CN104465912A - LED epitaxial structure and method achieving high luminous energy density output - Google Patents

Abstract

The invention relates to an LED epitaxy structure and an epitaxy method with high light energy density output. Two or more groups of LED basic structural units are connected in a tunnel structure to form a unified epitaxial device structure. The LED basic structural units include: An n-type layer, a light-emitting layer and a p-type layer, wherein the light-emitting layer is between the n-type layer and the p-type layer. Moreover, the n-type layer, the light-emitting layer and the p-type layer are composed of several sublayers. The LED epitaxial structure of the present invention can obtain higher photon energy flow density output under the lower current density injection condition, and improve the optical control factor of the device. At the same time, it also alleviates the problem of "efficiency droop" (Efficiency Droop) of LED devices under high current density driving conditions, and maintains a high energy conversion efficiency of the device.

Description

LED epitaxy structure and epitaxy method with high light energy density output

technical field

The invention relates to an LED epitaxy structure and an epitaxy method with high light energy density output, and belongs to the field of manufacturing LED optoelectronic devices.

Background technique

Based on arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P (0≤x, y≤1; x+ y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) and nitride Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1; wurtzite crystal structure) light-emitting diode LEDs made of semiconductor materials are gradually being used in electronic display screens, landscape lighting, miner's lamps, and street lamps due to their advantages in energy saving, environmental protection, and long life. , liquid crystal display backlight, general lighting, optical disc information storage, biomedicine and other fields are widely used. The above-mentioned compound semiconductors can cover the entire spectral energy range from infrared, visible to ultraviolet light, and the emission wavelength of LED devices can be accurately customized by controlling the cationic composition of the nitride alloy. From the perspective of the scope of application fields and market capacity, the application of nitride LEDs is the bulk and mainstream. For example, the semiconductor lighting industry represented by white LEDs.

Although the LEDs made of the above-mentioned compound semiconductors have high luminous efficiency due to direct bandgap transition luminescence, under the current technical conditions, the electro-optical conversion efficiency of LED devices will decrease under the driving condition of high current density, that is, "Efficiency Droop" phenomenon. Moreover, this phenomenon is particularly evident in nitride LEDs. Therefore, in general, in order to maintain high energy conversion efficiency and ensure high reliability, the drive current density used by the device is low, which reduces the photon energy flux density and the total photon output power of the LED device.

For some occasions that require devices to have high photon energy flux density output, that is, directional lighting applications that require devices to have high optical control factors, such as automotive headlights, spotlights, downlights, projector light sources, stadiums Lighting, etc., the contradictions caused by the above problems will be highlighted. In order to obtain higher photon energy density, the lighting fixtures manufactured under the traditional LED epitaxial structure often increase the driving current at the expense of efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for connecting two or more groups of LED basic structural units with a structure of tunnel nodes (tunnel diodes) for the current situation that the traditional LED epitaxial structure has only one group of basic structural units. A uniform LED epitaxial structure with high light energy density output is formed.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an LED epitaxial structure with high luminous energy density output, including a substrate layer and an epitaxial layer arranged in sequence; the epitaxial layer includes at least two groups of LED basic units and at least one tunnel section;

Each two groups of LED basic units are connected through a tunnel section.

The beneficial effects of the present invention are: the device made by adopting the LED epitaxial structure of the present invention can realize the reduction of the working current by increasing the total working voltage under the condition that the input electric power is kept constant, that is, the positive direction of each basic structural unit The voltage drop is accumulated in series through the tunnel junction, while the forward current of each basic structure is constant. In this way, the problem of "efficiency droop" of LED devices under high current density driving conditions can be alleviated, and the device can maintain a high energy conversion efficiency at a low operating current. Therefore, the adoption of the LED epitaxial structure of the present invention can obtain higher luminous energy flow output under the condition of lower current density injection, thereby improving the optical control factor of the device, and providing a better solution for subsequent LED lamp beads, lamps and lighting systems. The development of provides better flexibility and more possibilities.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the LED basic unit includes an n-type layer, a light-emitting layer and a p-type layer arranged in sequence.

The beneficial effect of adopting the above further solution is that the n-type layer and the p-type layer respectively provide the injection of carrier electrons and holes, and the light-emitting layer is a place where electrons and holes recombine and emit light.

Further, the n-type layer includes at least one n-type sublayer, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _{1 -xy} P(0≤x,y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y ≤1) and at least one of nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1) constitutes at least one n-type sublayer;

Each of the n-type sublayers is respectively n-type doped; the n-type doping concentration of each n-type sublayer is the same or different, and the n-type doping elements are Si, Sn, S, Se and At least one of Te.

Further, the p-type layer includes at least one p-type sublayer, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _{1 -xy} P(0≤x,y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y ≤1) and at least one of nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1) constitutes at least one p-type sublayer;

Each of the p-type sublayers is doped with p-type respectively;

The p-type doping concentration of each p-type sublayer is the same or different; the p-type doping element is at least one of Be, Mg, Zn, Cd and C.

Further, the light-emitting layer includes at least one thin film sublayer, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P(0≤x, y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x, y, z≤1; x+y≤1 ) and at least one of nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1) constitutes at least one thin film sublayer;

The at least one thin film sublayer is n-type, p-type doped or undoped; the n-type doping element is at least one of Si, Sn, S, Se, Te; the p-type doping element It is at least one of Be, Mg, Zn, Cd, and C.

Further, the tunnel section includes at least two tunnel sublayers, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _{1- xy} P (0≤x, y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x, y, z≤1; x+y≤ 1) and at least _one of nitrides _{AlxInyGa1 -xyN} (0≤x, y≤1; x+y≤1) constitute at least two tunnel sublayers.

Further, the at least two tunnel sublayers are heavily n-type doped and p-type heavily doped respectively; the n-type heavily doped element is at least one of Si, Sn, S, Se, Te; p-type The heavy doping element is at least one of Be, Mg, Zn, Cd and C.

Further, the substrate layer is a homogeneous substrate or a heterogeneous substrate; when the substrate layer is a heterogeneous substrate, a buffer layer is also provided between the substrate layer and the epitaxial layer, and the substrate layer is made of sapphire, silicon carbide, Silicon, gallium nitride, aluminum nitride, gallium arsenide, spinel, indium phosphide, boron nitride, diamond, zinc oxide, silicon dioxide, lithium aluminate, lithium gallate, lithium niobate, zirconium boride and one of hafnium borides.

The technical problem to be solved by the present invention is to provide a method for connecting two or more groups of LED basic structural units with a structure of tunnel nodes (tunnel diodes) for the current situation that the traditional LED epitaxial structure has only one group of basic structural units. Form a unified LED epitaxy method with high light energy density output.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an LED epitaxy method with high light energy density output, specifically comprising the following steps:

Step 1: Determine whether the substrate layer is a homogeneous substrate, if yes, perform step 3; otherwise, perform step 2;

Step 2: growing a buffer layer on the surface of the substrate layer;

Step 3: Grow a group of LED basic units on the surface of the substrate layer or the buffer layer;

Step 4: growing a tunnel node on the upper surface of the LED basic unit;

Step 5: Grow a group of LED basic units on the tunnel section;

Step 6: Determine whether the number of LED basic units reaches the preset value, if yes, go to step 7; otherwise, go to step 4;

Step 7: End the growth of the LED epitaxial structure.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the step 3 specifically includes the following steps:

Step 3.1: growing an n-type layer on the surface of the substrate layer or the buffer layer;

Step 3.2: growing a light-emitting layer on the surface of the n-type layer;

Step 3.3: growing a p-type layer on the surface of the light-emitting layer.

The beneficial effect of adopting the above further solution is that the n-type layer and the p-type layer respectively provide the injection of carrier electrons and holes, and the light-emitting layer is a place where electrons and holes recombine and emit light.

Further, the tunnel section includes at least two tunnel sublayers sequentially arranged between two LED basic units; and the at least two tunnel sublayers are heavily doped with n-type and heavily doped with p-type respectively.

Further, the growth method in step 1 to step 5 adopts metal organic vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), pulsed laser deposition (PLD), radio frequency magnetron sputtering (RF-MS), molecular beam At least one fabrication method in Epitaxy (MBE) is implemented.

Description of drawings

Fig. 1 is a schematic cross-sectional view of an LED epitaxial structure with high luminous energy density output according to Embodiment 1 of the present invention;

2 is a schematic cross-sectional view of an LED epitaxial structure with high luminous energy density output according to Embodiment 2 of the present invention;

Fig. 3 is a flow chart of an LED epitaxy method with high luminous energy density output according to the present invention;

4 is a schematic cross-sectional view of an LED epitaxial structure with high luminous energy density output according to Embodiment 3 of the present invention;

FIG. 5 is a schematic cross-sectional view of the specific structure of the tunnel node in the LED epitaxial structure described in Embodiment 3 of the present invention.

In the accompanying drawings, the list of parts represented by each label is as follows:

1. Substrate layer, 2. Buffer layer, 3. n-type layer, 4. Light emitting layer, 5. p-type layer, 6. Tunnel node, 7. Stress release layer, 8. Electron blocking layer, 9. GaN layer, 10 , p-type heavily doped GaN layer.

Detailed ways

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

As shown in Figure 1, it is a schematic cross-sectional view of an LED epitaxial structure with high luminous energy density output according to Embodiment 1 of the present invention, including a substrate layer 1, a buffer layer 2, a tunnel node 6 and two groups of LEDs arranged in sequence. Structural unit; the basic structural unit of the first group of LEDs is composed of n-type layer 3, p-type layer 5 and light-emitting layer 4, and the light-emitting layer 4 is located between n-type layer 3 and p-type layer 5; the second group of LED basic structure The units are composed of an n-type layer 3 , a p-type layer 5 and a light-emitting layer 4 , and the light-emitting layer 4 is located between the n-type layer 3 and the p-type layer 5 . The first group of LED basic structural units and the second group of LED basic structural units are connected through the tunnel node 6 . In this embodiment, the substrate material is a heterogeneous substrate with respect to the epitaxial layer, therefore, there is a buffer layer 2 between the n-type layer and the substrate.

In the specific epitaxial growth process, first select the substrate wafer, for example, select the heterogeneous substrate 1, then grow the buffer layer 2, and then start to grow the layers of the first group of LED basic structural units, followed by the n-type layer 3 , light emitting layer 4 and p-type layer 5 . Then, the tunnel section 6 is grown. Next, each layer of the basic structural unit of the second group of LEDs is grown successively, including the n-type layer 3 , the light-emitting layer 4 and the p-type layer 5 in sequence. In this way, a novel LED device structure with two sets of LED basic structural units is completed.

Under normal circumstances, care should be taken to adjust the epitaxial process parameters so that the emission wavelengths of the first group and the second group of LEDs are consistent or maintain a small wavelength difference range.

The n-type layer includes at least one n-type sublayer, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P(0≤x, y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x, y, z≤1; x+y≤1 ) and at least one of nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1) constitute at least one n-type sublayer;

Each of the n-type sublayers is respectively n-type doped; the n-type doping concentration of each n-type sublayer is the same or different, and the n-type doping elements are Si, Sn, S, Se and At least one of Te.

The p-type layer includes at least one p-type sublayer, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P(0≤x, y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x, y, z≤1; x+y≤1 ) and at least one of nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1) constitute at least one p-type sublayer;

Each of the p-type sublayers is doped with p-type respectively;

The p-type doping concentration of each p-type sublayer is the same or different; the p-type doping element is at least one of Be, Mg, Zn, Cd and C.

The light-emitting layer includes at least one thin film sublayer, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P ( 0≤x,y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) and At least one of the nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1) constitutes at least one thin film sublayer;

The at least one thin film sublayer is n-type, p-type doped or undoped; the n-type doping element is at least one of Si, Sn, S, Se, Te; the p-type doping element It is at least one of Be, Mg, Zn, Cd, and C.

The tunnel section includes at least two tunnel sublayers, arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P (0≤x, y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x, y, z≤1; x+y≤1) and at least one of nitrides _{AlxInyGa1 - xyN} (0≤x, y≤1; x+y≤1) constitute at least two tunnel sublayers.

The at least two tunnel sublayers are heavily n-type doped and p-type heavily doped respectively; the n-type heavily doped element is at least one of Si, Sn, S, Se, Te; p-type heavily doped The hetero element is at least one of Be, Mg, Zn, Cd, and C.

The substrate layer 1 is made of sapphire, silicon carbide, silicon, gallium nitride, aluminum nitride, gallium arsenide, spinel, indium phosphide, boron nitride, diamond, zinc oxide, silicon dioxide, lithium aluminate, One of lithium gallate, lithium niobate, zirconium boride, and hafnium boride.

As shown in Figure 2, it is a schematic cross-sectional view of a LED epitaxial structure with high luminous energy density output described in Embodiment 2 of the present invention; N groups (several groups) of LED basic structural units are connected through N-1 groups of tunnel nodes And carry out the situation of Lei stack. This situation is similar to the way in which two groups of LED basic structures are connected in FIG. 1 , except that the number of basic structural units is increased. It can be seen that the Nth group of LED structural units includes an n-type layer 3 , a p-type layer 5 and a light-emitting layer 4 , and the light-emitting layer 4 is located between the n-type layer 3 and the p-type layer 5 . Moreover, the N-1th group of LED basic structural units is connected to the Nth group of LED basic structural units through the tunnel node 6 . For the epitaxial growth method, the process is similar to the case of two groups of LED basic structural units, and each structural unit and the tunnel node between the two structural units need to be grown one by one. At the same time, it is usually necessary to ensure that the emission wavelength of each LED basic structural unit is similar or the same.

For the material of the substrate, it can be selected from sapphire, silicon carbide, silicon, gallium nitride, aluminum nitride, gallium arsenide, spinel, indium phosphide, boron nitride, diamond, zinc oxide, silicon dioxide, aluminate One selected from lithium, lithium gallate, lithium niobate, zirconium boride or hafnium boride.

For the n-type layer, its composition material is arsenide Al _x In _y Ga _1-xy As (0 ≤ x, y ≤ 1; x+y ≤ 1), phosphide Al _x In _y Ga _1-xy P (0 ≤ x,y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) and nitride At least one of Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1). Moreover, Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1) or Al _x In _y Ga _1-xy P (0≤x ,y≤1; x+y≤1) or Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) or Al _x In _y Ga _{1 -xy} N(0≤x, y≤1; x+y≤1) (0≤x, y≤1; x+y≤1). At the same time, each sublayer is doped with n-type. The doping element in the n-type layer is at least one of Si, Sn, S, Se and Te.

For the p-type layer, its constituent materials are arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P (0≤ x,y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) and nitride At least one of Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1). Moreover, Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1) or Al _x In _y Ga _1-xy P (0≤x ,y≤1; x+y≤1) or Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) or Al _x In _y Ga _{1 -xy} N(0≤x, y≤1; x+y≤1) (0≤x, y≤1; x+y≤1). At the same time, each sublayer is doped with p-type. The doping element in the p-type layer is at least one of Be, Mg, Zn, Cd and C.

For the light-emitting layer, its composition materials are arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P (0≤x ,y≤1; x+y≤1), phosphorus arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1), nitride Al At least one of _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1). Moreover, Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1) or Al _x In _y Ga _1-xy P (0≤x ,y≤1; x+y≤1) or Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) or Al _x In _y Ga _{1 -xy} N(0≤x, y≤1; x+y≤1) (0≤x, y≤1; x+y≤1).

In addition, at least one thin film sublayer in the light emitting layer can be n-type or p-type doped or undoped. Wherein, the n-type doping element is at least one of Si, Sn, S, Se, Te; the p-type doping element is at least one of Be, Mg, Zn, Cd, C.

For the tunnel section, it is characterized in that the constituent materials are arsenide Al _x In _y Ga _1-xy As (0≤x, y≤1; x+y≤1), phosphide Al _x In _y Ga _1-xy P( 0≤x, y≤1; x+y≤1), phosphorous arsenide Al _x In _y Ga _1-xy As _1-z P _z (0≤x, y, z≤1; x+y≤1), At least one of the nitrides Al _x In _y Ga _1-xy N (0≤x, y≤1; x+y≤1), and consists of two layers of Al _x In with the same composition or more than two layers of different compositions _y Ga _1-xy As (0≤x, y≤1; x+y≤1) or Al _x In _y Ga _1-xy P (0≤x, y≤1; x+y≤1) or Al _x In _y Ga _1-xy As _1-z P _z (0≤x,y,z≤1; x+y≤1) or Al _x In _y Ga _1-xy N(0≤x,y≤1; x+y ≤1) (0≤x, y≤1; x+y≤1).

In addition, the feature of the tunnel section is that at least two thin film sublayers in the tunnel section are heavily doped with n-type and heavily doped with p-type respectively. Wherein, the n-type doping element is at least one of Si, Sn, S, Se, Te; the p-type doping element is at least one of Be, Mg, Zn, Cd, C.

As shown in Figure 3, it is a LED epitaxy method with high light energy density output according to the present invention, which specifically includes the following steps:

Step 1: Determine whether the substrate is a homogeneous substrate, if yes, perform step 3; otherwise, perform step 2;

Step 2: growing a buffer layer on the surface of the substrate layer;

Step 3: growing an n-type layer on the substrate or buffer layer;

Step 4: growing a light-emitting layer on the surface of the n-type layer;

Step 5: growing a p-type layer on the surface of the light-emitting layer.

Step 6: growing a tunnel node on the upper surface of the LED basic unit;

Step 7: Grow a group of LED basic units on the tunnel section;

Step 8: Determine whether the number of LED basic units reaches the preset value, if yes, go to step 8; otherwise, go to step 5;

Step 9: End the growth of the LED epitaxial structure.

The tunnel section includes at least two tunnel sublayers sequentially arranged between two LED basic units; and the at least two tunnel sublayers are heavily doped with n-type and heavily doped with p-type respectively.

The growth method in the steps 1 to 7 adopts metal organic vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), pulsed laser deposition (PLD), radio frequency magnetron sputtering (RF-MS), molecular beam epitaxy ( At least one preparation method in MBE) is realized.

As shown in Figure 4, it is a schematic cross-sectional view of an LED epitaxial structure with high luminous energy density output as described in Embodiment 3 of the present invention; this embodiment chooses to carry out a nitride blue LED epitaxial structure on a SiC substrate, illustrating the present invention. The LED device structure and manufacturing method with high light energy density output are described.

The LED epitaxial structure with high light energy density output starts from the substrate and goes from bottom to top. The film layer structure that appears in sequence includes: a layer of AlGaN/GaN composite buffer layer 2 on the SiC substrate 1, followed by a layer of unintentionally doped Doped GaN thin film layer 9. Starting from the GaN thin film layer 9, two sets of LED basic structural units will be grown. Among them, the film layer structure of the first group of LED basic structural units includes: n-type GaN layer 3, stress release layer 7, light-emitting layer 4, electron blocking layer 8, p-type GaN layer 5; the second group of LED basic structural units Above one group of basic structural units, the film layer structure is similar to the first group, including the following film layers: n-type GaN layer 3, stress release layer 7, light-emitting layer 4, electron blocking layer 8, and p-type GaN layer 5. There is also a p-type heavily doped GaN layer 10 above the p-type GaN layer 5 , which is used to form an ohmic contact of the metal electrode during later chip processing. There is a tunnel section 6 between the two groups of LED basic structural units, and the specific structure of the tunnel section is shown in Figure 5, that is, a layer of In _0.2 Ga _0.8 is inserted between p-type heavily doped GaN and n-type heavily doped GaN. N.

According to the schematic diagram of the LED epitaxial device structure shown in Figure 4, the specific method of epitaxial growth on the MOCVD machine is as follows: first, a layer of AlGaN/GaN composite buffer layer 2 with a thickness of 400nm is grown on the SiC substrate 1, and the growth temperature is controlled. at about 1000°C. Then, a non-doped GaN layer 9 is grown to a thickness of 2 μm. Next, start to grow the first group of LED basic structural units: first grow a 2 μm thick n-type GaN layer 3 , the doping element is Si, and the doping concentration is 1.0×10 ¹⁹ . Next, grow a group of stress release layers 7 composed of In _0.04 Ga _0.96 N/GaN superlattice, wherein the single layer thickness of In _0.04 Ga _0.96 N and GaN is both 5 nm and the total thickness is 200 nm. Thereafter, the In _0.15 Ga _0.85 N/GaN multi-quantum well light-emitting layer 4 is grown, wherein the single-layer thicknesses of In _0.15 Ga _0.85 N and GaN are 3nm and 10nm respectively, and the number of periods of the multi-quantum well is four. Next, a 150nm Al _0.14 Ga _0.86 N electron blocking layer 8 is grown. A 0.2 μm thick p-type GaN layer 5 is grown again, the p-type doping element is Mg, and the doping concentration is 1.0×10 ²⁰ . In this way, the growth of the first group of LED basic structural units is completed.

Then, the tunnel section 6 is grown. Specifically, as shown in Figure 5, the tunneling section includes three sublayers: first grow a p-type heavily doped p ⁺⁺ -GaN layer with a thickness of 10nm, and the doping concentration is 5.0×10 ²⁰ ; grow another layer of 3nm The final non-doped In _0.2 Ga _0.8 N layer; finally grow a 10nm-thick n-type heavily doped n ⁺⁺ -GaN layer with a doping concentration of 2.0×10 ²⁰ .

Thereafter, the epitaxial growth of the second group of LED basic structural units is carried out according to the same parameter conditions and methods as the first group of LED basic structural units, but there are also places where the parameter conditions are different: the process conditions of the light-emitting layer 4 need to be adjusted to make it emit The wavelength is equal or approximately equal to the emission wavelength of the light emitting layer 4 . Finally, a layer of 10 nm-thick p-type Mg heavily doped GaN layer 10 with a concentration of 3.0×10 ²⁰ is grown on the basic structural units of the second group of LEDs.

In order to avoid redundant descriptions of many structural parameters and process conditions, this embodiment only gives examples of some of the changing factors. Similar effects can also be achieved by adjusting other structural or technological change factors, which will not be listed here.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. a LED epitaxial structure for high-light-energy density output, is characterized in that, comprise the substrate layer and epitaxial loayer that set gradually; Described epitaxial loayer comprises at least two group LED elementary cells and at least one tunnel joint;

Connected by a tunnel joint between described every two groups of LED elementary cells.

2. the LED epitaxial structure of a kind of high-light-energy density output according to claim 1, it is characterized in that, described LED elementary cell comprises the n-layer, luminescent layer and the p-type layer that set gradually.

3. the LED epitaxial structure of a kind of high-light-energy density output according to claim 2, it is characterized in that, described n-layer comprises at least one N-shaped sublayer, arsenide Al _xin _yga _1-x-yas (0≤x, y≤1; X+y≤1), phosphide Al _xin _yga _1-x-yp (0≤x, y≤1; X+y≤1), phosphorus arsenide Al _xin _yga _1-x-yas _1-zp _z(0≤x, y, z≤1; X+y≤1) and nitride Al _xin _yga _1-x-yn (0≤x, y≤1; X+y≤1) at least one form at least one N-shaped sublayer;

N-shaped doping is carried out respectively in described each N-shaped sublayer;

The doping content of the N-shaped doping of described each N-shaped sublayer is identical or different, and N-shaped doped chemical is at least one in Si, Sn, S, Se and Te.

4. the LED epitaxial structure of a kind of high-light-energy density output according to claim 2, it is characterized in that, described p-type layer comprises at least one p-type sublayer, arsenide Al _xin _yga _1-x-yas (0≤x, y≤1; X+y≤1), phosphide Al _xin _yga _1-x-yp (0≤x, y≤1; X+y≤1), phosphorus arsenide Al _xin _yga _1-x-yas _1-zp _z(0≤x, y, z≤1; X+y≤1), nitride Al _xin _yga _1-x-yn (0≤x, y≤1; X+y≤1) at least one form at least one p-type sublayer;

P-type doping is carried out respectively in described each p-type sublayer;

The doping content of the p-type doping of described each p-type sublayer is identical or different; P-type doped chemical is at least one in Be, Mg, Zn, Cd and C.

5. the LED epitaxial structure of a kind of high-light-energy density output according to claim 2, it is characterized in that, described luminescent layer comprises at least one film sublayer, arsenide Al _xin _yga _1-x-yas (0≤x, y≤1; X+y≤1), phosphide Al _xin _yga _1-x-yp (0≤x, y≤1; X+y≤1), phosphorus arsenide Al _xin _yga _1-x-yas _1-zp _z(0≤x, y, z≤1; X+y≤1) and nitride Al _xin _yga _1-x-yn (0≤x, y≤1; X+y≤1) at least one form at least one film sublayer;

N-shaped, p-type doping or undoped are carried out in described at least one film sublayer;

Described N-shaped doped chemical is at least one in Si, Sn, S, Se, Te; Described p-type doped chemical is at least one in Be, Mg, Zn, Cd, C.

6. the LED epitaxial structure that a kind of high-light-energy density according to any one of claim 1-5 exports, is characterized in that, described tunnel joint comprises at least two tunnel sub-layer, arsenide Al _xin _yga _1-x-yas (0≤x, y≤1; X+y≤1), phosphide Al _xin _yga _1-x-yp (0≤x, y≤1; X+y≤1), phosphorus arsenide Al _xin _yga _1-x-yas _1-zp _z(0≤x, y, z≤1; X+y≤1) and nitride Al _xin _yga _1-x-yn (0≤x, y≤1; X+y≤1) at least one form at least two tunnel sub-layer.

7. the LED epitaxial structure of a kind of high-light-energy density output according to claim 6, it is characterized in that, described at least two tunnel sub-layer carry out N-shaped heavy doping and p-type heavy doping respectively; Described N-shaped heavy doping element is at least one in S i, Sn, S, Se, Te; P-type heavy doping element is at least one in Be, Mg, Zn, Cd, C.

8. the LED epitaxial structure of a kind of high-light-energy density output according to claim 7, it is characterized in that, described substrate layer is homo-substrate or foreign substrate; When substrate layer is foreign substrate, between substrate layer and epitaxial loayer, be also provided with resilient coating.

9. a LED epitaxy method for high-light-energy density output, is characterized in that, specifically comprise the following steps:

Step 1: judge whether substrate layer is homo-substrate, if so, performs step 3; Otherwise, perform step 2;

Step 2: at substrate layer upper surface grown buffer layer;

Step: 3: grow one group of LED elementary cell at substrate layer or resilient coating upper surface;

Step 4: grow a tunnel joint at LED elementary cell upper surface;

Step 5: grow one group of LED elementary cell on tunnel joint;

Step 6: judge whether the quantity of LED elementary cell reaches preset value, if so, performs step 7; Otherwise, perform step 4;

Step 7: the growth terminating LED epitaxial structure.

10. the LED epitaxy method of a kind of high-light-energy density output according to claim 9, it is characterized in that, described step 3 specifically comprises the following steps:

Step 3.1: at substrate layer or resilient coating upper surface growing n-type layer;

Step 3.2: in n-layer upper surface light-emitting layer grows;

Step 3.3: in luminescent layer upper surface growth p-type layer.