A light emitting device and a method for manufacturing the same, and a display device

Abstract

The embodiment of the present disclosure provides a light-emitting device and a method for manufacturing the same, and a display device, wherein the light-emitting device comprises: a first metal layer; a first epitaxial structure located on one side of the first metal layer; a second epitaxial structure located on a side of the first epitaxial structure away from the first metal layer; a second metal layer located between the first epitaxial structure and the second epitaxial structure, the second metal layer having a hollow portion; and a transparent conductive layer located on a side of the second epitaxial structure away from the first metal layer. The technical solution of the embodiment of the present disclosure can improve the light-emitting brightness of the light-emitting device.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a light-emitting device and a method for preparing the same, and a display device. Background Art

[0002] Currently, due to the structural limitations of light-emitting devices, their luminance is relatively low and they are not suitable for preparing high-resolution display products. Summary of the invention

[0003] The embodiments of the present disclosure provide a light emitting device and a method for manufacturing the same, and a display device to solve or alleviate one or more technical problems in the prior art.

[0004] As one aspect of an embodiment of the present disclosure, an embodiment of the present disclosure provides a light emitting device, including:

[0005] A first metal layer;

[0006] A first epitaxial structure is located on one side of the first metal layer;

[0007] A second epitaxial structure is located on a side of the first epitaxial structure away from the first metal layer;

[0008] A second metal layer is located between the first epitaxial structure and the second epitaxial structure, and the second metal layer has a hollow portion;

[0009] The transparent conductive layer is located on a side of the second epitaxial structure away from the first metal layer.

[0010] In one embodiment, the light emitted by the first epitaxial structure and the second epitaxial structure is within the same wavelength band.

[0011] In one embodiment, the second metal layer further includes a bonding portion, and the orthographic projection of the hollow portion on the first metal layer is located within the range of the orthographic projection of the bonding portion on the first metal layer.

[0012] In one embodiment, the second metal layer further includes two bonding portions, and the orthographic projections of the two bonding portions on the first metal layer are respectively located on opposite sides of the orthographic projection of the hollow portion on the first metal layer.

[0013] In one embodiment, the orthographic projection of the bonding portion on the first metal layer and the orthographic projection of the hollow portion on the first metal layer cover the first metal layer, and the area of ​​the orthographic projection of the hollow portion on the first metal layer is greater than or equal to half of the area of ​​the first metal layer and smaller than the area of ​​the first metal layer.

[0014] In one embodiment, the light emitting device further includes: a first light adjustment layer, which is disposed on the same layer as the second metal layer and is located at the position of the hollow portion.

[0015] In one embodiment, the first epitaxial structure and the second epitaxial structure respectively include a first semiconductor layer, a light emitting layer and a second semiconductor layer stacked along the light emitting direction, and the second semiconductor layer of the second epitaxial structure protrudes away from the first metal layer to form a second light adjustment layer.

[0016] In one embodiment, the light emitting device further includes: a second light adjustment layer, which is disposed on a side of the second epitaxial structure away from the first metal layer.

[0017] In one embodiment, an orthographic projection of the hollow portion on the first metal layer overlaps with an orthographic projection of the second light adjustment layer on the first metal layer, and a refractive index of the hollow portion is less than a refractive index of the second epitaxial structure.

[0018] In one embodiment, the first epitaxial structure and the second epitaxial structure respectively include a first current diffusion layer, a first semiconductor layer, a light-emitting layer, a second semiconductor layer and a second current diffusion layer stacked along the light emitting direction, and the materials of the first current diffusion layer and the second current diffusion layer are both transparent conductive materials.

[0019] In one embodiment, there are a plurality of first epitaxial structures, and the plurality of first epitaxial structures are stacked and disposed between the second epitaxial structure and the first metal layer, and a second metal layer is disposed between adjacent first epitaxial structures.

[0020] As another aspect of an embodiment of the present disclosure, an embodiment of the present disclosure provides a display device, comprising a light emitting device according to any one of the above embodiments.

[0021] As another aspect of the embodiments of the present disclosure, the embodiments of the present disclosure provide a method for preparing a light emitting device, comprising:

[0022] A first wafer and a second wafer are formed respectively; the first wafer has a first substrate and a first epitaxial structure film and a first metal film stacked on one side of the first substrate, the first metal film has a plurality of hollow parts, and the second wafer has a second substrate and a second epitaxial structure film located on one side of the second substrate;

[0023] Bonding a side of the second epitaxial structure film away from the second substrate to a side of the first metal film away from the first substrate and peeling off the first substrate;

[0024] forming a second metal film on a side of the first epitaxial structure film away from the first metal film;

[0025] Patterning the second metal film, the first epitaxial structure film, the first metal film and the second epitaxial structure film respectively to form a plurality of light-emitting units, so that the light-emitting units have hollow portions;

[0026] The second substrate is peeled off, and a transparent conductive layer is formed on a side of the light-emitting unit away from the patterned second metal film to form a light-emitting device.

[0027] In one embodiment, forming the second wafer includes: forming a first light-adjusting film at a location where the hollow portion is located.

[0028] In one embodiment, forming the second wafer includes:

[0029] sequentially forming a first semiconductor film, a light emitting film, a second semiconductor film and a mask pattern on one side of a growth substrate;

[0030] transferring the mask pattern onto the second semiconductor film;

[0031] A second substrate is disposed on a side of the second semiconductor film facing away from the growth substrate, and the growth substrate is peeled off.

[0032] In one embodiment, the first epitaxial structure film includes a plurality of layers stacked along the light emitting direction, the plurality of first epitaxial structure films include a bottom epitaxial structure film located at the bottom layer in the light emitting direction, and a second metal film is formed on a side of the first epitaxial structure film away from the first metal film, including:

[0033] A second metal film is formed on a side of the bottom epitaxial structure film away from the first metal film.

[0034] The disclosed embodiment adopts the above-mentioned technical solution, and the first epitaxial structure and the second epitaxial structure are stacked between the first metal layer and the transparent conductive layer, and a second metal layer with a hollow portion is arranged between the first epitaxial structure and the second epitaxial structure, so that when a voltage is applied to the first metal layer and the transparent conductive layer, the light emitted by the first epitaxial structure can pass through the hollow portion and mix with the light emitted by the second epitaxial structure and emit, thereby improving the luminous brightness of the light-emitting device, making it suitable for preparing high-resolution display products, especially suitable for preparing Micro LED display products.

[0035] 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

[0036] 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 disclosed in accordance with the present disclosure and should not be regarded as limiting the scope of the present disclosure.

[0037] Figure 1A schematic cross-sectional view of a light emitting device according to a first embodiment of the present disclosure is shown.

[0038] Figure 2A A schematic top view of a second metal layer according to an embodiment of the present disclosure is shown.

[0039] Figure 2B Another schematic top view of the second metal layer according to an embodiment of the present disclosure is shown.

[0040] Figure 2C Another schematic top view of a second metal layer according to an embodiment of the present disclosure is shown.

[0041] Figure 3A A cross-sectional schematic diagram of a light emitting device according to a second embodiment of the present disclosure is shown.

[0042] Figure 3B A cross-sectional schematic diagram of another light emitting device according to the second embodiment of the present disclosure is shown.

[0043] Figure 4 A schematic cross-sectional view of a light emitting device according to a third embodiment of the present disclosure is shown.

[0044] Figure 5 A schematic flow chart showing a method for preparing a light emitting device according to a fourth embodiment of the present disclosure is shown.

[0045] Figure 6 A schematic flow chart showing a method for preparing a light emitting device according to a fifth embodiment of the present disclosure is shown.

[0046] Figure 7 A schematic flow chart showing a method for preparing a light emitting device according to a sixth embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0047] 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. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0048] In the related art, light-emitting devices such as LED (Light Emitting Diode) chips usually have only a single epitaxial structure, and their luminous brightness is low. When using light-emitting devices with such a structure to prepare display products, the brightness is generally increased by increasing the area or number of light-emitting devices, but this will reduce the display resolution, making the light-emitting devices unsuitable for preparing high-resolution display products.

[0049] In order to solve the above technical problems, the present disclosure provides a light emitting device. The present disclosure is described below in conjunction with the accompanying drawings.

[0050] Figure 1 A cross-sectional schematic diagram of a light emitting device 100 according to a first embodiment of the present disclosure is shown. The light emitting device of the present disclosure embodiment includes but is not limited to micrometer-level micron light emitting diodes (Micro LEDs for short) and sub-millimeter light emitting diodes (Mini LEDs for short), and the type and size of the light emitting device 100 can be selected and adjusted according to actual needs.

[0051] like Figure 1 As shown, the light emitting device 100 includes a first metal layer 11, a first epitaxial structure 12, a second epitaxial structure 13 and a second metal layer 14. The first epitaxial structure 12 is located on one side of the first metal layer 11, the second epitaxial structure 13 is located on the side of the first epitaxial structure 12 away from the first metal layer 11, the second metal layer 14 is located between the first epitaxial structure 12 and the second epitaxial structure 13, and the second metal layer 14 has a hollow portion 141; a transparent conductive layer 15 is located on the side of the second epitaxial structure 13 away from the first metal layer 11. Among them, the first metal layer 11 can be one of materials such as gold (Au), silver (Ag), nickel (Ni), copper (Cu) and their alloys. The second metal layer 12 can be at least one of materials such as gold, silver, nickel, copper and the like, and can also be one of transparent conductive materials such as indium tin oxide (ITO) and indium zinc oxide (IZO).

[0052] Exemplarily, the first epitaxial structure 12 and the second epitaxial structure 13 respectively include a first semiconductor layer 121, a light-emitting layer 122, and a second semiconductor layer 123 stacked along the light-emitting direction. The light-emitting direction may be the overall light-emitting direction of the light-emitting device 100, for example, the first metal layer 11 points to the direction of the transparent conductive layer 15. Among them, the first semiconductor layer 121 is an electron transport layer, and the second semiconductor layer 123 is a hole transport layer; or, the first semiconductor layer 121 is a hole transport layer, and the second semiconductor layer 123 is an electron transport layer. The light-emitting layer 122 is a multi-quantum well layer. The first epitaxial structure 12 and the second epitaxial structure 13 form a PN junction. When a voltage is applied to the first metal layer 11 and the transparent conductive layer 15, the multi-quantum well layer 122 of the first epitaxial structure 12 and the second epitaxial structure 13 emits light, thereby realizing the light emission of the first epitaxial structure 12 and the second epitaxial structure 13.

[0053] Exemplarily, the second metal layer 14 is disposed between the first epitaxial structure 12 and the second epitaxial structure 13, so that the first epitaxial structure 12 and the second epitaxial structure 13 are connected in series, that is, two PN junctions are connected in series. When the first epitaxial structure 12 and the second epitaxial structure 13 emit light, the light emitted by the first epitaxial structure 12 can pass through the hollow portion 141 and mix with the light emitted by the second epitaxial structure 13 and emit along the light emitting direction, so that the light emitting device 100 has a strong light emitting brightness.

[0054] In the related art, the light-emitting device with a single epitaxial structure has a low luminance and is not suitable for preparing high-resolution display products. In the embodiment of the present disclosure, the first epitaxial structure 12 and the second epitaxial structure 13 are stacked and arranged between the first metal layer 11 and the transparent conductive layer 15, and a second metal layer 14 having a hollow portion 141 is arranged between the first epitaxial structure 12 and the second epitaxial structure 13, so that when a voltage is applied to the first metal layer 11 and the transparent conductive layer 15, the light emitted by the first epitaxial structure 12 can pass through the hollow portion 141 and mix with the light emitted by the second epitaxial structure 13 and emit, thereby improving the luminance of the light-emitting device 100, making it suitable for preparing high-resolution display products, especially suitable for preparing Micro LED display products.

[0055] In one embodiment, the light emitted by the first epitaxial structure 12 and the second epitaxial structure 13 is within the same wavelength range.

[0056] Exemplarily, the light emitted by the first epitaxial structure 12 and the second epitaxial structure 13 is in the red light band, the green light band or the blue light band. The red light band has a wavelength range of 622nm to 780nm (including the endpoint values), the green light band has a wavelength range of 492nm to 577nm (including the endpoint values), and the blue light band has a wavelength range of 455nm to 492nm (including the endpoint values).

[0057] For example, please refer to Figure 3A or Figure 4 , the material of the first semiconductor layer 121 can be an N-type semiconductor, and the material of the second semiconductor layer 123 can be a P-type semiconductor; or, the material of the first semiconductor layer 121 can be a P-type semiconductor, and the material of the second semiconductor layer 123 can be an N-type semiconductor. By selecting different types of materials, the first epitaxial structure 12 and the second epitaxial structure 13 can emit light of different colors. For example, the N-type semiconductor can be selected from at least one of GaN, Si-doped GaN, and Si-doped AlGaN, the P-type semiconductor can be selected from at least one of Mg-doped GaN and Mg-doped AlGaN, the material of the light-emitting layer 122 can be InGaN, and by adjusting the proportion of indium (In) in the InGaN alloy, the light emitted by the first epitaxial structure 12 and the second epitaxial structure 13 can be located in the blue light band or the green light band. The intrinsic semiconductors of the N-type semiconductor and the P-type semiconductor are both selected from InGaAlP, so that the light emitted by the first epitaxial structure 12 and the second epitaxial structure 13 can be located in the red light band.

[0058] The above scheme, by setting the light emitted by the first epitaxial structure 12 and the second epitaxial structure 13 to be in the same wavelength range, is conducive to increasing the luminous brightness of the light emitting device 100. It is understandable that when it is necessary to mix light in different wavelength bands, the light emitted by the first epitaxial structure 12 and the second epitaxial structure 13 can also be set to be in different wavelength bands.

[0059] In one embodiment, if Figure 2A and Figure 2B As shown, the second metal layer 14 also includes a bonding portion 142, and the orthographic projection of the hollow portion 141 on the first metal layer 11 is located within the orthographic projection range of the bonding portion 142 on the first metal layer 11. Exemplarily, the orthographic projection of the bonding portion 142 on the first metal layer 11 surrounds the orthographic projection of the hollow portion 141 on the first metal layer 11. The shape of the orthographic projection of the hollow portion 141 on the first metal layer 11 and the shape of the orthographic projection of the bonding portion 142 on the first metal layer 11 can be selected and adjusted according to actual needs. For example, the orthographic projection of the hollow portion 141 on the first metal layer 11 can be one of closed figures such as a circle, an ellipse, a rectangle, a square, a pentagon and a hexagon. The orthographic projection of the bonding portion 142 on the first metal layer 11 can be an annular structure, which has an outer contour and an inner contour, wherein the geometric center of the outer contour coincides with the geometric center of the inner contour, and the shape of the outer contour and the inner contour can be any one of a circle, an ellipse, a rectangle, a square, and a polygon.

[0060] A portion of the light emitted by the first epitaxial structure 12 passes through the hollow portion 141 of the second metal layer 14 to mix with the light emitted by the second epitaxial structure 13, and another portion of the light emitted by the first epitaxial structure 12 is reflected by the bonding portion 142 and the first metal layer 11 in turn, and then passes through the hollow portion 141 to enter the second epitaxial structure 13 for mixing, which is beneficial to increase the luminous intensity and achieve light emission in a small area.

[0061] In one embodiment, if Figure 2C As shown, the second metal layer 14 also includes two bonding parts 142, and the orthographic projections of the two bonding parts 142 on the first metal layer 11 are respectively located on opposite sides of the orthographic projection of the hollow part 141 on the first metal layer 11. Exemplarily, the periphery of the orthographic projection of the bonding part 142 on the first metal layer 11 is at least partially surrounded by the orthographic projection of the hollow part 141 on the first metal layer 11. The shape of the orthographic projection of the bonding part 142 on the first metal layer 11 can be selected and adjusted according to actual needs. For example, the orthographic projection of the bonding part 142 on the first metal layer 11 can be one of closed figures such as a circle, an ellipse, a square and a rectangle. In this way, it is convenient to make the bonding part 142 smaller to avoid the bonding part 142 blocking the light emitted by the first epitaxial structure 12.

[0062] In one embodiment, if FIG. 2A to FIG. 2C As shown, the orthographic projection of the bonding portion 142 on the first metal layer 11 and the orthographic projection of the hollow portion 141 on the first metal layer 11 cover the first metal layer 11, and the area of ​​the orthographic projection of the hollow portion 141 on the first metal layer 11 is greater than or equal to one-half of the area of ​​the first metal layer 11 and is smaller than the area of ​​the first metal layer 11. By setting the area of ​​the orthographic projection of the hollow portion 141 on the first metal layer 11 to be larger, it is convenient for the light emitted by the first epitaxial structure 12 to pass through the hollow portion 141 as much as possible, thereby reducing the shielding of the light by the bonding portion 142. It should be noted that the dimensions of the hollow portion 141 and the bonding portion 142, such as the length of the diagonal line of the geometric outline of the hollow portion 141 and the bonding portion 142, the side length, the diameter, the area, etc., can be selected and adjusted according to actual needs, and the embodiments of the present disclosure do not limit them.

[0063] In one embodiment, if Figure 3A As shown, the light emitting device 100 also includes a first light adjustment layer 16. The first light adjustment layer 16 is arranged in the same layer as the second metal layer 14 and is located at the position of the hollow portion 141. Exemplarily, the first light adjustment layer 16 includes a transparent layer and scattering particles distributed in the transparent layer. The material of the transparent layer and the second metal layer 14 can be transparent conductive materials such as indium tin oxide (ITO) and indium zinc oxide (IZO), or transparent insulating materials such as resin. The material of the scattering particles can be metal oxides or metal materials such as titanium oxide, titanium dioxide, gold, and silver. By arranging the first light adjustment layer 16 at the position where the hollow portion 141 is located, when the light emitted by the first epitaxial structure 12 passes through the first light adjustment layer 16, the path of the light can be adjusted, for example, the light can be scattered so that the light passing through the first light adjustment layer 16 is scattered. In this way, not only can the brightness of the light emitting device 100 be improved, but also the light emitting device 100 has a larger light output angle, which is more helpful to improve the backlight uniformity effect in the application of backlight display products, shorten the light mixing distance, and facilitate the thinning and lightness of the product. In addition, when the material of the transparent layer is a transparent conductive material, the scattering particles can also have a conductive effect.

[0064] In one embodiment, if Figure 4As shown, the first epitaxial structure 12 and the second epitaxial structure 13 respectively include a first semiconductor layer 121, a light-emitting layer 122, and a second semiconductor layer 123 stacked along the light emitting direction, and the second semiconductor layer 123 of the second epitaxial structure 13 protrudes in a direction away from the first metal layer 11 to form a second light adjustment layer (not marked in the figure). Exemplarily, the second light adjustment layer formed by the first semiconductor layer 121 of the second epitaxial structure 13 may include a convex lens (not marked in the figure), such as a cylindrical convex lens or a spherical convex lens, so that the second light adjustment layer also has a focusing function. Among them, the orthographic projection area of ​​the convex lens on the first metal layer 11 is smaller than the area of ​​the first metal layer 11, and the orthographic projection of the blank portion 141 on the first metal layer 11 is located within the orthographic projection range of the convex lens on the first metal layer 11.

[0065] In the above scheme, the second semiconductor layer 123 of the second epitaxial structure 13 is reused to form the second light adjustment layer, which can converge the emission direction of the light, so that the overall light emission angle of the light emitting device 100 is reduced and the light emission brightness in a specific direction is higher. In addition, using the second semiconductor layer 123 of the second epitaxial structure 13 as the second light adjustment layer is also beneficial to saving consumables and reducing preparation costs.

[0066] In one embodiment, the light emitting device 100 further includes a second light adjustment layer (not shown in the figure), which is disposed on a side of the second epitaxial structure 13 away from the first metal layer 11. Exemplarily, the material of the second light adjustment layer can be a transparent insulating material such as resin. By providing the second light adjustment layer, the mixed light can be converged along the light emitting direction, thereby reducing the light emitting angle of the light emitting device 100 and increasing its brightness.

[0067] In one embodiment, please refer to Figure 2A , Figure 2B and Figure 4, the orthographic projection of the hollow portion 141 on the first metal layer 11 overlaps with the orthographic projection of the second light adjustment layer on the first metal layer 11, and the refractive index of the hollow portion 141 is less than the refractive index of the second epitaxial structure 13. Exemplarily, the orthographic projection area of ​​the hollow portion 141 on the first metal layer 11 is smaller than the orthographic projection area of ​​the second light adjustment layer on the first metal layer 11, and the orthographic projection of the hollow portion 141 on the first metal layer 11 is located within the outer contour of the orthographic projection of the second light adjustment layer on the first metal layer 11. This structure allows part of the light emitted by the first epitaxial structure 12 to directly pass through the hollow portion 141, and allows another part of the light that cannot directly pass through the hollow portion 141 to pass through the hollow portion 141 after being reflected by the first metal layer 11 and the second metal layer 12 in turn, so that the first epitaxial structure 12 can emit light in a small area. In addition, since the refractive index of the hollow portion 141 is lower than that of the second epitaxial structure 13, when the light enters the second epitaxial structure 13 from the hollow portion 141, it will be refracted, so that the propagation direction of the light emitted from the hollow portion 141 and incident into the second epitaxial structure 13 is closer to the normal line than the propagation direction of the light in the hollow portion 141, and has a certain focusing effect. In addition, the second light adjustment layer can further focus the mixed light, so that the light emitting device has a better focusing effect and a smaller light output angle.

[0068] Optionally, the second light adjustment layer may be a cylindrical convex lens or a spherical convex lens.

[0069] In one embodiment, if Figure 3B and Figure 4 As shown, the first epitaxial structure 12 and the second epitaxial structure 13 respectively include a first current diffusion layer 124, a first semiconductor layer 121, a light emitting layer 122, a second semiconductor layer 123 and a second current diffusion layer 125 stacked along the light emitting direction, and the materials of the first current diffusion layer 124 and the second current diffusion layer 125 are transparent conductive materials such as indium tin oxide (ITO) and indium zinc oxide (IZO). The first current diffusion layer 124 and the second current diffusion layer 125 can increase the uniformity of current diffusion and avoid absorbing light to reduce the brightness of the light emitting device 100.

[0070] In one embodiment, there are multiple first epitaxial structures 12, and multiple first epitaxial structures 12 are stacked between the second epitaxial structure 13 and the first metal layer 11, and a second metal layer 14 is provided between adjacent first epitaxial structures 12. Exemplarily, the orthographic projections of the hollow portions 141 of each second metal layer 14 on the first metal layer 11 overlap. By providing multiple first epitaxial structures 12, the light emitted by the multiple first epitaxial structures 12 can be mixed with the light emitted by the second epitaxial structure 13 after passing through the corresponding hollow portions 141 and emitted, which is beneficial to improving the brightness of the light-emitting device 100. It should be noted that the number of first epitaxial structures 12 can be one, two, or more than two, and the number can be selected and adjusted according to actual needs.

[0071] It is understandable that the above embodiments and drawings only show the core film layer of the light-emitting device 100 of the present disclosure, and the light-emitting device 100 may further include one or more of the following film layers: a buffer layer, a Bragg reflector layer, a current blocking layer, a first electrode, and a second electrode. The first electrode may be a first metal layer or an electrode connected to the first metal layer, and the second electrode is an electrode connected to the transparent conductive layer 15 of the second epitaxial structure 13.

[0072] For example, please refer to Figure 3B The buffer layer 126 is located between the first metal layer 11 and the first semiconductor layer 121 of the first epitaxial structure 12, between the first current diffusion layer 124 and the first semiconductor layer 121 of the first epitaxial structure 12, between the first semiconductor layer 121 and the second metal layer 14 of the second epitaxial structure 13, or between the first current diffusion layer 124 and the second metal layer 14 of the second epitaxial structure 13. The microstructure on the buffer layer 126 is formed when the first epitaxial structure 12 and the second epitaxial structure 13 are grown, which will be described below.

[0073] The Bragg reflector layer is located between the first metal layer 11 and the first semiconductor layer 121 of the first epitaxial structure 12; the Bragg reflector layer is a periodic film layer structure composed of alternating high refractive index materials and low refractive index materials. By adjusting the refractive index of the high refractive index material and the low refractive index material and the thickness of the periodic film layer, the energy gap position can be changed to make the Bragg reflector layer adapt to light in different wavelength ranges.

[0074] The current blocking layer is located between the second semiconductor layer 123 and the second current diffusion layer 125 of the first epitaxial structure 12, and / or between the second semiconductor layer 123 and the second current diffusion layer 125 of the second epitaxial structure 13. The current blocking layer can avoid current crowding at the second metal layer 14 and the second electrode, which is beneficial to further improve the current diffusion performance.

[0075] The present disclosure also provides a display device, including the light-emitting device of any one of the above embodiments. For example, the display device may be one of a backlight display device, a direct display device, and a liquid crystal display device. Display devices include but are not limited to mobile phones, tablet computers, televisions, monitors, laptop computers, digital photo frames, navigators, smart watches, and other products or components with display functions.

[0076] The present disclosure also provides a method for preparing the light emitting device 100. Figure 5 As shown, the method for preparing the light emitting device 100 includes:

[0077] Step S51, forming a first wafer and a second wafer (not marked in the figure) respectively; the first wafer has a first substrate 120A and a first epitaxial structure film 12A and a first metal film 14A stacked on one side of the first substrate 120A, the first metal film 14A has a plurality of hollow portions 141, and the second wafer has a second substrate 130A and a second epitaxial structure film 13A located on one side of the second substrate 130A;

[0078] Step S52, bonding the side of the second epitaxial structure film 13A away from the second substrate 130A to the side of the first metal film 14A away from the first substrate 120A, and peeling off the first substrate 120A;

[0079] Step S53, forming a second metal film 11A on a side of the first epitaxial structure film 12A away from the first metal film 14A;

[0080] Step S54, patterning the second metal film 11A, the first epitaxial structure film 12A, the first metal film 14A, and the second epitaxial structure film 13A respectively to form a plurality of light-emitting units 100A, so that the light-emitting unit 100A has a hollow portion 141;

[0081] Step S55: peel off the second substrate 130A, and arrange a transparent conductive layer 15 on the side of the light-emitting unit 100A away from the patterned second metal film 11A to form the light-emitting device 100. The patterned first metal film 14A constitutes the second metal layer 14, the patterned second metal film 11A constitutes the first metal layer 11, and the patterned first epitaxial structure film 12A and the patterned second epitaxial structure film 13A constitute the first epitaxial structure 12 and the second epitaxial structure 13, respectively.

[0082] For example, Figure 5As shown, forming the first wafer includes: step S511A, sequentially growing a first semiconductor film 121A, a light-emitting film 122A, and a second semiconductor film 123A on one side of a first substrate 120A, wherein the first semiconductor film 121A, the light-emitting film 122A, and the second semiconductor film 123A constitute a first epitaxial structure film 12A; step S512A, forming a first metal film 14A on a side of the first epitaxial structure film 12A away from the first substrate 120A. Forming the second wafer includes: step S511B, sequentially growing a first semiconductor film 121A, a light-emitting film 122A, and a second semiconductor film 123A on one side of a growth substrate 50, constituting a second epitaxial structure film 13A; step S512B, after pasting a second substrate 130A on a side of the second semiconductor film 123A away from the growth substrate 50, peeling off and removing the growth substrate 50.

[0083] Exemplarily, the material of the first substrate 120A and the growth substrate 50 may be one of sapphire, silicon, silicon carbide, glass, quartz, etc. When the material of the first substrate 120A and the growth substrate 50 is sapphire, forming the first epitaxial structure film 12A on the first substrate 120A, or forming the second epitaxial structure film 13A only on the growth substrate 50, will produce a large dislocation density, resulting in a low internal quantum efficiency of the light-emitting device 100. In this way, a periodic microstructure, such as a patterned sapphire substrate (Patterned Sapphire Substrate, PPS), may be provided on the growth surface of the first substrate 120A and / or the growth substrate 50, thereby reducing the dislocation density and increasing the escape probability of photons on the light-emitting film. In addition, a buffer layer (made of, for example, GaN or AlN) can be first provided on the surface of the first substrate 120A and the growth substrate 50 to provide a nuclear center for the film growth of the first epitaxial structure film 12A and / or the second epitaxial structure film 13A, thereby promoting the semiconductor material to change from three-dimensional island growth to two-dimensional lateral growth and reducing the dislocation density.

[0084] Step S52 includes: using one of the bonding processes such as eutectic bonding and hybrid bonding to bond the surface of the first metal film 14A facing away from the first substrate 120A with the surface of the first semiconductor film 121A of the second epitaxial structure film 13A facing away from the second substrate 130A, and peeling off and removing the first substrate 120A to expose the first semiconductor film 121A of the first epitaxial structure film 12A.

[0085] Step S53 includes forming a second metal film 11A on a side of the first semiconductor film 121A of the first epitaxial structure film 12A that is away from the first metal film 14A.

[0086] Step S54 includes: patterning the second metal film 11A, the first epitaxial structure film 12A, the first metal film 14A, and the second epitaxial structure film 13A in sequence to form an array of multiple light-emitting units 100A, so that one light-emitting unit 100A has a hollow portion 141; wherein the patterned second metal film 11A, the first epitaxial structure film 12A, the first metal film 14A, and the second epitaxial structure film 13A respectively constitute the first metal layer 11, the first epitaxial structure 12, the second metal layer 14, and the second epitaxial structure 13 of the light-emitting unit 100A.

[0087] Step S55 includes: removing the second substrate 130A by stripping, and forming a transparent conductive layer 15 on a side of the light emitting unit 100A away from the first metal layer 11 .

[0088] Preferably, from step S54 to step S55, the second substrate 130A can be peeled off and removed after the multiple light-emitting units 100A on the second substrate 130A are transferred to the driving substrate, so that the transparent conductive layer 15 can continue to be formed on the side of the second epitaxial structure 13 away from the first metal layer 11, and electrode bonding or conductive traces can be formed. It should be noted that the first semiconductor film 121A and the second semiconductor film 123A can be an electron transport film and a hole transport film, respectively, or a hole transport film and an electron transport film, respectively. The light-emitting film 122A is a multi-quantum well film. The material of the first semiconductor is the same as the material of the first semiconductor layer in this article, and the material of the second semiconductor film 123A is the same as the material of the second semiconductor layer in this article, which will not be repeated here.

[0089] In another example, Figure 6As shown, forming the first wafer includes: step S511A, growing a first semiconductor film 121A, a light-emitting film 122A and a second semiconductor film 123A in sequence on one side of a first substrate 120A, the first semiconductor film 121A, the light-emitting film 122A and the second semiconductor film 123A constitute a first epitaxial structure film 12A; step S512A, forming a first current diffusion film 125A and a first metal film 14A in sequence on a side of the first epitaxial structure film 12A away from the first substrate 120A, the first metal film 14A having a plurality of hollow portions 141; step S513A, forming a first light adjustment film 16A at the location of the hollow portions 141. Forming the second wafer includes: step S511B, sequentially growing a first semiconductor film 121A, a light-emitting film 122A, a second semiconductor film 123A and a first current diffusion film 125A on one side of a growth substrate 50, wherein the first semiconductor film 121A, the light-emitting film 122A and the second semiconductor film 123A constitute a second epitaxial structure film 13A; step S512B, after pasting the second substrate 130A on the side of the first current diffusion film 125A away from the growth substrate 50, peeling off and removing the growth substrate 50 to expose the first semiconductor film 121A of the second epitaxial structure film 13A; step S513B, forming a second current diffusion film 124A on the side of the first semiconductor film 121A of the second epitaxial structure film 13A away from the second substrate 130A.

[0090] Step S52 includes: using one of the bonding processes such as eutectic bonding and hybrid bonding to bond the surface of the first wafer 10A facing away from the first substrate 120A to the surface of the second wafer 10B facing away from the second substrate 130A, and peeling off the first substrate 120A to expose the first semiconductor film 121A of the first epitaxial structure film 12A.

[0091] Step S53 includes: sequentially forming a second current diffusion film 124A and a second metal film 11A on a side of the first epitaxial structure film 12A away from the first metal film 14A.

[0092] Step S54, patterning the second metal film 11A, the second current diffusion film 124A between the first epitaxial structure film 12A and the second metal film 11A, the first epitaxial structure film 12A, the first current diffusion film 125A between the first epitaxial structure film 12A and the first metal film 11A, the first metal film 14A, the second current diffusion film 124A between the first metal film 14A and the second epitaxial structure film 13A, the second epitaxial structure film 13A, and the first current diffusion film 125A between the second epitaxial structure film 13A and the second substrate 130A, respectively, to form the first metal layer 11, the first current diffusion layer 124 of the first epitaxial structure 12, the first epitaxial structure 12, the second current diffusion layer 125 of the first epitaxial structure 12, the second metal layer 14, the first current diffusion layer 124 of the second epitaxial structure 13, the second epitaxial structure 13, and the second current diffusion layer 125 of the second epitaxial structure 13, and form the light-emitting unit 100A.

[0093] Step S55, the second substrate 130A is peeled off and removed, the second current diffusion layer 125 located on the side of the second epitaxial structure 13 away from the first metal layer 11 is exposed, and a transparent conductive layer 15 is formed to obtain the light-emitting device 100. Optionally, the second current diffusion layer 125 can be used as the transparent conductive layer 15, or a new transparent conductive layer (not marked in the figure) can be formed on the side of the second current diffusion layer 125 away from the first metal layer 11.

[0094] In one embodiment, forming the first wafer includes: forming a first light adjustment film 16A at the locations of the plurality of hollow portions 141 of the first metal film 14A. Figure 6 As shown, forming the first wafer includes: step S513A, coating a plurality of hollow portions 141 of the first metal film 14A with a transparent material having scattering particles, such as a transparent insulating material having scattering particles or a transparent conductive material having scattering particles, to form a first light adjustment film 16A. In this way, when the light emitting device 100 is formed in step S55, the first light adjustment film 16A can form a first light adjustment layer 16 at the location of the hollow portion 141 of each light emitting device 100.

[0095] In one embodiment, if Figure 7 As shown, forming the second wafer includes:

[0096] Step S511C to step S514C, sequentially forming a first semiconductor film 121A, a light emitting film 122A, a second semiconductor film 123A and a mask pattern 72 on one side of the growth substrate 50;

[0097] Step S515C, transferring the mask pattern 72 onto the second semiconductor film 123A; wherein the first semiconductor film 121A, the light emitting film 122A and the second semiconductor 123A having the mask pattern can constitute a second epitaxial structure film 13A.

[0098] Step S516C to step S517C: a second substrate 130A is disposed on the side of the second semiconductor film 123A facing away from the growth substrate 50 , and the growth substrate 50 is peeled off.

[0099] For example, Figure 7 As shown, forming a mask pattern includes: step S512C, coating a photoresist 70 on the side of the second semiconductor film 123A away from the growth substrate 50; step S513C, patterning the photoresist 70 to form a photoresist pattern 71; step S514C, heating the photoresist pattern 71 using a thermal reflow process to form a lens-shaped mask pattern 72 having multiple spaced and parallel arranged lens-shaped patterns, wherein the lens-shaped mask pattern can have the morphology of a cylindrical convex lens or a spherical convex lens.

[0100] Step S515C includes: using a plasma etching process to sequentially etch the mask pattern 72 and the second semiconductor film 123A, so that the mask pattern is transferred to the second semiconductor film 123A, that is, the second semiconductor film 123A has a conformal morphology with the mask pattern 72. Specifically, when the mask pattern 72 and the second semiconductor film 123A are bombarded with plasma, each part of the mask pattern 72 is gradually etched with equal size until it is completely removed. Finally, the second semiconductor film 123A will have the same morphology as the mask pattern 72, that is, a plurality of spaced and parallel arranged convex lens structures are also formed in the second semiconductor film 123A, and the convex lenses can be cylindrical convex lenses or spherical convex lenses.

[0101] Steps S516C to S517C include: after attaching the second substrate 130A to the side of the second semiconductor film 123A away from the growth substrate 50, peeling off the growth substrate 50. Alternatively, steps S516C to S517C include: after sequentially forming the first current diffusion film 125A on the side of the second semiconductor film 123A away from the growth substrate 50 and attaching the second substrate 130A, peeling off the growth substrate 50.

[0102] The forming of the second wafer may further include step S518C of forming a second current spreading film 124A on a side of the first semiconductor film 121A facing away from the second substrate 130A.

[0103] Figure 7 Steps S52 to S55 and Figure 6 Steps S52 to S55 in are similar, and can be referred to above. Figure 6The difference is that Figure 7 In steps S53 to S55, the second metal film 11A, the first epitaxial structure film 12A, the first metal film 14A, and the second epitaxial structure film 13A are patterned in sequence, so that each light-emitting unit 100A has a hollow portion 141 and a second light-adjusting layer, wherein the second light-adjusting layer is formed by patterning the second semiconductor film 123A in the second epitaxial structure 13, and a second light-adjusting layer includes a convex lens, wherein the orthographic projection area of ​​the convex lens on the first metal layer 11 is smaller than the area of ​​the first metal layer 11, and the orthographic projection of the blank portion 141 on the first metal layer 11 is located within the orthographic projection range of the convex lens on the first metal layer 11. The light emitted by the first epitaxial structure 12 in the formed light-emitting device 100 passes through the hollow portion 141 and is mixed with the light emitted by the second epitaxial structure 13, and the second light-adjusting layer can focus the mixed light. It should be noted that, in this article, the first current spreading film 125A forms the second current spreading layer 125 in the light-emitting device after patterning, and the second current spreading film 124A forms the first current spreading layer 124 in the light-emitting device after patterning. In addition, since the second light adjustment layer has a conformal morphology to the mask pattern 72, after the first current spreading film 125A is patterned, the second current spreading layer 125 can also have a conformal morphology to the mask pattern 72.

[0104] In one embodiment, the first epitaxial structure film 12A includes a plurality of first epitaxial structure films 12A stacked along the light emitting direction, the plurality of first epitaxial structure films 12A include a bottom epitaxial structure film located at the bottom in the light emitting direction, and a second metal film 11A is formed on a side of the first epitaxial structure film 12A away from the first metal film 14A, including:

[0105] The second metal film 11A is formed on the side of the underlying epitaxial structure film facing away from the first metal film 14A.

[0106] For example, please refer to Figure 5 In step S52, after bonding a first epitaxial structure film 12A to a second epitaxial structure film 13A, the remaining first epitaxial structure films 12A may be bonded in sequence along a direction away from the light emitting direction in a similar bonding manner as step S52, thereby realizing a stacked arrangement of multiple first epitaxial structure films 12A, and using the first epitaxial structure film 12A located at the bottom layer in the light emitting direction as the bottom epitaxial structure film; and forming a second metal film 11A on the side of the bottom epitaxial structure film away from the first metal film 14A.

[0107] 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.

[0108] In addition, the terms "second" 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 the indicated technical features. Thus, a feature defined as "second" 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.

[0109] 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.

[0110] In the present disclosure, unless otherwise clearly specified and limited, a second feature being “above” or “below” a second feature may include the second and second features being in direct contact, or may include the second and second features being in contact not directly but through another feature between them. Moreover, a second feature being “above”, “above”, and “above” a second feature includes the second feature being directly above and obliquely above the second feature, or simply indicates that the second feature is higher in level than the second feature. A second feature being “below”, “below”, and “below” a second feature includes the second feature being directly above and obliquely above the second feature, or simply indicates that the second feature is lower in level than the second feature.

[0111] The disclosure above provides many different embodiments or examples to realize different structures of the present disclosure. In order to simplify the disclosure of 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, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0112] The above is only a specific implementation 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 substitutions within the technical scope disclosed in the present disclosure, 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 device, characterized in that: include: A first metal layer; A first epitaxial structure, located on one side of the first metal layer; a second epitaxial structure located on a side of the first epitaxial structure away from the first metal layer; A second metal layer is located between the first epitaxial structure and the second epitaxial structure, and the second metal layer has a hollow portion; The transparent conductive layer is located on a side of the second epitaxial structure away from the first metal layer.

2. The light emitting device according to claim 1, characterized in that: The light emitted by the first epitaxial structure and the second epitaxial structure is within the same wavelength band.

3. The light emitting device according to claim 1, characterized in that: The second metal layer further includes a bonding portion, and an orthographic projection of the hollow portion on the first metal layer is located within a range of an orthographic projection of the bonding portion on the first metal layer.

4. The light emitting device according to claim 1, characterized in that: The second metal layer further includes two bonding portions, and the orthographic projections of the two bonding portions on the first metal layer are respectively located on opposite sides of the orthographic projection of the hollow portion on the first metal layer.

5. The light emitting device according to claim 3 or 4, characterized in that: The orthographic projection of the bonding portion on the first metal layer and the orthographic projection of the hollow portion on the first metal layer cover the first metal layer, and the area of ​​the orthographic projection of the hollow portion on the first metal layer is greater than or equal to half of the area of ​​the first metal layer and smaller than the area of ​​the first metal layer.

6. The light emitting device according to claim 1, characterized in that: Also includes: The first light adjustment layer is disposed on the same layer as the second metal layer and is located at the position of the hollow portion.

7. The light emitting device according to claim 1, characterized in that: The first epitaxial structure and the second epitaxial structure respectively include a first semiconductor layer, a light emitting layer and a second semiconductor layer stacked along the light emitting direction. The second semiconductor layer of the second epitaxial structure protrudes away from the first metal layer to form a second light adjustment layer.

8. The light emitting device according to claim 1, characterized in that: Also includes: The second light adjustment layer is disposed on a side of the second epitaxial structure away from the first metal layer.

9. The light emitting device according to claim 7 or 8, characterized in that: An orthographic projection of the hollow portion on the first metal layer overlaps with an orthographic projection of the second light adjustment layer on the first metal layer, and a refractive index of the hollow portion is less than a refractive index of the second epitaxial structure.

10. The light emitting device according to claim 1, characterized in that: The first epitaxial structure and the second epitaxial structure respectively include a first current diffusion layer, a first semiconductor layer, a light emitting layer, a second semiconductor layer and a second current diffusion layer stacked along the light emitting direction. The first current diffusion layer and the second current diffusion layer are both made of transparent conductive material.

11. The light emitting device according to claim 1, characterized in that: There are a plurality of the first epitaxial structures, and the plurality of the first epitaxial structures are stacked and arranged between the second epitaxial structure and the first metal layer, and the second metal layer is arranged between adjacent first epitaxial structures.

12. A display device, characterized in that: A light emitting device comprising any one of claims 1 to 11.

13. A method for preparing a light emitting device, characterized in that: include: A first wafer and a second wafer are formed respectively; the first wafer has a first substrate and a first epitaxial structure film and a first metal film stacked on one side of the first substrate, the first metal film has a plurality of hollow parts, and the second wafer has a second substrate and a second epitaxial structure film located on one side of the second substrate; Bonding a side of the second epitaxial structure film away from the second substrate to a side of the first metal film away from the first substrate and peeling off the first substrate; forming a second metal film on a side of the first epitaxial structure film away from the first metal film; performing patterning on the second metal film, the first epitaxial structure film, the first metal film and the second epitaxial structure film respectively to form a plurality of light-emitting units, so that the light-emitting units have the hollow parts; The second substrate is peeled off, and a transparent conductive layer is disposed on a side of the light-emitting unit away from the patterned second metal film to form a light-emitting device.

14. The preparation method according to claim 13, characterized in that: Forming the second wafer includes: A first light adjustment film is formed at the location of the hollow portion.

15. The preparation method according to claim 13, characterized in that: Forming the second wafer includes: sequentially forming a first semiconductor film, a light emitting film, a second semiconductor film and a mask pattern on one side of a growth substrate; transferring the mask pattern onto the second semiconductor film; The second substrate is disposed on a side of the second semiconductor film facing away from the growth substrate, and the growth substrate is peeled off.

16. The preparation method according to claim 13, characterized in that: The first epitaxial structure film includes a plurality of layers stacked along a light emitting direction, the plurality of first epitaxial structure films include a bottom epitaxial structure film located at the bottom in the light emitting direction, and a second metal film is formed on a side of the first epitaxial structure film away from the first metal film, including: The second metal film is formed on a side of the underlying epitaxial structure film away from the first metal film.

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