[0036] The Al component contents of the first p-type AlGaN layer 52 and the third p-type AlGaN layer 54 are both greater than the Al component content of the second p-type AlGaN layer 53 .

[0037] The electron blocking layer 50 of the light-emitting diode provided in the embodiment of the present disclosure comprises a first AlN layer 51, a first p-type AlGaN layer 52, a second p-type AlGaN layer 53, a third p-type AlGaN layer 54 and a second AlN layer 55 stacked in sequence. The Al component content of the first p-type AlGaN layer 52 and the third p-type AlGaN layer 54 is greater than the Al component content of the second p-type AlGaN layer 53. In this way, a structural layer composed of AlN, high Al component AlGaN, low Al component AlGaN, high Al component AlGaN and AlN is formed.

[0038] Figure 2 Schematic diagram of the bandgap width of an electron blocking layer 50 provided in an embodiment of the present disclosure. Figure 2 As shown, from the perspective of energy band, from AlN, high Al component AlGaN to low Al component AlGaN, the bandgap width of the film layer first gradually narrows from wide to narrow. This is to increase the conduction band potential height from the last quantum barrier in the multi-quantum well layer 40 to the electron blocking layer 50. The increase in the conduction band potential barrier can effectively block electrons from being injected upward into the p-type layer 60. From low Al component AlGaN, high Al component AlGaN to AlN, the bandgap width of the film layer gradually widens in order to reduce the potential height of the valence band. Reducing the valence band potential barrier is conducive to the downward injection of holes into the multi-quantum well layer 40 and recombination with electrons, thereby improving the light-emitting effect of the light-emitting diode.

[0039] At the same time, since there is a polarization effect in the transition from AlN to AlGaN, the polarization effect will make the barrier height of the AlN layer on both sides of the electron blocking layer 50 reach a sudden change. This can better improve the effective potential height of the conduction band electrons, thereby more effectively preventing the leakage of electrons from the multi-quantum well layer 40; and also make the effective potential height of the valence band holes better reduced, making it easier for the holes to migrate to the multi-quantum well layer 40, thereby improving the problem of a large number of electrons leaking to the p-type layer 60 and improving the light-emitting effect of the light-emitting diode.

[0040] Optionally, the Al / Ga composition content ratio of the first p-type AlGaN layer 52 is equal to the same as the Al / Ga composition content ratio of the third p-type AlGaN layer 54 .

[0041] The Al / Ga component content ratio refers to the ratio of the Al component content to the Ga component content in the AlGaN layer.

[0042] Optionally, the Al / Ga composition content ratio of the first p-type AlGaN layer 52 is 1.5 to 9.

[0043] For example, the Al content of the first p-type AlGaN layer 52 is 0.9, the Ga content of the first p-type AlGaN layer 52 is 0.1, and the Al / Ga content ratio of the first p-type AlGaN layer 52 is 9.

[0044] Optionally, the Al / Ga composition content ratio of the second p-type AlGaN layer 53 is 1 to 2.3.

[0045] Exemplarily, the Al component content of the second p-type AlGaN layer 53 is 0.7, the Ga component content of the second p-type AlGaN layer 53 is 0.3, and the Al / Ga component content ratio of the second p-type AlGaN layer 53 is 2.3.

[0046] By controlling the Al / Ga component content ratio of the first p-type AlGaN layer 52 and the Al / Ga component content ratio of the second p-type AlGaN layer 53 within the above-mentioned range, the difference between the Al / Ga component content of the first p-type AlGaN layer 52 and the Al / Ga component content of the second p-type AlGaN layer 53 can be large enough to form a larger conduction band barrier height difference, thereby effectively blocking electrons from being injected into the p-type layer 60.

[0047] At the same time, by controlling the Al / Ga component content ratio of the third p-type AlGaN layer 54 and the Al / Ga component content ratio of the second p-type AlGaN layer 53 within the above-mentioned range, the difference between the Al / Ga component content of the third p-type AlGaN layer 54 and the Al / Ga component content of the second p-type AlGaN layer 53 can be large enough to make the valence band barrier lowered more significantly, thereby facilitating the injection of holes into the multi-quantum well layer 40.

[0048] Optionally, the first p-type AlGaN layer 52 , the second p-type AlGaN layer 53 , and the third p-type AlGaN layer 54 have the same thickness.

[0049] The thickness of the first p-type AlGaN layer 52 is greater than the thickness of the first AlN layer 51 , and the thickness of the second AlN layer 55 is less than or equal to the thickness of the first AlN layer 51 .

[0050] The main material of the light emitting diode in the embodiment of the present disclosure is AlGaN. By making the thickness of the first AlN layer 51 smaller than the thickness of the first p-type AlGaN layer 52, it is avoided to set the first AlN layer 51 with a large thickness. In this way, it is possible to avoid a large number of dislocation defects between the excessively thick AlN layer and the AlGaN layer due to lattice mismatch, thereby generating leakage channels and reducing the probability of leakage.

[0051] Meanwhile, the first AlN layer 51 may be thicker than the second AlN layer 55 . Thus, using the second AlN layer 55 with a smaller thickness can reduce the valence band barrier and make it easier for holes to migrate to the multi-quantum well layer 40 .

[0052] For a light-emitting diode with a high current density, the thickness of the first AlN layer 51 can be appropriately increased, the thickness of the first p-type AlGaN layer 52, the second p-type AlGaN layer 53 and the third p-type AlGaN layer 54 can be reduced year-on-year, and the total thickness of the electron blocking layer 50 can be kept unchanged. Because at a high current density, the increase in carriers can help increase the body resistance of the interface from the last quantum barrier to the electron blocking layer 50 by increasing the thickness of the first AlN layer 51, thereby reinforcing the probability of overflow.

[0053] Optionally, the thickness of the first p-type AlGaN layer 52 is 7 nm to 10 nm, the thickness of the second p-type AlGaN layer 53 is 7 nm to 10 nm, and the thickness of the third p-type AlGaN layer 54 is 7 nm to 10 nm.

[0054] Exemplarily, the thickness of the first p-type AlGaN layer 52 is 9 nm, the thickness of the second p-type AlGaN layer 53 is 9 nm, and the thickness of the third p-type AlGaN layer 54 is 9 nm.

[0055] Optionally, the thickness of the first AlN layer 51 is 3 nm to 6 nm.

[0056] Exemplarily, the thickness of the first AlN layer 51 is 3 nm.

[0057] Optionally, the thickness of the second AlN layer 55 is less than or equal to 3 nm.

[0058] Exemplarily, the thickness of the second AlN layer 55 is 3 nm.

[0059] In the embodiment of the present disclosure, setting each film layer within the above range can ensure that each film layer is in a relatively thin state, which is conducive to reflecting the potential barrier difference between the film layers, thereby achieving the purpose of blocking electron leakage.

[0060] Figure 3 Schematic diagram of the electron concentration of each film layer in a light-emitting diode provided by an embodiment of the present disclosure. Figure 3 As shown, curve B illustrates a light-emitting diode using the electron blocking layer 50 in the related art, and curve C illustrates a light-emitting diode having the electron blocking layer 50 in the embodiment of the present disclosure.

[0061] in, Figure 3 The left curve in the middle is the electron concentration curve in the n-type layer 30. Figure 3 The middle curve is the electron concentration curve in the electron blocking layer 50. Figure 3 The right curve in the middle is the electron concentration curve in the p-type layer 60 .

[0062] According to the attached Figure 3 It can be seen that the electron concentration of the p-type layer 60 in the embodiment of the present disclosure is less than or equal to 10 12 atoms / cm 3 In the related art, the electron concentration of the p-type layer 60 is higher than 10 13 atoms / cm 3 .

[0063] It can be seen that the electron blocking layer 50 in the embodiment of the present disclosure can significantly reduce the degree of electron leakage compared with the electron blocking layer 50 in the related technology. This shows that the electron blocking layer 50 in the embodiment of the present disclosure has a more significant electron confinement ability, so that the electrons are more concentrated in the active area, so that the electron-hole has a greater probability of recombination, thereby improving the luminous efficiency of the light-emitting diode.

[0064] Alternatively, if Figure 1 As shown, the light emitting diode further includes a substrate 10 , on which an n-type layer 30 , a multi-quantum well layer 40 , an electron blocking layer 50 and a p-type layer 60 are stacked.

[0065] Exemplarily, the substrate is a sapphire substrate, a silicon substrate or a silicon carbide substrate. The substrate can be a flat substrate or a patterned substrate.

[0066] As an example, in the embodiment of the present disclosure, the substrate is a sapphire substrate. The sapphire substrate is a commonly used substrate with mature technology and low cost. Specifically, it can be a patterned sapphire substrate or a sapphire flat sheet substrate.

[0067] Alternatively, if Figure 1 As shown, a buffer layer 20 is further included between the substrate 10 and the n-type layer 30 .

[0068] Among them, the AlN layer and the AlGaN layer are stacked in sequence.

[0069] Exemplarily, the AlN layer may include an AlN low temperature layer and an AlN high temperature layer sequentially formed on the substrate.

[0070] The thickness of the AlN low temperature layer is 1nm to 100nm. If the thickness of the AlN low temperature layer is set too thin, the effect of reducing the dislocation defects of the subsequently grown n-type AlGaN layer is relatively small, and the effect of improving the luminous efficiency of the deep ultraviolet light-emitting diode is not obvious. If the thickness of the AlN low temperature layer is set too thick, the AlN low temperature layer will increase its absorption of light.

[0071] As an example, in the embodiment of the present disclosure, the thickness of the AlN low-temperature layer is 10 nm.

[0072] The thickness of the AlN high temperature layer is 1μm to 5μm. The thickness of the AlN high temperature layer will affect the quality of the light-emitting diode. If the thickness of the AlN high temperature layer is too thin, the surface of the AlN high temperature layer will be loose and rough, and it will not provide a good template for the growth of subsequent structures. In this thickness range, the surface of the AlN high temperature layer is dense and flat, which is conducive to the growth of subsequent structures.

[0073] As an example, in the embodiment of the present disclosure, the thickness of the AlN high temperature layer is 2.5 μm.

[0074] Exemplarily, the AlGaN layer is located between the AlN layer and the n-type layer 30. The AlGaN layer is not doped, and the thickness of the AlGaN layer is 460 nm to 520 nm.

[0075] Optionally, the n-type layer 30 includes an n-type AlGaN layer.

[0076] Exemplarily, the thickness of the n-type AlGaN layer may be 600 nm to 800 nm. In the embodiment of the present disclosure, the thickness of the n-type AlGaN layer is 700 nm.

[0077] Optionally, the doping concentration of silicon in the n-type AlGaN layer is 10 17 cm -3 Up to 10 18 cm -3 Too high a doping concentration of silicon will reduce the crystal quality and increase defects, while too low a doping concentration of silicon will reduce the conductivity of the n-type AlGaN layer. 17 cm -3 Up to 10 18 cm -3 , which can make the n-type AlGaN layer have good crystal quality and sufficient electrical conductivity.

[0078] As an example, in the embodiment of the present disclosure, the doping concentration of silicon in the n-type AlGaN layer is 5×10 17 cm -3 .

[0079] Optionally, the multi-quantum well layer 40 includes 3 to 8 Al x Ga 1-x N quantum well layer and Al y Ga 1-y N quantum barrier layers, where 0<x<y<1. That is, the multi-quantum well layer 40 includes 3 to 8 periods of Al x Ga 1-x N quantum well layer and Al y Ga 1-y N quantum barrier layers.

[0080] As an example, in the embodiment of the present disclosure, the multi-quantum well layer 40 includes five periods of Al2O3 stacked alternately. x Ga 1-x N quantum well layer and Al y Ga 1-y N quantum barrier layers.

[0081] Optionally, Al x Ga 1-x The thickness of the N quantum well layer can be 2nm to 4nm. y Ga 1-yThe thickness of the N quantum barrier layer may be 9 nm to 14 nm.

[0082] For example, in the embodiments of the present disclosure, Al x Ga 1-x The thickness of the N quantum well layer is 3nm. y Ga 1-y The thickness of the N quantum barrier layer is 11 nm.

[0083] It should be noted that when growing the multi-quantum well layer, Al can also be grown on the n-type AlGaN layer first. y Ga 1-y N quantum barrier layers.

[0084] In the embodiment of the present disclosure, the p-type layer 60 includes a high temperature p-type GaN layer and a low temperature p-type GaN layer sequentially stacked on the electron blocking layer 50. Both the high temperature p-type GaN layer and the low temperature p-type GaN layer are doped with Mg.

[0085] In some examples, the thickness of the high temperature p-type GaN layer is 13 nm to 17 nm. As an example, in the embodiment of the present disclosure, the thickness of the high temperature p-type GaN layer is 15 nm.

[0086] In some examples, the thickness of the low temperature p-type GaN layer may be 5 nm to 9 nm. As an example, in the embodiment of the present disclosure, the thickness of the low temperature p-type GaN layer is 8 nm.

[0087] Figure 4 is a flow chart of a method for preparing a light emitting diode provided in an embodiment of the present disclosure. Figure 1 The light emitting diode shown. Figure 4 As shown, the preparation method comprises:

[0088] Step S11: providing a substrate.

[0089] Step S12: forming an n-type layer on the substrate.

[0090] Step S13: forming a multi-quantum well layer on the n-type layer.

[0091] Step S14 : forming a first AlN layer 51 , a first p-type AlGaN layer 52 , a second p-type AlGaN layer 53 , a third p-type AlGaN layer 54 and a second AlN layer 55 in sequence on the multi-quantum well layer to form an electron blocking layer 50 .

[0092] The Al component contents of the first p-type AlGaN layer 52 and the third p-type AlGaN layer 54 are both greater than the Al component content of the second p-type AlGaN layer 53 .

[0093] Step S15 : forming a p-type layer 60 on the electron blocking layer 50 .

[0094] The electron blocking layer 50 of the light emitting diode is designed to be a first AlN layer 51, a first p-type AlGaN layer 52, a second p-type AlGaN layer 53, a third p-type AlGaN layer 54 and a second AlN layer 55 stacked in sequence. The Al component content of the first p-type AlGaN layer 52 and the third p-type AlGaN layer 54 is greater than the Al component content of the second p-type AlGaN layer 53. In this way, a structural layer composed of AlN, high Al component AlGaN, low Al component AlGaN, high Al component AlGaN and AlN is formed.

[0095] From the perspective of energy band, from AlN, high Al component AlGaN to low Al component AlGaN, the bandgap width of the film layer first gradually narrows from wide to narrow. This is to increase the conduction band potential height from the last quantum barrier in the multi-quantum well layer 40 to the electron blocking layer 50. The increase in the conduction band potential barrier can effectively block electrons from being injected upward into the p-type layer 60. From low Al component AlGaN, high Al component AlGaN to AlN, the bandgap width of the film layer gradually widens in order to reduce the potential height of the valence band. Reducing the valence band potential barrier is conducive to the downward injection of holes into the multi-quantum well layer 40 and recombination with electrons, thereby improving the light-emitting effect of the light-emitting diode.

[0096] At the same time, since there is a polarization effect in the transition from AlN to AlGaN, the polarization effect will make the barrier height of the AlN layer on both sides of the electron blocking layer 50 reach a sudden change. This can better improve the effective potential height of the conduction band electrons, thereby more effectively preventing the leakage of electrons from the multi-quantum well layer 40; and also make the effective potential height of the valence band holes better reduced, making it easier for the holes to migrate to the multi-quantum well layer 40, thereby improving the problem of a large number of electrons leaking to the p-type layer 60 and improving the light-emitting effect of the light-emitting diode.

[0097] In step S11, the substrate is a sapphire substrate, a silicon substrate or a silicon carbide substrate. The substrate can be a flat substrate or a patterned substrate.

[0098] As an example, in the embodiment of the present disclosure, the substrate is a sapphire substrate. The sapphire substrate is a commonly used substrate with mature technology and low cost. Specifically, it can be a patterned sapphire substrate or a sapphire flat sheet substrate.

[0099] Optionally, the sapphire substrate may be pre-treated, the sapphire substrate may be placed in a MOCVD reaction chamber, and the sapphire substrate may be baked for 12 to 18 minutes. As an example, in the embodiment of the present disclosure, the sapphire substrate may be baked for 15 minutes.

[0100] Specifically, the baking temperature may be 1000° C. to 1200° C., and the pressure in the MOCVD reaction chamber during baking may be 100 mbar to 200 mbar.

[0101] Before step S12, the method further includes: epitaxially growing an AlN layer and an AlGaN layer on the substrate.

[0102] The AlN layer includes an AlN low-temperature layer and an AlN high-temperature layer.

[0103] The thickness of the AlN low-temperature layer is 1nm to 100nm. If the thickness of the AlN low-temperature layer is set too thin, the effect of reducing the dislocation defects of the subsequently grown n-type AlGaN layer is relatively small, and the effect of improving the luminous efficiency of the deep ultraviolet light-emitting diode is not obvious. If the thickness of the AlN low-temperature layer is set too thick, the AlN low-temperature layer will increase its absorption of light.

[0104] As an example, in the embodiment of the present disclosure, the thickness of the AlN low-temperature layer is 10 nm.

[0105] The thickness of the AlN high temperature layer is 1μm to 5μm. The thickness of the AlN high temperature layer will affect the quality of the light-emitting diode. If the thickness of the AlN high temperature layer is too thin, the surface of the AlN high temperature layer will be loose and rough, and it will not provide a good template for the growth of subsequent structures. In this thickness range, the surface of the AlN high temperature layer is dense and flat, which is conducive to the growth of subsequent structures.

[0106] As an example, in the embodiment of the present disclosure, the thickness of the AlN high temperature layer is 2.5 μm.

[0107] In the disclosed embodiment, both the AlN low temperature layer and the AlN high temperature layer are grown by MOCVD (Metal Organic Chemical Vapor Deposition).

[0108] Optionally, when forming the AlN low-temperature layer, the growth pressure is 50 mbar to 100 mbar. The growth pressure will affect sputtering, and a good quality AlN low-temperature layer can be grown within this pressure range.

[0109] Illustratively, in the embodiment of the present disclosure, the growth pressure of the AlN low-temperature layer is 60 mbar.

[0110] Optionally, when forming the AlN low temperature layer, the growth temperature is 800° C. to 1200° C. For example, in the embodiment of the present disclosure, the growth temperature of the AlN low temperature layer is 1100° C.

[0111] Optionally, when forming the AlN low temperature layer, ammonia and trimethylaluminum are used as reactants, and the V / III molar ratio is 350 to 3500. For example, in the embodiment of the present disclosure, the V / III molar ratio is 3000.

[0112] Optionally, when growing the AlN low temperature layer, the growth time is 800s to 1200s. Exemplarily, in the embodiment of the present disclosure, the growth time of the AlN low temperature layer is 1000s.

[0113] Optionally, when forming the AlN high temperature layer, the growth pressure is 30 mbar to 100 mbar. The growth pressure will affect sputtering, and a high quality AlN high temperature layer can be grown within this pressure range.

[0114] Exemplarily, in the embodiment of the present disclosure, the growth pressure of the AlN high temperature layer is 50 mbar.

[0115] Optionally, when forming the AlN high temperature layer, the growth temperature is 1300° C. to 1500° C. For example, in the embodiment of the present disclosure, the growth temperature of the AlN high temperature layer is 1350° C.

[0116] Optionally, when forming the AlN high temperature layer, ammonia and trimethylaluminum are used as reactants, and the V / III molar ratio is 200 to 500. For example, in the embodiment of the present disclosure, the V / III molar ratio is 300.

[0117] Optionally, when growing the AlN high temperature layer, the growth time is 3000s to 6000s. Exemplarily, in the embodiment of the present disclosure, the growth time of the AlN high temperature layer is 5000s.

[0118] Optionally, when growing the AlGaN layer, a non-doped AlGaN layer with a thickness of 460 nm to 520 nm is deposited on the AlN layer.

[0119] The process of forming the n-type layer 30 in step S12 may include: epitaxially growing an n-type AlGaN layer on the AlGaN layer.

[0120] Optionally, the growth temperature of the n-type AlGaN layer is 1000° C. to 1100° C. As an example, in the embodiment of the present disclosure, the growth temperature of the n-type AlGaN layer is 1060° C.

[0121] Optionally, the growth pressure of the n-type AlGaN layer may be 80 mbar to 110 mbar. As an example, in the embodiment of the present disclosure, the growth pressure of the n-type AlGaN layer is 100 mbar.

[0122] When growing the n-type AlGaN layer, silicon doping is performed. The silicon doping concentration in the n-type AlGaN layer can be 10 17 cm-3 Up to 10 18 cm -3 As an example, in the embodiment of the present disclosure, the silicon doping concentration in the n-type AlGaN layer is 5×10 17 cm -3 .

[0123] The thickness of the n-type AlGaN layer may be 600 nm to 800 nm. In the embodiment of the present disclosure, the thickness of the n-type AlGaN layer is 700 nm.

[0124] Step S13 may include: growing a multi-quantum well layer 40 on the n-type AlGaN layer.

[0125] When implemented, the multi-quantum well layer 40 may include multiple layers of Al x Ga 1-x N quantum well layer and multilayer Al y Ga 1- y N quantum barriers, where 0<x<y<1.

[0126] Optionally, Al x Ga 1-x N quantum well layer and Al y Ga 1-y The number of cycles of the N quantum barrier layers alternately stacked may be 3 to 8. For example, in the embodiment of the present disclosure, Al x Ga 1-x N quantum well layer and Al y Ga 1-y The number of cycles of alternating stacking of N quantum barrier layers is 5.

[0127] Optionally, Al x Ga 1-x The thickness of the N quantum well layer can be 2nm to 4nm. y Ga 1-y The thickness of the N quantum barrier layer may be 9 nm to 14 nm.

[0128] For example, in the embodiments of the present disclosure, Al x Ga 1-x The thickness of the N quantum well layer is 3nm. y Ga 1-y The thickness of the N quantum barrier layer is 11 nm.

[0129] Step S14 may include the following steps:

[0130] First, the temperature in the reaction chamber is raised to 900° C. to 1500° C., and the pressure in the reaction chamber is controlled to be 80 mbar to 120 mbar.

[0131] For example, the temperature in the reaction chamber may be 1000° C., and the pressure in the reaction chamber may be 100 mbar. By controlling the temperature and pressure in the reaction chamber within the above ranges, AlN layers and AlGaN layers of good quality can be grown.

[0132] Then, TMAl, NH 3 , and H 2 are introduced into the reaction chamber to grow a first AlN layer 51 with a thickness.

[0133] Next, TMAl, TEGa, Cp2Mg, NH3 and H2 are introduced into the reaction chamber to grow a first p-type AlGaN layer 52 .

[0134] Then, TMAl, TEGa, Cp2Mg, NH3 and H2 are introduced into the reaction chamber to grow a second p-type AlGaN layer 53 .

[0135] Next, TMAl, TEGa, Cp2Mg, NH3 and H2 are introduced into the reaction chamber to grow a third p-type AlGaN layer 54 .

[0136] Finally, TMAl, NH 3 , and H 2 are introduced into the reaction chamber to grow a second AlN layer 55 with a thickness.

[0137] Optionally, the Al / Ga composition ratios of the grown first p-type AlGaN layer 52 and the third p-type AlGaN layer 54 are the same, and the Al / Ga composition ratio of the first p-type AlGaN layer 52 is 1.5 to 9.

[0138] For example, the Al content of the first p-type AlGaN layer 52 is 0.9, the Ga content of the first p-type AlGaN layer 52 is 0.1, and the Al / Ga content ratio of the first p-type AlGaN layer 52 is 9.

[0139] Optionally, the Al / Ga composition content ratio of the grown second p-type AlGaN layer 53 is 1 to 2.3.

[0140] Exemplarily, the Al component content of the second p-type AlGaN layer 53 is 0.7, the Ga component content of the second p-type AlGaN layer 53 is 0.3, and the Al / Ga component content ratio of the second p-type AlGaN layer 53 is 2.3.

[0141] Optionally, the first p-type AlGaN layer 52 , the second p-type AlGaN layer 53 , and the third p-type AlGaN layer 54 are grown to have the same thickness.

[0142] Optionally, the thickness of the first p-type AlGaN layer 52 is greater than the thickness of the first AlN layer 51 , and the thickness of the second AlN layer 55 is less than or equal to the thickness of the first AlN layer 51 .

[0143] Exemplarily, the thickness of the first p-type AlGaN layer 52 is 7 nm to 10 nm, the thickness of the second p-type AlGaN layer 53 is 7 nm to 10 nm, and the thickness of the third p-type AlGaN layer 54 is 7 nm to 10 nm.

[0144] Exemplarily, the thickness of the first p-type AlGaN layer 52 is 9 nm, the thickness of the second p-type AlGaN layer 53 is 9 nm, and the thickness of the third p-type AlGaN layer 54 is 9 nm.

[0145] Optionally, the thickness of the first AlN layer 51 is 3 nm to 6 nm.

[0146] Exemplarily, the thickness of the first AlN layer 51 is 3 nm.

[0147] Optionally, the thickness of the second AlN layer 55 is less than or equal to 3 nm.

[0148] Exemplarily, the thickness of the second AlN layer 55 is 3 nm.

[0149] Step S15 may include: growing a high temperature p-type GaN layer and a low temperature p-type GaN layer on the multi-quantum well layer 40 .

[0150] Optionally, the growth temperature of the high temperature p-type GaN layer may be 800° C. to 1000° C. As an example, in the embodiment of the present disclosure, the growth temperature of the high temperature p-type GaN layer is 980° C.

[0151] Optionally, the growth pressure of the high temperature p-type GaN layer may be 250 mbar to 350 mbar. As an example, in the embodiment of the present disclosure, the growth pressure of the high temperature p-type GaN layer is 300 mbar.

[0152] Optionally, the thickness of the high temperature p-type GaN layer may be 13 nm to 17 nm. As an example, in the embodiment of the present disclosure, the thickness of the high temperature p-type GaN layer is 15 nm.

[0153] Optionally, the growth temperature of the low-temperature p-type GaN layer may be 800° C. to 900° C. As an example, in the embodiment of the present disclosure, the growth temperature of the low-temperature p-type GaN layer is 840° C.

[0154] Optionally, the thickness of the low temperature p-type GaN layer may be 5 nm to 9 nm. As an example, in the embodiment of the present disclosure, the thickness of the low temperature p-type GaN layer is 8 nm.

[0155] After step S15, the following further comprises: annealing the light emitting diode.

[0156] Optionally, annealing can be performed in a nitrogen atmosphere for 30 minutes to terminate the growth of the light-emitting diode, and then the heating system and the gas supply system are turned off until the temperature of the reaction chamber drops to room temperature.

[0157] In specific implementation, the embodiments of the present disclosure may use high-purity H2 and / or N2 as carrier gas, TEGa or TMGa as Ga source, TMIn as In source, SiH4 as n-type dopant, TMAl as aluminum source, and Cp2Mg as p-type dopant.

[0158] The above does not limit the present disclosure in any form. Although the present disclosure has been disclosed as above through the embodiments, it is not used to limit the present disclosure. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present disclosure. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure still falls within the scope of the technical solution of the present disclosure.

Claims

1. A light emitting diode, characterized in that: The light-emitting diode comprises an n-type layer (30), a multi-quantum well layer (40), an electron blocking layer (50) and a p-type layer (60) which are stacked in sequence; The electron blocking layer (50) comprises a first AlN layer (51), a first p-type AlGaN layer (52), a second p-type AlGaN layer (53), a third p-type AlGaN layer (54) and a second AlN layer (55) which are sequentially stacked on the multi-quantum well layer (40), wherein the Al component content of the first p-type AlGaN layer (52) and the third p-type AlGaN layer (54) is greater than the Al component content of the second p-type AlGaN layer (53).

2. The light emitting diode according to claim 1, characterized in that: The Al / Ga composition ratio of the first p-type AlGaN layer (52) is equal to the Al / Ga composition ratio of the third p-type AlGaN layer (54), and the Al / Ga composition ratio of the first p-type AlGaN layer (52) is 1.5 to 9.

3. The light emitting diode according to claim 1, characterized in that: The Al / Ga composition content ratio of the second p-type AlGaN layer (53) is 1 to 2.

3.

4. The light emitting diode according to any one of claims 1 to 3, characterized in that: The first p-type AlGaN layer (52), the second p-type AlGaN layer (53) and the third p-type AlGaN layer (54) have the same thickness; The thickness of the first p-type AlGaN layer (52) is greater than the thickness of the first AlN layer (51), and the thickness of the second AlN layer (55) is less than or equal to the thickness of the first AlN layer (51).

5. The light emitting diode according to claim 4, characterized in that: The thickness of the first p-type AlGaN layer (52) is 7 nm to 10 nm; The thickness of the first AlN layer (51) is 3 nm to 6 nm, and the thickness of the second AlN layer (55) is less than or equal to 3 nm.

6. The light emitting diode according to any one of claims 1 to 3, characterized in that: The electron concentration of the p-type layer (60) is less than or equal to 10 12 atoms / cm 3 .

7. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: providing a substrate; forming an n-type layer on the substrate; forming a multi-quantum well layer on the n-type layer; forming a first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer in sequence on the multi-quantum well layer to form an electron blocking layer, wherein the Al component contents of the first p-type AlGaN layer and the third p-type AlGaN layer are both greater than the Al component content of the second p-type AlGaN layer; A p-type layer is formed on the electron blocking layer.

8. The preparation method according to claim 7, characterized in that: A first AlN layer, a first p-type AlGaN layer, a second p-type AlGaN layer, a third p-type AlGaN layer and a second AlN layer are sequentially formed on the multi-quantum well layer, including: Raise the temperature in the reaction chamber to 900°C to 1500°C, and control the pressure in the reaction chamber to 80mbar to 120mbar; Introduce TMAl, NH3, and H2 into the reaction chamber to grow a first AlN layer of thickness; Introducing TMAl, TEGa, Cp2Mg, NH3 and H2 into the reaction chamber to grow a first p-type AlGaN layer; Introducing TMAl, TEGa, Cp2Mg, NH3 and H2 into the reaction chamber to grow a second p-type AlGaN layer; Introducing TMAl, TEGa, Cp2Mg, NH3 and H2 into the reaction chamber to grow a third p-type AlGaN layer; TMAl, NH3 and H2 are introduced into the reaction chamber to grow a second AlN layer with a thickness of 1.

9. The preparation method according to claim 7 or 8, characterized in that: The Al / Ga component content ratio of the grown first p-type AlGaN layer and the third p-type AlGaN layer is the same, and the Al / Ga component content ratio of the first p-type AlGaN layer is 1.5 to 9; The Al / Ga composition content ratio of the grown second p-type AlGaN layer is 1 to 2.

3.

10. The preparation method according to claim 7 or 8, characterized in that: The thicknesses of the first p-type AlGaN layer, the second p-type AlGaN layer and the third p-type AlGaN layer grown are the same; The thickness of the first p-type AlGaN layer is greater than the thickness of the first AlN layer, and the thickness of the second AlN layer is less than or equal to the thickness of the first AlN layer.

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