Light-emitting unit and preparation method thereof, light-emitting panel and display device

Abstract

The embodiment of the invention provides a light-emitting unit and a preparation method thereof, a light-emitting panel and a display device. The light-emitting unit comprises a first light-emitting body, a first DBR, a second light-emitting body, a second DBR and a third light-emitting body which are sequentially stacked in the first direction, and light emitted by the first light-emitting body, the second light-emitting body and the third light-emitting body is different in color. The first DBR is configured to allow light rays emitted by the first luminous body to pass through and reflect at least part of light rays emitted by the second luminous body and at least part of light rays emitted by the third luminous body; the second DBR is configured to allow light emitted by the first light emitting body and the second light emitting body to pass through and reflect at least part of light emitted by the third light emitting body. The light extraction efficiency of the light emitting unit is improved, the pixel area is reduced, and the pixel density can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a light-emitting unit and a preparation method thereof, a light-emitting panel and a display device. Background Art

[0002] Light-emitting diodes (LEDs) can include sub-millimeter light-emitting diodes (Mini Light Emitting Diode, referred to as Mini LED) and micro light-emitting diodes (Micro Light Emitting Diode, referred to as Micro LED). The size of MicroLED chips is usually a few microns to tens of microns, and has a very broad application scenario in wearable devices, augmented reality (AR), virtual reality (VR) and other fields.

[0003] The small size and high brightness of LEDs are crucial for near-eye and / or outdoor applications. However, it is difficult to achieve full-color LED displays using existing technologies. For example, if you want to achieve LED color display, you need to extract red LEDs, green LEDs, and blue LEDs from their respective epitaxial wafers, then accurately prepare LED chips of corresponding colors, and then assemble the R-LED chips, G-LED chips, and B-LED chips horizontally. Although this technology has made great improvements in resolution, yield, etc., it is still impossible to produce a color LED display with a high pixel density. In addition, a color LED display with this structure will cause optical loss and loss of color sharpness and richness. Summary of the invention

[0004] The embodiments of the present disclosure provide a light-emitting unit and a method for manufacturing the same, a light-emitting panel and a display device to solve or alleviate one or more technical problems in the prior art.

[0005] As a first aspect of an embodiment of the present disclosure, an embodiment of the present disclosure provides a light-emitting unit, including a first light-emitting body, a second light-emitting body, and a third light-emitting body stacked in sequence along a first direction, and also including a first distributed Bragg reflection layer and a second distributed Bragg reflection layer, the first distributed Bragg reflection layer is located between the first light-emitting body and the second light-emitting body, the second distributed Bragg reflection layer is located between the second light-emitting body and the third light-emitting body, and the colors of light emitted by the first light-emitting body, the second light-emitting body, and the third light-emitting body are different;

[0006] The first distributed Bragg reflection layer is configured to allow light emitted by the first light source to pass through, and to reflect at least part of the light emitted by the second light source and at least part of the light emitted by the third light source; the second distributed Bragg reflection layer is configured to allow light emitted by the first light source and the second light source to pass through, and to reflect at least part of the light emitted by the third light source.

[0007] In some embodiments,

[0008] The first distributed Bragg reflector layer and / or the second distributed Bragg reflector layer comprises first dielectric layers and second dielectric layers which are alternately stacked in sequence;

[0009] The first dielectric layer includes gallium nitride, and the refractive index of the first dielectric layer ranges from 2.6 to 2.8; and / or the second dielectric layer includes nanoporous gallium nitride, and the refractive index of the second dielectric layer ranges from 1.6 to 1.8.

[0010] In some embodiments,

[0011] The refractive index of the first dielectric layer is 2.7, and / or the refractive index of the second dielectric layer is 1.7.

[0012] In some embodiments, the stacking period number of the first distributed Bragg reflector layer is 4; and / or the stacking period number of the second distributed Bragg reflector layer is 5.

[0013] In some embodiments,

[0014] In the first distributed Bragg reflector layer, the thickness of the first dielectric layer ranges from 42 nm to 45 nm, and the thickness of the second dielectric layer ranges from 68.5 nm to 70.5 nm; and / or,

[0015] In the second distributed Bragg reflector layer, the thickness of the first dielectric layer ranges from 58 nm to 61 nm, and the thickness of the second dielectric layer ranges from 66 nm to 68.5 nm.

[0016] In some embodiments,

[0017] In the first distributed Bragg reflector layer, the thickness of the first dielectric layer is 43.5 nm, and the thickness of the second dielectric layer is 69.1 nm; and / or,

[0018] In the second distributed Bragg reflector layer, the thickness of the first dielectric layer is 59.3 nm, and the thickness of the second dielectric layer is in the range of 67.2 nm.

[0019] In some embodiments, the reflection stop band center wavelength of the first distributed Bragg reflector layer ranges from 460 nm to 480 nm, and / or the reflection stop band center wavelength of the second distributed Bragg reflector layer ranges from 400 nm to 420 nm.

[0020] In some embodiments, the reflection stop band center wavelength of the first distributed Bragg reflector layer is 470 nm, and / or the reflection stop band center wavelength of the second distributed Bragg reflector layer is 403 nm.

[0021] In some embodiments,

[0022] In the first distributed Bragg reflection layer, the porosity of the second dielectric layer ranges from 65% to 75%; in the second distributed Bragg reflection layer, the porosity of the second dielectric layer ranges from 65% to 75%.

[0023] In some embodiments, in the first distributed Bragg reflector layer, the porosity of the second dielectric layer is in the range of 70%; in the second distributed Bragg reflector layer, the porosity of the second dielectric layer is in the range of 70%.

[0024] In some embodiments, the first light emitter, the second light emitter and the third light emitter each include a first semiconductor layer, a corresponding active layer and a second semiconductor layer arranged in a stacked manner;

[0025] The first light-emitting body is configured to emit red light, the second light-emitting body is configured to emit green light, and the third light-emitting body is configured to emit blue light.

[0026] In some embodiments, it also includes a first electrode and a second electrode, a third electrode and a fourth electrode, and a fifth electrode and a sixth electrode. The first electrode and the second electrode are both connected to the first light-emitting body, and the first electrode and the second electrode are located on the side of the first light-emitting body facing the light-emitting unit; the third electrode and the fourth electrode are both connected to the second light-emitting body, and the third electrode and the fourth electrode are located on the side of the second light-emitting body facing the light-emitting unit; the fifth electrode and the sixth electrode are both connected to the third light-emitting body, and the fifth electrode and the sixth electrode are located on the side of the third light-emitting body facing the light-emitting unit.

[0027] As a second aspect of the embodiment of the present disclosure, the embodiment of the present disclosure provides a method for preparing a light-emitting unit, comprising:

[0028] preparing a first luminous body;

[0029] Prepare a first structure, wherein the first structure includes a first distributed Bragg reflection layer and a second light emitting body arranged in a stacked manner;

[0030] preparing a second structure, wherein the second structure comprises a second distributed Bragg reflection layer and a third light emitting body arranged in a stacked manner;

[0031] The first structure is stacked on a side of the first light-emitting body facing the light-emitting unit, so that the first distributed Bragg reflection layer is located between the first light-emitting body and the second light-emitting body;

[0032] The second structure is stacked on a side of the second light emitting body facing the light emitting side of the light emitting unit, so that the second distributed Bragg reflection layer is located between the second light emitting body and the third light emitting body;

[0033] Among them, the colors of light emitted by the first light emitter, the second light emitter and the third light emitter are different; the first distributed Bragg reflection layer is configured to allow the light emitted by the first light emitter to pass through, and reflect at least part of the light emitted by the second light emitter and at least part of the light emitted by the third light emitter; the second distributed Bragg reflection layer is configured to allow the light emitted by the first light emitter and the second light emitter to pass through, and reflect at least part of the light emitted by the third light emitter.

[0034] In some embodiments, preparing the first structure or preparing the second structure includes:

[0035] A first heavily doped gallium nitride layer is grown on one side of the substrate, and the doping concentration of the first heavily doped gallium nitride layer ranges from 4.6 to 10 19 / cm 3 ~5.0*10 19 / cm 3 ;

[0036] A periodic stacking structure is formed on the side of the first heavily doped gallium nitride layer facing away from the substrate, wherein the periodic stacking structure comprises a first dielectric layer and a first doping concentration gallium nitride layer alternately stacked in sequence, wherein the first dielectric layer comprises gallium nitride, and the doping concentration of the first doping concentration gallium nitride layer ranges from 0.9 to 10 19 / cm 3 ~1.2*10 19 / cm 3 ;

[0037] A first semiconductor layer, a corresponding active layer, and a second semiconductor layer are sequentially grown on a side of the periodic stacking structure facing away from the substrate, wherein the light emitting body comprises the first semiconductor layer, the corresponding active layer, and the second semiconductor layer;

[0038] The first structure or the second structure is etched to form a table exposing the first heavily doped gallium nitride layer, and the first heavily doped gallium nitride layer and the first doping concentration gallium nitride layer are etched by electrochemical etching, so that the first heavily doped gallium nitride layer forms a porous structure gallium nitride layer with a first porosity and is peeled off from the periodic stacking structure, and the first doping concentration gallium nitride layer forms a second dielectric layer with a second porosity, the second dielectric layer includes nanoporous gallium nitride, and the second porosity ranges from 65% to 75%.

[0039] In some embodiments, during the electrochemical etching process, the bias voltage of the anode is adjusted from 10 V to 15 V, and the electrolyte includes sodium nitrate or nitric acid.

[0040] In some embodiments, the first luminous body includes a first semiconductor layer, a first active layer, and a second semiconductor layer stacked in sequence, and the light-emitting unit also includes a first electrode and a second electrode, and the first electrode and the second electrode are both connected to the first luminous body;

[0041] The first structure is stacked on one side of the first light-emitting body facing the light-emitting unit, comprising:

[0042] Transferring the first structure to a side of the first light-emitting body facing the light-emitting side of the light-emitting unit, so that the first distributed Bragg reflector is located between the first light-emitting body and the second light-emitting body, and the first structure is provided with a first notch for avoiding the first electrode and a second notch for avoiding the second electrode;

[0043] Etching the second semiconductor layer and the corresponding active layer in the second light emitting body to form a second mesa, wherein the second mesa exposes the first semiconductor layer in the second light emitting body;

[0044] forming a third electrode and a fourth electrode, wherein the third electrode is coupled to the first semiconductor layer in the second light emitting body, and the fourth electrode is coupled to the second semiconductor layer in the second light emitting body;

[0045] In some embodiments, the second structure is stacked on a side of the second light-emitting body facing the light-emitting side of the light-emitting unit, including:

[0046] The second structure is transferred to the side of the second light-emitting body facing the light-emitting side of the light-emitting unit, so that the second distributed Bragg reflector is located between the second light-emitting body and the third light-emitting body, and the second structure is provided with a third notch for avoiding the first electrode and the third electrode and a fourth notch for avoiding the second electrode and the fourth electrode;

[0047] Etching the second semiconductor layer and the corresponding active layer in the third light emitting body to form a third mesa, wherein the third mesa exposes the first semiconductor layer in the third light emitting body;

[0048] A fifth electrode and a sixth electrode are formed, the fifth electrode is coupled to the first semiconductor layer in the third light emitting body, and the sixth electrode is coupled to the second semiconductor layer in the third light emitting body.

[0049] As a third aspect of an embodiment of the present disclosure, an embodiment of the present disclosure provides a light-emitting panel, comprising a driving backplane and any light-emitting unit of the present disclosure.

[0050] As a fourth aspect of the embodiments of the present disclosure, the embodiments of the present disclosure provide a display device, including the light-emitting panel in the embodiments of the present disclosure.

[0051] The technical solution of the embodiment of the present disclosure is to stack the first light-emitting body, the second light-emitting body and the third light-emitting body which respectively emit three different colors of light along the first direction, and set the first DBR between the first light-emitting body and the second light-emitting body, and set the second DBR between the second light-emitting body and the third light-emitting body, so that the light emitted by the first light-emitting body can be emitted from the upper side after passing through the first DBR and the second DBR; the light emitted upward by the second light-emitting body can be emitted from the upper side after passing through the second DBR, and the light emitted downward by the second light-emitting body is also emitted from the upper side after being reflected by the first DBR; the light emitted downward by the third light-emitting body is also emitted from the upper side after being reflected by the second DBR and the first DBR. It can be seen that the light-emitting unit of the present disclosure, by setting the first DBR and the second DBR, greatly reduces the light loss emitted downward by the corresponding light-emitting body, improves the light efficiency of the light-emitting unit emitted from the upper side, effectively enhances the light extraction efficiency, and improves the brightness and optical performance.

[0052] In addition, compared to the light-emitting unit in which the light-emitting bodies of three colors are arranged horizontally, the light-emitting unit of the present disclosure stacks the light-emitting bodies of three different colors in sequence along the first direction, so that the light mixing of the light-emitting unit is more uniform, which effectively solves the problem of uniform light mixing of the light-emitting unit. Moreover, the light-emitting unit is used as a pixel, and the three light-emitting bodies (sub-pixels) of different colors are stacked in sequence along the first direction. Compared with the method of arranging the three sub-pixels horizontally, the area of ​​the pixel is greatly reduced, and the pixel density of the display product can be significantly improved.

[0053] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present disclosure will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments according to the present disclosure and should not be regarded as limiting the scope of the present disclosure.

[0055] Figure 1 This is a schematic diagram of the structure of a light-emitting unit in an embodiment of the present disclosure;

[0056] Figure 2 is a schematic diagram of a first DBR in an embodiment of the present disclosure;

[0057] Figure 3 is a schematic diagram of a second DBR in an embodiment of the present disclosure;

[0058] Figure 4 It is a schematic plan view of the light emitting side of a light emitting unit in one embodiment of the present disclosure;

[0059] Figure 5 is a cross-sectional schematic diagram of a light emitting unit in one embodiment of the present disclosure;

[0060] Figure 6 is a schematic diagram of a process for preparing a first luminous body;

[0061] Figure 7 is a schematic diagram of a process for preparing a first structure;

[0062] Figure 8 is a schematic diagram of the process of preparing the second structure;

[0063] Fig. 9 This is a schematic diagram of the process of transferring the first luminophore during the preparation of the luminescent unit;

[0064] Fig.10 This is a schematic diagram of the process of transferring the first structure during the preparation of the light-emitting unit;

[0065] Fig.11 This is a schematic diagram of the process of transferring the second structure during the preparation of the light-emitting unit.

[0066] Description of reference numerals:

[0067] 11, first luminous body; 12, first structure; 121, second luminous body; 122, first DBR; 13, second structure; 131, third luminous body; 132, second DBR; 31-36, first electrode-sixth electrode;

[0068] 51. a first substrate; 52. a second substrate; 53. a third substrate;

[0069] 61. First semiconductor layer; 62. Second semiconductor layer; 63. Active layer; 64. First gallium nitride layer; 65. First heavily doped gallium nitride layer; 66. Periodic stacking structure; 67. Second gallium nitride layer. DETAILED DESCRIPTION

[0070] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure, and different embodiments may be combined arbitrarily without conflict. Therefore, the drawings and descriptions are considered to be illustrative in nature and not restrictive.

[0071] The related technology proposes an LED with vertically aligned R, G, and B sub-pixels, which physically stacks the R-LED chip, G-LED chip, and B-LED chip. The color LED chips of this structure have aligned light paths and the emitted light is naturally mixed.

[0072] Although vertically stacked color LED chips have improved optical loss, the brightness is reduced due to the serious loss of light emitted downward, and their optical performance cannot meet the requirements. In the related art, metal coating is used as the bottom reflector of nitride LED, but the metal coating reflector is opaque, so the metal coating reflector cannot be applied to stacked LED chips. As a result, low light extraction is still the main bottleneck limiting the optical performance of vertically stacked LED chips.

[0073] In order to solve some problems in the prior art or related art, an embodiment of the present disclosure provides a light emitting unit.

[0074] Figure 1 FIG. 1 is a schematic diagram of the structure of a light emitting unit in an embodiment of the present disclosure. Figure 1 As shown, the light-emitting unit includes a first light-emitting body 11, a second light-emitting body 121, and a third light-emitting body 131 stacked in sequence along a first direction, and also includes a first distributed Bragg reflector (distributed Bragg reflector, DBR layer) 122 and a second distributed Bragg reflector (second DBR) 132. The first distributed Bragg reflector 122 is located between the first light-emitting body 11 and the second light-emitting body 121. The second distributed Bragg reflector 132 is located between the second light-emitting body 121 and the third light-emitting body 131. The colors of the light emitted by the first light-emitting body 11, the second light-emitting body 121, and the third light-emitting body 131 are different. For example, the first light-emitting body 11 can emit a first color light, the second light-emitting body 121 can emit a second color light, and the third light-emitting body 131 can emit a third color light.

[0075] The first distributed Bragg reflector 122 is configured to allow the light emitted by the first light emitter 11 to pass through, and to reflect at least part of the light emitted by the second light emitter 121 and at least part of the light emitted by the third light emitter 131. The second distributed Bragg reflector 132 is configured to allow the light emitted by the first light emitter 11 and the second light emitter 121 to pass through, and to reflect at least part of the light emitted by the third light emitter 131.

[0076] In the light-emitting unit of the embodiment of the present disclosure, the first light-emitting body 11, the second light-emitting body 121 and the third light-emitting body 131 which respectively emit three different colors of light are stacked along the first direction, and the first DBR 122 is arranged between the first light-emitting body 11 and the second light-emitting body 121, and the second DBR 132 is arranged between the second light-emitting body 121 and the third light-emitting body 131, so that the light emitted by the first light-emitting body 11 can be emitted from the upper side after passing through the first DBR 122 and the second DBR 132; the light emitted upward by the second light-emitting body 121 can be emitted from the upper side after passing through the second DBR 132, and the light emitted downward by the second light-emitting body 121 is also emitted from the upper side after being reflected by the first DBR 122; the light emitted downward by the third light-emitting body 131 is also emitted from the upper side after being reflected by the second DBR 132 and the first DBR 122. It can be seen that the light-emitting unit of the present disclosure, by arranging the first DBR 122 and the second DBR 132, which greatly reduces the light loss emitted downward by the corresponding light-emitting body, improves the light efficiency emitted from the upper side of the light-emitting unit, effectively enhances the light extraction efficiency, and improves the brightness and optical performance.

[0077] In addition, compared to a light-emitting unit that arranges light-emitting bodies of three colors in a horizontal direction, the light-emitting unit of the present disclosure stacks light-emitting bodies of three different colors in sequence along a first direction, so that the light mixing of the light-emitting unit is more uniform, which effectively solves the problem of uniform light mixing of the light-emitting unit. Moreover, the light-emitting unit, as a pixel, stacks three light-emitting bodies (sub-pixels) of different colors in sequence along a first direction, which greatly reduces the area of ​​the pixel and can significantly improve the pixel density compared to the method of arranging three sub-pixels in a horizontal direction.

[0078] Figure 2 Schematic diagram of the first DBR in one embodiment of the present disclosure. In one embodiment of the present disclosure, the first DBR 122 may include a first dielectric layer 1221 and a second dielectric layer 1222 that are alternately stacked in sequence. The first dielectric layer 1221 may include gallium nitride, and the refractive index of the first dielectric layer 1221 may range from 2.6 to 2.8. The second dielectric layer 1222 may include nanoporous gallium nitride, and the refractive index of the second dielectric layer 1222 may range from 1.6 to 1.8.

[0079] Figure 3Schematic diagram of the second DBR in one embodiment of the present disclosure. Figure 3 As shown, the second DBR 132 may include a first dielectric layer 1221 and a second dielectric layer 1222 which are alternately stacked in sequence.

[0080] For example, the refractive index of the first dielectric layer 1221 may be 2.6, 2.7 or 2.8. The refractive index of the second dielectric layer 1222 may be 1.6, 1.7 or 1.8. In actual implementation, the refractive index of the first dielectric layer 1221 and the refractive index of the second dielectric layer 1222 may be determined as needed to obtain the first DBR 122 and the second DBR 132.

[0081] The first DBR 122 and the second DBR 132 of the embodiment of the present disclosure are both lattice-matched DBRs, and there is an obvious refractive index contrast between the first dielectric layer 1221 and the second dielectric layer 1222. Therefore, by using the first dielectric layer 1221 and the second dielectric layer 1222 to prepare the first DBR 122 or the second DBR 132, the number of stacking cycles can be reduced, the thickness of the DBR can be reduced, and the epitaxial growth time of the DBR can be reduced, thereby improving productivity.

[0082] It should be noted that, in the present disclosure, the first DBR 122 includes a first dielectric layer 1221 and a second dielectric layer 1222, and the second DBR 132 includes a first dielectric layer 1221 and a second dielectric layer 1222. It should be understood that the material of the first dielectric layer 1221 in the first DBR 122 and the first dielectric layer 1221 in the second DBR 132 may be the same, but the structural dimensions may be different. Similarly, the material of the second dielectric layer 1222 in the first DBR 122 and the second dielectric layer 1222 in the second DBR 132 may be the same, but the structural dimensions may be different.

[0083] DBR can provide high reflectivity in the desired spectral range and can be used to improve the light extraction efficiency of nitride-based LEDs. DBR includes dielectric layers with different refractive indices arranged alternately. The lattice-matched DBR has a significant refractive index contrast between each pair of alternating dielectric layers, which can reduce the number of stacking cycles of the DBR, thereby shortening the epitaxial growth time. In addition, the dielectric layers in the first DBR 122 or the second DBR 132 are lattice-matched, there is no lattice mismatch phenomenon, the strain and dislocation are low, and the formed DBR epitaxy quality is high.

[0084] In one embodiment, the refractive index n of the first dielectric layer 1221 is H is 2.7, and the refractive index n of the second dielectric layer 1222 is L is 1.7.

[0085] According to the volume average theory formula (1), the relationship between the porosity and refractive index of the dielectric layer can be determined.

[0086]

[0087] n GaN is 2.7, n Air is 1, is the porosity;

[0088] Applying formula (1) to the DBR in this disclosure, n GaN is the refractive index n of the second dielectric layer 1222 H , n eff is the refractive index n of the second dielectric layer 1222 L , is the porosity of the second dielectric layer 1222 .

[0089] It can be seen from formula (1) that the greater the porosity of the second dielectric layer 1222, the smaller its refractive index. H is 2.7, n L is 1.7, it can be inferred that the porosity of the second dielectric layer 1222 is about 70%.

[0090] In one embodiment, the first luminous body 11, the second luminous body 121 and the third luminous body 131 can all be LED chips. The first luminous body 11, the second luminous body 121 and the third luminous body 131 all include a first semiconductor layer 61, a corresponding active layer 63 and a second semiconductor layer 62 arranged in a stacked manner. In each luminous body, the film thickness of the first semiconductor layer 61, the corresponding active layer 63 and the second semiconductor layer 62 can be set as needed.

[0091] The first light emitting body 11 is configured to emit red light, the second light emitting body 121 is configured to emit green light, and the third light emitting body 131 is configured to emit blue light.

[0092] In order to allow the first DBR 122 to selectively transmit red light and reflect green light and blue light, the reflection stop band center wavelength of the first DBR 122 is set to a value range of 460nm to 480nm. For example, the reflection stop band center wavelength of the first DBR 122 is 460nm, 470nm or 480nm. For example, the reflection stop band center wavelength of the first DBR 122 is set to 470nm. In this way, it can be ensured that the first DBR 122 has a high reflectivity for light in the range of 430nm to 535nm, and the reflectivity for light of 620nm (red light) is relatively low, allowing light of about 620nm to pass through. Thus, the first DBR 122 allows red light to pass through, and has a higher reflectivity for blue light and green light.

[0093] In order to allow the second DBR 132 to selectively transmit red light and green light and reflect blue light, the value range of the reflection stop band center wavelength of the second DBR 132 is set to 400nm to 420nm. For example, the reflection stop band center wavelength of the second DBR 132 is 400nm, 403nm, 410nm or 420nm. For example, the reflection stop band center wavelength of the second DBR 132 is 403nm. In this way, it can be ensured that the second DBR 132 has a high reflectivity for light in the range of 400nm to 480nm, and has a very low reflectivity for light of 524nm (green light) and 620nm (red light), allowing light of 524nm (green light) and 620nm (red light) to pass through. Therefore, the second DBR 132 allows red light and green light to pass through, and has a higher reflectivity for blue light.

[0094] In the present disclosure, the difference between the refractive index of the first dielectric layer 1221 and the second dielectric layer 1222 is about 1, and the difference between the refractive index of the first dielectric layer 1221 and the second dielectric layer 1222 is relatively large, so a DBR with a reflection bandwidth of about 100 nm can be obtained. For example, the first DBR 122 has a high reflectivity for light in the range of 430 nm to 535 nm, and the reflection bandwidth of the first DBR 122 is about 105 nm; the second DBR 132 has a high reflectivity for light in the range of 400 nm to 480 nm, and the reflection bandwidth of the second DBR 132 is about 80 nm.

[0095] Formula (2) is the peak reflectivity formula of DBR:

[0096]

[0097] Where P represents the number of stacking cycles. From formula (2), it can be seen that the peak reflectivity R of the DBR is different from the refractive index difference of the dielectric layer (n H With n L The difference in refractive index between the dielectric layers is related to the number of stacking periods P. The greater the refractive index difference between the dielectric layers, the greater the peak reflectivity value, and the greater the number of stacking periods, the greater the peak reflectivity value. However, in actual implementation, due to the constraints of manufacturing costs, the number of stacking periods cannot be increased indefinitely, and excessive film thickness will increase the stress inside the film, resulting in problems such as film quality degradation and surface cracks, which is not conducive to device assembly.

[0098] The thickness d of the dielectric layer can be calculated by formula (3), where λ is the center wavelength of the reflection stop band of the dielectric layer, and n is the refractive index of the dielectric layer.

[0099] d=λ / 4n, Formula (3)

[0100] In one embodiment, in the first DBR 122, the thickness of the first dielectric layer 1221 ranges from 42 nm to 45 nm, and the thickness of the second dielectric layer 1222 ranges from 68.5 nm to 70.5 nm. For example, the thickness of the first dielectric layer 1221 may be 42 nm, 43 nm, 43.5 nm, 44 nm, or 45 nm. The thickness of the second dielectric layer 1222 may be 68.5 nm, 69.1 nm, or 70.5 nm. For example, the thickness of the first dielectric layer 1221 may be 43.5 nm, and the thickness of the second dielectric layer 1222 may be 69.1 nm.

[0101] In one embodiment, in the second DBR 132, the thickness of the first dielectric layer 1221 ranges from 58 nm to 61 nm, and the thickness of the second dielectric layer 1222 ranges from 66 nm to 68.5 nm. For example, the thickness of the first dielectric layer 1221 may be 58 nm, 59 nm, 59.3 nm, 60 nm, or 61 nm. The thickness of the second dielectric layer 1222 may be 66 nm, 66.8 nm, 67.2 nm, 67.8 nm, or 68.5 nm. For example, the thickness of the first dielectric layer 1221 may be 59.3 nm, and the thickness of the second dielectric layer 1222 may be 67.2 nm.

[0102] The inventors of the present disclosure have found through repeated research that according to the refractive index n of the first medium layer mentioned above H and the refractive index n of the second dielectric layer L , and the first DBR and the second DBR are respectively set according to the thickness mentioned above, and the incident angle range is limited to 0-35°, the reflectivity of the first DBR 122 at 452nm can reach 96%, and the reflectivity at 524nm can reach 85%; the reflectivity of the second DBR 132 at 452nm can reach more than 85%. After the inventor repeatedly optimized the first DBR 122 and the second DBR 132, the number of stacking periods of the first DBR 122 and the second DBR 132 were obtained to be 4 and 5 respectively.

[0103] In the first DBR 122, if Figure 2 As shown, the first dielectric layer 1221 and the second dielectric layer 1222 are alternately stacked in sequence, and the number of cycles of the first dielectric layer 1221 and the second dielectric layer 1222 is 4.

[0104] In the second DBR 132, if Figure 3 As shown, the first dielectric layer 1221 and the second dielectric layer 1222 are alternately stacked in sequence, and the number of cycles of the first dielectric layer 1221 and the second dielectric layer 1222 is 5.

[0105] In one embodiment, in the light emitting unit, parameter values ​​of the first DBR 122 and the second DBR 132 are as shown in Table 1.

[0106] Table 1 shows the parameter values ​​of the first DBR and the second DBR in one embodiment of the present disclosure.

[0107] Table 1. Thickness and period number of DBR structure

[0108]

[0109] Note: H is the thickness of high refractive index material (μ-GaN); t L is the thickness of the low refractive index material (NP-GaN); N c is the number of stacking cycles.

[0110] It is understood that μ-GaN represents undoped gallium nitride.

[0111] In the embodiment of the present disclosure, the light-emitting unit is set according to Table 1, and a simulation test is performed on the light-emitting unit. When the incident angle range of the light is limited to 0-35°, the reflectivity of the first DBR 122 at 452nm can reach 96%, and the reflectivity at 524nm can reach 85%; the reflectivity of the second DBR 132 at 452nm can reach more than 85%.

[0112] Figure 4 is a schematic plan view of the light emitting side of a light emitting unit in one embodiment of the present disclosure, Figure 5 : is a cross-sectional schematic diagram of a light-emitting unit in an embodiment of the present disclosure, in order to clearly show the corresponding relationship between each light-emitting body and the corresponding electrode, Figure 5 The first luminous body 11 is Figure 4 In the AA section, the second light emitting body 121 is Figure 4 The BB section in FIG. 1 shows that the third light emitting body 131 is Figure 4 The CC section in Figure 4 and Figure 5 As shown, the light-emitting unit may further include a first electrode 31 and a second electrode 32, a third electrode 33 and a fourth electrode 34, a fifth electrode 35 and a sixth electrode 36. The first electrode 31 and the second electrode 32 are both connected to the first luminescent body 11, and the first luminescent body 11 emits light under the excitation of the first electrode 31 and the second electrode 32. The third electrode 33 and the fourth electrode 34 are both connected to the second luminescent body 121, and the second luminescent body 121 emits light under the excitation of the third electrode 33 and the fourth electrode 34. The fifth electrode 35 and the sixth electrode 36 are both connected to the third luminescent body 131, and the third luminescent body 131 emits light under the excitation of the fifth electrode 35 and the sixth electrode 36.

[0113] like Figure 5As shown, the light-emitting unit can be arranged on the substrate 40, that is, the first light-emitting body 11 is located on the substrate 40, so that the light-emitting unit is located on the substrate 40, and the light-emitting side of the light-emitting unit is the upper side. In order to facilitate the connection between the light-emitting unit and the driving backplane, the first electrode 31 and the second electrode 32 are located on the side of the first light-emitting body 11 facing the light-emitting side of the light-emitting unit, that is, the first electrode 31 and the second electrode 32 are located on the upper side of the first light-emitting body 11; the third electrode 33 and the fourth electrode 34 are located on the side of the second light-emitting body 121 facing the light-emitting side of the light-emitting unit, that is, the third electrode 33 and the fourth electrode 34 are located on the upper side of the second light-emitting body 121; the fifth electrode 35 and the sixth electrode 36 are located on the side of the third light-emitting body 131 facing the light-emitting side of the light-emitting unit, that is, the fifth electrode 35 and the sixth electrode 36 are located on the upper side of the third light-emitting body 131. In such a structure, each electrode is located on the same side of the light-emitting unit, which facilitates the wiring of each electrode.

[0114] In one embodiment, the six electrodes may be evenly arranged in the plane of the light emitting unit, such as Figure 4 The second luminous body 121 is provided with a first notch for avoiding the first electrode 31 and a second notch for avoiding the second electrode 32. The third luminous body 131 is provided with a third notch for avoiding the first electrode 31 and the third electrode 33, and a fourth notch for avoiding the second electrode 32 and the fourth electrode 34.

[0115] The first luminous body 11 may include a stacked first semiconductor layer 61 , a first active layer 63 , and a second semiconductor layer 62 . The first electrode 31 may be connected to the first semiconductor layer 61 , and the second electrode 32 may be connected to the second semiconductor layer 62 .

[0116] The second luminous body 121 may include a first semiconductor layer 61 , a second active layer 63 , and a second semiconductor layer 62 , which are stacked. The third electrode 33 may be connected to the first semiconductor layer 61 , and the fourth electrode 34 may be connected to the second semiconductor layer 62 .

[0117] The third light emitting body 131 may include a first semiconductor layer 61 , a third active layer 63 , and a second semiconductor layer 62 , which are stacked. The fifth electrode 35 may be connected to the first semiconductor layer 61 , and the sixth electrode 36 may be connected to the second semiconductor layer 62 .

[0118] One of the first semiconductor layer 61 and the second semiconductor layer 62 may be a P-type doped semiconductor layer, and the other may be an N-type doped semiconductor layer. The P-type doped semiconductor layer may include In x Al y Ga 1-x-yA p-type nitride semiconductor layer of the N(0≤x<1, 0≤y<1, 0≤x + y<1) component, where the p-type impurity can be magnesium. For example, the material of the p-type doped semiconductor layer can include p-type doped gallium nitride (GaN). The n-type doped semiconductor layer can include In x Al y Ga 1-x-y An n-type nitride semiconductor layer of the N(0≤x<1, 0≤y<1, 0≤x + y<1) component, where the n-type impurity can be silicon. For example, the material of the n-type doped semiconductor layer can include n-type doped gallium nitride (GaN).

[0119] The second semiconductor layer 62 can be a single-layer structure, but in some example embodiments, it can have a multi-layer structure containing different components. The active layer 63 can have a multi-quantum well (MQW) structure, where the quantum well layer and the quantum barrier layer are stacked alternately with each other. For example, the quantum well layer and the quantum barrier layer can respectively include In x Al y Ga 1-x-y N(0≤x≤1, 0≤y≤1, 0≤x + y≤1) of different components. In one example, the quantum well layer can include In x Ga 1-x N(0<x≤1) component, and the quantum barrier layer can include GaN or AlGaN. The active layer 63 is not limited to the MQW structure and can have a single quantum well (SQW) structure. The active layer can be formed by alternately stacking multiple groups of quantum wells. By stacking two materials with different bandgaps, different barrier structures are formed. The material with a lower doping level (well) has a narrower bandgap and a lower barrier; the material with a higher doping level (barrier) has a wider bandgap and a higher barrier.

[0120] The present disclosure also provides a method for preparing a light-emitting unit, including the following steps.

[0121] Prepare the first light-emitting body 11.

[0122] Prepare the first structure body 12, where the first structure body 12 includes a first DBR 122 and a second light-emitting body 121 stacked.

[0123] Prepare the second structure body 13, where the second structure body 13 includes a second DBR 132 and a third light-emitting body 131 stacked.

[0124] Stack the first structure body 12 on the side of the first light-emitting body 11 facing the light-emitting side of the light-emitting unit, such that the first DBR 122 is located between the first light-emitting body 11 and the second light-emitting body 121.

[0125] The second structure 13 is stacked on a side of the second light emitting body 121 facing the light emitting side of the light emitting unit, so that the second DBR 132 is located between the second light emitting body 121 and the third light emitting body 131 .

[0126] Among them, the colors of the light emitted by the first light emitter 11, the second light emitter 121 and the third light emitter 131 are different; the first DBR 122 is configured to allow the light emitted by the first light emitter 11 to pass through, and reflect at least part of the light emitted by the second light emitter 121 and at least part of the light emitted by the third light emitter 131; the second DBR 132 is configured to allow the light emitted by the first light emitter 11 and the second light emitter 121 to pass through, and reflect at least part of the light emitted by the third light emitter 131.

[0127] In one embodiment, the first structure 12 or the second structure 13 is prepared, including: growing a first heavily doped gallium nitride layer 65 on one side of the substrate, wherein the doping concentration of the first heavily doped gallium nitride layer 65 is in the range of 4.6*10 19 / cm 3 ~5.0*10 19 / cm 3 A periodic stacking structure 66 is formed on the side of the first heavily doped gallium nitride layer 65 facing away from the substrate. The periodic stacking structure 66 includes a first dielectric layer 1221 and a first doping concentration gallium nitride layer alternately stacked in sequence. The first dielectric layer 1221 includes gallium nitride. The doping concentration of the first doping concentration gallium nitride layer ranges from 0.9*10 19 / cm 3 ~1.2*10 19 / cm 3 ; A first semiconductor layer 61, a corresponding active layer 63, and a second semiconductor layer 62 are sequentially grown on the side of the periodic stacking structure 66 away from the substrate, and the light-emitting body includes the first semiconductor layer 61, the corresponding active layer 63, and the second semiconductor layer 62; the first structure 12 or the second structure 13 is etched to form a table surface exposing the first heavily doped gallium nitride layer 65, and the first heavily doped gallium nitride layer 65 and the first doping concentration gallium nitride layer are etched by electrochemical etching technology, so that the first heavily doped gallium nitride layer 65 forms a porous structure gallium nitride layer with a first porosity and is peeled off from the periodic stacking structure 66, and the first doping concentration gallium nitride layer forms a second dielectric layer 1222 with a second porosity, and the second dielectric layer 1222 includes nanoporous gallium nitride, and the value range of the second porosity is 65% to 75%. The first porosity is greater than the second porosity.

[0128] In some embodiments, during the electrochemical etching process, the bias voltage of the anode is adjusted from 10 V to 15 V, and the electrolyte includes sodium nitrate or nitric acid.

[0129] In some embodiments, the first light emitting body 11 includes a first semiconductor layer 61a, a first active layer 63a and a second semiconductor layer 62a stacked in sequence, and the light emitting unit also includes a first electrode 31 and a second electrode 32, and the first electrode 31 and the second electrode 32 are both connected to the first light emitting body 11.

[0130] The first structure 12 is stacked on a side of the first light-emitting body 11 facing the light-emitting unit, including: transferring the first structure 12 to a side of the first light-emitting body 11 facing the light-emitting unit, so that the first distributed Bragg reflection layer 122 is located between the first light-emitting body 11 and the second light-emitting body 121, and the first structure 12 is provided with a first notch for avoiding the first electrode 31 and a second notch for avoiding the second electrode 32; etching the second semiconductor layer 62b and the corresponding active layer 63b in the second light-emitting body 121 to form a second mesa T2, and the second mesa T2 exposes the first semiconductor layer 61b in the second light-emitting body 121; forming a third electrode 33 and a fourth electrode 34, the third electrode 33 is coupled to the first semiconductor layer 61b in the second light-emitting body 121, and the fourth electrode 34 is coupled to the second semiconductor layer 62b in the second light-emitting body 121.

[0131] The second structure 13 is stacked on a side of the second light-emitting body 121 facing the light-emitting unit, including: transferring the second structure 13 to a side of the second light-emitting body 121 facing the light-emitting unit, so that the second distributed Bragg reflection layer 132 is located between the second light-emitting body 121 and the third light-emitting body 131, and the second structure 13 is provided with a third notch for avoiding the first electrode 31 and the third electrode 33 and a fourth notch for avoiding the second electrode 32 and the fourth electrode 34; the second semiconductor layer 62c and the corresponding active layer 63c in the third light-emitting body 131 are etched to form a third mesa T3, and the third mesa T3 exposes the first semiconductor layer 61c in the third light-emitting body 131; and a fifth electrode 35 and a sixth electrode 36 are formed, the fifth electrode 35 is coupled to the first semiconductor layer 61c in the third light-emitting body 131, and the sixth electrode 36 is coupled to the second semiconductor layer 62c in the third light-emitting body 131.

[0132] The technical solution of the embodiment of the present disclosure is further explained below through the preparation process of the light-emitting unit in one embodiment of the present disclosure. It can be understood that the "patterning" mentioned in this article, when the patterned material is an inorganic material or metal, "patterning" includes processes such as coating photoresist, mask exposure, development, etching, and stripping photoresist, and when the patterned material is an organic material, "patterning" includes processes such as mask exposure and development. The evaporation, deposition, coating, and coating mentioned in this article are all mature preparation processes in the relevant technology.

[0133] (1) Process of preparing the first luminous body 11.

[0134] A first semiconductor layer 61a, a first active layer 63a and a second semiconductor layer 62a are sequentially grown on one side of the third substrate 53. Figure 6 As shown, Figure 6 Schematic diagram of the process of preparing the first luminous body. The material of the third substrate 53 may include gallium arsenide (GaAs). In one embodiment of the present disclosure, the material of the first semiconductor layer 61a may include N-type doped AlGaInP, the second semiconductor layer 62a may include a first sublayer 621 and a second sublayer 622 arranged in a stacked manner, the material of the first sublayer 621 may include P-type doped AlGaInP, the material of the second sublayer 622 may include highly doped P-GaP, and the second sublayer 622 may serve as a P-type ohmic contact layer. After the first luminous body 11 is temporarily bonded to the temporary substrate, the third substrate 53 is thinned to a preset thickness, so that the thickness of the third substrate 53 is about 100 μm. The thinning process may include: using a preset solution to corrode the GaAs substrate, the ratio of ammonia water: hydrogen peroxide in the preset solution = 3 to 5:15; the preset solution has a high corrosion selectivity for GaAs and GaInP, so that the corrosion stops evenly at the GaInP layer. When etching the GaAs substrate, the GaAs substrate and hydrogen peroxide will react to generate respective oxides of Ga and As, and these oxides cannot be completely dissolved by ammonia and will accumulate on the reaction surface to prevent further corrosion of the GaAs substrate. In order to speed up the corrosion rate of the GaAs substrate, during the etching process of the GaAs substrate, the wafer can be shaken continuously or ultrasonically, thereby speeding up the reaction rate of GaAs and the preset solution, so that the solution replacement speed on the reaction surface is accelerated, and the respective oxides of Ga and As are prevented from accumulating on the reaction surface to prevent further corrosion of the GaAs substrate. After the GaAs substrate is peeled off, the preparation of the epitaxial wafer of the first luminous body 11 is completed, as shown in FIG. Figure 6 As shown in (b).

[0135] (2) Process of preparing the first structure 12 .

[0136] A first gallium nitride layer 64, a first heavily doped gallium nitride layer 65, a first periodic stacking structure 66a, a second gallium nitride layer 67, a first semiconductor layer 61b, a second active layer 63b and a second semiconductor layer 62b are sequentially grown on the first substrate 51. Figure 7 As shown, Figure 7Schematic diagram of the process of preparing the first structure. The first substrate 51 may be a sapphire substrate, or a substrate of other materials, such as a silicon substrate, an aluminum oxide substrate, a diamond substrate, etc. The material of the first gallium nitride layer 64 and the second gallium nitride layer 67 may include μ-GaN, that is, undoped gallium nitride. The thickness of the first heavily doped gallium nitride layer 65 is about 130nm, and the doping concentration of the first heavily doped gallium nitride layer 65 ranges from 4.6*10 19 / cm 3 ~5.0*10 19 / cm 3 For example, the doping concentration of the first heavily doped gallium nitride layer 65 is 4.8*10 19 / cm 3 The first heavily doped gallium nitride layer 65 may be an N-doped gallium nitride layer. The first periodic stacked structure 66a includes a first dielectric layer 1221 and a first doping concentration gallium nitride layer alternately stacked in sequence. The first dielectric layer 1221 includes gallium nitride. The doping concentration of the first doping concentration gallium nitride layer ranges from 0.9*10 19 / cm 3 ~1.2*10 19 / cm 3 The first doping concentration gallium nitride layer may be an N-doped gallium nitride layer. For example, the doping concentration of the first doping concentration gallium nitride layer is 1.2*10 19 / cm 3 In the first periodic stacking structure 66 a , the first dielectric layer 1221 is adjacent to the first heavily doped gallium nitride layer 65 , which can facilitate subsequent stripping of the first heavily doped gallium nitride layer 65 .

[0137] In one embodiment, the stacking period number of the first periodic stacking structure 66a is 4, that is, the cycle number of the first dielectric layer 1221 and the second dielectric layer 1222 is 4. The thickness of the first dielectric layer 1221 is 43.5 nm, and the thickness of the first doping concentration gallium nitride layer is 69.1 nm. The thickness of the second gallium nitride layer 67 can be about 50 nm, and the thickness of the first semiconductor layer 61b is about 100 nm. The thickness of the second active layer 63b and the second semiconductor layer 62b can be set as needed.

[0138] The epitaxial wafer on the first substrate 51 is patterned, and the second semiconductor layer 62b, the second active layer 63b, the first semiconductor layer 61b, the second gallium nitride layer 67, the first periodic stacking structure 66a and part of the first heavily doped gallium nitride layer 65 at the fourth mesa T4 are etched away, and the fourth mesa T4 exposes the surface of the first heavily doped gallium nitride layer 65, as shown in FIG. Figure 7 As shown in (b).

[0139] When preparing nanoporous materials, the morphology of the pores can be controlled by the conductivity of the sample and the anodic bias. Higher doping levels are conducive to the formation of high porosity and correspondingly reduce the threshold deviation of porosification.

[0140] In one embodiment of the present disclosure, an electrochemical etching (EC etching) process is used to etch the first heavily doped gallium nitride layer 65 and the first doping concentration gallium nitride layer in the first periodic stacking structure 66a. Figure 7 The epitaxial structure shown in (b) is used as the anode, and 0.3 mol / L NaNO 3 or HNO 3 As the electrolyte, platinum (Pt) is used as the counter electrode, and the electrochemical etching time can be set as needed, for example, the time is about 30 minutes. By adjusting the anode bias range from 10V to 15V, the electrochemical etching of the first heavily doped gallium nitride layer 65 and the first doping concentration gallium nitride layer is achieved, so that the first doping concentration gallium nitride layer becomes a nanoporous gallium nitride layer with a second porosity, and the second porosity is about 70%, that is, the first doping concentration gallium nitride layer becomes the second dielectric layer 1222. Thus, the first periodic stacked structure 66a becomes the first DBR 122.

[0141] The first heavily doped gallium nitride layer 65 has a high doping concentration and is easier to be etched into nanoporous. Thus, the first heavily doped gallium nitride layer 65 becomes a nanoporous gallium nitride layer with a first porosity, and the first porosity is greater than the second porosity. Then, the etched structure is placed in a solution with high surface energy (such as a deionized water solution). Under the action of capillary force, the water separates the nanoporous gallium nitride layer with the first porosity from the first DBR 122, thereby obtaining a first structure 12, as shown in FIG. Figure 7 It should be noted that, since the first porosity is relatively large, the nanoporous gallium nitride layer formed by the first heavily doped gallium nitride layer 65 can be separated from the first dielectric layer in the periodic stacking structure.

[0142] (3) Process of preparing the second structure 13 .

[0143] A first gallium nitride layer 64, a first heavily doped gallium nitride layer 65, a second periodic stacking structure 66b, a second gallium nitride layer 67, a first semiconductor layer 61c, a third active layer 63c and a second semiconductor layer 62c are sequentially grown on the first substrate 51. Figure 8 As shown, Figure 8 Schematic diagram of the process of preparing the second structure. The first substrate 51 can be a sapphire substrate, and can also be a substrate of other materials, such as a silicon substrate, an aluminum oxide substrate, a diamond substrate, etc. The thickness of the first heavily doped gallium nitride layer 65 is about 130nm, and the doping concentration of the first heavily doped gallium nitride layer 65 ranges from 4.6*10 19 / cm3 ~5.0*10 19 / cm 3 For example, the doping concentration of the first heavily doped gallium nitride layer 65 is 4.8*10 19 / cm 3 The first heavily doped gallium nitride layer 65 may be an N-doped gallium nitride layer. The second periodic stacked structure 66b includes a first dielectric layer 1221 and a first doping concentration gallium nitride layer alternately stacked in sequence. The first dielectric layer 1221 includes gallium nitride. The doping concentration of the first doping concentration gallium nitride layer ranges from 0.9*10 19 / cm 3 ~1.2*10 19 / cm 3 The first doping concentration gallium nitride layer may be an N-doped gallium nitride layer. For example, the doping concentration of the first doping concentration gallium nitride layer is 1.2*10 19 / cm 3 In the second periodic stacking structure 66 b , the first dielectric layer 1221 is adjacent to the first heavily doped gallium nitride layer 65 , which can facilitate subsequent stripping of the first heavily doped gallium nitride layer 65 .

[0144] In one embodiment, the stacking period number of the second periodic stacking structure 66b is 5, that is, the cycle number of the first dielectric layer 1221 and the second dielectric layer 1222 is 5. The thickness of the first dielectric layer 1221 is 59.3 nm, and the thickness of the first doping concentration gallium nitride layer is 67.2 nm. The thickness of the second gallium nitride layer 67 can be about 50 nm, and the thickness of the first semiconductor layer 61c is about 100 nm. The thickness of the third active layer 63c and the second semiconductor layer 62c can be set as needed.

[0145] The epitaxial wafer on the second substrate is patterned, and the second semiconductor layer 62c, the third active layer 63c, the first semiconductor layer 61c, the second gallium nitride layer 67, the second periodic stacking structure 66b and part of the first heavily doped gallium nitride layer 65 at the position of the fifth mesa T5 are etched away, and the surface of the first heavily doped gallium nitride layer 65 is exposed on the fifth mesa T5. Figure 8 As shown in (b).

[0146] The first heavily doped gallium nitride layer 65 and the first doping concentration gallium nitride layer in the first stacked structure may be etched by an electrochemical etching process, so that the first doping concentration gallium nitride layer becomes a nanoporous gallium nitride layer with a second porosity of about 70%, that is, the first doping concentration gallium nitride layer becomes a second dielectric layer 1222. Thus, the first periodic stacked structure 66b becomes a second DBR 132.

[0147] The first heavily doped gallium nitride layer 65 has a high doping concentration and becomes a nanoporous gallium nitride layer with a first porosity, and the first porosity is greater than the second porosity. Then, the etched structure is placed in a solution with a high surface energy (such as a deionized water solution), and the water, under the action of capillary force, separates the nanoporous gallium nitride layer with the first porosity from the second DBR 132, thereby obtaining a second structure 13, as shown in FIG. Figure 8 As shown in (c).

[0148] It should be noted that the thickness of each film layer in the first structure body 12 and the second structure body 13 can be set as required.

[0149] (4) The process of transferring the first light-emitting body 11.

[0150] The epitaxial wafer of the first luminous body 11 is transferred to the substrate. Figure 6 The epitaxial wafer shown in (b) is transferred to a substrate, such as Fig. 9 As shown in (a), Fig. 9 This is a schematic diagram of the process of transferring the first luminescent body during the preparation of the luminescent unit.

[0151] The material of the substrate may include silicon (Si) silicon dioxide (SiO 2 ) at least one of.

[0152] The epitaxial wafer of the first light emitting body 11 is patterned, and the second semiconductor layer 62a, the first active layer 63a and a part of the first semiconductor layer 61a at the position of the first mesa T1 are etched away to form the first mesa T1, and the first mesa T1 exposes the first semiconductor layer 61a. Fig. 9 Then, the first electrode 31 and the second electrode 32 are prepared, the first electrode 31 is connected to the first semiconductor layer 61a, and the second electrode 32 is connected to the second semiconductor layer 62a, as shown in FIG. Fig. 9 A first insulating layer may be provided on the upper side of the first luminous body 11, and the first insulating layer may be provided with a first via hole and a second via hole, and then a first electrode 31 and a second electrode 32 are formed on the first insulating layer, the first electrode 31 is connected to the first semiconductor layer 61a through the first via hole, and the second electrode 32 is connected to the second semiconductor layer 62a through the second via hole.

[0153] (5) Process of stacking the first structure 12 .

[0154] The epitaxial wafer of the first structure 12 is transferred to the side of the first light emitting body 11 away from the substrate, for example, Figure 7 The first structure 12 in (c) is transferred to the top of the first luminous body 11, so that the first structure 12 is stacked on the first luminous body 11, as shown in FIG. Fig.10 As shown in (a), Fig.10Schematic diagram of the process of transferring the first structure during the preparation of the light-emitting unit. An insulating layer is provided between the first structure 12 and the first light-emitting body 11, so that the first DBR 122 is located between the first light-emitting body 11 and the second light-emitting body 121. The first structure 12 is provided with a first notch and a second notch, the first notch is used to avoid the first electrode 31, and the second notch is used to avoid the second electrode 32. The first notch and the second notch can be formed by conventional techniques in the art during the preparation of the first structure 12. For example, the first notch and the second notch are etched while the fourth mesa T4 is etched.

[0155] The second light emitting body 121 is patterned, and the second semiconductor layer 62b, the second active layer 63b and a part of the first semiconductor layer 61b at the position of the second mesa T2 are etched away to form the second mesa T2, and the second mesa T2 exposes the first semiconductor layer 61b. Fig.10 Then, the third electrode 33 and the fourth electrode 34 are prepared, the third electrode 33 is connected to the first semiconductor layer 61b, and the fourth electrode 34 is connected to the second semiconductor layer 62b, as shown in FIG. Fig.10 The process of preparing the third electrode 33 and the fourth electrode 34 may be the same as the process of preparing the first electrode 31 and the second electrode 32, and will not be described in detail here.

[0156] (6) Process of transferring the second structure 13 .

[0157] The epitaxial wafer of the second structure 13 is transferred to the side of the second light emitting body 121 away from the substrate, for example, Figure 8 The second structure 13 in (c) is transferred to the top of the second luminous body 121, so that the second structure 13 is stacked on the second luminous body 121, as shown in FIG. Fig.11 As shown in (a), Fig.11 Schematic diagram of the process of transferring the second structure during the preparation of the light-emitting unit. An insulating layer is provided between the third structure and the second light-emitting body 121, so that the second DBR 132 is located between the second light-emitting body 121 and the third light-emitting body 131. The second structure 13 is provided with a third notch and a fourth notch, the third notch is used to avoid the first electrode 31 and the third electrode 33, and the fourth notch is used to avoid the second electrode 32 and the fourth electrode 34. The third notch and the fourth notch can be formed by conventional techniques in the art during the preparation of the second structure 13. For example, the third notch and the fourth notch are etched while the fifth mesa T5 is etched.

[0158] The third light emitting body 131 is patterned, and the second semiconductor layer 62c, the third active layer 63c and a part of the first semiconductor layer 61c at the position of the third mesa T3 are etched away to form the third mesa T3, wherein the third mesa T3 exposes the first semiconductor layer 61c. Fig.11Then, the fifth electrode 35 and the sixth electrode 36 are prepared, the fifth electrode 35 is connected to the first semiconductor layer 61c, and the sixth electrode 36 is connected to the second semiconductor layer 62c, as shown in FIG. Fig.11 As shown in (c). The process of preparing the fifth electrode 35 and the sixth electrode 36 can be the same as the process of preparing the first electrode 31 and the second electrode 32, which will not be repeated here. At this point, the preparation of the light-emitting unit is completed.

[0159] The embodiments of the present disclosure further provide a light-emitting panel, comprising a driving backplane and a light-emitting unit in any embodiment of the present disclosure.

[0160] Based on the inventive concept of the foregoing embodiments, an embodiment of the present disclosure further provides a display device, which includes the light-emitting panel of the embodiment of the present disclosure.

[0161] The light-emitting panel in the embodiment of the present disclosure can be installed in a display device as a display panel, or can be installed in a display device as a light source. The display device can be: electronic paper, mobile phone, tablet computer, television, monitor, notebook computer, digital photo frame, navigator, wearable display device, and any other product or component with display function.

[0162] The light-emitting panel in the embodiment of the present disclosure can also be used as a light source in lighting products.

[0163] In the description of this specification, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0164] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0165] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0166] In the present disclosure, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being “above”, “above”, and “above” a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0167] The disclosure above provides many different embodiments or examples to implement different structures of the present disclosure. In order to simplify the present disclosure, the components and settings of specific examples are described above. Of course, they are only examples, and the purpose is not to limit the present disclosure. In addition, the present disclosure can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0168] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of various changes or replacements within the technical scope disclosed in the present disclosure. Different parts in different embodiments can be combined with each other without conflict, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A light emitting unit, characterized in that: The invention comprises a first luminous body, a second luminous body and a third luminous body stacked in sequence along a first direction, and further comprises a first distributed Bragg reflection layer and a second distributed Bragg reflection layer, wherein the first distributed Bragg reflection layer is located between the first luminous body and the second luminous body, and the second distributed Bragg reflection layer is located between the second luminous body and the third luminous body, and the colors of the light emitted by the first luminous body, the second luminous body and the third luminous body are different; The first distributed Bragg reflection layer is configured to allow light emitted by the first light source to pass through, and to reflect at least part of the light emitted by the second light source and at least part of the light emitted by the third light source; the second distributed Bragg reflection layer is configured to allow light emitted by the first light source and the second light source to pass through, and to reflect at least part of the light emitted by the third light source.

2. The light emitting unit according to claim 1, characterized in that: The first distributed Bragg reflector layer and / or the second distributed Bragg reflector layer comprises first dielectric layers and second dielectric layers which are alternately stacked in sequence; The first dielectric layer includes gallium nitride, and the refractive index of the first dielectric layer ranges from 2.6 to 2.8; and / or the second dielectric layer includes nanoporous gallium nitride, and the refractive index of the second dielectric layer ranges from 1.6 to 1.

8.

3. The light emitting unit according to claim 2, characterized in that: The refractive index of the first dielectric layer is 2.7, and / or the refractive index of the second dielectric layer is 1.

7.

4. The light emitting unit according to claim 2 or 3, characterized in that: The stacking period number of the first distributed Bragg reflector layer is 4; and / or the stacking period number of the second distributed Bragg reflector layer is 5.

5. The light emitting unit according to claim 2 or 3, characterized in that: In the first distributed Bragg reflector layer, the thickness of the first dielectric layer ranges from 42 nm to 45 nm, and the thickness of the second dielectric layer ranges from 68.5 nm to 70.5 nm; and / or, In the second distributed Bragg reflector layer, the thickness of the first dielectric layer ranges from 58 nm to 61 nm, and the thickness of the second dielectric layer ranges from 66 nm to 68.5 nm.

6. The light emitting unit according to claim 5, characterized in that: In the first distributed Bragg reflector layer, the thickness of the first dielectric layer is 43.5 nm, and the thickness of the second dielectric layer is 69.1 nm; and / or, In the second distributed Bragg reflector layer, the thickness of the first dielectric layer is 59.3 nm, and the thickness of the second dielectric layer is in the range of 67.2 nm.

7. The light emitting unit according to claim 2 or 3, characterized in that: The central wavelength of the reflection stop band of the first distributed Bragg reflector is in the range of 460 nm to 480 nm, and / or the central wavelength of the reflection stop band of the second distributed Bragg reflector is in the range of 400 nm to 420 nm.

8. The light emitting unit according to claim 7, characterized in that: The central wavelength of the reflection stop band of the first distributed Bragg reflector is 470 nm, and / or the central wavelength of the reflection stop band of the second distributed Bragg reflector is 403 nm.

9. The light emitting unit according to claim 2 or 3, characterized in that: In the first distributed Bragg reflector layer, the porosity of the second dielectric layer ranges from 65% to 75%; in the second distributed Bragg reflector layer, the porosity of the second dielectric layer ranges from 65% to 75%.

10. The light emitting unit according to claim 9, characterized in that: In the first distributed Bragg reflector layer, the porosity of the second dielectric layer is in the range of 70%; in the second distributed Bragg reflector layer, the porosity of the second dielectric layer is in the range of 70%.

11. The light emitting unit according to claim 1, characterized in that: The first luminous body, the second luminous body and the third luminous body each include a first semiconductor layer, a corresponding active layer and a second semiconductor layer which are stacked; The first light-emitting body is configured to emit red light, the second light-emitting body is configured to emit green light, and the third light-emitting body is configured to emit blue light.

12. The light emitting unit according to claim 1, characterized in that: It also includes a first electrode and a second electrode, a third electrode and a fourth electrode, and a fifth electrode and a sixth electrode. The first electrode and the second electrode are both connected to the first light-emitting body, and the first electrode and the second electrode are located on the side of the first light-emitting body facing the light-emitting unit; the third electrode and the fourth electrode are both connected to the second light-emitting body, and the third electrode and the fourth electrode are located on the side of the second light-emitting body facing the light-emitting unit; the fifth electrode and the sixth electrode are both connected to the third light-emitting body, and the fifth electrode and the sixth electrode are located on the side of the third light-emitting body facing the light-emitting unit.

13. A method for preparing a light-emitting unit, characterized in that: include: preparing a first luminous body; Prepare a first structure, wherein the first structure includes a first distributed Bragg reflection layer and a second light-emitting body arranged in a stacked manner; preparing a second structure, wherein the second structure comprises a second distributed Bragg reflection layer and a third light emitting body arranged in a stacked manner; The first structure is stacked on a side of the first light-emitting body facing the light-emitting side of the light-emitting unit, so that the first distributed Bragg reflection layer is located between the first light-emitting body and the second light-emitting body; The second structure is stacked on a side of the second light-emitting body facing the light-emitting side of the light-emitting unit, so that the second distributed Bragg reflection layer is located between the second light-emitting body and the third light-emitting body; The colors of the light emitted by the first light emitter, the second light emitter and the third light emitter are different; the first distributed Bragg reflection layer is configured to allow the light emitted by the first light emitter to pass through, and to reflect at least part of the light emitted by the second light emitter and at least part of the light emitted by the third light emitter; the second distributed Bragg reflection layer is configured to allow the light emitted by the first light emitter and the second light emitter to pass through, and to reflect at least part of the light emitted by the third light emitter.

14. The method according to claim 13, characterized in that The step of preparing the first structure or the second structure comprises: A first heavily doped gallium nitride layer is grown on one side of the substrate, wherein the doping concentration of the first heavily doped gallium nitride layer is in the range of 4.6*10 19 / cm 3 ~5.0*10 19 / cm 3 ; A periodic stacking structure is formed on a side of the first heavily doped gallium nitride layer away from the substrate, wherein the periodic stacking structure comprises a first dielectric layer and a first doping concentration gallium nitride layer alternately stacked in sequence, wherein the first dielectric layer comprises gallium nitride, and the doping concentration of the first doping concentration gallium nitride layer ranges from 0.9 to 10 19 / cm 3 ~1.2*10 19 / cm 3 ; A first semiconductor layer, a corresponding active layer, and a second semiconductor layer are sequentially grown on a side of the periodic stacking structure away from the substrate, wherein the light emitting body comprises the first semiconductor layer, the corresponding active layer, and the second semiconductor layer; The first structure or the second structure is etched to form a table exposing the first heavily doped gallium nitride layer, and the first heavily doped gallium nitride layer and the first doping concentration gallium nitride layer are etched by electrochemical etching, so that the first heavily doped gallium nitride layer forms a porous structure gallium nitride layer with a first porosity and is peeled off from the periodic stacking structure, and the first doping concentration gallium nitride layer forms a second dielectric layer with a second porosity, the second dielectric layer includes nanoporous gallium nitride, the second porosity ranges from 65% to 75%, and the first porosity is greater than the second porosity.

15. The method according to claim 14, characterized in that During the electrochemical etching process, the bias voltage of the anode is adjusted from 10V to 15V, and the electrolyte includes sodium nitrate or nitric acid.

16. The method according to claim 14, characterized in that The first luminous body includes a first semiconductor layer, a first active layer, and a second semiconductor layer stacked in sequence, and the light-emitting unit also includes a first electrode and a second electrode, and the first electrode and the second electrode are both connected to the first luminous body; The first structure is stacked on a side of the first light-emitting body facing the light-emitting side of the light-emitting unit, comprising: Transferring the first structure to a side of the first light-emitting body facing the light-emitting side of the light-emitting unit, so that the first distributed Bragg reflector is located between the first light-emitting body and the second light-emitting body, and the first structure is provided with a first notch for avoiding the first electrode and a second notch for avoiding the second electrode; Etching the second semiconductor layer and the corresponding active layer in the second light emitting body to form a second mesa, wherein the second mesa exposes the first semiconductor layer in the second light emitting body; A third electrode and a fourth electrode are formed, wherein the third electrode is coupled to the first semiconductor layer in the second light emitting body, and the fourth electrode is coupled to the second semiconductor layer in the second light emitting body.

17. The method according to claim 16, characterized in that The second structure is stacked on a side of the second light-emitting body facing the light-emitting side of the light-emitting unit, comprising: Transferring the second structure to a side of the second light-emitting body facing the light-emitting side of the light-emitting unit, so that the second distributed Bragg reflector is located between the second light-emitting body and the third light-emitting body, and the second structure is provided with a third notch for avoiding the first electrode and the third electrode and a fourth notch for avoiding the second electrode and the fourth electrode; Etching the second semiconductor layer and the corresponding active layer in the third light emitting body to form a third mesa, wherein the third mesa exposes the first semiconductor layer in the third light emitting body; A fifth electrode and a sixth electrode are formed, wherein the fifth electrode is coupled to the first semiconductor layer in the third light emitting body, and the sixth electrode is coupled to the second semiconductor layer in the third light emitting body.

18. A light-emitting panel, characterized in that: The invention comprises a driving backplane and a light emitting unit according to any one of claims 1 to 12.

19. A display device, characterized in that: Comprising the light emitting panel as claimed in claim 18.

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