Micro light emitting element

Abstract

The present invention provides a micro light emitting element, comprising a first type cladding layer, a light emitting layer, a second type cladding layer, a multi-layer window layer, and at least one intermediate layer. The light emitting layer is on the first type cladding layer, and the second type cladding layer is on the light emitting layer. The light emitting layer is between the first type cladding layer and the second type cladding layer. The multi-layer window layer is on the second type cladding layer. The intermediate layer is between two adjacent layers of the multi-layer window layer. The ion doping concentration of the intermediate layer is less than or equal to the ion doping concentration of the multi-layer window layer.

Description

TECHNICAL FIELD

[0001] The present invention relates to a light emitting element, and more particularly to a micro light emitting element. BACKGROUND

[0002] In the development of light emitting diodes, researchers have developed high-brightness visible light emitting diodes (LEDs) such as red LEDs, yellow LEDs or orange LEDs using aluminum gallium indium phosphide (AlGaInP). In order to solve the problem of uneven current distribution outside the ohmic contact region, a common approach is to form a window layer using gallium phosphide (GaP) on a p-type cladding layer (e.g. a p-type aluminum gallium indium phosphide layer). However, because the lattice constant of the window layer does not match the lattice constant of the p-type cladding layer, a high density of dislocation defects is easily formed in the window layer, which causes the leakage current of the light emitting diode to rise, resulting in poor light emitting efficiency of the light emitting diode. SUMMARY

[0003] The present invention is directed to a micro light emitting element having better light emitting efficiency.

[0004] According to an embodiment of the present invention, a micro light emitting element includes a first type cladding layer, a light emitting layer, a second type cladding layer, a multi-layer window layer, and at least one intermediate layer. The light emitting layer is on the first type cladding layer, and the second type cladding layer is on the light emitting layer. The light emitting layer is between the first type cladding layer and the second type cladding layer. The multi-layer window layer is on the second type cladding layer. The intermediate layer is between two adjacent layers of the window layer. The ion doping concentration of the intermediate layer is less than or equal to the ion doping concentration of the multi-layer window layer.

[0005] According to another embodiment of the present invention, a micro light emitting element includes a first type cladding layer, a light emitting layer, a second type cladding layer, a multi-layer window layer, and at least one intermediate layer. The light emitting layer is on the first type cladding layer, and the second type cladding layer is on the light emitting layer. The light emitting layer is between the first type cladding layer and the second type cladding layer. The multi-layer window layer is on the second type cladding layer, and the material of the multi-layer window layer has a first lattice constant. The intermediate layer is between two adjacent layers of the window layer, and the material of the intermediate layer has a second lattice constant. The ratio of the second lattice constant to the first lattice constant is greater than or equal to 1.01 times or less than or equal to 0.99 times.

[0006] Based on the above, in the micro light emitting element of the present invention, any two adjacent layers of the window layer are separated by an intermediate layer, and the intermediate layer can be used to block the generation of dislocation defects from a lower layer of the window layer to an upper layer of the window layer, so as to reduce the density of dislocation defects in the window layer and improve the leakage current condition. Because the leakage current condition is improved, the light emitting efficiency of the micro light emitting element is improved. Attached Figure Description

[0007] FIG. 1A , FIG. 1B , FIG. 2A , FIG. 2B , FIGS. 3A-3D , FIG. 4A , FIG. 4B , FIG. 5 and FIG. 6 These are cross-sectional schematic diagrams of micro light-emitting elements according to different embodiments of the present invention;

[0008] FIG. 7 This is a cross-sectional schematic diagram of the epitaxial structure of a micro light-emitting element according to an embodiment of the present invention. Detailed Implementation

[0009] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element references are used in the drawings and description to denote the same or similar parts.

[0010] FIG. 1A , FIG. 1B , FIG. 2A , FIG. 2B , FIGS. 3A-3D , FIG. 4A , FIG. 4B , FIG. 5 and FIG. 6 This is a cross-sectional schematic diagram of a micro light-emitting element according to different embodiments of the present invention. Please refer to... FIG. 1A In this embodiment, the micro-light-emitting element 100 includes a first-type cladding layer 110, a light-emitting layer 120, a second-type cladding layer 130, a first window layer 140, a second window layer 141, and an interposer layer 150. The first-type cladding layer 110 can be a quaternary or ternary material, such as an n-type aluminum gallium indium phosphide layer or an aluminum indium phosphide layer. The second-type cladding layer 130 can also be a quaternary or ternary material, such as a p-type aluminum gallium indium phosphide layer or an aluminum indium phosphide layer. The light-emitting layer 120 may have a multiple quantum well (MQW) structure and is located on (or covers) the first-type cladding layer 110. Furthermore, the second-type cladding layer 130 is located on (or covers) the light-emitting layer 120, and the light-emitting layer 120 is located between the first-type cladding layer 110 and the second-type cladding layer 130.

[0011] The first cladding layer 110, the light emitting layer 120, and the second cladding layer 130 are sequentially stacked from bottom to top, and the first window layer 140, the intermediate layer 150, and the second window layer 141 are sequentially stacked from bottom to top on the second cladding layer 130. Further, the first window layer 140 is located on (or covers) the second cladding layer 130, wherein the intermediate layer 150 is located on (or covers) the first window layer 140, and the second window layer 141 is located on (or covers) the intermediate layer 150. That is, the intermediate layer 150 is located between the first window layer 140 and the second window layer 141, and separates the first window layer 140 and the second window layer 141. In addition, the first window layer 140 is closest to the second cladding layer 130, and the second window layer 141 is relatively far away from the second cladding layer 130.

[0012] The first window layer 140 and the second window layer 141 can be gallium phosphide (GaP) or indium phosphide (InP) window layers, and are used to diffuse current to improve the uniformity of current distribution outside the ohmic contact region. In some embodiments, the material of the intermediate layer 150 includes (Al x Ga 1-x ) 1-y In y P, wherein 1≥x≥0, and 1>y>0. In some embodiments, 1>x>0.5, and y>0.5, but are not limited thereto. In some embodiments, the material of the intermediate layer 150 includes SiC, SiC, AlN, GaN, ZnO, BeSe, MgS, BeTe, GaAs, AlAs, InP, MgSe, CdSe, or ZnTe.

[0013] In some embodiments, the first window layer 140, the second window layer 141, and the intermediate layer 150 can all be doped with metal ions (such as magnesium ions), wherein the ion doping concentration of the second window layer 141 is greater than the ion doping concentration of the first window layer 140, and the ion doping concentration of the intermediate layer 150 is less than or equal to the ion doping concentration of the first window layer 140. In some embodiments, the first window layer 140 and the second window layer 141 can both be doped with metal ions (such as magnesium ions), wherein the ion doping concentration of the second window layer 141 is greater than the ion doping concentration of the first window layer 140, and the ion doping concentration of the intermediate layer 150 is 0, that is, the intermediate layer 150 is not doped with metal ions. Because the ion doping concentration of the first window layer 140 closest to the second cladding layer 130 is low, it helps to reduce the extent of diffusion of doped ions to the second cladding layer 130.

[0014] As FIG. 1AAs shown, the micro light emitting element 100 further comprises a first type electrode 101, a second type electrode 102, and a contact layer 103, wherein the contact layer 103 is located between the first type electrode 101 and the first type cladding layer 110, and the first type electrode 101 is electrically connected to the first type cladding layer 110 through the contact layer 103. On the other hand, the contact layer 103, the first type cladding layer 110, the light emitting layer 120, the second type cladding layer 130, the first window layer 140, the intermediate layer 150, and the second window layer 141 are sequentially stacked from bottom to top, and the first window layer 140 is located between the intermediate layer 150 and the second type cladding layer 130. In detail, the second type electrode 102 penetrates through the contact layer 103, the first type cladding layer 110, the light emitting layer 120, and the second type cladding layer 130, and is electrically connected to the first window layer 140. That is, the second type electrode 102 is electrically connected to the second type cladding layer 130 through the first window layer 140.

[0015] As shown in FIG. 1, the micro light emitting element 100 further comprises a first type electrode 101, a second type electrode 102, and a contact layer 103, wherein the contact layer 103 is located between the first type electrode 101 and the first type cladding layer 110, and the first type electrode 101 is electrically connected to the first type cladding layer 110 through the contact layer 103. On the other hand, the contact layer 103, the first type cladding layer 110, the light emitting layer 120, the second type cladding layer 130, the first window layer 140, the intermediate layer 150, and the second window layer 141 are sequentially stacked from bottom to top, and the first window layer 140 is located between the intermediate layer 150 and the second type cladding layer 130. In detail, the second type electrode 102 penetrates through the contact layer 103, the first type cladding layer 110, the light emitting layer 120, and the second type cladding layer 130, and is electrically connected to the first window layer 140. That is, the second type electrode 102 is electrically connected to the second type cladding layer 130 through the first window layer 140. FIG. 1A As shown, the remaining outer surfaces of the micro light emitting element 100 excluding the light emitting surface are covered by an insulating layer 105. The first type electrode 101 penetrates through the insulating layer 105 covering the contact layer 103 to electrically connect (or contact) the contact layer 103. In addition, the second type electrode 102 penetrates through the contact layer 103, the first type cladding layer 110, the light emitting layer 120, and the second type cladding layer 130, and finally electrically connects the first window layer 140. In addition, the side wall surface of the second type electrode 102 located in the contact layer 103, the first type cladding layer 110, the light emitting layer 120, the second type cladding layer 130, and the first window layer 140 is covered by the insulating layer 105 to be electrically isolated from the contact layer 103, the first type cladding layer 110, the light emitting layer 120, and the second type cladding layer 130, but the end surface of the second type electrode 102 located in the first window layer 140 is not covered by the insulating layer 105 to electrically connect the first window layer 140.

[0016] In this embodiment, the intermediate layer 150 separates the first window layer 140 and the second window layer 141, and the dislocation defects formed in the first window layer 140 due to the mismatch of the lattice constant of the first window layer 140 and the lattice constant of the second type cladding layer 130 can be blocked by the intermediate layer 150. That is, the intermediate layer 150 can be used to block the dislocation defects from continuing to generate from the first window layer 140 to the second window layer 141, so as to reduce the dislocation defect density in the window layer, especially the dislocation defect density in the second window layer 141, and improve the leakage current condition. Since the leakage current condition is improved, it is helpful to improve the light emitting efficiency of the micro light emitting element 100.

[0017] Specifically, the first window layer 140 is closer to the second type cladding layer 130 than the second window layer 141, and the defect density of the dislocations in the second window layer 141 is reduced under the blocking of the intermediate layer 150. That is, the defect density of the dislocations in the first window layer 140 is greater than the defect density of the dislocations in the second window layer 141. For example, the ratio of the defect density of the dislocations in the first window layer 140 to the defect density of the dislocations in the second window layer 141 is between 2 and 100, so that the current can be more conducted in the second window layer 141 with low defect density.

[0018] In some embodiments, the sum of the thickness T1 of the first window layer 140 and the thickness T2 of the second window layer 141 can be more than 50 times and less than 1500 times, for example, 200 times or 700 times, the thickness T3 of the intermediate layer 150. In some embodiments, the thickness T2 of the second window layer 141 is greater than the thickness T1 of the first window layer 140, and can be more than 2.5 times and less than 10 times the thickness T1 of the first window layer 140. In this way, the characteristics of the overall window layer will depend more on the second window layer 141 with a higher thickness ratio, and even the third and subsequent window layers, rather than the first window layer 140, which will significantly reduce the defect density of the dislocations in the overall window layer.

[0019] In some embodiments, the thickness T1 of the first window layer 140 can be less than or equal to 1500 nanometers. In some embodiments, the second window layer 141 is farther away from the second type cladding layer 130 than the first window layer 140, and is a layer of window layer farthest away from the second type cladding layer 130, wherein the thickness T2 of the second window layer 141 can be more than 0.7 times the sum of the thickness T1 of the first window layer 140, the thickness T2 of the second window layer 141, and the thickness T3 of the intermediate layer 150. In some embodiments, the thickness T3 of the intermediate layer 150 is less than or equal to 100 nanometers, and can be between 6 nanometers and 30 nanometers, for example, 10 nanometers. If the thickness of the intermediate layer 150 is too large, it is easy to cause defects in the intermediate layer 150 itself, and conversely, if the thickness is too thin, it cannot produce the effect of blocking the defects generated from the first window layer 140 to the second window layer 141.

[0020] In some embodiments, the lattice constant of the first window layer 140 and the second window layer 141 is equal to 5.45 angstroms, and the lattice constant of the intermediate layer 150 is greater than or equal to 5.5045 angstroms (for example, greater than or equal to 1.01 times the lattice constant of the first window layer 140 and the second window layer 141) or less than or equal to 5.3955 angstroms (for example, less than or equal to 0.99 times the lattice constant of the first window layer 140 and the second window layer 141). For example, when the lattice constant of the intermediate layer 150 is greater than or equal to 5.5045 angstroms, the lattice constant of the intermediate layer 150 is preferably greater than or equal to 5.65 angstroms.

[0021] In some embodiments, the materials of the first window layer 140 and the second window layer 141 have a first lattice constant, and the material of the interposer layer 150 has a second lattice constant. The second lattice constant may be more than 1.01 times the first lattice constant, or less than 0.99 times the first lattice constant. In some embodiments, the second lattice constant may be more than 1.02 times the first lattice constant, or less than 0.98 times the first lattice constant. In some embodiments, the second lattice constant may be more than 1.03 times the first lattice constant, or less than 0.97 times the first lattice constant.

[0022] In some embodiments, the materials of the first window layer 140 and the second window layer 141 have a first lattice constant of 5.45 Å, and the material of the interposer layer 150 has a second lattice constant of 5.65 Å. In some embodiments, the materials of the first window layer 140 and the second window layer 141 are GaP, and the material of the interposer layer 150 is Al. 0.5 In 0.5 P. In some embodiments, the lattice constant difference between the intermediate layer 150 and the first window layer 140 (or the second window layer 141) is greater than the lattice constant difference between the second type cladding layer 130 and the first window layer 140 (or the second window layer 141), so as to improve the effect of blocking the generation of differential run-out defects from the first window layer 140 to the second window layer 141.

[0023] FIG. 1B The micro light-emitting element 100A shown is FIG. 1A The micro light-emitting element 100 shown has a similar structure, but differs in that: FIG. 1B As shown, the micro light-emitting element 100A further includes a third window layer 142 located on the second window layer 141, and the interposer layer includes a first interposer layer 151 and a second interposer layer 152 separated from each other. The first interposer layer 151 is located between the first window layer 140 and the second window layer 141, and the second interposer layer 152 is located between the second window layer 141 and the third window layer 142.

[0024] That is, the first window layer 140 is separated from the second window layer 141 by the first interlayer 151, and the second window layer 141 is separated from the third window layer 142 by the second interlayer 152. Thus, the first interlayer 151 can be used to block the propagation of dislocation defects from the first window layer 140 to the second window layer 141, and the second interlayer 152 can be used to block the propagation of dislocation defects from the second window layer 141 to the third window layer 142. Thus, the dislocation defect density in the third window layer 142, which is farthest from the second type cladding layer 130, is less than the dislocation defect density in the second window layer 141, and the dislocation defect density in the second window layer 141 is less than the dislocation defect density in the first window layer 140. In other words, the dislocation defect density in the window layer closest to the second type cladding layer 130 is greater than the dislocation defect density in the remaining window layers.

[0025] As shown in FIG. 1A, the micro light emitting element 100 includes a substrate 110, a first type cladding layer 120, a second type cladding layer 130, a first window layer 140, a second window layer 141, a third window layer 142, a first interlayer 151, and a second interlayer 152. FIG. 1B As shown in FIG. 1A, the micro light emitting element 100 includes a substrate 110, a first type cladding layer 120, a second type cladding layer 130, a first window layer 140, a second window layer 141, a third window layer 142, a first interlayer 151, and a second interlayer 152.

[0026] FIG. 2A As shown in FIG. 1B, the micro light emitting element 100B includes a substrate 110, a first type cladding layer 120, a second type cladding layer 130, a first window layer 140, a second window layer 141, a third window layer 142, an interlayer 151, and a second interlayer 152. FIG. 1A As shown in FIG. 1B, the micro light emitting element 100B includes a substrate 110, a first type cladding layer 120, a second type cladding layer 130, a first window layer 140, a second window layer 141, a third window layer 142, an interlayer 151, and a second interlayer 152. FIG. 2A As shown in FIG. 1B, the micro light emitting element 100B includes a substrate 110, a first type cladding layer 120, a second type cladding layer 130, a first window layer 140, a second window layer 141, a third window layer 142, an interlayer 151, and a second interlayer 152.

[0027] In some embodiments, the interlayer includes three or more interlayer sub-layers connected in series, and the thickness of the interlayer sub-layer farther from the second type cladding layer 130 is smaller. In addition, the interlayer sub-layer farther from the second type cladding layer 130 has a smaller lattice constant difference with the first window layer 140 (or the second window layer 141). In some embodiments, the materials of the interlayer sub-layers 150a and 150b can be (Al x Ga 1-x ) 1-y In yP, and the element ratio of the intermediate layer 150a is different from that of the intermediate layer 150b. In some embodiments, the materials of the intermediate layer 150a and the intermediate layer 150b can be SiC, SiC, AlN, GaN, ZnO, BeSe, MgS, BeTe, GaAs, AlAs, InP, MgSe, CdSe, or ZnTe, and the materials of the intermediate layer 150a and the intermediate layer 150b can be the same or different.

[0028] FIG. 2B The micro light emitting element 100C shown in FIG. 10C has a structure similar to that of the micro light emitting element 100 shown in FIG. 1, except that, as shown in FIG. 10C, the first intermediate layer includes the intermediate layer 150a and the intermediate layer 150b connected to each other, and the second intermediate layer includes the intermediate layer 151a and the intermediate layer 151b connected to each other. FIG. 1B The micro light emitting element 100 shown in FIG. 10D has a structure similar to that of the micro light emitting element 100 shown in FIG. 1, except that, as shown in FIG. 10D, the first intermediate layer includes the intermediate layer 150a and the intermediate layer 150b connected to each other, and the second intermediate layer includes the intermediate layer 151a and the intermediate layer 151b connected to each other. FIG. 2B The micro light emitting element 100C shown in FIG. 10C has a structure similar to that of the micro light emitting element 100 shown in FIG. 1, except that, as shown in FIG. 10C, the first intermediate layer includes the intermediate layer 150a and the intermediate layer 150b connected to each other, and the second intermediate layer includes the intermediate layer 151a and the intermediate layer 151b connected to each other.

[0029] For example, the distance between the intermediate layer and the second type cladding layer 130 is farther, the thickness of the intermediate layer is smaller, and the difference between the lattice constant of the intermediate layer and the first window layer 140 (or the second window layer 141) is smaller. In addition, the materials of the two intermediate layers connected to each other can be (Al x Ga 1-x ) 1-y In y P, and the element ratio of the intermediate layer 150a is different from that of the intermediate layer 150b. In some embodiments, the materials of the intermediate layer 150a and the intermediate layer 150b can be SiC, SiC, AlN, GaN, ZnO, BeSe, MgS, BeTe, GaAs, AlAs, InP, MgSe, CdSe, or ZnTe, and the materials of the intermediate layer 150a and the intermediate layer 150b can be the same or different.

[0030] In some embodiments, the number of intermediate layers can be multiple layers, which can be separated from each other, wherein at least one of the multiple intermediate layers is a single layer structure, and at least another of the multiple intermediate layers can include two or more intermediate layers, or each intermediate layer includes two or more intermediate layers.

[0031] FIG. 3A The micro light emitting element 100C shown in FIG. 10C has a structure similar to that of the micro light emitting element 100 shown in FIG. 1, except that, as shown in FIG. 10C, the first intermediate layer includes the intermediate layer 150a and the intermediate layer 150b connected to each other, and the second intermediate layer includes the intermediate layer 151a and the intermediate layer 151b connected to each other. FIG. 1A The micro light emitting element 100 shown in FIG. 10D has a structure similar to that of the micro light emitting element 100 shown in FIG. 1, except that, as shown in FIG. 10D, the first intermediate layer includes the intermediate layer 150a and the intermediate layer 150b connected to each other, and the second intermediate layer includes the intermediate layer 151a and the intermediate layer 151b connected to each other. FIG. 3A The micro light emitting element 100D shown in FIG. 10D has a structure similar to that of the micro light emitting element 100 shown in FIG. 1, except that, as shown in FIG. 10D, the micro light emitting element 100D further includes the buffer layer 160, and the material can be Al 0.5 In 0.5P. Buffer layer 160 is located between second type cladding layer 130 and first window layer 140, and buffer layer 160 and intermediate layer 150 are located on opposite sides of first window layer 140. On the other hand, second type electrode 102 passes through buffer layer 160 and is inserted into first window layer 140 to electrically connect to first window layer 140.

[0032] FIG. 3B The micro light-emitting element 100E shown is FIG. 1B The structure of the micro light-emitting element 100A shown is similar, but the difference is: FIG. 3B As shown, the micro light-emitting element 100E also includes a buffer layer 160, and the material can be Al. 0.5 In 0.5 P. Buffer layer 160 is located between second type cladding layer 130 and first window layer 140, and buffer layer 160 and first interposer layer 151 are located on opposite sides of first window layer 140. On the other hand, second type electrode 102 passes through buffer layer 160 and is inserted into first window layer 140 to electrically connect to first window layer 140.

[0033] In other embodiments similar to the micro-light-emitting element 100E, the second type electrode 102 may further penetrate through the first interposer layer 151 and be inserted into the second window layer 141 to electrically connect the second window layer 141. Because the second type electrode 102 electrically connects to the second window layer 141, which has a lower defect density in the differential array, it facilitates current diffusion to improve the uniformity of current distribution outside the ohmic contact region.

[0034] FIG. 3C The micro light-emitting element 100F shown is FIG. 2A The structure of the micro light-emitting element 100B shown is similar, but the difference is: FIG. 3C As shown, the micro light-emitting element 100F also includes a buffer layer 160, and the material can be Al. 0.5 In 0.5 P. Buffer layer 160 is located between second type cladding layer 130 and first window layer 140, and buffer layer 160 and intermediate layer 150 are located on opposite sides of first window layer 140. On the other hand, second type electrode 102 passes through buffer layer 160 and is inserted into first window layer 140 to electrically connect to first window layer 140.

[0035] FIG. 3D The micro light-emitting element 100G shown is FIG. 2B The structure of the micro light-emitting element 100C shown is similar, but the difference is: FIG. 3D As shown, the micro light-emitting element 100G also includes a buffer layer 160, and the material can be (Al). m Ga 1-m ) 1-n In nP,1≥m≥0, and 1>n>0. The buffer layer 160 is located between the second type cladding layer 130 and the first window layer 140, and the buffer layer 160 and the first intermediate layer 151 are located on opposite sides of the first window layer 140. On the other hand, the second type electrode 102 penetrates through the buffer layer 160 and is inserted into the first window layer 140 to electrically connect the first window layer 140.

[0036] FIG. 4A The micro light emitting element 100H shown is similar in structure to the micro light emitting element 100A shown in FIG. 1A, except that, as shown, the second type electrode 102 penetrates through the first intermediate layer 151 and is inserted into the second window layer 141 to electrically connect the second window layer 141, which helps the current to flow and distribute in the second window layer 141 having a relatively lower defect density of the dislocation first, and then into the first window layer 140. FIG. 1A FIG. 4A The second type electrode 102 penetrating through the intermediate layer 150 and being inserted into the second window layer 141 to electrically connect the second window layer 141 helps the current to flow and distribute in the second window layer 141 having a relatively lower defect density of the dislocation first, and then into the first window layer 140.

[0037] In other embodiments similar to the micro light emitting element 100H, the second type electrode 102 can further penetrate through the intermediate sub-layer 150a and the intermediate sub-layer 150b and be inserted into the second window layer 141 to electrically connect the second window layer 141. Since the second type electrode 102 electrically connects the second window layer 141 having a relatively lower defect density of the dislocation, it is advantageous to diffuse the current to improve the uniformity of the current distribution outside the ohmic contact region.

[0038] FIG. 4B The micro light emitting element 100I shown is similar in structure to the micro light emitting element 100A shown in FIG. 1A, except that, as shown, the second type electrode 102 penetrates through the first intermediate layer 151 and is inserted into the second window layer 141 to electrically connect the second window layer 141, which helps the current to flow and distribute in the second window layer 141 having a relatively lower defect density of the dislocation first, and then into the first window layer 140. FIG. 1B FIG. 4B The second type electrode 102 penetrating through the first intermediate layer 151 and being inserted into the second window layer 141 to electrically connect the second window layer 141 helps the current to flow and distribute in the second window layer 141 having a relatively lower defect density of the dislocation first, and then into the first window layer 140. In an embodiment not shown, the second type electrode 102 can further penetrate through the second window layer 141 and the second intermediate layer 152 and be inserted into the third window layer 142 to electrically connect the third window layer 142, which helps the current to flow and distribute in the third window layer 142 having a relatively lower defect density of the dislocation first, and then into the second window layer 141, and then into the first window layer 140.

[0039] In an embodiment not shown, the number of window layers can be more than four, and the number of intermediate layers can be more than three, and they are separated from each other to separate the four or more window layers. For example, the window layer farther away from the second type cladding layer 130 has a greater thickness, or the window layer farthest away from the second type cladding layer 130 has the greatest thickness. In addition, the intermediate layer farther away from the second type cladding layer 130 has a smaller thickness.

[0040] ​​FIG. 5 The micro light emitting element 100J is similar to the micro light emitting element 100A shown in FIG. 1A, except that the micro light emitting element 100J further comprises a plurality of spacer layers 144 between the first interlayer 151 and the second interlayer 152, and the plurality of spacer layers 144 are arranged alternately between the first interlayer 151, the plurality of third interlayers 153, and the second interlayer 152. FIG. 1B The micro light emitting element 100A shown in FIG. 1A is similar to the micro light emitting element 100 shown in FIG. 1, except that the micro light emitting element 100A further comprises a plurality of spacer layers 144 between the first interlayer 151 and the second interlayer 152, and the plurality of spacer layers 144 are arranged alternately between the first interlayer 151, the plurality of third interlayers 153, and the second interlayer 152. FIG. 5 As shown in FIG. 1C, the micro light emitting element 100A further comprises a plurality of spacer layers 144 between the first interlayer 151 and the second interlayer 152, and the plurality of spacer layers 144 are arranged alternately between the first interlayer 151, the plurality of third interlayers 153, and the second interlayer 152.

[0041] The first interlayer 151, the plurality of third interlayers 153, the second interlayer 152, and the plurality of spacer layers 144 form a stack structure, the first interlayer 151 is separated from a third interlayer 153 closest to the first interlayer 151 by a spacer layer 144, two adjacent third interlayers 153 are separated by a spacer layer 144, and a third interlayer 153 closest to the second interlayer 152 is separated from the second interlayer 152 by a spacer layer 144.

[0042] In the stack structure, the thickness of any spacer layer 144 is greater than or equal to 0.1 times and less than or equal to 10 times, such as 3 times, of the thickness of the first interlayer 151, the thickness of the second interlayer 152, or the thickness of any third interlayer 153. For example, the material of the spacer layer 144 can be the same as the material of the window layer, such as GaP, but not limited thereto. In other embodiments similar to the micro light emitting element 100A, the second electrode 102 can further pass through the stack structure and be inserted into the second window layer 141 to electrically connect the second window layer 141. Since the second electrode 102 electrically connects the second window layer 141 with a lower defect density, it is beneficial to diffuse the current to improve the uniformity of the current distribution outside the ohmic contact region.

[0043] FIG. 6 The micro light emitting element 100K is similar to the micro light emitting element 100H shown in FIG. 1D, except that the micro light emitting element 100K further comprises a plurality of spacer layers 144 between the first interlayer 151 and the second interlayer 152, and the plurality of spacer layers 144 are arranged alternately between the first interlayer 151, the plurality of third interlayers 153, and the second interlayer 152. FIG. 4A The micro light emitting element 100H shown in FIG. 1D is similar to the micro light emitting element 100 shown in FIG. 1, except that the micro light emitting element 100H further comprises a plurality of spacer layers 144 between the first interlayer 151 and the second interlayer 152, and the plurality of spacer layers 144 are arranged alternately between the first interlayer 151, the plurality of third interlayers 153, and the second interlayer 152. FIG. 6 As shown in FIG. 1F, the micro light emitting element 100K further comprises a plurality of spacer layers 144 between the first interlayer 151 and the second interlayer 152, and the plurality of spacer layers 144 are arranged alternately between the first interlayer 151, the plurality of third interlayers 153, and the second interlayer 152.

[0044] That is, in the micro light emitting elements of the above different embodiments, the second electrode 102 and the second window layer 141 electrically connected to each other can have a platform structure 104, wherein the second electrode 102 is located on one side of the platform structure 104, and at least one interlayer is located in the platform structure 104.

[0045] FIG. 7 Figure 1 is a schematic cross-sectional view of a micro light emitting diode epitaxial structure according to an embodiment of the present application. Referring to Figure 1, a micro light emitting diode epitaxial structure 10 includes a substrate 11 and an epitaxial structure 1001 on the substrate 11. The substrate 11 can be a gallium arsenide substrate. The epitaxial structure 1001 includes, from bottom to top, a contact layer 103, a first type cladding layer 110, a light emitting layer 120, a second type cladding layer 130, a first window layer 140, an intermediate layer 150, and a second window layer 141. FIG. 7 The micro light emitting diode epitaxial structure 10 includes a substrate 11 and an epitaxial structure 1001 on the substrate 11. The substrate 11 can be a gallium arsenide substrate. The epitaxial structure 1001 includes, from bottom to top, a contact layer 103, a first type cladding layer 110, a light emitting layer 120, a second type cladding layer 130, a first window layer 140, an intermediate layer 150, and a second window layer 141. The micro light emitting diodes of the above embodiments can be made based on the epitaxial structure 1001 or variations of the epitaxial structure 1001. Due to the reduced defect density of the dislocations in the window layers, the epitaxial quality of the micro light emitting diode epitaxial structure 10 is improved.

[0046] In summary, in the micro light emitting diode and the micro light emitting diode epitaxial structure of the present application, two adjacent window layers are separated by an intermediate layer to block the dislocation defects formed in the lower window layer due to the mismatch of the lattice constant of the lower window layer and the lattice constant of the second type cladding layer. That is, the intermediate layer can be used to block the dislocation defects from continuing to form from the lower window layer to the upper window layer, so as to reduce the defect density of the dislocations in the window layers and improve the leakage current. Due to the improvement of the leakage current, the light emitting efficiency of the micro light emitting diode is improved. In addition, due to the reduced defect density of the dislocations in the window layers, the epitaxial quality of the micro light emitting diode epitaxial structure is improved.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications to the technical solutions described in the above embodiments, or make equivalent replacements to some or all of the technical features. Such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A micro light emitting element, characterized by, The application comprises: a first type cladding layer; a light emitting layer on the first type cladding layer; a second type cladding layer on the light emitting layer, and the light emitting layer is between the first type cladding layer and the second type cladding layer; a multi-layer window layer on the second type cladding layer; and at least one intermediate layer between any two adjacent window layers, wherein the ion doping concentration of the at least one intermediate layer is less than or equal to the ion doping concentration of the multi-layer window layer, the multi-layer window layer comprises at least a first window layer closest to the second type cladding layer and a second window layer farthest from the second type cladding layer, wherein the thickness of the second window layer is greater than the thickness of the first window layer, and the defect density of dislocation in the window layer closest to the second type cladding layer is greater than the defect density of dislocation in the remaining multi-layer window layer, the sum of the thickness of the first window layer and the thickness of the second window layer is 50 times to 1500 times the thickness of the at least one intermediate layer, and the thickness of the second window layer is 2.5 times to 10 times the thickness of the first window layer. The ion doping concentration of the first window layer is less than the ion doping concentration of the second window layer.

2. The micro light emitting element according to claim 1, wherein The multi-layer window layer is composed of the same material, which comprises GaP or InP.

3. The micro light emitting element according to claim 1, wherein The lattice constant difference between the at least one intermediate layer and the multi-layer window layer is greater than the lattice constant difference between the second type cladding layer and the multi-layer window layer.

4. The micro light emitting element according to claim 1, wherein The material of the at least one intermediate layer comprises (Al x Ga 1-x ) 1-y In y P, 1≥x≥0, and 1>y>0.

5. The micro light emitting element according to claim 1, wherein The material of the multi-layer window layer has a first lattice constant, and the material of the at least one intermediate layer has a second lattice constant, wherein the ratio of the second lattice constant to the first lattice constant is greater than or equal to 1.01 times or less than or equal to 0.99 times.

6. The micro light emitting element according to claim 1, wherein The thickness of the at least one intermediate layer is less than or equal to 100 nanometers.

7. The micro light emitting element according to claim 1, wherein The at least one intermediate layer comprises two connected intermediate sub-layers, and the element ratio of the two intermediate sub-layers is different.

8. The micro light emitting element according to claim 1, wherein In the two connected intermediate sub-layers, the lattice constant difference between the intermediate sub-layer farthest from the second type cladding layer and the multi-layer window layer is less than the lattice constant difference between the other intermediate sub-layer closest to the second type cladding layer and the multi-layer window layer.

9. The micro light emitting element according to claim 8, wherein Further comprising a multi-layer spacing layer between the first window layer and the second window layer, wherein the number of the at least one intermediate layer is multiple, and the multi-layer intermediate layer and the multi-layer spacing layer alternately arranged between the multi-layer intermediate layer form a stack structure, in which the ratio of the thickness of any one of the multi-layer spacing layer to the thickness of any one of the multi-layer intermediate layer is greater than or equal to 0.1 times and less than or equal to 10 times.

10. The micro light emitting element according to claim 1, wherein Further comprising a first type electrode electrically connected to the first type cladding layer and a second type electrode electrically connected to the second type cladding layer, the second type electrode passes through the first type cladding layer, the light emitting layer, the second type cladding layer, the first window layer and the at least one intermediate layer and is electrically connected to the second window layer.

11. The micro light emitting element according to claim 1, wherein The number of the at least one intermediate layer is multiple, and the multi-layer intermediate layer is respectively between any two adjacent window layers.

12. The micro light emitting element according to claim 1, wherein The application comprises:

13. A micro light emitting element characterized by comprising: a first type cladding layer; ​ a light emitting layer on the first cladding layer; a second cladding layer on the light emitting layer, and the light emitting layer is between the first cladding layer and the second cladding layer; a multi-layer window layer on the second cladding layer, and the material of the multi-layer window layer has a first lattice constant; and at least one intermediate layer between two adjacent window layers, and the material of the at least one intermediate layer has a second lattice constant, wherein the ratio of the second lattice constant to the first lattice constant is greater than or equal to 1.01 times or less than or equal to 0.99 times, the multi-layer window layer at least includes a first window layer closest to the second cladding layer and a second window layer farther away from the second cladding layer, wherein the thickness of the second window layer is greater than the thickness of the first window layer, and the defect density of dislocation in the window layer closest to the second cladding layer is greater than the defect density of dislocation in the remaining multi-layer window layer, the sum of the thickness of the first window layer and the thickness of the second window layer is 50 times to 1500 times the thickness of the at least one intermediate layer, and the thickness of the second window layer is 2.5 times to 10 times the thickness of the first window layer.

14. The micro light emitting element according to claim 13, wherein The multi-layer window layer is composed of the same material, which includes gallium phosphide or indium phosphide.

15. The micro light emitting element according to claim 13, wherein The material of the at least one intermediate layer comprises (Al x Ga 1-x ) 1-y In y P, 1≥x≥0, and 1>y>0.

16. The micro light emitting element according to claim 13, wherein The thickness of the at least one intermediate layer is less than or equal to 100 nanometers.

17. The micro light emitting element according to claim 13, wherein It also includes a first electrode electrically connected to the first cladding layer and a second electrode electrically connected to the second cladding layer, and the second electrode passes through the first cladding layer, the light emitting layer, the second cladding layer, the first window layer and the at least one intermediate layer and is electrically connected to the second window layer.

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