LED epitaxial wafer, LED chip and method for preparing LED epitaxial wafer

Abstract

The present invention provides an LED epitaxial wafer, an LED chip and a method for preparing the LED epitaxial wafer, belonging to the technical field of light-emitting diodes. The LED epitaxial wafer comprises a substrate and an epitaxial layer. The epitaxial layer comprises an n-type window layer, an n-type semiconductor layer, an active layer, a p-type semiconductor layer and a p-type window layer which are stacked in sequence. The p-type window layer comprises a periodically distributed superlattice unit. The superlattice unit comprises Al x In 1‑x P sublayer, Ga x In 1‑x P sublayer and GaP sublayer, wherein the bandgap width and doping concentration of the three sublayers in the same superlattice unit are different. x In 1‑x The doping concentration of the P sublayer is higher than that of the other two sublayers, and the doping concentration of the same sublayer in the superlattice unit gradually increases along the stacking direction. The present invention introduces a superlattice structure into the p-type window layer to improve current injection efficiency and reduce light absorption.

Description

Technical Field

[0001] The invention relates to the technical field of light emitting diodes, and in particular to an LED epitaxial wafer, an LED chip and a method for preparing the LED epitaxial wafer. Background Art

[0002] In recent years, AlGaInP quaternary high-brightness light-emitting diodes (LEDs) have been widely used. Compared with traditional GaP, GaAs and GaAlAs materials, this material has the advantages of wide direct transition band gap, high luminous efficiency, strong current carrying capacity, good stability and good temperature resistance. It plays an increasingly important role in signal lights, interior and exterior indicator lights for vehicles, traffic lights, mobile phones, electronic instruments, indoor and outdoor displays, information processing, communications and other fields.

[0003] The commonly used structure of the current AlGaInP quaternary high-brightness light-emitting diode includes a substrate, an epitaxial wafer, an n-type electrode, and a p-type electrode. The commonly used structure of the epitaxial wafer includes an n-type window layer, an n-type semiconductor layer, an active layer of alternating GaInP / AlGaInP, a p-type semiconductor layer, and a p-type window layer. The main component of the p-type window layer is GaP doped with Mg, which mainly acts as a current spreading layer.

[0004] However, when the light-emitting diode is working, the current is expanded laterally through the p-type window layer, and the current is injected into the active layer in the process. Since the current expansion capacity of the p-type window layer, whose main component is GaP, is limited, the current density of the p-type current expansion layer is higher near the bottom of the p-type electrode, while the current density of the area farther from the p-type electrode is lower, resulting in low overall current injection efficiency, reducing the light extraction efficiency of the LED. In addition, the thickness of the p-type window layer, whose main component is GaP, is usually set to be relatively thick, thereby absorbing a greater degree of emitted light, further reducing the light extraction efficiency of the light-emitting diode. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide an LED epitaxial wafer, an LED chip and a method for preparing an LED epitaxial wafer, aiming to innovatively design the p-type window layer to improve the current injection efficiency of the p-type window layer and reduce the light absorption degree of the p-type window layer, so as to achieve the purpose of improving the light extraction efficiency of the light-emitting diode.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides an LED epitaxial wafer, comprising a substrate and an epitaxial layer, wherein the epitaxial layer is arranged on one side of the substrate, the epitaxial layer comprises an n-type window layer, an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and a p-type window layer stacked in sequence, the p-type window layer comprises superlattice units periodically distributed along a stacking direction, the superlattice units comprise Alx In 1-x P sublayer, Ga x In 1-x P sublayer and GaP sublayer, wherein the bandgap width and doping concentration of the three sublayers in the same superlattice unit are different, and the value range of x is 0.5≤x<1. x In 1-x The doping concentration of the P sublayer is higher than the doping concentration of the other sublayers in the same superlattice unit, and the doping concentration of the same sublayer in the superlattice unit gradually increases along the stacking direction.

[0008] Furthermore, Al x In 1-x P sublayer, Ga x In 1-x The doping sources of the P sublayer and the GaP sublayer are both Mg or Zn.

[0009] Furthermore, the doping concentration of the doping source is 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 .

[0010] Furthermore, Al x In 1-x The thickness of the P sublayer is 20nm~50nm, and the Ga x In 1-x The thickness of the P sublayer is 50nm~100nm, and the thickness of the GaP sublayer is 50nm~100nm.

[0011] Furthermore, the period of the superlattice unit is 10-50.

[0012] In a second aspect, the present invention provides an LED chip, comprising the aforementioned LED epitaxial wafer, and connecting electrodes formed on the LED epitaxial wafer.

[0013] In a third aspect, the present invention provides a method for preparing an LED epitaxial wafer, comprising the following steps:

[0014] providing a substrate;

[0015] growing an n-type window layer on the substrate;

[0016] growing an n-type semiconductor layer on the n-type window layer;

[0017] growing an active layer on the n-type semiconductor layer;

[0018] growing a p-type semiconductor layer on the active layer;

[0019] A p-type window layer is grown on the p-type semiconductor layer, wherein the p-type window layer includes superlattice units periodically distributed along the stacking direction, and the superlattice units include Al x In 1-x P sublayer, Ga x In 1-x P sublayer and GaP sublayer, the bandgap width and doping concentration of the three sublayers in the same superlattice unit are different, the value range of x is 0.5≤x<1, and the Ga in the same superlattice unit is x In 1-x The doping concentration of the P sublayer is higher than the doping concentration of the other sublayers in the same superlattice unit, and the doping concentration of the same sublayer in the superlattice unit gradually increases along the stacking direction.

[0020] Furthermore, a p-type window layer is grown on the active layer using MOVCD technology, wherein the growth temperature is set to 650°C-800°C, the growth pressure is set to 40mbar-60mbar, the doping source is Mg or Zn, and the doping concentration is set to 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 .

[0021] The beneficial effects of the present invention include at least: by providing a plurality of alternately arranged Al x In 1-x P sublayer, Ga x In 1-x The p-type window layer of the P sublayer and the GaP sublayer forms energy band bending and potential barriers at the interface of these sublayers, and the change of the energy band can regulate the transmission characteristics of the carriers and improve the current expansion effect; at the same time, the addition of In can promote the activation of the doping source in the relevant sublayers, thereby optimizing the energy band structure and improving their conductivity. Compared with the traditional p-type window layer whose main component is GaP, the thickness of the p-type window layer can be greatly thinned while maintaining comparable performance, thereby reducing the light absorption of the p-type window layer and further improving the light extraction efficiency of the light-emitting diode chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of an LED epitaxial wafer in one embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of an LED chip in one embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of a p-type window layer in one embodiment of the present invention;

[0025] Figure 4 is a flow chart of a method for preparing an LED epitaxial wafer in one embodiment of the present invention;

[0026] Description of main component symbols:

[0027] Substrate-100, buffer layer-110, cut-off layer-120, epitaxial layer-200, n-type window layer-210, n-type semiconductor layer-220, active layer-230, p-type semiconductor layer-240, p-type window layer-250, superlattice unit-251, Al x In 1-x P sublayer - 2511, Ga x In 1-x P sublayer-2512, GaP sublayer-2513, contact layer-260, DBR reflective layer-270, n-type electrode-500, p-type electrode-600, pad 700;

[0028] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0030] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0032] AlGaInP material has the property of direct transition, and the high efficiency of composite luminescence makes the luminescence efficiency high. It is a wide bandgap material, and the bandgap width can be continuously adjusted with the change of In component, so as to achieve high-brightness luminescence in the ultra-wide wavelength range of 560nm~650nm from red light to blue-green light of LED. In addition, it can also transition from direct band gap to indirect band gap, with an energy level range of 1.9eV~2.3eV.

[0033] Based on the content in the background technology, the main component of the p-type window layer of the traditional light-emitting diode prepared based on AlGaInP material is GaP doped with Mg. When the light-emitting diode is working, the current is expanded laterally through the p-type window layer, thereby injecting the current into the active layer. However, the p-type window layer whose main component is GaP has limited current expansion capability, so that the current density of the p-type window layer in the area near the bottom of the p-type electrode is higher, while the current density of the area far from the p-type electrode is lower, which ultimately leads to low overall current injection efficiency and reduces the light extraction efficiency of the LED. Moreover, in order to provide better current distribution and reduce current aggregation, the thickness of the p-type window layer whose main component is GaP is usually set to be relatively thick, resulting in a greater degree of absorption of the emitted light by the p-type window layer, further reducing the light extraction efficiency of the light-emitting diode.

[0034] Based on this, the present application provides an LED epitaxial wafer, an LED chip and a method for preparing an LED epitaxial wafer, which improves the current spreading effect by setting the p-type window layer as a superlattice structure. At the same time, the thickness of the p-type window layer can be thinned, and the light absorption effect of the p-type window layer can be reduced, thereby achieving the purpose of improving the light output efficiency of the light-emitting diode.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] First, please refer to Figure 1 , an LED epitaxial wafer provided by an embodiment of the present invention, includes a substrate 100 and an epitaxial layer 200. The epitaxial layer 200 is arranged on one side of the substrate 100. The epitaxial layer 200 includes an n-type window layer 210, an n-type semiconductor layer 220, an active layer 230, a p-type semiconductor layer 240, and a p-type window layer 250 stacked in sequence.

[0037] Wherein, the substrate 100 can be any one or any combination of a sapphire substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, a gallium oxide substrate, and a gallium arsenide substrate. In addition, since the AlGaInP lattice perfectly matches the lattice of the gallium arsenide substrate, a high-quality LED epitaxial wafer can be produced on the gallium arsenide substrate, and for this reason, the substrate 100 is preferably a gallium arsenide substrate. The n-type window layer 210 can be any one or a combination of an AlInP window layer with n-type doping and an AlGaInP window layer with n-type doping. The n-type semiconductor layer 220 can be any one or a combination of an AlGaInP layer with n-type doping and an AlInP layer with n-type doping. The active layer 230 can be a multi-quantum well structure, specifically an active layer with alternating GaInP / AlGaInP arrangements, and the bandgap width of the AlGaInP material can be changed by changing the In component. The p-type semiconductor layer 240 can be any one or a combination of an AlGaInP layer with p-type doping and an AlInP layer with p-type doping. The p-type window layer 250 includes superlattice units 251 periodically distributed along the stacking direction. The superlattice unit 251 includes Al x In 1-x P sublayer 2511, Ga x In 1-x P sublayer 2512 and GaP sublayer 2513.

[0038] In order to achieve the purpose of the invention of this application, the structure of the p-type window layer 250 is optimized in this embodiment, which is specifically reflected in the following aspects:

[0039] First, since the value range of x is related to the bandgap width of the quantum well layer in the active layer 230 of the multi-quantum well structure, in order to ensure that the bandgap width of the p-type window layer 250 is always greater than the bandgap width of the quantum well layer in the active layer 230, and to avoid non-radiative recombination caused by light absorption due to a small bandgap width, in this embodiment, the value range of x is set to 0.5≤x<1.

[0040] Second, first of all, due to Al x In 1-x P sublayer 2511, Ga x In 1-x The bandgap widths of the P sublayer 2512 and the GaP sublayer 2513 are related to their respective doping concentrations. x In 1-x The P sublayer 2511 can further reduce the non-radiative recombination caused by the overflow of electrons to the p-type layer, thereby improving the light extraction efficiency of the light-emitting diode. x In 1-xA certain potential barrier difference is generated between the P sublayer 2512 and the GaP sublayer 2513, which can promote the flow of holes into the active layer 230 and improve the hole injection efficiency. At the same time, the activation energy of the doping source is positively correlated with the Al component. The higher the Al component, the higher the activation energy of the doping source. In reduces the activation energy of the doping source. Appropriate In can effectively reduce the activation energy of the doping source and increase the concentration of the activated doping source. Therefore, in this embodiment, the Al in the same superlattice unit 251 is x In 1-x P sublayer 2511, Ga x In 1-x The bandgap width and doping concentration of the P sublayer 2512 and the GaP sublayer 2513 are set to be different, and the Ga x In 1-x The doping concentration of the P sublayer 2512 is set higher than that of the Al in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511 is x In 1-x The doping concentration of the P sublayer 2512 is set higher than the doping concentration of the GaP sublayer 2513 in the same superlattice unit 251 .

[0041] Third, as the growth period of the superlattice unit 251 increases, Ga x In 1-x The doping concentration of the P sublayer 2512 gradually increases, which can improve the crystal quality of the p-type window layer 250 and avoid abnormal problems such as roughening and protrusions on the surface of the epitaxial wafer due to high doping concentration. x In 1-x The doping concentration of the P sublayer 2512 is gradually increased, and the uniformity of the holes flowing from the p-type layer to the active layer 230 can be improved. In this way, the thickness of the p-type window layer 250 can be thinned to reduce the degree to which the p-type window layer 250 absorbs the emitted light, and the light extraction efficiency of the light-emitting diode can be further improved. In addition, the higher the doping concentration of the p-type window layer 250 close to the electrode side, the lower the contact resistance can be, and the higher the electro-optical conversion efficiency can be. Therefore, in this embodiment, the Al in all superlattice units 251 along the stacking direction is reduced. x In 1-x The doping concentration of the P sublayer 2511 is set to gradually increase, and the Ga x In 1-x The doping concentration of the P sublayer 2512 is also set to gradually increase, and the doping concentration of the GaP sublayer 2513 in all superlattice units 251 along the stacking direction is also set to gradually increase.

[0042] In some optional embodiments, Al x In 1-x P sublayer 2511, Ga x In 1-x The doping sources of the P sublayer 2512 and the GaP sublayer 2513 are both Mg or Zn, and the doping concentration of the doping source is 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 .

[0043] In some optional embodiments, Al x In 1-X The thickness of the P sublayer 2511 is 20nm~50nm, Ga x In 1-x The thickness of the P sublayer 2512 is 50 nm to 100 nm, and the thickness of the GaP sublayer 2513 is 50 nm to 100 nm.

[0044] In some optional embodiments, the period of the superlattice unit 251 is 10-50.

[0045] Second, as Figure 2 As shown, the present invention also provides an LED chip, including the aforementioned LED epitaxial wafer, and an n-type electrode 500 and a p-type electrode 600 formed on the LED epitaxial wafer. Exemplarily, the structure of the LED chip is a flip-chip structure, including a sapphire substrate, an epitaxial layer 200 bonded to the sapphire substrate, and an n-type electrode 500 and a p-type electrode 600 connected to the epitaxial layer 200. Among them, the epitaxial layer 200 includes a contact layer 260, a p-type window layer 250, a p-type semiconductor layer 240, an active layer 230, an n-type semiconductor layer 220, an n-type window layer 210, and a DBR reflective layer 270 stacked in sequence; the p-type window layer 250 includes superlattice units 251 periodically distributed along the stacking direction, and the superlattice unit 251 includes Al stacked in sequence. x In 1-x P sublayer 2511, Ga x In 1-x P sublayer 2512 and GaP sublayer 2513, the value range of x is set to 0.5≤x<1, and the Al x In 1-x P sublayer 2511, Ga x In 1-x The bandgap width and doping concentration of the P sublayer 2512 and the GaP sublayer 2513 are different, and the Ga x In 1-xThe doping concentration of the P sublayer 2512 is higher than that of the Al in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511, Ga in the same superlattice unit 251 x In 1-x The doping concentration of the P sublayer 2512 is higher than the doping concentration of the GaP sublayer 2513 in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511 gradually increases, and the Ga x In 1-x The doping concentration of the P sublayer 2512 also gradually increases, and the doping concentration of the GaP sublayer 2513 in all superlattice units 251 along the stacking direction also gradually increases.

[0046] Thirdly, Figure 4 As shown, the embodiment of the present invention further provides a method for preparing the aforementioned LED epitaxial wafer, which specifically includes steps S10 to S60:

[0047] S10, providing a substrate 100, the substrate 100 can be any one of a sapphire substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, a gallium oxide substrate, and a gallium arsenide substrate, or any combination thereof. Since the AlGaInP lattice perfectly matches the lattice of the gallium arsenide substrate, high-quality LED epitaxial wafers can be produced on the gallium arsenide substrate, and the gallium arsenide substrate has a mature preparation process, high stability, and high cost performance, so the substrate 100 is preferably a gallium arsenide substrate.

[0048] S20, growing an n-type window layer 210 on the substrate 100, the n-type window layer 210 is mainly used to form an n-type contact semiconductor layer to complete the injection and extraction of current. Optionally, the n-type window layer 210 can be any one of an AlInP window layer and an AlGaInP window layer, or a combination of the two.

[0049] Exemplarily, the n-type window layer 210 is an AlGaInP window layer with n-type doping, and its specific deposition process using metal organic chemical vapor deposition (MOCVD) technology is as follows: the temperature of the reaction chamber is controlled at 600°C to 700°C, TMAl (trimethylaluminum) is used as the aluminum source, TMGa (trimethylgallium) is used as the gallium source, TMIn (trimethylindium) is used as the indium source, and PH3 (phosphine) is used as the phosphorus source, and the growth thickness of the deposited AlGaInP window layer is controlled to be 200nm to 500nm.

[0050] S30, growing an n-type semiconductor layer 220 on the n-type window layer 210, wherein the n-type semiconductor layer 220 is mainly used to provide n-type carriers. Optionally, the n-type semiconductor layer 220 can be any one of an AlGaInP layer with n-type doping and an AlInP layer with n-type doping, or a combination of the two.

[0051] Exemplarily, the n-type semiconductor layer 220 is an AlInP layer with n-type doping, and the specific deposition process thereof using metal organic chemical vapor deposition (MOCVD) technology is as follows: the reaction chamber temperature is controlled at 650° C. to 750° C., the reaction chamber pressure is controlled at 40 mbar to 60 mbar, TMAl (trimethylaluminum) is used as the aluminum source, TMIn (trimethylindium) is used as the indium source, PH3 (phosphine) is used as the phosphorus source, Si2H6 (disilane) is used as the dopant, and the Si doping concentration is 1.0×10 17 atoms / cm 3 ~1.0×10 19 atoms / cm 3 , the growth thickness of the deposited AlInP layer is controlled to be between 100nm and 450nm.

[0052] S40 , growing an active layer 230 on the n-type semiconductor layer 220 . Specifically, the active layer 230 is an active layer in which GaInP / AlGaInP are alternately arranged. The bandgap width of the AlGaInP material can be changed by changing the In component.

[0053] Exemplarily, the specific deposition process of the active layer of alternating GaInP / AlGaInP using metal organic chemical vapor deposition (MOCVD) technology is as follows: the temperature of the reaction chamber is controlled at 620°C to 720°C, TMAl (trimethylaluminum) is used as the aluminum source, TMGa (trimethylgallium) is used as the gallium source, TMIn (trimethylindium) is used as the indium source, PH3 (phosphine) is used as the phosphorus source, the AlGaInP barrier layer is grown to a thickness of 60Å-200Å, the GaInP well layer is grown to a thickness of 30Å-80Å, and the alternating arrangement period is 8 to 18.

[0054] S50, growing a p-type semiconductor layer 240 on the active layer 230, the p-type semiconductor layer 240 is mainly used to provide p-type carriers. Optionally, the p-type semiconductor layer 240 can be any one of a p-doped AlGaInP layer and a p-doped AlInP layer, or a combination of the two.

[0055] Since both the n-type semiconductor layer 220 and the p-type semiconductor layer 240 contain high Al components, their bandgap width is larger than that of the active layer 230, which can restrain minority carriers, so that electron-hole pairs are effectively bound in the active layer 230, thereby increasing the probability of electron-hole recombination and improving the luminous efficiency of the LED. In addition, due to the large bandgap width of the n-type semiconductor layer 220 and the p-type semiconductor layer 240, most of the light emitted from the light-emitting area will not be absorbed when passing through the n-type semiconductor layer 220 and the p-type semiconductor layer 240, thereby improving the external quantum efficiency of the LED.

[0056] Exemplarily, the p-type semiconductor layer 240 is an AlInP layer with p-type doping, and the specific deposition process thereof using metal organic chemical vapor deposition (MOCVD) technology is as follows: the reaction chamber temperature is controlled at 700°C to 800°C, the reaction chamber pressure is controlled at 40 mbar to 60 mbar, TMAl (trimethylaluminum) is used as the aluminum source, TMIn (trimethylindium) is used as the indium source, PH3 (phosphine) is used as the phosphorus source, CP2Mg (dipentyl magnesium) is used as the dopant, and the Mg doping concentration is 1.0×10 17 atoms / cm 3 ~1.0×10 19 atoms / cm 3 The thickness of the grown AlInP layer is 100nm~550nm.

[0057] S60 , growing a p-type window layer 250 on the p-type semiconductor layer 240 .

[0058] Specifically, Figure 3 As shown, the p-type window layer 250 includes superlattice units 251 periodically distributed along the stacking direction, and the superlattice unit 251 includes Al x In 1-x P sublayer 2511, Ga x In 1-x P sublayer 2512 and GaP sublayer 2513.

[0059] Exemplarily, the specific deposition process of the p-type window layer 250 using metal organic chemical vapor deposition (MOCVD) technology is as follows: the reaction chamber temperature is controlled at 650°C to 800°C, the reaction chamber pressure is controlled at 40mbar to 60mbar, TMAl (trimethylaluminum) is used as an aluminum source, TMIn (trimethylindium) is used as an indium source, TMGa (trimethylgallium) is used as a gallium source, PH3 (phosphine) is used as a phosphorus source, and CP2Mg (dipentyl magnesium) is used as a dopant to sequentially grow Al with a thickness of 20nm to 50nm. x In 1-x P sublayer 2511, Al x In1-x The Mg doping concentration in the P sublayer 2511 is 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 , Ga with a thickness of 50nm to 100nm x In 1-x P sublayer 2512, Ga x In 1-x The Mg doping concentration in the P sublayer 2512 is 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 , a GaP sublayer 2513 with a thickness of 50 nm to 100 nm, and a Mg doping concentration of 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 Repeat the above steps to finally deposit 10 to 50 alternating Mg-doped Al x In 1-x P sublayer 2511, Ga x In 1-x P sublayer 2512 and GaP sublayer 2513.

[0060] Among them, Al in the same superlattice unit 251 x In 1-x P sublayer 2511, Ga x In 1-x The bandgap width and doping concentration of the P sublayer 2512 and the GaP sublayer 2513 are different, and the value range of x is 0.5≤x<1. x In 1-x The doping concentration of the P sublayer 2512 is higher than that of the Al in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511 is also higher than the doping concentration of the GaP sublayer 2513 in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511 gradually increases, and the Ga x In 1-x The doping concentration of the P sublayer 2512 also gradually increases, and the doping concentration of the GaP sublayer 2513 in all superlattice units 251 along the stacking direction also gradually increases.

[0061] In some optional embodiments, the following step S11 is further included between steps S10 and S20:

[0062] Step S11: growing a buffer layer 110 on the substrate 100 . The purpose of the buffer layer 110 is to provide an intermediate layer between two different materials to improve the interface characteristics between them, reduce defects, and improve the stability and performance of the overall structure. Therefore, the buffer layer 110 needs to be determined according to the materials used for the substrate 100 and the n-type window layer 210 .

[0063] For example, the substrate 100 is a GaAs substrate, the n-type window layer 210 is an AlGaInP window layer with n-type doping, and the buffer layer 110 is a GaAs buffer layer with Si doping. The specific deposition process using metal organic chemical vapor deposition (MOCVD) technology is as follows: the reaction chamber temperature is controlled at 600°C to 700°C, TMGa (trimethylgallium) is used as a gallium source, AsH3 (arsenic) is used as an arsenic source, Si2H6 (disilane) is used as a dopant, and the Si doping concentration is 1.0×10 16 atoms / cm 3 ~1.0×10 19 atoms / cm 3 , grow a GaAs buffer layer with a thickness of 100nm to 400nm.

[0064] In some optional embodiments, the following step S12 is further included between steps S11 and S20:

[0065] Step S12: growing a stop layer 120 on the buffer layer 110. The stop layer 120 is mainly used to improve the selectivity when wet etching the GaAs substrate and block the etching solution from corroding the epitaxial layer 200. Optionally, the stop layer 120 can be any one or any combination of an AlGaInP stop layer and a GaInP stop layer.

[0066] Exemplarily, the stop layer 120 is a GaInP stop layer doped with Si, and the specific deposition process thereof using metal organic chemical vapor deposition (MOCVD) technology is as follows: the reaction chamber temperature is controlled at 650°C to 750°C, TMGa (trimethylgallium) is used as the gallium source, TMIn (trimethylindium) is used as the indium source, PH3 (phosphine) is used as the phosphorus source, Si2H6 (disilane) is used as the dopant, and the Si doping concentration is 1.0×10 16 atoms / cm 3 ~1.0×10 19 atoms / cm 3 , grow a GaInP cutoff layer with a thickness of 250nm to 800nm.

[0067] In some optional embodiments, Figure 2 As shown, a contact layer 260 is deposited on the p-type window layer 250 , and the contact layer 260 is mainly used to form an ohmic contact.

[0068] Since the GaAs substrate absorbs the emitted light to a large extent, the light extraction efficiency of the light-emitting diode is reduced. For this reason, the present embodiment also bonds a sapphire substrate to the contact layer 260, then inverts the LED epitaxial wafer, and peels off and removes the GaAs substrate, GaAs buffer layer, and GaInP cutoff layer until the n-type window layer 210 is exposed; then, etching is performed from the side of the n-type window layer 210 until the p-type window layer 250 is exposed; then, an n-type electrode 500 is fabricated on the n-type window layer 210, and a p-type electrode 600 is fabricated on the exposed p-type window layer 250.

[0069] In some optional embodiments, Figure 2 As shown, in order to further improve the light extraction efficiency of the light emitting diode, a DBR reflective layer 270 is evaporated on the epitaxial layer 200 on the side of the n-type window layer 210. The DBR reflective layer 270 can be made of AlAs / AlGaAs material. The DBR reflective layer 270 mainly plays the role of passivation and reflection. At the same time, in order to lead out the connection electrode, the DBR reflective layer 270 needs to be opened to facilitate the pad 700 to electrically connect the n-type electrode 500 and the p-type electrode 600. Finally, the sapphire substrate is thinned, and then laser cutting is performed to separate the AlGaInP light emitting diode chip with a flip-chip structure of the designed size.

[0070] The present invention will be further described below with specific embodiments:

[0071] Embodiment 1:

[0072] The present embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The LED chip includes a sapphire substrate and an epitaxial layer 200 bonded to the sapphire substrate. The epitaxial layer 200 includes a contact layer 260, a p-type window layer 250, a p-type semiconductor layer 240, an active layer 230, an n-type semiconductor layer 220, and an n-type window layer 210 stacked in sequence. The p-type window layer 250 includes superlattice units 251 periodically distributed along the stacking direction. The growth period of the superlattice unit 251 is 30. The superlattice unit 251 includes AlGaInP superlattice units stacked in sequence. x In 1-x P sublayer 2511, Ga x In 1-x P sublayer 2512 and GaP sublayer 2513. Specifically, the value of x is 0.5, and the Al in the first grown superlattice unit 251 x In1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.1×10 18 atoms / cm 3 , Al x In 1-x The bandgap of the P sublayer 2511 is 1.9 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 32 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 1.2×10 18 atoms / cm 3 , Ga x In 1-x The bandgap of the P sublayer 2512 is 1.6 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 73 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.1×10 18 atoms / cm 3 The bandgap of the GaP sublayer 2513 is 1.85 eV, and the thickness of the GaP sublayer 2513 is 68 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer of adjacent superlattice units 251 along the stacking direction increases by 5%.

[0073] Embodiment 2:

[0074] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the first embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 27, and the Al in the first grown superlattice unit 251 is 27. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.0×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 25 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 1.5×10 18 atoms / cm 3 , Ga x In 1-xThe thickness of the P sublayer 2512 is 82 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.3×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 59 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 3%.

[0075] Embodiment three:

[0076] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the first embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 34, and the Al in the first grown superlattice unit 251 is x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.5×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 29 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.0×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 63 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.2×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 71 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 6%.

[0077] Embodiment 4:

[0078] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the first embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 31, the value of x is 0.6, and the Al in the first grown superlattice unit 251 is 1. x In 1-xThe doping concentration of the P sublayer 2511 doped with element Mg is 1.6×10 18 atoms / cm 3 , Al x In 1-x The bandgap of the P sublayer 2511 is 2.01 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 38 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 2.1×10 18 atoms / cm 3 , Ga x In 1-x The bandgap of the P sublayer 2512 is 1.65 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 69 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.6×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 57 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 4%.

[0079] Embodiment five:

[0080] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the fourth embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 28, and the Al in the first grown superlattice unit 251 is 28. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.2×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 26 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 1.3×10 18 atoms / cm 3 , Ga x In 1-xThe thickness of the P sublayer 2512 is 73 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.1×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 69 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 5%.

[0081] Embodiment six:

[0082] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the fourth embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 29, and the Al in the first grown superlattice unit 251 is 29. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.1×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 27 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 1.7×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 58 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.3×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 75 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 7%.

[0083] Embodiment seven:

[0084] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the first embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 33, the value of x is 0.7, and the Al in the first grown superlattice unit 251 is 1.3 times the value of x. x In 1-xThe bandgap of the P sublayer 2511 is 2.12 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 28 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 1.9×10 18 atoms / cm 3 , Ga x In 1-x The bandgap of the P sublayer 2512 is 1.7 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 65 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.5×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 73 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 3%.

[0085] Embodiment eight:

[0086] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the seventh embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 27, and the Al in the first grown superlattice unit 251 is 27. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.9×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 25 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.5×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 71 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.2×10 18 atoms / cm 3, the thickness of the GaP sublayer 2513 is 65 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 5%.

[0087] Embodiment nine:

[0088] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the seventh embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 31, and the Al in the first grown superlattice unit 251 is x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.3×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 31 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.3×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 53 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.7×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 82 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 6%.

[0089] Embodiment ten:

[0090] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the first embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 35, the value of x is 0.8, and the Al in the first grown superlattice unit 251 is 1.35. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.9×10 18 atoms / cm 3 , Al x In 1-xThe bandgap of the P sublayer 2511 is 2.23 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 39 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 2.7×10 18 atoms / cm 3 , Ga x In 1-x The bandgap of the P sublayer 2512 is 1.75 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 68 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.9×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 58 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 7%.

[0091] Embodiment eleven:

[0092] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the tenth embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 29, and the Al in the first grown superlattice unit 251 is 29. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.6×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 32 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.3×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 87 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.1×10 18 atoms / cm 3, the thickness of the GaP sublayer 2513 is 71 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 4%.

[0093] Embodiment 12:

[0094] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the tenth embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 36, and the Al in the first grown superlattice unit 251 is x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.1×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 35 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.6×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 75 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.2×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 75 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 5%.

[0095] Embodiment 13:

[0096] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the first embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 34, the value of x is 0.9, and the Al in the first grown superlattice unit 251 is 1.34. x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.5×10 18 atoms / cm 3 , Al x In 1-xThe bandgap of the P sublayer 2511 is 2.34 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 26 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 1.9×10 18 atoms / cm 3 , Ga x In 1-x The bandgap of the P sublayer 2512 is 1.8 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 79 nm, and the thickness of the GaP sublayer 2513 in the first grown superlattice unit 251 is 73 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 4%.

[0097] Embodiment 14:

[0098] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the thirteenth embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 35, and the Al in the first grown superlattice unit 251 is x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.0×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 29 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.5×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 65 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.7×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 65 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 5%.

[0099] Embodiment 15:

[0100] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the thirteenth embodiment is that in this embodiment, the growth period of the superlattice unit 251 is 31, and the Al in the first grown superlattice unit 251 is x In 1-x The doping concentration of the P sublayer 2511 doped with element Mg is 1.7×10 18 atoms / cm 3 , Al x In 1-x The thickness of the P sublayer 2511 is 31 nm. The Ga x In 1- x The doping concentration of the P sublayer 2512 doped with element Mg is 2.9×10 18 atoms / cm 3 , Ga x In 1-x The thickness of the P sublayer 2512 is 72 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.3×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 68 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 6%.

[0101] Comparative Example 1:

[0102] This embodiment provides an AlGaInP light-emitting diode chip with a flip-chip structure. The difference from the AlGaInP light-emitting diode chip with a flip-chip structure provided in the seventh embodiment is that in this embodiment, the value of x is 0.45, and the Al in the first grown superlattice unit 251 is x In 1-x The bandgap of the P sublayer 2511 is 1.845 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 38 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 2.1×10 18 atoms / cm 3 , Ga x In 1-xThe bandgap of the P sublayer 2512 is 1.575 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 58 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.2×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 57 nm. In addition, as the growth period of the superlattice unit 251 increases, the doping concentration of the doping element Mg in the same sublayer in adjacent superlattice units 251 along the stacking direction increases by 5%.

[0103] Comparative Example 2:

[0104] This embodiment provides an AlGaInP light-emitting diode chip with an inverted structure. The difference from the AlGaInP light-emitting diode chip with an inverted structure provided in the second embodiment is that in this embodiment, the value of x is 1.0, and the Al in the first grown superlattice unit 251 is x In 1-x The bandgap of the P sublayer 2511 is 2.45 eV, and the Al x In 1-x The thickness of the P sublayer 2511 is 28 nm. The Ga x In 1-x The doping concentration of the P sublayer 2512 doped with element Mg is 1.9×10 18 atoms / cm 3 , Ga x In 1-x The bandgap of the P sublayer 2512 is 1.85 eV, and Ga x In 1-x The thickness of the P sublayer 2512 is 69 nm, and the doping concentration of the GaP sublayer 2513 doped with the element Mg in the first grown superlattice unit 251 is 1.6×10 18 atoms / cm 3 , the thickness of the GaP sublayer 2513 is 69nm.

[0105] Comparative Example 3:

[0106] This embodiment provides an AlGaInP light-emitting diode chip with an inverted structure. The difference from the AlGaInP light-emitting diode chips with an inverted structure provided in the first to fifteenth embodiments and the first and second comparative examples is that in this embodiment, the p-type window layer 250 is a p-type GaP window layer, and the doping concentration of the doping element Mg in the p-type GaP window layer is 2.1×10 18 atoms / cm 3, the thickness of the p-type GaP window layer is 6500nm.

[0107] The AlGaInP light emitting diode chips with flip-chip structures provided by Examples 1 to 15 and Comparative Examples 1 to 3 were tested under the same conditions to obtain the results of the luminous intensity obtained by each Example, and the degree of improvement of the luminous intensity of Examples 1 to 15 and Comparative Examples 1 to 2 was obtained by taking the luminous intensity obtained by Comparative Example 3 as a reference. The specific data are shown in Table 1:

[0108] Table 1

[0109]

[0110] It can be seen from Table 1 that under the same test conditions, since the AlGaInP light-emitting diode chips with flip-chip structures provided in Examples 1 to 15 of the present invention adopt a p-type window layer 250 with a superlattice structure to improve the current spreading effect, compared with Comparative Example 3 which only adopts the traditional p-type window layer whose main component is GaP, the luminous intensity is improved, and the sum of the thicknesses of the sub-layers of the p-type window layer 250 is much smaller than the thickness of the traditional p-type window layer whose main component is GaP, which is beneficial to reducing costs and avoiding the p-type window layer 250 absorbing the emitted light.

[0111] At the same time, since x is set to 0.45 in Comparative Example 1 and x is set to 1 in Comparative Example 2, the values ​​of x in both are outside the value range of x 0.5≤x<1 in the AlGaInP light-emitting diode chips with inverted structures provided by Examples 1 to 15 of the present invention, and the luminous intensity is reduced, and the luminous intensity is lower than that of the traditional AlGaInP light-emitting diode chip with inverted structure whose main component is GaP p-type window layer. This may be because the x value is too high or too low, and the corresponding Al content is too high or too low, resulting in the degradation of material performance.

[0112] In summary, the present application sets the p-type window layer 250 to be a periodically distributed superlattice unit 251, and the superlattice unit 251 includes Al x In 1-x P sublayer 2511, Ga x In 1-x P sublayer 2512 and GaP sublayer 2513, and in the same superlattice unit 251, Al x In 1-x P sublayer 2511, Ga x In 1-x The bandgap width and doping concentration of the P sublayer 2512 and the GaP sublayer 2513 are set to be different, and the value range of x is set to 0.5≤x<1. x In1-x The doping concentration of the P sublayer 2512 is higher than that of the Al in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511 is also higher than the doping concentration of the GaP sublayer 2513 in the same superlattice unit 251. x In 1-x The doping concentration of the P sublayer 2511 gradually increases, and the Ga x In 1-x The doping concentration of the P sublayer 2512 also gradually increases, and the doping concentration of the GaP sublayer 2513 in all superlattice units 251 along the stacking direction also gradually increases, so that band bending and potential barriers are formed at the interface of these sublayers, and the change of the energy band can regulate the transmission characteristics of the carriers, thereby improving the current expansion effect. At the same time, the addition of In can promote the activation of the doping source in the relevant sublayers, thereby optimizing the energy band structure and improving their conductivity. Compared with the traditional GaP window layer with p-type doping, the thickness of the p-type window layer can be greatly thinned while maintaining comparable performance, thereby reducing the light absorption of the p-type window layer, and further improving the light extraction efficiency of the light-emitting diode chip.

[0113] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0114] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the protection scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An LED epitaxial wafer, characterized in that: The LED epitaxial wafer comprises: substrate; An epitaxial layer is arranged on one side of the substrate, the epitaxial layer includes an n-type window layer, an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and a p-type window layer stacked in sequence, the p-type window layer includes superlattice units periodically distributed along the stacking direction, and the superlattice units include Al x In 1-x P sublayer, Ga x In 1-x P sublayer and GaP sublayer; Among them, the Al x In 1-x The P sublayer, the Ga x In 1-x The doping sources of the P sublayer and the GaP sublayer are both Mg or Zn, the bandgap widths and doping concentrations of the three sublayers in the same superlattice unit are different, the value range of x is 0.5≤x<1, and the Ga in the same superlattice unit is x In 1-x The doping concentration of the P sublayer is higher than the doping concentration of the other sublayers in the same superlattice unit, and the doping concentration of the same sublayer in the superlattice unit gradually increases along the stacking direction.

2. The LED epitaxial wafer according to claim 1, characterized in that: The doping concentration of the doping source is 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 .

3. The LED epitaxial wafer according to claim 1, characterized in that: The Al x In 1-x The thickness of the P sublayer is 20nm~50nm, and the Ga x In 1-x The thickness of the P sublayer is 50nm-100nm, and the thickness of the GaP sublayer is 50nm-100nm.

4. The LED epitaxial wafer according to any one of claims 1 to 3, characterized in that: The period of the superlattice unit is 10-50.

5. An LED chip, characterized in that: It comprises the LED epitaxial wafer as claimed in any one of claims 1 to 4, and a connecting electrode formed on the LED epitaxial wafer.

6. A method for preparing an LED epitaxial wafer, characterized in that: The preparation method comprises the following steps: providing a substrate; growing an n-type window layer on the substrate; growing an n-type semiconductor layer on the n-type window layer; growing an active layer on the n-type semiconductor layer; growing a p-type semiconductor layer on the active layer; A p-type window layer is grown on the p-type semiconductor layer, wherein the p-type window layer includes superlattice units periodically distributed along a stacking direction, and the superlattice units include Al x In 1-x P sublayer, Ga x In 1-x P sublayer and GaP sublayer, the Al x In 1-x The P sublayer, the Ga x In 1-x The doping sources of the P sublayer and the GaP sublayer are both Mg or Zn, the bandgap widths and doping concentrations of the three sublayers in the same superlattice unit are different, the value range of x is 0.5≤x<1, and the Ga in the same superlattice unit is x In 1-x The doping concentration of the P sublayer is higher than the doping concentration of the other sublayers in the same superlattice unit, and the doping concentration of the same sublayer in the superlattice unit gradually increases along the stacking direction.

7. The method for preparing an LED epitaxial wafer according to claim 6, characterized in that: The p-type window layer is grown on the active layer using MOVCD technology, wherein the growth temperature is set to 650°C-800°C, the growth pressure is set to 40mbar-60mbar, the doping source is Mg or Zn, and the doping concentration is set to 1.0×10 18 atoms / cm 3 ~1.0×10 20 atoms / cm 3 .

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