CN102751393A - Light emitting diode structure - Google Patents

Abstract

A light emitting diode structure comprises a first type semiconductor layer, a light emitting layer, a second type semiconductor layer, a first conductive layer and a second conductive layer. The light emitting layer is disposed on the first type semiconductor layer. The light-emitting layer comprises a plurality of energy barrier layers and a plurality of quantum well layers, wherein the quantum well layers are respectively clamped between the energy barrier layers. The second type semiconductor layer is configured on the light emitting layer, wherein the thickness of the quantum well layer closest to the second type semiconductor layer is at least more than or equal to 1.1 times of the average thickness of other quantum well layers. The first conductive layer is electrically connected with the first type semiconductor layer. The second conductive layer is electrically connected to the second type semiconductor layer. The LED structure can improve the overall luminous efficiency of the LED structure.

Description

LED structure

technical field

The invention relates to a light emitting diode structure, and in particular to a light emitting diode structure with better luminous efficiency.

Background technique

In recent years, due to the continuous improvement of the luminous efficiency of light-emitting diodes, light-emitting diodes have gradually replaced fluorescent lamps and incandescent bulbs in some fields, such as scanner light sources that require high-speed response, backlights for liquid crystal displays, or dashboards for front lights. Lighting, traffic lights, and general lighting installations, etc. Common light-emitting diodes are formed using nitride semiconductor materials, and most of the above-mentioned light-emitting diodes are formed on sapphire substrates in an epitaxial manner.

The traditional LED structure usually includes a substrate, an N type cladding layer (N type cladding layer), a multiple quantum well structure (multiple quantum wells structure), a P type confinement layer, an N type electrode and a P type electrode. The N-type lower confinement layer, the multiple quantum well structure, and the P-type upper confinement layer are sequentially arranged on the substrate, and the N-type electrode and the P-type electrode are respectively electrically connected to the N-type lower confinement layer and the P-type upper confinement layer, wherein the driving force is applied. Applying voltage to the N-type electrode and the P-type electrode can drive the LED structure to emit light.

Generally speaking, the thickness of the quantum well layer in the multiple quantum well structure is usually designed to be the same, and if the thickness of the quantum well layer is too thick, defects will be generated and affect the luminous efficiency of the LED structure. Therefore, how to effectively design The thickness of the quantum well layer in the multiple quantum well structure, while avoiding defects, can effectively improve the luminous efficiency of the light emitting diode structure, which is an important issue.

Contents of the invention

The invention provides a light emitting diode structure with better luminous efficiency.

Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

In order to achieve one or part or all of the above objectives or other objectives, an embodiment of the present invention provides a light emitting diode structure, including a first type semiconductor layer, a light emitting layer, a second type semiconductor layer, a first conductive layer and a second Two conductive layers. The light emitting layer is configured on the first type semiconductor layer. The light-emitting layer includes several energy barrier layers and several quantum well layers, wherein the quantum well layers are respectively sandwiched between the energy barrier layers. The second-type semiconductor layer is disposed on the light-emitting layer, wherein the thickness of the quantum well layer closest to the second-type semiconductor layer is at least 1.1 times the average thickness of the other quantum well layers. The first conductive layer is electrically connected to the first type semiconductor layer. The second conductive layer is electrically connected to the second type semiconductor layer.

In an embodiment of the present invention, the thickness of the quantum well layer closest to the second-type semiconductor layer is greater than the thickness of each of the other quantum well layers.

In an embodiment of the present invention, the thickness of the quantum well layer closest to the second-type semiconductor layer is at least 1.2 times the average thickness of the other quantum well layers.

In an embodiment of the present invention, the thickness of the quantum well layer closest to the second-type semiconductor layer is less than or equal to three times the average thickness of the other quantum well layers.

In an embodiment of the present invention, each of the other quantum well layers has the same thickness.

In an embodiment of the present invention, the light emitting diode structure further includes an epitaxial substrate, wherein the first type semiconductor layer, the light emitting layer and the second type semiconductor layer are sequentially stacked on the epitaxial substrate, and the light emitting layer and the second type semiconductor layer The layer is configured on a part of the first-type semiconductor layer and exposes a part of the first-type semiconductor layer, and the first conductive layer is configured on the first-type semiconductor layer exposed by the light-emitting layer and the second-type semiconductor layer.

In an embodiment of the present invention, the first conductive layer is disposed on the other side of the first type semiconductor layer, and the first type semiconductor layer is located between the light emitting layer and the first conductive layer. In an embodiment of the present invention, the LED structure further includes a conductive substrate disposed between the first type semiconductor layer and the first conductive layer.

In an embodiment of the present invention, the first-type semiconductor layer is an N-type semiconductor layer, and the second-type semiconductor layer is a P-type semiconductor layer.

In an embodiment of the present invention, the material of the first-type semiconductor layer and the second-type semiconductor layer is at least one of gallium nitride, aluminum gallium nitride, indium gallium nitride, and aluminum indium gallium nitride doped with II Composed of group elements or group IV elements.

In an embodiment of the present invention, the material of the energy barrier layers includes gallium nitride, and the material of the quantum well layers includes indium gallium nitride.

Based on the above, the present invention makes the thickness of the quantum well layer closest to the second type semiconductor layer greater than or equal to the thickness of each of the other quantum well layers, and the thickness of the quantum well layer closest to the second type semiconductor layer is at least greater than or equal to The average thickness of these other quantum well layers is 1.1 times, preferably 1.2 times, so that when the light-emitting diode structure is driven, the quantum well layer closest to the second-type semiconductor layer can carry more carriers, Therefore, the overall luminous efficiency of the light emitting diode structure can be improved.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with reference to the accompanying drawings.

Description of drawings

FIG. 1 is a partial cross-sectional view of a light emitting diode structure according to an embodiment of the present invention.

2A to 2D are partial schematic diagrams of different implementations of the light-emitting layer in FIG. 1 .

FIG. 3 is a partial cross-sectional view of a light emitting diode structure according to an embodiment of the present invention.

Reference signs:

100, 200: light emitting diode structure 110, 210: first type semiconductor layer

120, 220: Light-emitting layer 122: Barrier layer

124a, 124b: quantum well layer 130, 230: second type semiconductor layer

140: Epitaxy substrate 150: Current blocking layer

160: Current distribution layer 170: Buffer layer

240: Conductive substrate E1: The first conductive layer

E2: Second conductive layer H1, H2, H3: Thickness

Detailed ways

The foregoing and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only referring to the directions of the drawings. Accordingly, the directional terms are used to illustrate and not to limit the invention.

FIG. 1 is a partial cross-sectional view of a light-emitting diode structure according to an embodiment of the present invention, and FIGS. 2A-2D are partial schematic diagrams of different implementations of the light-emitting layer in FIG. 1 . Please refer to FIG. 1 and FIG. 2A first. The LED structure 100 of this embodiment includes a first-type semiconductor layer 110, a light-emitting layer 120, a second-type semiconductor layer 130, a first conductive layer E1 and a second conductive layer. Layer E2. The light-emitting layer 120 is disposed on the first-type semiconductor layer 110 , and the second-type semiconductor layer 130 is disposed on the light-emitting layer 120 , that is, the light-emitting layer 120 is located between the first-type semiconductor layer 110 and the second-type semiconductor layer 130 . In this embodiment, the first-type semiconductor layer 110 is, for example, an N-type semiconductor layer, and the second-type semiconductor layer 130 is a P-type semiconductor layer. Specifically, the materials of the first-type semiconductor layer 110 and the second-type semiconductor layer 130 can be made of at least one of gallium nitride, aluminum gallium nitride, indium gallium nitride, and aluminum indium gallium nitride doped with group II elements or It is composed of group IV elements, and gallium nitride is used as an example in this embodiment. In other embodiments, the material selected for the first-type semiconductor layer 110 and the second-type semiconductor layer 130 can also be a binary compound, such as aluminum nitride and indium nitride; a ternary compound (ternary compound) , such as aluminum gallium nitride, gallium indium nitride, aluminum indium nitride, aluminum gallium arsenide, indium gallium arsenide; and quaternary compounds (quaternary compound) gallium indium aluminum nitride, aluminum indium gallium phosphide or combinations thereof, This part depends on the user's needs and design.

In the light-emitting diode structure 100, the light-emitting layer 120 of this embodiment includes several energy barrier layers 122 and several quantum well layers 124a, 124b, wherein these quantum well layers 124a, 124b are respectively sandwiched between these energy barrier layers 122 , as shown in Figure 2A. In other words, the light-emitting layer 120 of this embodiment presents a multiple quantum well structure, especially, in this multiple quantum well structure, the thickness H1 of the quantum well layer 124a closest to the second-type semiconductor layer 130 is at least It will be greater than or equal to 1.1 times, preferably 1.2 times, the average thickness of these other quantum well layers 124b, so that when the light emitting diode structure 100 is driven, the quantum well layer 124a closest to the second type semiconductor layer 130 can Carrying more carriers can improve the overall luminous efficiency of the LED structure 100 . In this embodiment, the thickness H1 of the quantum well layer 124a closest to the second-type semiconductor layer 130 may be greater than the thickness H2 of each of the other quantum well layers 124b.

Taking the light-emitting layer 120 (multiple quantum wells) shown in FIG. 2A as an example, if the thicknesses H1 and H2 of the quantum well layers 124 a and 124 b are both 2.8 nm, the overall luminous brightness of the light-emitting diode structure 100 is 750 mcd. Conversely, if the thickness H1 of the quantum well layer 124a closest to the second-type semiconductor layer 130 is increased to 3.1 nm, while the thickness H2 of the other quantum well layers 124b remains unchanged, the overall luminous brightness of the LED structure 100 can be improved. Boost to 820mcd. In other words, by designing the thickness H1 of the quantum well layer 124a closest to the second-type semiconductor layer 130 in this embodiment to be greater than the thickness H2 of each of the other quantum well layers 124b, the luminance of the light emitting diode structure 100 can be improved at least 9.33%.

It should be noted that although making the thickness H1 of the quantum well layer 124a greater than the thickness H2 of each of the other quantum well layers 124b helps to improve the luminous efficiency of the light emitting diode structure 100, an excessive thickness of the quantum well layer 124a will also make the It produces defects, thereby reducing the luminous brightness of the LED structure 100 . Therefore, the thickness of the quantum well layer 124a closest to the second-type semiconductor layer 130 is in principle less than or equal to 3 times the average thickness of the other quantum well layers 124b, preferably less than 2.5 times the average thickness. In this embodiment, the thicknesses H1 and H2 of the quantum well layers 124a and 124b are in principle about 0.5nm to 8nm, preferably 2nm to 4.5nm. In addition, since the first-type semiconductor layer 110 and the second-type semiconductor layer 130 in this embodiment are illustrated with gallium nitride as an example, the material of the energy barrier layer 122 in this embodiment can be gallium nitride, and the quantum well The material of the layers 124a and 124b can be InGaN.

Please continue to refer to FIG. 1 and FIG. 2A. In the light-emitting diode structure 100, the light-emitting layer 120 can adopt a multiple quantum well structure as shown in FIG. 2A, that is, the thickness of the quantum well layer 124a closest to the second-type semiconductor layer 130 H1 may be greater than the thickness H2 of each quantum well layer 124b, and the thickness H2 of these quantum well layers 124b are substantially the same, but the invention is not limited thereto. In other embodiments, the light-emitting layer 120 of the light-emitting diode structure 100 shown in FIG. 1 can also adopt the multiple quantum well structure as shown in FIGS. 2B-2D , and still have better luminous efficiency, which will be described in detail below. The shape of each multiple quantum well.

In FIG. 2B, the thickness H1 of the quantum well layer 124a closest to the second-type semiconductor layer 130 is greater than the thickness H2 of each quantum well layer 124b, and the thickness H2 of these quantum well layers 124b is substantially away from the second-type semiconductor layer. 130 becomes smaller; in Fig. 2C, the thickness H1 of the quantum well layer 124a closest to the second type semiconductor layer 130 can be equal to the thickness H3 of the quantum well layer 124b closest to the first type semiconductor layer 110 and greater than other quantum wells The thickness H2 of the well layer 124b, and the thickness H1 of the quantum well layer 124a closest to the second-type semiconductor layer 130 will be greater than or equal to 1.1 times the average of the thicknesses H2, H3 of these quantum well layers 124b; in FIG. 2D, the most The thickness H1 of the quantum well layer 124a close to the second-type semiconductor layer 130 is equal to the thickness H3 of another certain quantum well layer 124b, and greater than the thickness H2 of the other quantum well layer 124b, and the quantum well closest to the second-type semiconductor layer 130 The thickness H1 of the layer 124a is greater than or equal to 1.1 times the average of the thicknesses H2, H3 and the quantum well layers 124b.

It can be seen from FIG. 1 that the light emitting diode structure of this embodiment is a horizontal light emitting diode structure, so the light emitting diode structure 100 further includes an epitaxial substrate 140, wherein the first type semiconductor layer 110, the light emitting layer 120 and the second type semiconductor layer The layers 130 are sequentially stacked on the epitaxial substrate 140 , and the light-emitting layer 120 and the second-type semiconductor layer 130 are disposed on a part of the first-type semiconductor layer 110 and part of the first-type semiconductor layer 110 is exposed. Specifically, after the first-type semiconductor layer 110, the light-emitting layer 120, and the second-type semiconductor layer 130 are sequentially stacked on the epitaxial substrate 140, a part of the light-emitting layer 120 and the second-type semiconductor layer can be removed through a lithographic etching process. type semiconductor layer 130 to expose part of the first type semiconductor layer 110, as shown in FIG. 1 . After that, the first conductive layer E1 is disposed on the first-type semiconductor layer 110 exposed by the light-emitting layer 120 and the second-type semiconductor layer 130, and the second conductive layer E2 is disposed on the second-type semiconductor layer 130 to drive In the LED structure 100 , the first conductive layer E1 is electrically connected to the first-type semiconductor layer 110 , and the second conductive layer E2 is electrically connected to the second-type semiconductor layer 130 . In this embodiment, the first conductive layer E1 and the second conductive layer E2 can be a single layer or a multi-layer metal stack, and the materials of the two can also be selected such as: gold, silver, platinum, copper, chromium, tin, The material of lead, hafnium, tungsten, molybdenum, neodymium, titanium, tantalum, aluminum, zinc and other metals, the above-mentioned alloys, the above-mentioned metal oxides, the above-mentioned metal nitrides, or the combination of the above-mentioned materials depends on the needs of users.

In this embodiment, in order to improve the overall electrical performance and luminous efficiency of the LED structure 100 , the LED structure 100 may further include a current blocking layer 150 and a current spreading layer 160 . The current blocking layer 150 is disposed on a portion of the second-type semiconductor layer 130 . In addition, the current spreading layer 160 is disposed on a portion of the second-type semiconductor layer 13 to cover the current blocking layer 150 . In this embodiment, the current spreading layer 160 can be a transparent conductive layer, and its material is, for example, indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide ( indium tin zinc oxide (ITZO), zinc oxide (zinc oxide), aluminum tin oxide (aluminum tin oxide, ATO), aluminum zinc oxide (aluminum zinc oxide, AZO), cadmium indium oxide (cadmium indium oxide, CIO), Cadmium zinc oxide (CZO), gallium zinc oxide (GZO) and tin fluoride oxide (FTO).

It is worth mentioning that, in order to grow or epitaxial the high-quality first-type semiconductor layer 110 on the substrate 110, a buffer layer 170 may be formed on the substrate 110 before forming the first-type semiconductor layer 110 on the substrate 110. on, as shown in Figure 1.

FIG. 3 is a partial cross-sectional view of a light emitting diode structure according to an embodiment of the present invention. Please refer to FIG. 3 , the LED structure 200 of this embodiment includes a first-type semiconductor layer 210 , a light-emitting layer 220 , a second-type semiconductor layer 230 , a first conductive layer E1 and a second conductive layer E2 . The light-emitting layer 220 is disposed on the first-type semiconductor layer 210 , and the second-type semiconductor layer 230 is disposed on the light-emitting layer 220 , that is, the light-emitting layer 220 is located between the first-type semiconductor layer 210 and the second-type semiconductor layer 230 . In this embodiment, the first-type semiconductor layer 210 can be an N-type semiconductor layer, and the second-type semiconductor layer 230 can be a P-type semiconductor layer. Specifically, the materials of the first-type semiconductor layer 210 and the second-type semiconductor layer 230 can be made of at least one of gallium nitride, aluminum gallium nitride, indium gallium nitride, and aluminum indium gallium nitride doped with group II elements or It is composed of group IV elements, and gallium nitride is used as an example in this embodiment. In other embodiments, the material selected for the first-type semiconductor layer 210 and the second-type semiconductor layer 230 can also be a binary compound, such as aluminum nitride and indium nitride; a ternary compound (ternary compound) , such as aluminum gallium nitride, gallium indium nitride, aluminum indium nitride, aluminum gallium arsenide, indium gallium arsenide; and quaternary compounds (quaternary compound) gallium indium aluminum nitride, aluminum indium gallium phosphide or combinations thereof, This part depends on the user's needs and design.

It can be seen from FIG. 3 that the light emitting diode structure 200 of this embodiment is a vertical light emitting diode structure, so the first conductive layer E1 is disposed on the other side of the first type semiconductor layer 210, and the first type semiconductor layer 210 is located on the light emitting diode layer. layer 220 and the first conductive layer E1. In this embodiment, the LED structure 200 may include a conductive substrate 240 disposed between the first-type semiconductor layer 210 and the first conductive layer E1. It should be noted that, since the light-emitting layer 220 of this embodiment also adopts the implementation described above for the light-emitting layer 110, that is, the light-emitting layer 220 can also adopt the implementation forms shown in Figures 2A to 2D, therefore, this The luminous efficiency of the light emitting diode structure 200 of the embodiment can also be effectively improved, and for this part, reference can be made to the foregoing description, and details will not be repeated here.

To sum up, the LED structure of the present invention has at least the following advantages. First, by making the thickness of the quantum well layer closest to the second-type semiconductor layer greater than or equal to the thickness of each of the other quantum well layers, and the thickness of the quantum well layer closest to the second-type semiconductor layer is at least greater than or equal to the thickness of the other quantum well layers The average thickness of the well layer is 1.1 times, preferably 1.2 times, so that when the light-emitting diode structure is driven, the quantum well layer closest to the second-type semiconductor layer can carry more carriers, thereby improving The overall luminous efficiency of a light-emitting diode structure. In addition, since the thickness of the quantum well layer closest to the second-type semiconductor layer is less than or equal to 3 times the average thickness of the other quantum well layers, the overall luminous efficiency of the light-emitting diode structure can be effectively improved, and the quantum well can be avoided at the same time. If the layer is too thick, defects will be generated, which will affect the overall luminous efficiency of the LED structure.

The above is only a preferred embodiment of the present invention, and should not limit the scope of the present invention, that is, all simple equivalent changes and modifications made according to the patent scope of the present invention and the description of the invention are still the same. It belongs to the scope covered by the patent of the present invention. In addition, any embodiment or patent scope of the present invention does not need to achieve all the objects or advantages or features disclosed in the present invention. In addition, the abstract and the title are only used to assist in the search of patent documents, and are not used to limit the scope of rights of the present invention.

Claims (11)

1. light emitting diode construction comprises:

First type semiconductor layer;

Luminescent layer is disposed on this first type semiconductor layer, and this luminescent layer comprises several energy barrier layers and several quantum well layers, and wherein those quantum well layers are located in respectively between those energy barrier layers;

Second type semiconductor layer is disposed on this luminescent layer, wherein near the thickness of this quantum well layer of this second type semiconductor layer at least more than or equal to 1.1 times of the average thickness of other those quantum well layers;

First conductive layer electrically connects this first type semiconductor layer; And

Second conductive layer electrically connects this second type semiconductor layer.

2. light emitting diode construction according to claim 1 is wherein near the thickness of this quantum well layer of this second type semiconductor layer thickness greater than other each those quantum well layers.

3. light emitting diode construction according to claim 1, wherein near the thickness of this quantum well layer of this second type semiconductor layer at least more than or equal to 1.2 times of the average thickness of other those quantum well layers.

4. light emitting diode construction according to claim 1 is wherein near smaller or equal to the average thickness of other those quantum well layers 3 times of the thickness of this quantum well layer of this second type semiconductor layer.

5. light emitting diode construction according to claim 1, wherein the thickness of other each those quantum well layers is all identical.

6. light emitting diode construction according to claim 1; Also comprise brilliant substrate of heap of stone; Wherein this first type semiconductor layer, this luminescent layer and this second type semiconductor layer are stacked on this brilliant substrate of heap of stone in regular turn; And this luminescent layer and this second type semiconductor layer are disposed on the subregion of this first type semiconductor layer and expose this first type semiconductor layer of part, and this first conductive layer is disposed on this first type semiconductor layer that is exposed by this luminescent layer and this second type semiconductor layer.

7. light emitting diode construction according to claim 1, wherein this first conductive layer is disposed at the opposite side of this first type semiconductor layer, and this first type semiconductor layer is between this luminescent layer and this first conductive layer.

8. light emitting diode construction according to claim 7 also comprises electrically-conductive backing plate, is disposed between this first type semiconductor layer and this first conductive layer.

9. light emitting diode construction according to claim 1, wherein this first type semiconductor layer is a n type semiconductor layer, and this second type semiconductor layer is a p type semiconductor layer.

10. light emitting diode construction according to claim 1, wherein the material of this first type semiconductor layer and this second type semiconductor layer is that one of them doped with II family element or IV family element constitute at least by gallium nitride, aluminium gallium nitride alloy, InGaN, aluminum indium nitride gallium.

11. light emitting diode construction according to claim 1, wherein the material of those energy barrier layers comprises gallium nitride, and the material of those quantum well layers comprises InGaN.

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