CN111725368A - GaN-based vertical structure Micro-cavity-LED based on electroplating technology and preparation method thereof - Google Patents
GaN-based vertical structure Micro-cavity-LED based on electroplating technology and preparation method thereof Download PDFInfo
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- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/10—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
- H01L33/105—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector with a resonant cavity structure
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- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
- H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds
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- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
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- H01L33/06—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
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- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/10—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
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- H01L33/26—Materials of the light emitting region
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- H01L33/32—Materials of the light emitting region containing only elements of group III and group V of the periodic system containing nitrogen
Abstract
The invention discloses a GaN-based vertical structure Micro-cavity LED based on electroplating technology and a preparation method thereof, and the Micro-cavity LED has narrow luminous half-height width and good luminous directivity; by reducing the thickness of the chip and taking the metal reflector of the p-GaN layer (5) and the dielectric film reflector of the n-GaN layer as the end faces of the resonant cavity, the resonant Micro-cavity structure in the vertical direction is formed, light emission from the side wall is inhibited, and the light emission directivity of the front side is improved, so that the crosstalk effect between adjacent pixels displayed by the Micro-LED is reduced. Meanwhile, the specific wavelength is selected by the resonant Micro-cavity structure, so that the light-emitting spectrum of the resonant Micro-cavity structure is narrowed, the spectral purity is higher, and the Micro-LED display threshold value is favorably improved; the current expansion is good, the voltage is low, the current density is low, and the LED lamp has the advantages of light effect, saturated current and long-term reliability; and secondly, the Cu substrate has good electrical conductivity and thermal conductivity, and the chip thermal resistance is small.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a GaN-based Micro-LED with a vertical structure microcavity based on an electroplating technology and a preparation method thereof.
Background
Micro-LEDs have important applications in display and visible light communications. The display industry is the leading industry in the information age, the annual value is over billions of dollars, and the advantages of Light Emitting Diodes (LEDs) which are replaced by energy conservation, high efficiency, durability, no mercury and the like are gradually the mainstream of the display illumination field. Micro-LEDs are considered to be the most potential display technology following TFT-LCD and AMOLED technologies due to their excellent characteristics of ultra-high resolution, high brightness, ultra-power saving, and fast response speed. In Micro-LED display, the size of a pixel unit is reduced to improve the display precision and resolution. The LED is similar to a Lambertian light source, and the light outlet angle of the LED is large. The thickness of the chip obtained by the simulation of Trace-Pro software is 10 μm, and when the size of the chip is 50 μm, the light emitting proportion of the side wall reaches 15%. It can be seen that as the size of the Micro-LED pixel unit is reduced, the area ratio of the side wall of the Micro-LED pixel unit is increased along with the reduction of the size, so that the light emitted from the side wall is increased and cannot be ignored, the cross talk effect of the adjacent pixel units is significant, and the display performance of the Micro-LED, such as contrast and definition, is greatly reduced. At present, the research on Micro-LED display focuses more on key process technologies such as mass transfer, and the research on the problem of cross talk is lacked. Professor Guohao in Taiwan, Taiwan traffic university, and the like utilize photoetching and other processes to manufacture a 'dam' around each Micro-LED pixel and absorb side walls and partial oblique emergent light so as to reduce the 'cross talk' effect of adjacent pixels. However, this approach adds process steps and the dam itself acts as part of the pixel, limiting further reduction in overall pixel size. In addition, the conventional Micro-LED has a wide light-emitting half-height width reaching 20nm, which limits performances such as a display threshold value based on the Micro-LED.
In addition, the visible light communication based on the Micro-LED has the characteristics of available visible light resources, wide visible light available frequency band bandwidth, strong safety (no signal when shielding exists) and the like, and has a great deal of application prospect in the intelligent interconnected society. However, the Micro-LED based on GaN base has slow light emitting rate due to the piezoelectric polarization effect of MQW (quantum well), which greatly limits the bandwidth of the Micro-LED as a visible light communication light source.
Disclosure of Invention
The invention aims to provide a GaN-based Micro-cavity Micro-LED with a vertical structure based on an electroplating technology and a preparation method thereof.
The invention discloses a GaN-based vertical structure microcavity Micro-LED based on an electroplating technology, which comprises a Micro-LED chip and a seventh substrate, wherein the Micro-LED chip is positioned on the seventh substrate; the Micro-LED chip comprises a dielectric film, an n-GaN layer, an MQW layer, a p-GaN layer and a reflector electrode from top to bottom, wherein the reflector electrode is connected with a substrate seven; the widths of the n-GaN layer, the MQW layer and the p-GaN layer are equal, and the width of the reflector electrode is equal to that of the substrate seven; the width of the dielectric film is smaller than that of the n-GaN layer, and the table top can be exposed from the two sides of the n-GaN layer; the width of the reflector electrode is larger than that of the n-GaN layer, the MQW layer and the p-GaN layer, the table top can be exposed from the two sides of the reflector electrode, and the n-GaN layer, the MQW layer and the p-GaN layer can be exposed from the two side walls; a passivation layer is arranged on the table top and the side wall; and an ohmic contact metal layer is arranged on the passivation layer on one side, and the top of the ohmic contact metal layer is provided with a table top with a part leaking out of the n-GaN layer.
The size of the Micro-LED chip is 10-1000 mu m; the reflector electrode is Ni/Ag/Pt/Au, and is also a metal electrode.
The invention relates to a preparation method of a GaN-based vertical structure microcavity Micro-LED based on an electroplating technology, which comprises the following steps:
(1) growing a u-GaN layer, an n-GaN layer, an MQW layer and a p-GaN layer on the first substrate in sequence to obtain an LED epitaxial material;
(2) preparing a reflector electrode on the surface of the p-GaN layer in the step (1);
(3) preparing a seventh substrate on the electrode surface of the reflector obtained in the step (2);
(4) removing the first substrate of the structure obtained in the step (3);
(5) removing the u-GaN layer and part of the n-GaN layer of the structure obtained in the step (4) to the designed cavity length by dry etching;
(6) etching the structure obtained in the step (5) to form a chip mesa 2 to a reflector;
(7) preparing a passivation layer on the upper surface of the chip table board 2 obtained in the step (6) and on the side walls of the n-GaN layer, the MQW layer and the p-GaN layer, and preparing the passivation layer on the upper surface of the n-GaN layer except two sides of the position of the dielectric film, wherein the prepared passivation layer is in a right-angled Z shape;
(8) preparing ohmic contact metal on the passivation layer on one side of the structure obtained in the step (7), wherein part of the upper part of the ohmic contact metal is in contact with the upper surface of the n-GaN layer;
(9) and (5) depositing a dielectric film on the surface of the n-GaN layer of the Micro-LED chip with the vertical structure obtained in the step (8), and cutting to obtain the Micro-LED chip with the GaN-based vertical structure.
In the step (1), the first substrate is one of gem, silicon carbide and gallium nitride, the thickness of the u-GaN layer is 4-6 μm, the thickness of the n-GaN layer is 4-6 μm, the thickness of the MQW layer is 50-500 nm, and the thickness of the p-GaN layer is 50-200 nm; the MQW layer is formed by InGaN layers and GaN layers in an alternating cycle mode, wherein the thickness of the InGaN layer is 2nm, and the thickness of the GaN layer is 10 nm; the preparation method of the u-GaN layer, the n-GaN layer, the MQW layer and the p-GaN layer is MOCVD growth.
In the step (2), the preparation method of the reflector electrode is an electron beam evaporation method, and the deposition temperature is 110-130 ℃; the mirror electrode was Ni/Ag/Pt/Au, and the thickness of the mirror electrode was 0.5/200/50/200 nm.
In the step (3), the preparation method of the substrate seven is one of electroplating and bonding; the material of the substrate seven is one of Cu, Ni and Si, and the thickness of the substrate seven is 70-100 mu m.
In the step (4), the removing method of the first substrate is one of laser stripping, grinding and polishing and wet etching.
In the step (5), the thickness of the etched n-GaN layer is 50-500 nm, and the designed cavity length is integral multiple of the wavelength.
In the step (6), after etching, the width of the reflector surface layer is larger than that of the u-GaN layer, the n-GaN layer, the MQW layer and the p-GaN layer, the u-GaN layer, the n-GaN layer, the MQW layer and the p-GaN layer are positioned in the middle of the reflector surface layer, and the leaking parts on the two sides are the chip table top 2.
In the step (7), the passivation layer is SiO2、Ta2O5In one of the above methods, the passivation layer is prepared by chemical deposition, and the thickness of the passivation layer is 200-250 nm.
In the step (8), the ohmic contact metal is Cr/Al/Ti/Au; the preparation method is an electron beam evaporation method; the deposition temperature is 15-25 ℃.
In the step (9), the dielectric film is SiO2、Si3N4、TiO2The preparation method is PECVD deposition, and the thickness of the dielectric film is 251-264 nm.
The invention has the beneficial effects that:
first, the luminous half-height width is narrow, and the luminous directionality is good. By reducing the thickness of the chip and taking the metal reflector of the p-GaN layer (5) and the dielectric film reflector of the n-GaN layer as the end faces of the resonant cavity, the resonant Micro-cavity structure in the vertical direction is formed, light emission from the side wall is inhibited, and the light emission directivity of the front side is improved, so that the crosstalk effect between adjacent pixels displayed by the Micro-LED is reduced. Meanwhile, the specific wavelength of the resonant Micro-cavity structure is selected, so that the light-emitting spectrum of the resonant Micro-cavity structure is narrowed, the spectral purity is higher, and the Micro-LED display threshold value can be improved;
secondly, the light emitting speed is high. Due to Purcell effect, the size of the formed vertical direction resonance microcavity is reduced, the light emitting speed of the Micro-LED is improved, and therefore the bandwidth of a Micro-LED light source in visible light communication is improved;
high brightness and high efficiency. The GaN material and the air have large refractive index difference, and a total reflection phenomenon occurs at an interface, so that most of emitted light of the LED device is confined in the device. Meanwhile, the thick film effect of the epitaxial nitride enables a plurality of waveguide modes to exist in the device, and emitted light is coupled into the waveguide modes, transmitted in the device and finally absorbed and lost. The spontaneous emissivity at the resonance wavelength increases due to the microcavity effect. Meanwhile, most of the emergent angles of the light are concentrated in the light extraction window, and only a few light is absorbed by the active layer, so that the light-emitting brightness of the light-emitting diode is higher. The Micro-LED with the reduced thickness can inhibit a waveguide mode in the conventional thick film Micro-LED, improve the light extraction efficiency of the Micro-LED, and improve the display brightness of the Micro-LED and the signal stability of visible light communication;
fourthly, the integration level is higher, and the temperature stability is good. The thickness of the chip is mostly in the magnitude of the wavelength of the light-emitting center, so that the integration level of Micro-LED display is greatly improved. The emission spectrum of a conventional LED quantum well widens with increasing temperature and the peak wavelength is red-shifted. Due to the existence of the upper reflector and the lower reflector, the wavelength deviation of the vertical structure Micro-LED depends on the temperature coefficient of the optical cavity, and the temperature stability is good.
And fifthly, the photoelectric thermal performance is more excellent. The vertical structure LED has large active area and less n-GaN light absorption; the current expansion is good, the voltage is low, the current density is low, and the LED lamp has advantages in light effect, saturated current and long-term reliability; and secondly, the Cu substrate has good electrical conductivity and thermal conductivity, and the chip thermal resistance is small.
Drawings
FIG. 1 is a schematic structural diagram corresponding to step (1) in the preparation method provided by the present invention;
FIG. 2 is a schematic structural diagram corresponding to step (2) in the preparation method provided by the present invention;
FIG. 3 is a schematic structural diagram corresponding to step (3) in the preparation method provided by the present invention;
FIG. 4 is a schematic structural diagram corresponding to step (4) in the preparation method provided by the present invention;
FIG. 5 is a schematic structural diagram corresponding to step (5) in the preparation method provided by the present invention;
FIG. 6 is a schematic structural diagram corresponding to step (6) in the preparation method provided by the present invention;
FIG. 7 is a schematic structural diagram corresponding to step (7) in the preparation method provided by the present invention;
FIG. 8 is a schematic structural diagram corresponding to step (8) in the preparation method provided by the present invention;
FIG. 9 is a schematic structural view of a vertical microcavity GaN-based Micro-LED provided by the present invention.
Description of reference numerals:
1. a first substrate; 2. a u-GaN layer; 3. an n-GaN layer; 4. an MQW (quantum well) layer; 5. a p-GaN layer; 6. a mirror electrode; 7. a substrate seven; 8. a passivation layer; 9. an ohmic contact metal; 10. a dielectric film; 11 chip mesa.
Detailed Description
In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is given with reference to specific embodiments.
Example 1
The structure of the vertical microcavity GaN-based Micro-LED is shown in FIG. 9, and comprises a Micro-LED chip and a substrate seven 7, wherein the Micro-LED chip is positioned on the substrate seven; the Micro-LED chip comprises a dielectric film 10, an n-GaN layer 3, an MQW layer 4, a p-GaN layer 5 and a reflector electrode 6 from top to bottom, wherein the reflector electrode 6 is connected with a substrate seven 7; the widths of the n-GaN layer 3, the MQW layer 4 and the p-GaN layer 5 are equal, and the width of the reflector electrode 6 is equal to that of the substrate seven 7; the width of the dielectric film 10 is smaller than that of the n-GaN layer 3, and the table top 11 can be leaked from two sides of the n-GaN layer; the width of the reflector electrode is larger than that of the n-GaN layer 3, the MQW layer 4 and the p-GaN layer 5, the table top 11 can be exposed from the two sides of the reflector electrode 6, and the n-GaN layer 3, the MQW layer 4 and the p-GaN layer 5 can be exposed from the two side walls; a passivation layer 8 is arranged on the table-board 11 and the side wall; the passivation layer 8 is in a right-angled Z shape; an ohmic contact metal layer 9 is arranged on the passivation layer 8 on one side, and the top of the ohmic contact metal layer 9 is partially contacted with the leakage mesa 11 on the n-GaN layer 3.
The reflector electrode in the invention is Ni/Ag/Pt/Au, and is also a metal electrode.
Example 2
The preparation method of the vertical microcavity GaN-based Micro-LED provided by the embodiment comprises the following steps:
(1) sapphire (substrate 1) in the (0001) plane) On the surface of the substrate, a u-GaN layer 2 (thickness 5 μm), an n-GaN layer 3 (thickness 5 μm), [ InGaN (2nm)/GaN (10nm) were sequentially grown by MOCVD]8An MQW (quantum well) layer 4 (96 nm In thickness), a p-GaN layer 5 (100 nm In thickness), and an LED epitaxial material having an emission wavelength determined by the In composition In the MQW (quantum well) layer 4, 460nm In this example, were obtained. The structure of the LED epitaxial material obtained in step (1) is shown in fig. 1.
(2) And manufacturing a reflector electrode 6 on the p-GaN layer 5 by an electron beam evaporation method, wherein the deposition temperature is 120 ℃, the reflector electrode is Ni/Ag/Pt/Au, and the thickness of the reflector electrode 6 is 0.5/200/50/200 nm. The structure obtained after this step is shown in fig. 2.
(3) And (3) preparing a substrate 7 on the reflector electrode 6 obtained in the step (2) by using an electroplating method. Specifically, a Cu layer 7 of Cu having a thickness of 100 μm was plated using a copper plating bath. The structure obtained after this step is shown in fig. 3.
(4) And (3) peeling off and removing the sapphire (substrate 1) of the structure obtained in the step (3) by using a 248nm KrF laser. The structure obtained after this step is shown in fig. 4.
(5) And etching the complete u-GaN layer 2 by dry etching (ICP), and etching part of the n-GaN layer 3 to the designed cavity length (375nm) under the following etching conditions: ICP Power 500W, RF Power 150W, Cl2/BCl340sccm and 5sccm, respectively, and an etching time of 680s and an etching depth of 9.8 μm in total. The structure obtained after this step is shown in fig. 5.
(6) The chip mesa 11 is etched to the mirror electrode layer 6 by dry etching (ICP). The etching conditions are as follows: ICP Power 500W, RF Power 50W, Cl2/BCl3Spin-coat AZ4620 type photoresist 4 μm thick at 40sccm and 5sccm, respectively, for an etching time of 100s and an etching depth of about 400 nm. The structure obtained after this step is shown in fig. 6.
(7) Depositing a layer of SiO on the n-GaN layer 3, the table 11 and the side wall of the chip by using vapor deposition (PECVD)2 Passivation layer 8 of SiO2The thickness was about 225 nm. The structure obtained after this step is shown in fig. 7, and it can be seen that the shape of the passivation layer 8 is a right-angled zigzag shape.
(8) And (4) preparing ohmic contact metal 9 on the n-GaN layer 3 of the structure obtained in the step (7) and the passivation layer 8 on one side by using an electron beam evaporation method. Wherein the deposition temperature is 20 ℃, and the ohmic contact metal is Cr/Al/Ti/Au. The resulting structure after this step is shown in figure 8,
(9) depositing three layers of SiO on the surface of the n-GaN layer 3 of the structure obtained in the step (8)2/TiO2A dielectric film layer 10 of SiO2TiO with a thickness of 78nm2The thickness is 51nm, the dielectric film reflectivity is about 89%, and the vertical microcavity GaN-based Micro-LED is obtained after cutting, as shown in FIG. 9.
The size of the finally obtained vertical microcavity GaN-based Micro-LED is 30,50,80 and 100 μm.
Example 3
The preparation method of the vertical microcavity GaN-based Micro-LED provided by the embodiment comprises the following steps:
(1) firstly, a u-GaN layer 2 (thickness 5 μm), an n-GaN layer 3 (thickness 5 μm), and [ InGaN (2nm)/GaN (10nm) are sequentially grown on a (111) plane Si (substrate 1) by MOCVD]8And an MQW (quantum well) layer 4 (with the thickness of 96nm) and a p-GaN layer 5 (with the thickness of 100nm) to obtain the LED epitaxial material. The structure of the LED epitaxial material obtained in step (1) is shown in fig. 1.
(2) And manufacturing a reflector electrode 6 on the p-GaN layer 5 by using an electron beam evaporation method, wherein the deposition temperature is 120 ℃, and the reflector electrode is Ni/Ag/Pt/Au. The mirror electrode 6 had a thickness of 0.5/200/50/200 nm. The structure obtained after this step is shown in fig. 2.
(3) And (3) preparing a substrate 7 on the reflector electrode 6 obtained in the step (2) by using an electroplating method. Specifically, a layer of Cu is electroplated by using a copper plating solution, and the thickness of the Cu layer is 100 mu m; then, a layer of Ni is electroplated by replacing the Ni-plating solution, wherein the thickness of the Ni layer is 7-10 μm. The structure obtained after this step is shown in fig. 3.
(4) And (4) etching and removing Si (substrate 1) of the structure obtained in the step (4) by using HF acid. The structure obtained after this step is shown in fig. 4.
(5) And etching the complete u-GaN layer 2 by using dry etching (ICP), and etching part of the n-GaN layer 3-375 nm under the etching conditions that: ICP Power 500W, RF Power 150W, Cl2/BCl340sccm and 5sccm respectively, an etching time of 650s and an etching depthAnd 9.3 μm. The resulting structure after this step is shown in fig. 5.
(6) The mesa of the chip is etched to the mirror electrode layer 6 by dry etching (ICP). The etching conditions are as follows: ICP Power 500W, RF Power 50W, Cl2/BCl3Spin-coat a 4 μm thick AZ4620 type photoresist at 40sccm and 5sccm, respectively, for an etch time of 150s and an etch depth of about 600 nm. The structure obtained after this step is shown in fig. 6.
(7) Depositing a layer of SiO on the n-GaN layer 3 and the side wall of the chip by utilizing the vapor deposition (PECVD)2 Passivation layer 8 of SiO2The thickness was about 225 nm. The structure obtained after this step is shown in fig. 7, and it can be seen that the passivation layer 8 is in the shape of a right-angled zigzag
(8) And (4) preparing ohmic contact metal 9 on the n-GaN layer 3 and the passivation layer 8 of the structure obtained in the step (7) by using an electron beam evaporation method. Wherein the deposition temperature is 20 ℃, and the ohmic contact metal is Cr/Al/Ti/Au. The structure obtained after this step is shown in fig. 8.
(9) Depositing four layers of SiO on the surface of the n-GaN layer 3 of the structure obtained in the step (8)2/Si3N4A dielectric film layer 10 of SiO2Thickness of 78nm, Si3N4The thickness is 56nm, the reflectivity of the dielectric film is about 85%, and the vertical microcavity GaN-based Micro-LED is obtained after cutting, and the structure of the vertical microcavity GaN-based Micro-LED is shown in FIG. 9.
The size of the finally obtained vertical microcavity GaN-based Micro-LED is 30,50,80 and 100 μm.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A GaN-based vertical structure Micro-cavity Micro-LED based on an electroplating technology is characterized by comprising a Micro-LED chip and a seventh substrate, wherein the Micro-LED chip is positioned on the seventh substrate; the Micro-LED chip comprises a dielectric film, an n-GaN layer, an MQW layer, a p-GaN layer and a reflector electrode from top to bottom, wherein the reflector electrode is connected with a substrate seven; the widths of the n-GaN layer, the MQW layer and the p-GaN layer are equal, and the width of the reflector electrode is equal to that of the substrate seven; the width of the dielectric film is smaller than that of the n-GaN layer, and the table top can be exposed from the two sides of the n-GaN layer; the width of the reflector electrode is larger than that of the n-GaN layer, the MQW layer and the p-GaN layer, the table top can leak out of the two sides of the reflector electrode, and the n-GaN layer, the MQW layer and the p-GaN layer can leak out of the two side walls; a passivation layer is arranged on the table top and the side wall; and an ohmic contact metal layer is arranged on the passivation layer on one side, and the top of the ohmic contact metal layer is provided with a table top with a part leaking out of the n-GaN layer.
2. The electroplating-technology-based GaN-based vertical-structure microcavity Micro-LED according to claim 1, wherein the size of the Micro-LED chip is 10-1000 μm; the reflector electrode is Ni/Ag/Pt/Au, and is also a metal electrode.
3. A method for preparing a GaN-based vertical structure microcavity Micro-LED based on electroplating technology according to claim 1 or 2, comprising the steps of:
(1) growing a u-GaN layer, an n-GaN layer, an MQW layer and a p-GaN layer on the first substrate in sequence to obtain an LED epitaxial material;
(2) preparing a reflector electrode on the surface of the p-GaN layer in the step (1);
(3) preparing a seventh substrate on the electrode surface of the reflector obtained in the step (2);
(4) removing the first substrate of the structure obtained in the step (3);
(5) removing the u-GaN layer and part of the n-GaN layer of the structure obtained in the step (4) to the designed cavity length by dry etching;
(6) etching the structure obtained in the step (5) to form a chip mesa 2 to a reflector;
(7) preparing a passivation layer on the upper surface of the chip table board 2 obtained in the step (6) and on the side walls of the n-GaN layer, the MQW layer and the p-GaN layer, and preparing the passivation layer on the upper surface of the n-GaN layer except two sides of the position of the dielectric film, wherein the prepared passivation layer is in a right-angled Z shape;
(8) preparing ohmic contact metal on the passivation layer on one side of the structure obtained in the step (7), wherein part of the upper part of the ohmic contact metal is in contact with the upper surface of the n-GaN layer;
(9) and (5) depositing a dielectric film on the surface of the n-GaN layer of the Micro-LED chip with the vertical structure obtained in the step (8), and cutting to obtain the Micro-LED chip with the GaN-based vertical structure.
4. The method for preparing a GaN-based vertical Micro-cavity LED based on an electroplating technology according to claim 3, wherein in the step (1), the substrate I is one of gem, silicon carbide and gallium nitride, the thickness of the u-GaN layer is 4-6 μm, the thickness of the n-GaN layer is 4-6 μm, the thickness of the MQW layer is 50-500 nm, and the thickness of the p-GaN layer is 50-200 nm; the MQW layer is formed by InGaN layers and GaN layers in an alternating cycle mode, wherein the thickness of the InGaN layer is 2nm, and the thickness of the GaN layer is 10 nm; the preparation method of the long u-GaN layer, the n-GaN layer, the MQW layer and the p-GaN layer is MOCVD growth.
5. The method for preparing the GaN-based vertical Micro-cavity LED based on the electroplating technology according to claim 3, wherein in the step (2), the preparation method of the reflector electrode is electron beam evaporation, and the deposition temperature is 110-130 ℃; the mirror electrode was Ni/Ag/Pt/Au, and the thickness of the mirror electrode was 0.5/200/50/200 nm.
6. The method for preparing the GaN-based vertical structure microcavity Micro-LED based on the electroplating technology according to claim 3, wherein in the steps (3) and (4), the substrate seven is prepared by one of electroplating and bonding; the material of the substrate seven is one of Cu, Ni and Si, and the thickness of the substrate seven is 70-100 mu m; the first substrate removing method is one of laser stripping, grinding and polishing and wet etching.
7. The electroplating-technology-based GaN-based vertical-structure microcavity Micro-LED manufacturing method according to claim 3, wherein in the step (5), the thickness of the etched n-GaN layer is 50-500 nm, and the designed cavity length is an integral multiple of the cavity length.
8. The method for preparing a Micro-LED with GaN-based vertical Micro-cavity structure based on electroplating technology as claimed in claim 3, wherein in step (6), after etching, the width of the reflector layer is larger than that of the u-GaN layer, the n-GaN layer, the MQW layer and the p-GaN layer, the u-GaN layer, the n-GaN layer, the MQW layer and the p-GaN layer are located in the middle of the reflector layer, and the two side leaking parts are the chip mesa 2.
9. The method for preparing the GaN-based vertical Micro-cavity LED based on electroplating technology according to claim 3, wherein in the steps (7) and (8), the passivation layer is SiO2、Ta2O5In one of the above methods, the preparation method of the passivation layer is a chemical deposition method, and the thickness of the passivation layer is 200-250 nm; the ohmic contact metal is Cr/Al/Ti/Au; the preparation method is an electron beam evaporation method; the deposition temperature is 15-25 ℃.
10. The method for preparing the Micro-LED with GaN-based vertical Micro-cavity structure based on electroplating technology as claimed in claim 3, wherein in step (9), the dielectric film is SiO2、Si3N4、TiO2The preparation method is PECVD deposition, and the thickness of the dielectric film is 251-264 nm.
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