Display substrate, preparation method and display device

Abstract

The invention relates to a display substrate, a preparation method and a display device. The display substrate comprises a substrate body and a plurality of light-emitting units located on the substrate body, and further comprises cavities formed in the peripheral sides of the light-emitting units, and the height of the cavities in the light-emitting direction is larger than or equal to the height of the light-emitting units in the light-emitting direction. The cavity is formed in the peripheral side of the light-emitting unit, that is, the light-emitting unit is located in the cavity, and in the etching process, laser does not irradiate the side wall of the light-emitting unit, but irradiates the side, away from the light-emitting unit, of the wall part of the cavity. Therefore, the side wall defects of the light-emitting units are few, and the light-emitting efficiency of the display substrate is improved.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and particularly to a display substrate, a preparation method and a display device. Background Art

[0002] With the development of display technologies, micro light emitting diode displays (Micro Light Emitting Diode Display, abbreviated as Micro LED) have the advantages of high brightness, long lifespan, low power consumption, fast response speed, etc.

[0003] However, due to the small size of Micro LEDs, the ratio of the sidewall area to the mesa area of the Micro LED light-emitting chip is relatively large. And more defects are generated on the sidewalls of the Micro LED light-emitting chip during the etching process, and these defects trigger non-radiative recombination, resulting in low light extraction efficiency of the Micro LED display device. Summary of the Invention

[0004] The present application aims to provide a display substrate, a preparation method and a display device to solve the technical problem of low light extraction efficiency of Micro LED display devices in related technologies.

[0005] In a first aspect, an embodiment of the present application provides a display substrate, including a substrate and a plurality of light-emitting units located on the substrate, and further including a cavity provided on the periphery of the light-emitting units, where the height of the cavity along the light-emitting direction is greater than or equal to the height of the light-emitting units along the light-emitting direction.

[0006] In a possible implementation manner, the wall of the cavity includes a non-light-transmitting organic layer.

[0007] In a possible implementation manner, the wall of the cavity further includes a metal layer, and the metal layer is coated on the outer side of the organic layer.

[0008] In a possible implementation manner, the wall of the cavity further includes an adhesion layer, and the adhesion layer is located between the organic layer and the metal layer.

[0009] In a possible implementation manner, the light-emitting unit sequentially includes a cathode layer, an N-type semiconductor layer and a P-type semiconductor layer along the light-emitting direction, and the light-emitting unit further includes an anode layer located between the P-type semiconductor layer and the wall of the cavity, where the materials of the P-type semiconductor layer and the N-type semiconductor layer are aluminum gallium indium phosphide.

[0010] In a second aspect, an embodiment of the present application provides a preparation method of a display substrate, applied to the display substrate mentioned in the first aspect, and the preparation method includes:

[0011] Provide a growth substrate.

[0012] Form a sacrificial layer on the growth substrate.

[0013] Form a plurality of cavities on the sacrificial layer.

[0014] Deposit and form a light-emitting unit in the cavity, and the height of the cavity along the light-emitting direction is greater than or equal to the height of the light-emitting unit along the light-emitting direction.

[0015] After stripping off the sacrificial layer, transfer the cavity and the light-emitting unit to the substrate.

[0016] In a possible implementation manner, evaporate and deposit to form a plurality of cavities on the sacrificial layer, including:

[0017] Evaporate and deposit an organic layer on the sacrificial layer to form the wall portions of the plurality of cavities;

[0018] Evaporate and deposit a metal layer on the organic layer.

[0019] In a possible implementation manner, after evaporating and depositing an organic layer on the glass substrate and before evaporating and depositing a metal layer on the organic layer, it further includes:

[0020] Evaporate and deposit an adhesion layer on the organic layer.

[0021] In a possible implementation manner, deposit and form a light-emitting unit in the cavity, including:

[0022] Deposit and form a P-type semiconductor layer and an N-type semiconductor layer in the cavity.

[0023] Evaporate and deposit a cathode layer on the N-type semiconductor layer.

[0024] Evaporate and deposit an anode layer between the P-type semiconductor layer and the wall portion of the cavity.

[0025] Perform rapid thermal annealing on the P-type semiconductor layer, N-type semiconductor layer, cathode layer and anode layer to eliminate defects in the P-type semiconductor layer, N-type semiconductor layer, cathode layer and anode layer.

[0026] In a third aspect, an embodiment of the present application provides a display device, including: the display substrate mentioned in the first aspect.

[0027] An embodiment of the present application provides a display substrate, a preparation method and a display device. The display substrate includes a substrate and a plurality of light-emitting units located on the substrate, and further includes cavities provided on the periphery of the light-emitting units. The height of the cavity along the light-emitting direction is greater than or equal to the height of the light-emitting unit along the light-emitting direction. By providing cavities on the outer periphery of the light-emitting units, the present application avoids the side walls of the light-emitting units from being etched, thereby reducing the defects on the side walls of the light-emitting units, reducing the probability of non-radiative transitions occurring inside the light-emitting units, and improving the light-emitting efficiency of the light-emitting units. Description of the Drawings

[0028] The features, advantages, and technical effects of the exemplary embodiments of the present application will be described below with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals. The drawings are not drawn to actual scale and are only used to illustrate the relative positional relationship. The layer thickness of some parts is exaggerated in the drawing for ease of understanding, and the layer thickness in the drawings does not represent the proportional relationship of the actual layer thickness.

[0029] Figure 1 A schematic structural diagram of a display substrate provided in the first embodiment of the present application is shown;

[0030] Figure 2 A schematic flowchart of a method for manufacturing a display substrate provided in the second embodiment of the present application is shown;

[0031] Figure 3 A schematic structural diagram of a display device provided in the third embodiment of the present application is shown.

[0032] Reference numerals:

[0033] 100, display substrate;

[0034] 10, substrate;

[0035] 20, light-emitting unit; 21, cathode layer; 22, N-type semiconductor layer; 23, quantum well; 24, P-type semiconductor layer; 25, anode layer;

[0036] 30, cavity; 31, wall portion; 311, organic layer; 312, metal layer; 313, adhesion layer;

[0037] 200, display device. Detailed implementation manners

[0038] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present application by showing examples of the present application. In the drawings and the following description, at least some of the well-known structures and technologies are not shown in order to avoid unnecessarily obscuring the present application; and, for clarity, the dimensions of the regional structures may be exaggerated. In addition, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0039] Due to the small size of Micro LEDs, the ratio of the sidewall area to the mesa area of the Micro LED light-emitting chip is relatively large. During the etching process of the sidewalls of the Micro LED light-emitting chip, more defects are generated, and these defects trigger non-radiative recombination, resulting in a low light extraction efficiency of the Micro LED display device.

[0040] In view of this, the embodiments of the present application provide a display substrate, a manufacturing method, and a display device. By providing a cavity on the outer peripheral side of the light-emitting unit, the sidewalls of the light-emitting unit are prevented from being etched, thereby reducing the defects on the sidewalls of the light-emitting unit, reducing the probability of non-radiative transitions occurring inside the light-emitting unit, and improving the light extraction efficiency of the light-emitting unit.

[0041] The following describes the specific structures and processes of the display substrate, the manufacturing method, and the display device provided by each embodiment of the present application with reference to the accompanying drawings.

[0042] First Embodiment

[0043] Figure 1 FIG. shows a schematic structural diagram of a display substrate 100 provided by the first embodiment of the present application.

[0044] As Figure 1 shown, the first embodiment of the present application provides a display substrate 100, including a substrate 10 and a plurality of light-emitting units 20 located on the substrate 10, and further including a cavity 30 provided on the peripheral side of the light-emitting units 20. The height of the cavity 30 along the light extraction direction is greater than or equal to the height of the light-emitting units 20 along the light extraction direction.

[0045] In this embodiment, the light-emitting unit 20 may be a quantum dot light-emitting diode (Quantum Dot LightEmitting Diodes, abbreviated as QLED). Among them, quantum dots are an important type of low-dimensional semiconductor material, and the sizes in its three dimensions are not greater than twice the exciton Bohr radius of the corresponding semiconductor material. Quantum dots are generally spherical or quasi-spherical, and their diameters are usually between 2 and 20 nm. Common quantum dots are composed of IV, II-VI, IV-VI, or III-V elements. Specific examples include silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots, and indium arsenide quantum dots, etc. When stimulated by light or electricity, quantum dots will emit colored light, and the color of the light is determined by the composition material, size, and shape of the quantum dots. Therefore, high-peak pure color light from red to blue can be obtained by changing the morphology of the quantum dots (for example, changing the particle size of the quantum dots).

[0046] In the related art, when preparing the display substrate 100, etching the light-emitting unit 20 easily causes more defects on the sidewalls of the light-emitting unit 20. These defects cause non-radiative transitions inside the light-emitting unit 20, and these non-radiative transitions release energy in the form of heat without generating light, resulting in a low luminous efficiency of the display substrate 100. In this application, by providing a cavity 30 on the peripheral side of the light-emitting unit 20, that is, the light-emitting unit 20 is located in the cavity 30. During the etching process, the laser does not irradiate on the sidewalls of the light-emitting unit 20, but irradiates on the side of the cavity wall 31 facing away from the light-emitting unit 20. Therefore, there are fewer sidewall defects of the light-emitting unit 20 in this application, improving the luminous efficiency of the display substrate 100.

[0047] In some embodiments, the wall portion 31 of the cavity 30 includes a non-transmissive organic layer 311.

[0048] Since the wall portion 31 of the cavity 30 includes a non-transmissive organic layer 311, and the height of the cavity 30 along the light-emitting direction is greater than or equal to the height of the light-emitting unit 20 along the light-emitting direction, the light emitted by the light-emitting unit 20 in each cavity 30 will not enter other cavities 30, avoiding light leakage and color mixing between multiple light-emitting units 20.

[0049] Specifically, the material of the organic layer 311 can be a black matrix or polytetrafluoroethylene, and its thickness is 7-9 μm.

[0050] In some embodiments, the wall portion 31 of the cavity 30 further includes a metal layer 312, and the metal layer 312 is coated on the outer side of the organic layer 311.

[0051] The metal layer 312 can reflect the light emitted by the light-emitting unit 20, increasing the utilization rate of the light emitted by the light-emitting unit 20. Specifically, the thickness of the metal layer 312 is Its material can be any one or more of aluminum, copper, and silver. This application does not specifically limit the material of the metal layer 312.

[0052] In some embodiments, the wall portion 31 of the cavity 30 further includes an adhesion layer 313, and the adhesion layer 313 is located between the organic layer 311 and the metal layer 312.

[0053] The adhesion between the organic layer 311 and the metal layer 312 is poor, that is, it is difficult to firmly adhere to the metal layer 312 outside the organic layer 311. Therefore, in this embodiment, an adhesion layer 313 is provided between the metal layer 312 and the organic layer 311. Specifically, the material of the adhesion layer 313 can be silicon dioxide SiO 2 or silicon nitride SiN x .

[0054] In some embodiments, the light-emitting unit 20 sequentially includes a cathode layer 21, an N-type semiconductor layer 22, and a P-type semiconductor layer 24 along the light-emitting direction. The light-emitting unit 20 further includes an anode layer 25 located between the P-type semiconductor layer 24 and the wall portion 31 of the cavity 30. Among them, the materials of the P-type semiconductor layer 24 and the N-type semiconductor layer 22 are aluminum gallium indium phosphide.

[0055] Specifically, the light-emitting unit 20 further includes a quantum well 23, which is located between the N-type semiconductor layer 22 and the P-type semiconductor layer 24. The cathode layer 21 generates electrons, and the anode layer 25 generates holes. The electrons pass through the N-type semiconductor layer 22 to reach the quantum well 23, and the holes pass through the P-type semiconductor layer 24 to reach the quantum well 23. The electrons and holes in the quantum well 23 recombine and release energy in the form of light, that is, the light-emitting unit 20 realizes light emission.

[0056] Among them, the materials of the P-type semiconductor layer 24 and the N-type semiconductor layer 22 are aluminum gallium indium phosphide (AlGaInP). AlGaInP is a direct bandgap semiconductor material, and with the change of the material composition, the radiation wavelength range is from green light to red light.

[0057] The light-emitting chip in this application adopts a flip-chip process. The epitaxial growth of the light-emitting chip is carried out on a sapphire growth substrate, and then the light-emitting chip and the cavity 30 are transferred to the substrate 10 in a large quantity.

[0058] AlGaInP has good lattice matching with the sapphire growth substrate, and a high-quality AlGaInP epitaxial layer can be prepared. The performance of the prepared red light chip can also be greatly improved, and the external quantum efficiency of the device can reach more than 50%.

[0059] In this embodiment, by arranging the cavity 30 on the peripheral side of the light-emitting unit 20, that is, the light-emitting unit 20 is located in the cavity 30. During the etching process, the laser does not irradiate on the side wall of the light-emitting unit 20, but irradiates on the side of the wall portion 31 of the cavity 30 facing away from the light-emitting unit 20. Therefore, there are fewer side wall defects in the light-emitting unit 20 in this application, which improves the light-emitting efficiency of the display substrate 100. In this application, by arranging the non-transparent wall portion 31 of the cavity 30, the situation of light leakage and color mixing between multiple light-emitting units 20 is avoided; by arranging the metal layer 312 outside the organic layer 311, the metal layer 312 reflects the light emitted by the light-emitting unit 20, increasing the utilization rate of the light emitted by the light-emitting unit 20; by arranging the adhesion layer 313 between the organic layer 311 and the metal layer 312, the metal layer 312 and the organic layer 311 are firmly bonded; it is worth noting that the materials of the P-type semiconductor layer 24 and the N-type semiconductor layer 22 are aluminum gallium indium phosphide, which improves the external quantum efficiency of the light-emitting unit 20.

[0060] Second Embodiment

[0061] Figure 2Schematic flow chart showing a method for manufacturing a display substrate provided in the second embodiment of the present application.

[0062] As Figure 2 shown, the second embodiment of the present application provides a method for manufacturing a display substrate, which is applied to the display substrate mentioned in the first embodiment. The manufacturing method includes:

[0063] Step S101: Provide a growth substrate.

[0064] In this embodiment, the display substrate adopts a flip-chip process. Among them, the growth substrate is a sapphire substrate.

[0065] Step S102: Form a sacrificial layer on the growth substrate.

[0066] Among them, the material of the sacrificial layer is gallium nitride (GaN).

[0067] Step S103: Form a plurality of cavities on the sacrificial layer.

[0068] The cavities are formed by physical vapor deposition.

[0069] Step S104: Deposit and form a light-emitting unit in the cavity. The height of the cavity along the light-emitting direction is greater than or equal to the height of the light-emitting unit along the light-emitting direction.

[0070] Specifically, a light-emitting unit is formed in the cavity by a novel epitaxial growth technique.

[0071] Step S105: After stripping off the sacrificial layer, transfer the cavity and the light-emitting unit to a substrate.

[0072] In this embodiment, by providing a growth substrate, a sacrificial layer is formed on the growth substrate; a plurality of cavities are formed on the sacrificial layer; a light-emitting unit is deposited and formed in the cavity, and the height of the cavity along the light-emitting direction is greater than or equal to the height of the light-emitting unit along the light-emitting direction; after stripping off the sacrificial layer, the cavity and the light-emitting unit are transferred to a substrate. The light-emitting unit is located in the cavity. During the etching process, the laser does not irradiate on the side wall of the light-emitting unit, but irradiates on the side of the cavity wall away from the light-emitting unit. Therefore, there are fewer side wall defects in the light-emitting unit in the present application, and the light-emitting efficiency of the display substrate is improved.

[0073] In some embodiments, step S103 evaporates and deposits to form a plurality of cavities on the sacrificial layer, which specifically includes:

[0074] Step S1031: Evaporate and deposit an organic layer on the sacrificial layer to form the wall parts of a plurality of cavities.

[0075] Specifically, since the wall of the cavity includes a non-translucent organic layer, the light emitted by the light-emitting units in each cavity will not enter other cavities, avoiding light leakage and color mixing between multiple light-emitting units. After depositing the organic layer, several cavities are formed through a mask process.

[0076] Step S1033: Evaporate a metal layer on the organic layer.

[0077] The metal layer can reflect the light emitted by the light-emitting units, increasing the utilization rate of the light emitted by the light-emitting units.

[0078] In some embodiments, between step S1031: Evaporate an organic layer on the sacrificial layer to form the walls of multiple cavities; and step S1033: Evaporate a metal layer on the organic layer, it further includes:

[0079] Step S1032: Evaporate an adhesion layer on the organic layer.

[0080] The adhesion between the organic layer and the metal layer is poor, that is, it is difficult to firmly adhere to the metal layer outside the organic layer. Therefore, in this embodiment, an adhesion layer is provided between the metal layer and the organic layer. Specifically, the material of the adhesion layer can be silicon dioxide SiO2 or silicon nitride SiNx which has good affinity with both organic substances and metals.

[0081] In some embodiments, step S104: Deposit and form a light-emitting unit in the cavity, specifically including:

[0082] Step S1041: Deposit and form a P-type semiconductor layer and an N-type semiconductor layer in the cavity.

[0083] Step S1042: Evaporate a cathode layer on the N-type semiconductor layer.

[0084] Step S1043: Evaporate an anode layer between the P-type semiconductor layer and the wall of the cavity.

[0085] Step S1044: Perform rapid thermal annealing on the P-type semiconductor layer, N-type semiconductor layer, cathode layer, and anode layer to eliminate defects in the P-type semiconductor layer, N-type semiconductor layer, cathode layer, and anode layer.

[0086] In some embodiments, the anode layer and the cathode layer have a reflective effect. After the light-emitting unit is flip-chip bonded, the photons emitted from the multiple quantum wells will scatter in all directions. When scattered to the P-type semiconductor layer and the N-type semiconductor layer, part of the light is emitted towards the anode layer and the cathode layer, and this part of the light cannot be utilized, resulting in losses. Therefore, after depositing the P-type semiconductor layer and the N-type semiconductor layer, a cathode layer is evaporated on the N-type semiconductor layer, and an anode layer is evaporated between the P-type semiconductor layer and the wall of the cavity to improve the light utilization rate.

[0087] Specifically, since the materials of the P-type semiconductor layer and the N-type semiconductor layer are aluminum gallium indium phosphide (AlGaInP), and the components of aluminum (Al), gallium (Ga), indium (In), and phosphorus (P) are different, the cathode layer and the anode layer cannot be evaporated simultaneously. The cathode layer with a thickness of 200 - 250 nm is evaporated above the P-type semiconductor layer by means of electron beam evaporation, and then an anode layer with a thickness of 200 - 250 nm is evaporated on the upper surface of the P-type semiconductor layer by electron beam evaporation. After the evaporation of the cathode layer and the anode layer is completed, a rapid thermal processing (RTP) process is carried out to restore the crystal structure and eliminate defects. At the same time, donor and acceptor impurities can be activated, so that an ohmic contact is formed between the N-type semiconductor layer and the cathode layer, and rapid oxidation can be prevented, improving the stability of the light-emitting unit. Among them, the annealing temperature reaches 300 - 350 °C, and the time is about 1 h.

[0088] In this embodiment, by providing a growth substrate, a sacrificial layer is formed on the growth substrate; a plurality of cavities are formed on the sacrificial layer; a light-emitting unit is deposited and formed in the cavities, and the height of the cavities along the light-emitting direction is greater than or equal to the height of the light-emitting unit along the light-emitting direction; after the sacrificial layer is peeled off, the cavities and the light-emitting unit are transferred to a substrate. The light-emitting unit is located in the cavities. During the etching process, the laser does not irradiate on the side walls of the light-emitting unit, but irradiates on the side of the cavity wall away from the light-emitting unit. Therefore, there are fewer side wall defects in the light-emitting unit of the present application, improving the light-emitting efficiency of the display substrate. Among them, the cavity wall includes an organic layer and a metal layer, enabling the cavity wall to reflect light and improving the light utilization rate; an adhesion layer is also evaporated between the metal layer and the organic layer to improve the stability of the cavity.

[0089] Third Embodiment

[0090] Figure 3 The structural schematic diagram of a display device 200 provided by the third embodiment of the present application is shown.

[0091] As Figure 3 shown, the third embodiment of the present application provides a display device 200, including: the display substrate 100 mentioned in the first embodiment.

[0092] It should be easily understood that the terms "on...", "above...", and "over..." in the present application should be interpreted in the broadest manner, so that "on..." not only means "directly on something", but also includes the meaning of "on something" with intermediate features or layers therebetween, and "above..." or "over..." not only includes the meaning of "above" or "over" something, but also can include the meaning of "above" or "over" something without intermediate features or layers therebetween (i.e., directly on something).

[0093] As used herein, the term "layer" may refer to a portion of a material that includes a region having a certain thickness. A layer may extend over the entire underlying or overlying structure, or may have a smaller extent than the underlying or overlying structure. In addition, a layer may be a region of a homogeneous or heterogeneous continuous structure, the thickness of which is less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of the continuous structure or between any pair of lateral planes at the top and bottom surfaces. A layer may extend laterally, vertically, and / or along a tapered surface. A substrate may be a layer, may include one or more layers therein, and / or may have one or more layers located thereon, thereabove, and / or therebelow. A layer may include multiple layers. For example, an interconnect layer may include one or more conductors and contact layers (in which contacts, interconnect lines, and / or vias are formed) and one or more dielectric layers.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A display substrate, comprising a base substrate and a plurality of light-emitting units located on the base substrate, characterized in that: It also includes a cavity arranged on the periphery of the light emitting unit, and the height of the cavity along the light emitting direction is greater than or equal to the height of the light emitting unit along the light emitting direction.

2. The display substrate according to claim 1, characterized in that: The wall of the cavity includes a non-light-transmitting organic layer.

3. The display substrate according to claim 2, characterized in that: The wall of the cavity further includes a metal layer, and the metal layer is coated on the outer side of the organic layer.

4. The display substrate according to claim 3, characterized in that: The wall of the cavity further includes an adhesion layer, and the adhesion layer is located between the organic layer and the metal layer.

5. The display substrate according to claim 4, characterized in that: The light-emitting unit includes a cathode layer, an N-type semiconductor layer and a P-type semiconductor layer in sequence along the light emitting direction, and the light-emitting unit also includes an anode layer located between the P-type semiconductor layer and the wall of the cavity, wherein the material of the P-type semiconductor layer and the N-type semiconductor layer is aluminum gallium indium phosphorus.

6. A method for preparing a display substrate, applied to the display substrate according to any one of claims 1 to 5, characterized in that: The preparation method comprises: providing a growth substrate; forming a sacrificial layer on the growth substrate; forming a plurality of cavities on the sacrificial layer; A light-emitting unit is deposited in the cavity, wherein the height of the cavity along the light-emitting direction is greater than or equal to the height of the light-emitting unit along the light-emitting direction; After the sacrificial layer is peeled off, the cavity and the light-emitting unit are transferred to a substrate.

7. The method for preparing a display substrate according to claim 6, characterized in that: The step of forming a plurality of cavities by evaporating on the sacrificial layer comprises: Vapor-depositing an organic layer on the sacrificial layer to form a plurality of wall portions of the cavity; A metal layer is evaporated on the organic layer.

8. The method for preparing a display substrate according to claim 7, characterized in that: After the organic layer is evaporated on the glass substrate and before the metal layer is evaporated on the organic layer, the method further includes: An adhesion layer is evaporated on the organic layer.

9. The method for preparing a display substrate according to claim 8, characterized in that: The step of depositing a light-emitting unit in the cavity comprises: Depositing a P-type semiconductor layer and an N-type semiconductor layer in the cavity; Vapor depositing a cathode layer on the N-type semiconductor layer; Vapor depositing an anode layer between the P-type semiconductor layer and the wall of the cavity; The P-type semiconductor layer, the N-type semiconductor layer, the cathode layer and the anode layer are subjected to rapid thermal annealing to eliminate defects in the P-type semiconductor layer, the N-type semiconductor layer, the cathode layer and the anode layer.

10. A display device, characterized in that: include: A display substrate as claimed in any one of claims 1 to 5.

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