CN105655454B - High modulation light emitting diode and preparation method thereof - Google Patents

Abstract

The invention provides a highly modulated light-emitting diode and a preparation method thereof. The high-modulation light-emitting transistor includes a light-emitting diode chip. The light-emitting diode chip includes a substrate, a light-emitting epitaxial structure, a collector, a base, and an emitter. The light-emitting epitaxial structure is arranged on the substrate, and the light-emitting epitaxial structure includes a first N-type A semiconductor layer, a first P-type semiconductor layer, a quantum well layer, a second P-type semiconductor layer, a second N-type semiconductor layer, and a conductive layer, wherein the first P-type semiconductor layer includes a P-type aluminum gallium nitrogen electron blocking layer, a P type contact layer and P-type indium gallium nitride layer, the quantum well layer is an undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer, the collector is set on the first N-type semiconductor layer, and the base is set On the P-type contact layer, the emitter is arranged on the conductive layer. The light emitting diode provided by the invention has the advantages of high light extraction efficiency and high-speed modulation.

Description

High modulation light emitting diode and its preparation method

【Technical field】

The invention relates to the technical field of visible light communication, in particular to a highly modulated light-emitting diode and a preparation method thereof.

【Background technique】

In recent years, light-emitting diode (Light Emitting Diode, LED) lighting technology, known as "green lighting", has developed rapidly. Compared with traditional lighting sources, white light-emitting diodes not only have low power consumption, long service life, small size, environmental protection, but also have the advantages of good modulation performance and high response sensitivity. On the one hand, white light-emitting diodes have the characteristics of high emission power and safety to human eyes; on the other hand, they have the advantages of fast response, good modulation, no electromagnetic interference, and no need to apply for radio spectrum. Therefore, by utilizing the illumination of white light emitting diodes, many scholars have proposed a visible light communication (Visible-Light Communication, VLC) system based on white light emitting diodes for illumination. White light-emitting diode lighting communication is a new technology that combines light-emitting diode lighting technology and optical communication technology. The distance of this communication ranges from several meters to tens of meters. It has the characteristics of safety, energy saving, and large communication capacity. As a The new wireless communication means has attracted more and more attention at home and abroad. At present, the modulation bandwidth of commercial white light emitting diodes is limited, only about 3-50MHz. This is because the original intention of the white light emitting diode design is for lighting, not for communication, and its junction capacitance is very large, which limits the modulation bandwidth. Therefore, under the premise of ensuring high power output, the development of LED light sources with higher modulation bandwidth will greatly promote the development of visible light communication technology.

The modulation bandwidth of light-emitting diodes is the decisive factor for the channel capacity and transmission rate of visible light communication systems, and is affected by many factors such as the actual modulation depth and volt-ampere characteristics of the device. The modulation characteristics of light-emitting diodes with traditional structures are difficult to meet the high-speed modulation characteristics of visible light communication, and the construction of light-emitting devices with new structures is particularly important in the future VLC industry. The existing high-speed modulation light-emitting transistor with a new structure based on the heterojunction bipolar transistor (HBT) structure has the disadvantage of low light extraction efficiency. Although it meets the bandwidth conditions of visible light communication, it is difficult to meet the requirements of indoor lighting. .

When a forward voltage is applied to the PN junction of the light-emitting diode, the PN junction will have a current flow. The recombination of electrons and holes in the PN junction transition layer will generate photons, but not every pair of electrons and holes will generate photons. Since the PN junction of the LED is an impurity semiconductor, there are material quality, dislocation factors, and process issues. Various defects will cause problems such as impurity ionization, excitation scattering and lattice scattering, so that when electrons transition from excited state to ground state, there will be a non-radiative transition when exchanging energy with lattice atoms or ions, that is, no photons will be generated, and this part of energy will not It is converted into light energy and converted into heat energy and is lost in the PN junction, so there is a composite carrier conversion efficiency, which is represented by the symbol Nint.

Nint=(number of photons generated by recombination carriers/total number of recombination carriers)×100%

In LEDs, not all photons generated can effectively escape from the device, and some excited photons will be absorbed by the semiconductor again or reflected back on the light-emitting surface after total reflection, so there is a problem of LED photon escape rate. This can be expressed as the rate at which photons generated in the LED escape into the air.

Nout=(the number of photons escaped into the air/the total number of photons produced by the PN junction)×100%

The light extraction rate of the light-emitting transistor can also be characterized by the quantum efficiency of the LED, and how to improve the light output rate of the light-emitting transistor is the key point of the present invention.

Therefore, there is a need to provide an improved LED that avoids the above drawbacks.

【Content of invention】

In order to solve the technical problem of low light extraction rate of the above-mentioned high-modulation light-emitting diode, the present invention provides a high-modulation light-emitting diode.

The invention provides a highly modulated light-emitting diode, which includes a light-emitting diode chip. The light-emitting diode chip includes a substrate, a light-emitting epitaxial structure, a collector, a base, and an emitter. The light-emitting epitaxial structure includes sequentially stacked first N type semiconductor layer, a first P-type semiconductor layer, a quantum well layer, a second P-type semiconductor layer, a second N-type semiconductor layer and a conductive layer, and the first N-type semiconductor layer is stacked on the epitaxial growth surface of the substrate Above, the first P-type semiconductor layer includes a P-type AlGaN electron blocking layer, a P-type InGaN layer, and a P-type AlGaN electron blocking layer and a P-type InGaN layer. P-type contact layer, the P-type AlGaN electron blocking layer is stacked on the first N-type semiconductor layer, and the quantum well layer is undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN In the quantum well layer, the collector is set on the first N-type semiconductor layer, the base is set on the P-type contact layer, and the emitter is set on the conductive layer.

In a preferred embodiment of the highly modulated light-emitting diode provided by the present invention, the P-type AlGaN electron blocking layer is a P-type Al0.15Ga0.85N electron blocking layer.

In a preferred embodiment of the high-modulation light-emitting diode provided by the present invention, the first N-type semiconductor layer includes a GaN buffer layer, a GaN depletion layer, and a gallium nitride depletion layer interposed between the GaN buffer layer and the A heavily doped N-type GaN contact layer between the GaN depletion layers, and the GaN buffer layer is stacked on the epitaxial growth surface of the substrate.

In a preferred embodiment of the highly modulated light-emitting diode provided by the present invention, the collector is disposed on the surface of the heavily doped N-type GaN contact layer away from the GaN buffer layer.

In a preferred embodiment of the high modulation light emitting diode provided by the present invention, the second P-type semiconductor layer is an InGaN layer heavily doped with Mg.

In a preferred embodiment of the high-modulation light-emitting diode provided by the present invention, the second N-type semiconductor layer includes a stacked N-type GaN layer and a second GaN contact layer, and the N-type GaN The layer is arranged on the surface of the second P-type semiconductor layer away from the quantum well layer, and the second gallium nitride contact layer is a gallium nitride layer heavily doped with silicon.

In a preferred embodiment of the high-modulation light-emitting diode provided by the present invention, the surface of the second gallium nitride contact layer close to the conductive layer is a rough surface with raised microstructures.

The present invention simultaneously provides a kind of preparation method of highly modulated light-emitting diode, comprising:

Step 1: Provide a substrate, and grow a light-emitting epitaxial structure on the epitaxial growth surface of the substrate, wherein the light-emitting epitaxial structure includes a first N-type semiconductor layer and a first P-type semiconductor layer stacked on the substrate in sequence , a quantum well layer, a second P-type semiconductor layer and a second N-type semiconductor layer, the first P-type semiconductor layer includes a P-type AlGaN electron blocking layer, a P-type heavily doped InGaN layer and an interposed A heavily doped P-type contact layer between the P-type AlGaN electron blocking layer and the P-type InGaN layer, the P-type AlGaN electron blocking layer stacked on the first N-type semiconductor layer, The quantum well layer is an undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer, and the second N-type semiconductor layer includes a stacked N-type gallium nitride layer and a second nitride Gallium contact layer;

Step 2, activating the first P-type semiconductor layer and the second P-type semiconductor layer in the light-emitting epitaxial structure obtained in Step 1 by high-temperature annealing;

Step 3, roughening the second gallium nitride contact layer by a wet etching method to form a rough surface with a raised microstructure, and then epitaxially growing a conductive layer to obtain a substrate;

Step 4, forming a collector contact mesa and a base contact mesa by the substrate through an etching process and a photolithography process;

Step 5. Spin-coat photoresist on the substrate on which the collector contact mesa and the base contact mesa have been formed, expose the emitter contact mesa after exposure, vapor-deposit ohmic contact electrodes, and place the conductive layer away from the second N-type The surface of the semiconductor layer forms an emitter;

Step 6. Spin-coat photoresist on the substrate obtained in step 5, expose the base contact mesa after exposure, vapor-deposit ohmic contact electrodes, and place the heavily doped P-type contact layer away from the P-type AlGaN electrons. The surface of the barrier layer forms the base;

Step 7. Spin-coat photoresist on the substrate obtained in step 6, expose the collector contact mesa after exposure, evaporate an ohmic contact electrode, and form a collector on the surface of the first N-type semiconductor layer away from the substrate .

In a preferred embodiment of the method for preparing a high-modulation light-emitting diode provided by the present invention, the first step adopts a metal organic chemical vapor phase epitaxy growth technique to grow the light-emitting epitaxial structure.

In a preferred embodiment of the method for preparing a highly modulated light-emitting diode provided by the present invention, step 4 includes the following steps:

Form the collector contact mesa by an etching process and a photolithography process: the substrate is coated with a positive resist to form a first mask, and then the first mask is subjected to a first photolithography and etching process to forming a collector contact mesa;

The base contact mesa is formed by etching process and photolithography process: the substrate after the collector contact mesa is formed is coated with a positive resist to form a second mask, and then the second mask is subjected to a second photolithography and etch process to form the base contact mesa.

Compared with the prior art, the highly modulated light-emitting diode and its preparation method provided by the present invention have the following

Beneficial effect:

1. The first P-type semiconductor layer includes a P-type AlGaN electron blocking layer, a P-type InGaN layer, and an interlayer between the P-type AlGaN electron blocking layer and the P-type InGaN layer. P-type contact layer, the quantum well layer is an undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer, and the invention improves the quantum efficiency of the device by improving the structure of the base region and the quantum well layer ; While having a high modulation bandwidth, the light extraction efficiency of the high-speed modulation light-emitting diode is improved.

2. The high-modulation light-emitting diode provided by the present invention combines the traditional planar light-emitting diode structure with the HBT structure. When a large current is passed through the electrodes of the high-modulation light-emitting diode, only fast The carriers that recombine and emit light, while the carriers that are not recombined will be swept away by the BC junction (that is, B is the base, C is the collector, and the space charge region formed at their interface is called the BC junction), effectively The diffusion capacitance of the high-modulation light-emitting diode is reduced, and the response speed of the high-modulation light-emitting diode is improved; at the same time, since the change of the quantum well layer structure will cause more carriers to undergo radiative recombination, it can The internal quantum efficiency of the highly modulated light-emitting diode is effectively improved.

3. The present invention roughens the second gallium nitride contact layer by wet etching to form a rough surface with a raised microstructure, and then epitaxially grows the conductive layer, and the second gallium nitride contact layer is the light-emitting layer , roughening the light-emitting surface, reducing the probability of full emission of light inside the light-emitting diode chip, improving its external quantum efficiency, thereby improving the light-emitting efficiency of the light-emitting diode chip.

【Description of drawings】

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work, wherein:

Fig. 1 is a schematic structural view of a highly modulated light-emitting diode provided by the present invention;

Fig. 2 is a schematic diagram of the substrate and light-emitting epitaxial structure of the highly modulated light-emitting diode shown in Fig. 1;

Figure 3(a) is a schematic diagram of the quantum well layer structure of the prior art light-emitting transistor;

Figure 3(b) is a schematic diagram of the quantum well layer structure of the highly modulated light-emitting diode shown in Figure 2;

Fig. 4 is a flow chart of the preparation method of the highly modulated light-emitting diode provided by the present invention;

FIG. 5 is a flow chart of Step 4 in the manufacturing method of the highly modulated light-emitting diode shown in FIG. 4 .

【Detailed ways】

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to FIG. 1 and FIG. 2 at the same time. FIG. 1 is a schematic structural diagram of a highly modulated light-emitting diode provided by the present invention, and FIG. 2 is a schematic diagram of a substrate and a light-emitting epitaxial structure of a highly modulated light-emitting diode shown in FIG. 1 .

The high modulation light emitting diode includes a light emitting diode chip 100, the light emitting diode chip 100 includes a substrate 110, a light emitting epitaxial structure 130, a collector 150, a base 170 and an emitter 190, and the light emitting epitaxial structure 130 is set on the The epitaxial growth surface of the substrate 110 .

The substrate 110 is a sapphire substrate, and in this embodiment, the substrate 110 is a 2-inch sapphire substrate.

The light-emitting epitaxial structure 130 includes a first N-type semiconductor layer 131, a first P-type semiconductor layer 133, a quantum well layer 135, a second P-type semiconductor layer 136, a second N-type semiconductor layer 137, and a conductive layer stacked in sequence. 139. in,

The first N-type semiconductor layer 131 includes a GaN buffer layer 1311, a heavily doped N-type GaN contact layer 1313, and a GaN depletion layer 1315 stacked in sequence. The gallium contact layer 1313 is interposed between the gallium nitride buffer layer 1311 and the gallium nitride depletion layer 1315, the gallium nitride buffer layer 1311 is disposed on the substrate 110, the gallium nitride buffer layer Layer 1311 is an unintentionally doped buffer layer, the heavily doped N-type gallium nitride contact layer 1313 is a heavily doped silicon-doped gallium nitride layer, and the gallium nitride depletion layer 1315 is unintentionally doped depletion layer.

The first P-type semiconductor layer 133 includes a P-type AlGaN electron blocking layer 1331, a P-type contact layer 1333 and a P-type InGaN layer 1335 stacked in sequence, and the P-type contact layer 1333 is interposed between the Between the P-type AlGaN electron blocking layer 1331 and the P-type InGaN layer 1335, the P-type AlGaN electron blocking layer 1331 is located on the gallium nitride depletion layer 1315 away from the heavily doped N-type The surface of the gallium nitride contact layer, the P-type aluminum gallium nitrogen electron blocking layer 1331, its molecular formula is Al _0.15 Ga _0.85 N, the P-type contact layer 1333 is a heavily doped P-type contact layer, and the P-type contact layer 1333 is a heavily doped P-type contact layer. The InGaN layer 1335 is an InGaN layer heavily doped with magnesium, and its molecular formula is In _0.05 Ga _0.95 N;

The quantum well layer 135 is a 4-period undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer, which is arranged on the surface of the P-type indium gallium nitride layer 1335;

The second P-type semiconductor layer 136 is a P-type heavily doped magnesium indium gallium nitride layer, and its molecular formula is In _0.05 Ga _0.95 N;

The second N-type semiconductor layer 137 includes an N-type GaN layer 1371 and a second GaN contact layer 1373, and the N-type GaN layer 137 is located on the second P-type semiconductor layer 136 away from the On the surface of the quantum well layer 135, the second gallium nitride contact layer 1373 is a heavily doped silicon gallium nitride layer.

The surface of the second gallium nitride contact layer 1373 close to the surface of the conductive layer 139 forms a rough surface with a raised microstructure. The second gallium nitride contact layer 1373 is a light-emitting layer, and the light-emitting surface is roughened to reduce The possibility of total emission of light inside the light-emitting diode chip improves its external quantum efficiency, thereby increasing the light extraction rate of the high-modulation light-emitting diode.

The conductive layer 139 is an indium tin oxide transparent conductive layer disposed on the surface of the second gallium nitride contact layer 1373 .

The collector electrode 150 is disposed on the first N-type semiconductor layer 131 , specifically on the surface of the heavily doped N-type GaN contact layer 1313 away from the GaN buffer layer 1311 . In this embodiment, there are two of them, which are arranged symmetrically on both sides of the gallium nitride depletion layer 1315 .

The base 170 is disposed on the surface of the P-type contact layer 1333 away from the P-type AlGaN electron blocking layer 1331 . In this embodiment, there are two of them, which are arranged symmetrically on both sides of the P-type heavily doped InGaN layer 1335 .

The emitter 190 is disposed on the conductive layer 139 . In this embodiment, there are two of them, symmetrically disposed on the surface of the conductive layer 139 away from the second gallium nitride contact layer 1373 .

Please refer to Fig. 3(a) and Fig. 3(b) in combination, Fig. 3(a) is a schematic diagram of the quantum well layer structure of the light-emitting transistor in the prior art, and Fig. 3(b) is the quantum well of the highly modulated light-emitting diode shown in Fig. 2 Schematic diagram of the layer structure. The structure of the quantum well layer 135 is changed, and the changed structure of the quantum well layer will allow more carriers to undergo radiative recombination.

The principle that the highly modulated light-emitting diode provided by the present invention has high light extraction efficiency is as follows: the present invention combines the traditional planar light-emitting diode structure with the HBT structure, and when a large current is applied to the electrode of the highly modulated light-emitting diode, there is The source light-emitting region only leaves the fast recombination light carriers, and the unrecombined carriers will be absorbed by the BC junction (that is, B is the base, C is the collector, and the space charge region formed at their interface is called BC junction) is swept away, effectively reducing the diffusion capacitance of the high modulation light-emitting diode, and improving the response speed of the high modulation light-emitting diode; at the same time, due to the change of the quantum well layer structure, more carriers will be radiated Recombination, the internal quantum efficiency of the high-modulation light-emitting diode can be effectively improved under high current, thereby improving the light extraction efficiency.

Please refer to FIG. 4 and FIG. 5 . FIG. 4 is a flowchart of a method for manufacturing a highly modulated light-emitting diode provided by the present invention, and FIG. 5 is a flowchart of Step 4 in the method for manufacturing a highly modulated light-emitting diode shown in FIG. 4 .

Based on the structure of the above-mentioned high-modulation light-emitting diode, the present invention also provides a method for preparing a high-modulation light-emitting diode, the steps are as follows:

Step S1, providing a substrate, and growing a light-emitting epitaxial structure on the epitaxial growth surface of the substrate to obtain an epitaxial wafer:

Specifically, on the epitaxial growth surface of the substrate, the first N-type semiconductor layer, the first P-type semiconductor layer, the quantum well layer, the second P-type semiconductor layer, the second P-type semiconductor layer, and the Two N-type semiconductor layers, the substrate is a sapphire substrate, wherein:

The first N-type semiconductor layer includes a gallium nitride buffer layer, a gallium nitride depletion layer, and heavily doped N-type gallium nitride interposed between the gallium nitride buffer layer and the gallium nitride depletion layer a contact layer, the gallium nitride buffer layer is disposed on the substrate;

The first P-type semiconductor layer includes a P-type AlGaN electron blocking layer, a P-type InGaN layer, and a P-type InGaN layer interposed between the P-type AlGaN electron blocking layer and the P-type InGaN layer. a contact layer, the P-type AlGaN electron blocking layer is disposed on the GaN depletion layer;

The quantum well layer is an undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer;

The second P-type semiconductor layer is an indium gallium nitride layer heavily doped with magnesium;

The second N-type semiconductor layer includes an N-type GaN layer and a second GaN contact layer, and the N-type GaN layer is disposed on the second P-type semiconductor layer.

Step S2, activating the first P-type semiconductor layer and the second P-type semiconductor layer in the epitaxial wafer obtained in Step S1 by high-temperature annealing.

A higher P-type hole concentration can be obtained by activating the P-type layer in the epitaxial wafer by high-temperature annealing.

Step S3 , roughening the second gallium nitride contact layer by wet etching to form a rough surface with a raised microstructure, and then epitaxially growing the conductive layer to obtain a substrate.

Step S4, forming a collector contact mesa and a base contact mesa by an etching process or a photolithography process, which specifically includes the following steps;

Step S41, forming a collector contact mesa by an etching process or a photolithography process:

Coating the substrate obtained in step S3 with a positive resist to form a first mask, and then subjecting the first mask to photolithography for the first time, that is, developing after exposure, and performing a degumming process to form a collector The glue on the contact mesa is removed, and the glue on the remaining unexposed part is retained to form the pattern to be engraved, and then an etching process is performed to form the collector contact mesa; that is, the substrate is etched to expose the first nitrogen GaN contact layer;

Step S42, forming a base contact mesa by an etching process or a photolithography process:

Coating positive resist on the substrate on which the collector contacts the mesa is formed to form a second mask, and then subjecting the second mask to photolithography for the second time, that is, developing after exposure, and performing a degumming process, so that the mask to be formed The glue on the base contact mesa is removed, and the glue on the remaining unexposed part is retained to form the pattern to be engraved, and then an etching process is performed to form the base electrode contact mesa; that is, the substrate is etched until the exposed P-type contact layer.

Step S5, forming an emitter on the surface of the conductive layer:

Spin-coat photoresist on the substrate with the collector contact mesa and the base electrode contact mesa formed in step S4, expose the emitter contact mesa after exposure, and vapor-deposit ohmic contact electrodes on the conductive layer away from the first electrode contact mesa. The surface of the two N-type semiconductor layers forms an emitter;

Step S6, forming a base on the surface of the P-type contact layer:

The photoresist is spin-coated on the substrate obtained in step S5, and the base contact mesa is exposed after exposure, and the ohmic contact electrode is evaporated to form a base on the surface of the P-type contact layer far away from the P-type AlGaN electron blocking layer. pole;

Step S7, forming a collector on the surface of the first gallium nitride contact layer:

The photoresist is spin-coated on the substrate obtained in step S6, and the collector contact mesa is exposed after exposure, and the ohmic contact electrode is evaporated, and the surface of the first gallium nitride contact layer in the first N-type semiconductor layer is far away from The surface of the substrate forms a collector. The highly modulated light-emitting diode and its preparation method provided by the present invention have the following beneficial effects:

1. The first P-type semiconductor layer 133 includes a P-type AlGaN electron blocking layer 1331, a P-type InGaN layer 1335, and a P-type AlGaN electron blocking layer 1331 and a P-InGaN layer. The P-type contact layer 1333 between the layers 1335, the base 170 is arranged on the P-type contact layer 1333, and the quantum well layer 135 is undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN For the quantum well layer, the invention improves the quantum efficiency of the device by improving the structure of the base region and the quantum well layer; while having a high modulation bandwidth, it improves the light extraction efficiency of the high-speed modulation light-emitting diode.

2. The high-modulation light-emitting diode provided by the present invention combines the traditional planar light-emitting diode structure with the HBT structure. When a large current is passed through the electrodes of the high-modulation light-emitting diode, only fast The carriers that recombine and emit light, while the carriers that are not recombined will be swept away by the BC junction (that is, B is the base, C is the collector, and the space charge region formed at their interface is called the BC junction), effectively The diffusion capacitance of the high-modulation light-emitting diode is reduced, and the response speed of the high-modulation light-emitting diode is improved; at the same time, since the change of the quantum well layer structure will cause more carriers to undergo radiative recombination, it can The internal quantum efficiency of the highly modulated light-emitting diode is effectively improved.

3. The present invention roughens the second gallium nitride contact layer 1373 by wet etching to form a rough surface with a raised microstructure, and then epitaxially grows the conductive layer 139, and the second gallium nitride contact layer 1373 Layer 1373 is a light-extracting layer, which roughens the light-exiting surface to reduce the probability of total emission of light inside the LED chip 100 and improve its external quantum efficiency, thereby increasing the light-extracting rate of the LED chip 100 .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A highly modulated light-emitting diode, characterized in that it comprises a light-emitting diode chip, the light-emitting diode chip includes a substrate, a light-emitting epitaxial structure, a collector, a base, and an emitter, and the light-emitting epitaxial structure includes sequentially stacked The first N-type semiconductor layer, the first P-type semiconductor layer, the quantum well layer, the second P-type semiconductor layer, the second N-type semiconductor layer and the conductive layer, the first N-type semiconductor layer is stacked on the substrate On the epitaxial growth surface, the first P-type semiconductor layer includes a P-type AlGaN electron blocking layer, a P-type InGaN layer, and a P-type AlGaN electron blocking layer and a P-InGaN layer. The P-type contact layer between the P-type AlGaN electron blocking layer is stacked on the first N-type semiconductor layer, and the quantum well layer is undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer, the collector is set on the first N-type semiconductor layer, the base is set on the P-type contact layer, and the emitter is set on the conductive layer. 2 . The highly modulated light emitting diode according to claim 1 , wherein the P-type AlGaN electron blocking layer is a P-type Al _0.15 Ga _0.85 N electron blocking layer. 3. The highly modulated light-emitting diode according to claim 1, wherein the first N-type semiconductor layer comprises a gallium nitride buffer layer, a gallium nitride depletion layer, and a gallium nitride depletion layer interposed between the gallium nitride buffer layer A heavily doped N-type GaN contact layer between the GaN depletion layer, and the GaN buffer layer stacked on the epitaxial growth surface of the substrate. 4 . The highly modulated light emitting diode according to claim 3 , wherein the collector is disposed on a surface of the heavily doped N-type GaN contact layer away from the GaN buffer layer. 5 . The highly modulated light emitting diode according to claim 1 , wherein the second P-type semiconductor layer is an InGaN layer heavily doped with magnesium. 6. The highly modulated light-emitting diode according to claim 1, wherein the second N-type semiconductor layer comprises an N-type gallium nitride layer and a second GaN contact layer, and the N-type nitrogen The gallium nitride layer is disposed on the surface of the second P-type semiconductor layer away from the quantum well layer, and the second gallium nitride contact layer is a gallium nitride layer heavily doped with silicon. 7 . The high modulation light emitting diode according to claim 6 , wherein the surface of the second gallium nitride contact layer close to the conductive layer is a rough surface with raised microstructures. 8. A preparation method for highly modulated light-emitting diodes, characterized in that, comprising: Step 1: Provide a substrate, and grow a light-emitting epitaxial structure on the epitaxial growth surface of the substrate to obtain an epitaxial wafer, wherein the light-emitting epitaxial structure includes a first N-type semiconductor layer, a first P type semiconductor layer, a quantum well layer, a second P-type semiconductor layer, and a second N-type semiconductor layer, and the first P-type semiconductor layer includes a P-type AlGaN electron blocking layer and a P-type heavily doped InGaN layer and a heavily doped P-type contact layer interposed between the P-type AlGaN electron blocking layer and the P-type InGaN layer, and the P-type AlGaN electron blocking layer is stacked on the first N-type The semiconductor layer, the quantum well layer is an undoped In _0.2 Ga _0.8 N/In _0.05 Ga _0.95 N/GaN quantum well layer, and the second N-type semiconductor layer includes a stacked N-type gallium nitride layer and a first gallium nitride contact layer; Step 2, activating the first P-type semiconductor layer and the second P-type semiconductor layer in the epitaxial wafer obtained in Step 1 by high-temperature annealing; Step 3, roughening the second gallium nitride contact layer by a wet etching method to form a rough surface with a raised microstructure, and then epitaxially growing a conductive layer to obtain a substrate; Step 4, forming a collector contact mesa and a base contact mesa by the substrate through an etching process and a photolithography process; Step 5. Spin-coat photoresist on the substrate on which the collector contact mesa and the base contact mesa have been formed, expose the emitter contact mesa after exposure, vapor-deposit ohmic contact electrodes, and place the conductive layer away from the second N-type The surface of the semiconductor layer forms an emitter; Step 6. Spin-coat photoresist on the substrate obtained in step 5, expose the base contact mesa after exposure, vapor-deposit ohmic contact electrodes, and place the heavily doped P-type contact layer away from the P-type AlGaN electrons. The surface of the barrier layer forms the base; Step 7. Spin-coat photoresist on the substrate obtained in step 6, expose the collector contact mesa after exposure, evaporate an ohmic contact electrode, and form a collector on the surface of the first N-type semiconductor layer away from the substrate . 9 . The method for manufacturing a high-modulation light-emitting diode according to claim 8 , characterized in that, in the first step, the light-emitting epitaxial structure is grown by metal organic chemical vapor phase epitaxy deposition growth technology. 10. The method for preparing a highly modulated light-emitting diode according to claim 8, wherein step 4 comprises the following steps: Form the collector contact mesa by an etching process and a photolithography process: the substrate is coated with a positive resist to form a first mask, and then the first mask is subjected to a first photolithography and etching process to forming a collector contact mesa; The base contact mesa is formed by etching process and photolithography process: the substrate after the collector contact mesa is formed is coated with a positive resist to form a second mask, and then the second mask is subjected to a second photolithography and etch process to form the base contact mesa.