Epitaxial wafer for improving lighting effect and preparation method thereof

Abstract

The invention relates to the technical field of epitaxial wafer preparation, in particular to an epitaxial wafer for improving the lighting effect and a preparation method thereof. The epitaxial wafer comprises a substrate, and a Buffer layer, an undoped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well layer, a current expansion layer and a P-type GaN layer are sequentially arranged on the substrate. And the current expansion layer comprises a photon extraction layer and an electron blocking layer. According to the invention, photon extraction is added, better current expansion is formed, and the purpose of improving the luminous efficiency is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of epitaxial wafer preparation, and particularly relates to an epitaxial wafer for improving light efficiency and a preparation method thereof. Background Art

[0002] An LED chip is a semiconductor electronic component that can emit light and is widely used in fields such as lighting. An LED epitaxial wafer is a solid light source, which is a light-emitting device made using a semiconductor P-N junction. When a forward current is conducted, electrons and holes in the semiconductor recombine, and the released energy is emitted in the form of photons or partly in the form of photons. LED epitaxial wafer lighting has significant advantages such as high efficiency, energy saving, environmental protection, and long service life, and has been widely used in various aspects such as street lights, display screens, indoor lighting, and automotive lights. Light efficiency is the most important measure of the competitiveness of LED epitaxial wafers. How to improve the light efficiency of LED epitaxial wafers on the basis of existing technologies is an eternal topic for increasing the competitiveness of LED epitaxial wafers.

[0003] There is total internal reflection of light at the growth interface of existing LED products, which is not conducive to the concentrated extraction of photons. At the same time, existing products have high requirements for current spreading. When an external current is applied, the chip voltage is extremely likely to increase or even burn out due to the current congestion effect. Better current spreading is needed to alleviate current congestion and improve the problem of unbalanced carrier injection in LEDs, thereby improving light efficiency.

[0004] A deep ultraviolet LED epitaxial wafer, an epitaxial growth method, and an LED chip disclosed in Publication No. CN116632138A provide a hole conduction layer formed by periodically alternating growth of a plurality of two-dimensional AlN sub-layers, and introduce alkaline earth metal elements Mg, Ca, Zn, Sr doping into the hole conduction layer to achieve P doping of the two-dimensional AlN sub-layers and provide holes. At the same time, due to the introduction of magnetic particles, shallow acceptor impurity levels can be introduced into the AlN structure. Due to the introduction of shallow acceptor impurity levels, it is more conducive to hole ionization and conduction, thereby improving the light emission efficiency of deep ultraviolet LEDs. However, there are problems such as low hole ionization rate leading to unbalanced carrier injection. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide an epitaxial wafer for improving light efficiency and a preparation method thereof.

[0006] The technical solution adopted by the present application to solve its technical problem is: an epitaxial wafer for improving light efficiency includes a substrate, and a Buffer (buffer) layer, an undoped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well layer, a current spreading layer, and a P-type semiconductor layer are sequentially arranged on the substrate;

[0007] The current spreading layer includes a photon extraction layer and an electron blocking layer.

[0008] The current spreading layer is doped with Mg element.

[0009] The photon extraction layer has an AlInGaN-MgN structure;

[0010] The electron blocking layer has a perovskite oxide heterointerface structure.

[0011] The perovskite oxide heterointerface is a LaAlO3-SrMnO3 layer and a LaMnO3-SrTiO3 layer.

[0012] A method for preparing an epitaxial wafer for improving light efficiency, which is used to prepare the above-mentioned epitaxial wafer for improving light efficiency; includes the following steps:

[0013] Prepare a substrate; the substrate can be sapphire, or a Si substrate or a SiC substrate.

[0014] Grow a Buffer layer, an undoped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well layer, a current spreading layer and a P-type semiconductor layer on the substrate in sequence;

[0015] The current spreading layer includes a photon extraction layer and an electron blocking layer, and the current spreading layer is doped with Mg element.

[0016] When growing the Buffer layer, deposit an AlN thin film layer of 15 nm to 30 nm by PVD method, and then in the MOCVD equipment, introduce hydrogen at a high temperature of 1000 °C to 1150 °C and a low pressure of 50 torr to 200 torr to clean the substrate surface, and then cool down to 600 °C - 850 °C to grow the Buffer layer;

[0017] When growing the undoped GaN layer, grow the undoped GaN layer in the MOCVD equipment, control the growth temperature to be 1000 °C to 1180 °C, the pressure to be 50 torr to 250 torr, and finally deposit an undoped GaN layer of 1.5 μm to 3 μm;

[0018] When growing the N-type GaN layer, grow it in the MOCVD equipment, the dopant of the N-type GaN layer is Si, control the temperature in the MOCVD reaction chamber to be 1080 °C to 1150 °C, the pressure to be 100 torr to 250 torr, and finally deposit an N-type doped GaN layer of 1.5 μm to 3 μm; where the doping concentration of Si is 1E17 atoms / cm 3 ~1E20 atoms / cm 3 ;

[0019] When growing the stress relaxation layer, adjust the temperature to 800 - 900 °C, control the pressure at 150 - 300 torr, and grow a stress relaxation layer with a thickness of 50 - 100 nm;

[0020] When growing the multi - quantum well layer, control the reaction chamber temperature at 750 - 950 °C, control the pressure at 100 - 300 torr, and grow 10 - 15 periods of quantum well layers; the quantum well layer consists of alternately grown quantum barriers and quantum wells, and the total thickness of the InGaN / GaN quantum well layer is about 150 - 250 nm.

[0021] The photon extraction layer grows an AlInGaN layer - MgN layer within the temperature range of 650 - 850 °C, controls the pressure at 100 - 300 torr, and grows to a thickness of 10 - 50 nm;

[0022] The electron blocking layer is a perovskite oxide heterointerfacial structure, which is composed of a LaAlO3 layer - SrMnO3 layer and a LaMnO3 layer - SrTiO3 layer from bottom to top. Control the reaction chamber temperature at 900 °C - 1000 °C, control the reaction chamber pressure at 100 - 300 torr, and grow to a thickness of 25 - 80 nm.

[0023] The photon extraction layer grows a P - type semiconductor layer at a relatively low temperature. Control the growth temperature of the photon extraction layer at 650 - 850 °C. The lower temperature inhibits the surface mobility of atoms, enabling atoms to quickly adhere after reaching the growth surface, forming a rough interface; at the same time, appropriately adjust the flow rate and ratio of the metal source and reaction gas, affecting the rate of atoms reaching the growth surface and the reaction process, increasing the ammonia flow rate, adjusting the V / III ratio of the gas flow field, changing the thin - film growth mode, making the film grow more three - dimensionally, and promoting interface roughening. This rough interface can disrupt the total reflection condition of light waves at the interface, increasing the probability of light exiting from the inside of the LED to the outside, thereby improving the light extraction efficiency.

[0024] The doping concentration of the doping element Mg in the current spreading layer is 1E18 atoms / cm 3 ~5E19 atoms / cm 3 。

[0025] The electron blocking layer can confine more electrons in the active region to recombine with holes to emit light, thus greatly improving the recombination efficiency of electrons and holes. At the same time, it can play a certain role in regulating the lateral diffusion of electrons, making the distribution of electrons in the active region more uniform, and further enhancing the light - emitting efficiency of the LED.

[0026] The thickness of the AlInGaN layer is 10-40nm, the thickness of the MgN layer is 3-10nm, the thickness of the LaAlO3 layer is 10nm-30nm, the thickness of the SrMnO3 layer is 10nm-20nm, the thickness of the LaMnO3 layer is 5nm-20nm, and the thickness of the SrTiO3 layer is 1nm-10nm.

[0027] The P-type semiconductor layer is a composite layer of a P-type GaN layer and a P-type contact layer deposited in sequence;

[0028] The P-type GaN layer is a GaN layer doped with Mg, and the Mg doping concentration is 1E19 atoms / cm 3 ~3E20atoms / cm 3 , thickness 30nm~100nm, growth temperature 900℃~1000℃, growth pressure 150torr~300torr;

[0029] The P-type contact layer is a GaN layer doped with Mg, and the Mg doping concentration is 5E19atoms / cm 3 ~5E20atoms / cm 3 , thickness 10nm~20nm, growth temperature 900℃~1000℃, growth pressure 200torr~400torr.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] The present invention provides an epitaxial wafer for improving light efficiency and a preparation method thereof, so as to increase photon extraction and form better current expansion to improve light efficiency.

[0032] The current expansion layer is composed of a photon extraction layer and an electron blocking layer. The photon extraction layer can change the growth mode of the material by growing a P-type semiconductor layer at a relatively low temperature, so that the interface between the P layer and the quantum well layer becomes rough. This rough interface can destroy the total reflection condition of the light wave at the interface, increase the probability of light being emitted from the inside of the LED to the outside, and thus improve the light extraction efficiency;

[0033] The electron blocking layer can form a LaAlO3-SrMnO3 or LaMnO3-SrTiO3 double-layer two-dimensional electron gas channel. In addition to having excellent properties such as wide bandgap, high breakdown field strength, high electron saturation drift velocity, high thermal conductivity, and stable chemical properties, perovskite oxide heterostructure materials also have a large band offset and a strong polarization effect. Through polarization stress, a two-dimensional electron gas conductive channel can be generated at the heterojunction interface, increasing the donor carrier concentration, enhancing the ability of electrons to be injected into the active region, and improving the problem of unbalanced carrier injection caused by the low hole ionization rate of traditional p-type materials in LEDs. At the same time, the carrier distribution can be reasonably regulated and optimized, which is conducive to the holes in the P layer moving more uniformly towards the quantum well, forming better current spreading to improve the light efficiency.

[0034] Electrons and holes recombine in the quantum well to generate photons. At the interface between the quantum well and the P layer, some photons are totally reflected due to the angle. The photon extraction layer increases the extraction amount of photons through roughening the interface to improve the efficiency. The electron blocking layer can confine more electrons in the active region to recombine with holes to emit light, thus greatly improving the recombination efficiency of electrons and holes. At the same time, it can play a certain role in regulating the lateral diffusion of electrons, making the distribution of electrons in the active region more uniform, and further improving the light-emitting efficiency of the LED. Brief Description of the Drawings

[0035] Figure 1 It is a schematic diagram of the epitaxial wafer structure of the present invention;

[0036] Figure 2 It is a flowchart for preparing the epitaxial wafer of the present invention.

[0037] In the figure: 100, substrate; 200, Buffer layer; 300, undoped GaN layer; 400, N-type GaN layer; 500, stress release layer; 600, multiple quantum well layer; 700, current spreading layer; 711, AlInGaN layer; 712, MgN layer; 721, LaAlO3 layer; 722, SrMnO3 layer; 731, LaMnO3 layer; 732, SrTiO3 layer; 800, P-type semiconductor layer. Detailed Description of the Invention

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the attached drawings). If the specific posture changes, the directional indications will also change accordingly.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. shall be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] Embodiment 1

[0042] Referring to Figure 1 and Figure 2 , this embodiment provides an epitaxial wafer for improving current spreading, which sequentially includes a substrate 100, a Buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a stress release layer 500, a multi-quantum well layer 600, a current spreading layer 700, and a P-type semiconductor layer 800 from bottom to top. The preparation process is as follows:

[0043] Prepare a substrate 100; then grow a Buffer layer 200 on the substrate 100. Specifically, first deposit an AlN thin film layer by the PVD method. During the growth of the AlN thin film layer, control the growth temperature at 600 °C, the sputtering power at 3500 W, and the pressure at 5 torr, and finally deposit a 20-nm AlN buffer layer;

[0044] Subsequently, in the MOCVD equipment, introduce hydrogen at a high temperature of 1050 °C and a low pressure of 100 Torr to clean the surface of the substrate, and then cool down to 800 °C with a pressure of 100 Torr to grow the Buffer layer;

[0045] Perform an annealing treatment in a hydrogen atmosphere at a temperature of 1050 °C and a pressure of 150 torr.

[0046] Grow an undoped GaN layer 300 on the Buffer layer 200: Grow the undoped GaN layer 300 in the MOCVD equipment, control the growth temperature at 1050 °C and the pressure at 150 torr, and finally deposit a 2-μm undoped GaN layer 300.

[0047] Growing an N-type GaN layer 400 on an undoped GaN layer 300: The N-type GaN layer 400 is grown in a MOCVD apparatus, and the dopant is Si;

[0048] When growing the N-type GaN layer 400, control the temperature in the reaction chamber of the MOCVD apparatus to be 1090 °C and the pressure to be 150 torr, and finally deposit a 2-μm N-type doped GaN layer. The doping element of the N-type GaN layer is Si, and the doping concentration of Si is 4E19 atoms / cm 3 .

[0049] Growing the stress release layer 500 on the N-type GaN layer 400: When growing the stress release layer 500, adjust the reaction chamber temperature to 850 °C, control the reaction chamber pressure at 200 torr, and the growth thickness is 70 nm.

[0050] Growing the multiple quantum well layer 600 on the stress release layer 500: The multiple quantum well layer 600 includes alternately grown GaN quantum barriers and InGaN quantum wells, with a total thickness of 150 nm. When growing the quantum barriers, control the reaction chamber temperature at about 865 °C, when growing the quantum wells, control the reaction chamber temperature at about 790 °C, control the reaction chamber pressure at 200 torr, and grow 11 cycles of the quantum well layer;

[0051] Growing a current spreading layer 700 on the multiple quantum well layer 600. When preparing the current spreading layer 700, stack an AlInGaN layer 711, a MgN layer 712, a LaAlO3 layer 721, a SrMnO3 layer 722, a LaMnO3 layer 731, and a SrTiO3 layer 732 from bottom to top in sequence. It is doped with the element Mg, and the doping concentration of the Mg is: 6E18 atoms / cm 3 ;

[0052] Control the reaction chamber temperature at 755 °C and the reaction chamber pressure at 200 torr, and grow an AlInGaN layer 711 with a thickness of 30 nm and a MgN layer 712 with a thickness of 5 nm in sequence;

[0053] Control the reaction chamber temperature at 850 °C to grow an electron blocking layer, where the thickness of the LaAlO3 layer 721 is 25 nm, the thickness of the SrMnO3 layer 722 is 15 nm, the thickness of the LaMnO3 layer 731 is 15 nm, and the thickness of the SrTiO3 layer 722 is 5 nm;

[0054] Growing a P-type semiconductor layer 800 on the current spreading layer 700. The P-type semiconductor layer 800 is a composite layer of a P-type GaN layer and a P-type contact layer deposited in sequence;

[0055] Both the P-type GaN layer and the P-type contact layer are doped with the element Mg. Among them, the doping concentration of Mg in the P-type GaN layer is 4E19 atoms / cm 3 , with a thickness of 90 nm, a growth temperature of 950 °C, and a growth pressure of 200 torr;

[0056] The doping concentration of Mg in the P-type contact layer is 8E19 atoms / cm 3 , with a thickness of 20 nm, a growth temperature of 900 °C, and a growth pressure of 200 torr.

[0057] Example 2

[0058] The difference from Example 1 is that a Buffer layer 200 is grown on the substrate 100.

[0059] Prepare a substrate 100; then grow a Buffer layer 200 on the substrate 100. Specifically, first deposit an AlN thin film layer by PVD method. During the growth of the AlN thin film layer, control the growth temperature at 600 °C, the sputtering power at 3500 W, and the pressure at 5 torr, and finally deposit a 20-nm AlN buffer layer;

[0060] Subsequently, in the MOCVD equipment, hydrogen is introduced at a high temperature of 1050 °C and a low pressure of 100 Torr to clean the surface of the substrate, and then the temperature is lowered to 800 °C, the pressure is 100 Torr, and the Buffer layer is grown;

[0061] Annealing treatment is carried out in a hydrogen atmosphere, with a temperature of 1050 °C and a pressure of 150 torr.

[0062] Grow an undoped GaN layer 300 on the Buffer layer 200: Grow the undoped GaN layer 300 in the MOCVD equipment, control the growth temperature at 1000 °C, the pressure at 250 torr, and finally deposit a 1.5-μm undoped GaN layer 300.

[0063] Grow an N-type GaN layer 400 on the undoped GaN layer 300: Grow the N-type GaN layer 400 in the MOCVD equipment, and the dopant is Si;

[0064] When growing the N-type GaN layer 400, control the temperature in the reaction chamber of the MOCVD equipment at 1080 °C, the pressure at 250 torr, and finally deposit a 3-μm N-type doped GaN layer. The doping element of the N-type GaN layer is Si, and the doping concentration of Si is 1E20 atoms / cm 3 .

[0065] The stress release layer 500 is grown on the N-type GaN layer 400: When growing the stress release layer 500, the reaction chamber temperature is adjusted to 800 °C, the reaction chamber pressure is controlled at 150 torr, and the growth thickness is 100 nm.

[0066] The multi-quantum well layer 600 is grown on the stress release layer 500: The multi-quantum well layer 600 includes alternately grown GaN quantum barriers and InGaN quantum wells with a total thickness of 200 nm. When growing the quantum barriers, the reaction chamber temperature is controlled at about 950 °C, and when growing the quantum wells, the reaction chamber temperature is controlled at about 850 °C. The reaction chamber pressure is controlled at 300 torr, and 15 cycles of quantum well layers are grown;

[0067] The doping concentration of Mg in the current spreading layer 700 is: 5E19 atoms / cm 3 ;

[0068] The reaction chamber temperature is controlled at 755 °C and the reaction chamber pressure is controlled at 100 torr to grow the photon extraction layer; the reaction chamber temperature is controlled at 950 °C to grow the electron blocking layer;

[0069] In the current spreading layer 700, the thickness of the AlInGaN layer 711 is 10 nm, the thickness of the MgN layer 712 is 3 nm, the thickness of the LaAlO3 layer 721 is 10 nm, the thickness of the SrMnO3 layer 722 is 10 nm, the thickness of the LaMnO3 layer 731 is 6 nm, and the thickness of the SrTiO3 layer 732 is 1 nm.

[0070] The doping concentration of Mg in the P-type GaN layer in the P-type semiconductor layer 800 is 3E20 atoms / cm 3 , with a thickness of 100 nm, a growth temperature of 900 °C, and a growth pressure of 150 torr;

[0071] The doping concentration of Mg in the P-type contact layer is 5E20 atoms / cm 3 , with a thickness of 18 nm, a growth temperature of 960 °C, and a growth pressure of 280 torr.

[0072] Example 3

[0073] The difference from Example 1 is that a Buffer layer 200 is grown on the substrate 100.

[0074] First, an AlN thin film layer is deposited by PVD. During the process of growing the AlN thin film layer, the growth temperature is controlled at 550 °C, the sputtering power is 3500 W, the pressure is 5 torr, and finally a 30-nm AlN buffer layer is deposited;

[0075] Subsequently, in the MOCVD equipment, hydrogen gas is introduced at a high temperature of 1050 °C and a low pressure of 100 Torr to clean the substrate surface, and then the temperature is reduced to 800 °C with a pressure of 150 Torr to grow the Buffer layer;

[0076] Annealing treatment is carried out in a hydrogen atmosphere at a temperature of 1050 °C and a pressure of 150 Torr.

[0077] Grow the undoped GaN layer 300 on the Buffer layer 200: Grow the undoped GaN layer 300 in the MOCVD equipment, control the growth temperature at 1180 °C and the pressure at 50 Torr, and finally deposit a 3-μm-thick undoped GaN layer 300.

[0078] Grow the N-type GaN layer 400 on the undoped GaN layer 300: Grow the N-type GaN layer 400 in the MOCVD equipment with the dopant being Si;

[0079] When growing the N-type GaN layer 400, control the temperature in the reaction chamber of the MOCVD equipment at 1150 °C and the pressure at 100 Torr, and finally deposit a 1.5-μm-thick N-type doped GaN layer. The doping element of the N-type GaN layer is Si, and the doping concentration of Si is 1E17 atoms / cm 3 。

[0080] Grow the stress release layer 500 on the N-type GaN layer 400: When growing the stress release layer 500, adjust the reaction chamber temperature to 900 °C, control the reaction chamber pressure at 300 Torr, and grow to a thickness of 50 nm.

[0081] Grow the multiple quantum well layer 600 on the stress release layer 500: The multiple quantum well layer 600 consists of alternating growth of GaN quantum barriers and InGaN quantum wells with a total thickness of 250 nm. When growing the quantum barriers, control the reaction chamber temperature at about 850 °C, when growing the quantum wells, control the reaction chamber temperature at about 750 °C, control the reaction chamber pressure at 100 Torr, and grow 10 cycles of the quantum well layer;

[0082] The doping concentration of Mg in the current spreading layer 700 is: 1E18 atoms / cm 3 ;

[0083] Control the reaction chamber temperature at 850 °C and the reaction chamber pressure at 100 Torr to grow the photon extraction layer; control the reaction chamber temperature at 1000 °C to grow the electron blocking layer;

[0084] In the current spreading layer 700, the thickness of the AlInGaN layer 711 is 40 nm, the thickness of the MgN layer 712 is 8 nm, the thickness of the LaAlO3 layer 721 is 28 nm, the thickness of the SrMnO3 layer 722 is 20 nm, the thickness of the LaMnO3 layer 731 is 18 nm, and the thickness of the SrTiO3 layer 732 is 8 nm.

[0085] In the P-type semiconductor layer 800, the doping concentration of Mg in the P-type GaN layer is 1E19 atoms / cm 3 , the thickness is 30 nm, the growth temperature is 1000 °C, and the growth pressure is 300 torr;

[0086] The doping concentration of Mg in the P-type contact layer is 5E19 atoms / cm 3 , the thickness is 10 nm, the growth temperature is 1000 °C, and the growth pressure is 400 torr.

[0087] Example 4

[0088] The difference from Example 1 is that in the current spreading layer 700, the thickness of the AlInGaN layer 711 is 35 nm, the thickness of the MgN layer 712 is 3 nm, the thickness of the LaAlO3 layer 721 is 30 nm, the thickness of the SrMnO3 layer 722 is 12 nm, the thickness of the LaMnO3 layer 731 is 20 nm, and the thickness of the SrTiO3 layer 732 is 2 nm.

[0089] Example 5

[0090] The difference from Example 1 is that in the current spreading layer 700, the thickness of the AlInGaN layer 711 is 12 nm, the thickness of the MgN layer 712 is 10 nm, the thickness of the LaAlO3 layer 721 is 12 nm, the thickness of the SrMnO3 layer 722 is 18 nm, the thickness of the LaMnO3 layer 731 is 5 nm, and the thickness of the SrTiO3 layer 732 is 10 nm.

[0091] Comparative Example 1:

[0092] This comparative example provides a method for growing an LED epitaxial structure, which is different from Example 1 in that: there is no electron blocking layer in the current spreading layer, and the rest is the same as Example 1.

[0093] Comparative Example 2:

[0094] This comparative example provides a method for growing an LED epitaxial structure, which is different from Example 1 in that: there is no photon extraction layer in the current spreading layer, and the rest is the same as Example 1.

[0095]

[0096] As shown in the above table comparing the improvement of luminous efficacy between Examples 1-5 and Comparative Examples 1-2, it can be seen that the improvement of luminous efficacy of this application is better.

[0097] The above are only alternative embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made using the content of the specification of the present invention under the concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An epitaxial wafer for improving light efficiency, characterized in that, It includes a substrate (100), on which a Buffer layer (200), an undoped GaN layer (300), an N-type GaN layer (400), a stress relaxation layer (500), a multi-quantum well layer (600), a current spreading layer (700), and a P-type semiconductor layer (800) are sequentially disposed. The current spreading layer (700) includes a photon extraction layer and an electron blocking layer.

2. The epitaxial wafer for improving light efficiency according to claim 1, characterized in that, Mg element is doped in the current spreading layer (700).

3. The epitaxial wafer for improving light efficiency according to claim 1 or 2, characterized in that The photon extraction layer has an AlInGaN-MgN structure. The electron blocking layer has a perovskite oxide heterojunction structure.

4. The epitaxial wafer for improving light efficiency according to claim 3, characterized in that, The perovskite oxide heterojunction is a LaAlO3-SrMnO3 layer and a LaMnO3-SrTiO3 layer.

5. A method for preparing an epitaxial wafer to improve light efficiency, characterized in that, For preparing an epitaxial wafer for improving light efficiency as described in any one of claims 1-4; it includes the following steps: Prepare a substrate (100). Grow a Buffer layer (200), an undoped GaN layer (300), an N-type GaN layer (400), a stress relaxation layer (500), a multi-quantum well layer (600), a current spreading layer (700), and a P-type semiconductor layer (800) sequentially on the substrate (100). The current spreading layer (700) includes a photon extraction layer and an electron blocking layer, and Mg element is doped in the current spreading layer (700).

6. The method for preparing an epitaxial wafer for improving light efficiency according to claim 5, characterized in that, When growing the Buffer layer (200), deposit an AlN thin film layer with a thickness of 15 nm to 30 nm by PVD method, then in an MOCVD device, introduce hydrogen within a temperature range of 1000 °C to 1150 °C and a pressure range of 50 torr to 200 torr to clean the surface of the substrate (100), and then cool down to 600 °C - 850 °C to grow the Buffer layer. When growing the undoped GaN layer (300), the growth temperature is 1000 °C to 1180 °C, the pressure is 50 torr to 250 torr, and finally deposit an undoped GaN layer with a thickness of 1.5 μm to 3 μm. When growing the N-type GaN layer (400), the dopant of the N-type GaN layer (400) is Si, the temperature is 1080 °C to 1150 °C, the pressure is 100 torr to 250 torr, and finally deposit an N-type doped GaN layer with a thickness of 1.5 μm to 3 μm. When growing the stress relaxation layer, adjust the temperature to 800 - 900 °C, control the pressure at 150 - 300 torr, and grow a stress relaxation layer with a thickness of 50 - 100 nm. When growing the multi-quantum well layer, control the temperature at 750 - 950 °C, control the pressure at 100 - 300 torr, and grow 10 - 15 cycles of quantum well layers.

7. The method for preparing an epitaxial wafer for enhancing light efficiency according to claim 5, characterized in that, The photon extraction layer grows an AlInGaN layer (711)-MgN layer (712) within a temperature range of 650 - 850 °C, control the pressure at 100 - 300 torr, and grow a thickness of 10 - 50 nm. The electron blocking layer is a perovskite oxide heterointerfacial structure, which is composed of a LaAlO3 layer (721)-SrMnO3 layer (722) and a LaMnO3 layer (731)-SrTiO3 layer (732) from bottom to top. The temperature is controlled at 900 °C to 1000 °C, the reaction chamber pressure is controlled at 100 to 300 torr, and the growth thickness is 25 to 80 nm.

8. The method for preparing an epitaxial wafer for improving light efficiency according to claim 5, wherein The doping concentration of the doping element Mg in the current spreading layer is 1E18 atoms / cm 3 ~5E19 atoms / cm 3 .

9. An epitaxial wafer for improving light efficiency according to claim 7, characterized in that, The thickness of the AlInGaN layer (711) is 10 to 40 nm, the thickness of the MgN layer (712) is 3 to 10 nm, the thickness of the LaAlO3 layer (721) is 10 nm to 30 nm, the thickness of the SrMnO3 layer (722) is 10 nm to 20 nm, the thickness of the LaMnO3 layer (731) is 5 nm to 20 nm, and the thickness of the SrTiO3 layer (732) is 1 nm to 10 nm.

10. The method for preparing an epitaxial wafer for improving light efficiency according to claim 5, wherein The P-type semiconductor layer (800) is a composite layer of a P-type GaN layer and a P-type contact layer deposited in sequence; The P-type GaN layer is a GaN layer doped with Mg, and the doping concentration of Mg is 1E19 atoms / cm 3 ~3E20 atoms / cm 3 , with a thickness of 30 nm to 100 nm, a growth temperature of 900 °C to 1000 °C, and a growth pressure of 150 torr to 300 torr; The P-type contact layer is a Mg-doped GaN layer, and the doping concentration of Mg is 5E19 atoms / cm 3 ~5E20 atoms / cm 3 , the thickness is 10 nm to 20 nm, the growth temperature is 900 °C to 1000 °C, and the growth pressure is 200 torr to 400 torr.

Images