Light emitting diode

Abstract

To provide an innovative light emitting diode structure that improves the problems of low luminous efficiency, uneven luminescence, and uneven colors caused by non-uniform current distribution in conventional light emitting diodes, and increases the brightness of light emitting diodes.SOLUTION: The present invention relates to a light emitting diode that includes a substrate and a semiconductor epitaxial structure. The semiconductor epitaxial structure is placed on the substrate. The semiconductor epitaxial structure has a semiconductor composite layer and a plurality of current diffusion layers. Each current diffusion layer is located within the semiconductor composite layer. In the plurality of current diffusion layers, current diffusion layers with high doping concentration and current diffusion layers with low doping concentration are alternately stacked.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to light emitting diodes, and more particularly to light emitting diodes having uniform current spreading. [Background technology]

[0002] Light-emitting diodes (LEDs), a type of solid-state light-emitting device, have advantages such as low power consumption, low heat generation, long life, drop resistance, small size, fast response, good photoelectric properties, and stable emission wavelength, and are therefore widely used in home appliances, display lamps, optoelectronic products, etc. With the development of optoelectronic technology, the luminous efficiency, operating life, and brightness of solid-state light-emitting devices have been greatly improved, and light-emitting diodes have become the mainstream of lighting devices in the future.

[0003] Light-emitting diodes work by applying a voltage between two different types of semiconductor materials, directing electrons and holes to the PN junction region. Current diffusion allows carriers to move from high-concentration regions to low-concentration regions, resulting in effective carrier injection. Once electrons and holes are injected into the PN junction region, they combine in this region. The combination process releases energy, which is the light emitted by the LED. Current diffusion allows a large number of electrons and holes to meet in the light-emitting region, increasing the chances of carrier combination and improving light-emitting efficiency. If the carrier density is not uniform, only some areas will emit light, resulting in uneven lighting and color variation.

[0004] In order to overcome the above problems, it has become an urgent task in the industry to develop an innovative light emitting diode structure that can improve the above problem of poor current spreading and increase the brightness of the light emitting diode. Summary of the Invention

[0005] The main object of the present invention is to provide an innovative light emitting diode structure which improves the problems of reduced light emitting efficiency, uneven light emission, and uneven color caused by non-uniform current distribution in conventional light emitting diodes, and which increases the brightness of the light emitting diode.

[0006] In order to achieve the above object, the present invention provides a light emitting diode including a substrate and a semiconductor epitaxial structure, the semiconductor epitaxial structure being disposed on the substrate, the semiconductor epitaxial structure having a semiconductor composite layer and a plurality of current spreading layers, each current spreading layer being disposed within the semiconductor composite layer, and the plurality of current spreading layers being stacked with alternating current spreading layers having high doping concentrations and current spreading layers having low doping concentrations.

[0007] In an embodiment of the present invention, the material of each current spreading layer is one selected from the group consisting of indium gallium phosphide (InGaP), aluminum gallium indium phosphide (AlGaInP), aluminum indium phosphide (AlInP), indium gallium arsenide (InGaAs), aluminum indium gallium arsenide (AlInGaAs), aluminum gallium arsenide (AlGaAs), aluminum gallium arsenide phosphide (AlGaAsP), gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), and indium gallium arsenide phosphide (InGaAsP).

[0008] In an embodiment of the present invention, the doping material of each current spreading layer includes silicon or tellurium.

[0009] In an embodiment of the present invention, one of the two vertically adjacent current spreading layers has a thickness of about 0.9 to 3.5E18 / cm 3 and the other has a high doping concentration of about 0.9 to 3.5E17 / cm 3 has a low doping concentration of .

[0010] In an embodiment of the present invention, in the plurality of current spreading layers, a thickness of a lower current spreading layer is greater than a thickness of an adjacent upper current spreading layer.

[0011] In an embodiment of the present invention, the thickness of the current diffusion layer is b + a×(N - 1), where N is the total number of the current diffusion layers, N is a positive integer from 1 to 1000, b is the thickness of the first layer of the plurality of current diffusion layers, 0 < b < 10 micrometers, and a is the increasing thickness of each layer of the current diffusion layer, 0 < a < 10 micrometers.

[0012] To achieve the above object, the present invention provides another light-emitting diode including a substrate and a semiconductor epitaxial structure. The semiconductor epitaxial structure is disposed on the substrate. The semiconductor epitaxial structure has a semiconductor composite layer and a plurality of current diffusion layers. Each current diffusion layer is disposed within the semiconductor composite layer. In the plurality of current diffusion layers, the thickness of the lower current diffusion layer is greater than the thickness of the adjacent upper current diffusion layer.

[0013] Those skilled in the art can understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described below.

Brief Description of the Drawings

[0014] [Figure 1] Schematic diagram showing the structure of a light-emitting diode in an embodiment of the present invention [Diagram 2] Schematic diagram showing the structure of a light-emitting diode in an embodiment of the present invention [Diagram 3] Enlarged schematic diagram of a part of the structure of a light-emitting diode in an embodiment of the present invention

Embodiments for Carrying Out the Invention

[0015] The contents of the present invention will be described below through examples. The examples of the present invention are examples of embodiments, and are not intended to limit the present invention to the environments, applications, or specific aspects described in the examples. Therefore, the explanation of the examples is for explaining the present invention, but does not limit the present invention. In the embodiments and drawings, components that are not directly related to the present invention are omitted and not shown. The dimensional relationship between the components in the drawings is for ease of understanding, and does not limit the actual dimensions.

[0016] FIG. 1 is a schematic diagram showing the structure of a light-emitting diode in an embodiment of the present invention. As shown in the figure, in this embodiment, the light-emitting diode includes a substrate 10, a semiconductor epitaxial structure 20, and an electrode structure 30. The semiconductor epitaxial structure 20 is disposed on the substrate 10. In the embodiment of the present invention, the substrate 10 is a semiconductor substrate. Preferably, during the manufacturing process of the light-emitting diode, the silicon substrate and the semiconductor epitaxial structure 20 are wafer-bonded. The electrode structure 30 is disposed on the semiconductor epitaxial structure 20. It should be noted that the semiconductor epitaxial structure 20 of the light-emitting diode according to the present invention includes a semiconductor composite layer 100 and a plurality of current spreading layers 200. Each current spreading layer 200 is disposed in the semiconductor composite layer 100.

[0017] The following description will be given with reference to Figs. 1 and 2. Fig. 2 shows the structure of a light-emitting diode in an embodiment of the present invention. The semiconductor composite layer 100 has a P-type semiconductor layer 110, a light-emitting layer 120, an N-type semiconductor lower layer 130, and an N-type semiconductor upper layer 140. Specifically, the P-type semiconductor layer 110 is disposed on a substrate 10. The light-emitting layer 120 is disposed on the P-type semiconductor layer 110. The N-type semiconductor lower layer 130 is disposed on the light-emitting layer 120. The N-type semiconductor upper layer 140 is disposed on a plurality of current spreading layers 200. In a preferred embodiment of the present invention, the current spreading layer 200 is an epitaxial stacked structure of homogeneous semiconductors having the same material composition. Specifically, the material of the P-type semiconductor layer 110 may be aluminum gallium indium phosphide, aluminum indium phosphide, or gallium phosphide doped with magnesium or carbon. The material of the N-type semiconductor lower layer 130 and the N-type semiconductor upper layer 140 includes aluminum gallium indium phosphide doped with silicon or tellurium. x Ga 0.5-x In 0.5 P(x=0~0.5). The doping concentration of silicon or tellurium is about 0.9~3.5E18 / cm 3 The thickness of the N-type semiconductor lower layer 130 and the N-type semiconductor upper layer 140 is about 0.05 to 5 micrometers, respectively. The light emitting layer 120 is formed with a multiple quantum well (MQW) structure. In this embodiment, the multiple quantum well has an emission wavelength of 600 to 700 nanometers, but is not limited thereto. The current spreading structure disclosed in the present invention is also applicable to light emitting diodes with other emission bands.

[0018] The following description will be given with reference to Figs. 1, 2, and 3. Fig. 3 is a schematic diagram showing an enlarged portion of the light-emitting diode of the present invention. In order to improve the problems of current concentration and poor diffusion in conventional light-emitting diodes, a plurality of current diffusion layers 200 are disposed between the N-type semiconductor lower layer 130 and the N-type semiconductor upper layer 140 in the semiconductor epitaxial structure 20 of the light-emitting diode of the present invention. This provides a uniform current diffusion effect, improving the brightness of the light-emitting diode. Specifically, in the present invention, in order to achieve the current diffusion effect, a current diffusion layer with a high doping concentration and a current diffusion layer with a low doping concentration are alternately laminated in the plurality of current diffusion layers disposed between the N-type semiconductor upper layer and the lower layer. For example, the first current diffusion layer 210 adjacent to the N-type semiconductor upper layer 140 is an epitaxial layer of aluminum gallium indium phosphide with a low doping concentration. Specifically, the composition of the aluminum gallium indium phosphide is Al x Ga 0.5-x In 0.5 P (x = 0 to 0.5). Silicon or tellurium is used as the doping element, and the doping concentration is about 0.9 to 3.5E17 / cm 3 The second current spreading layer 210 adjacent to the first current spreading layer 210 is an epitaxial layer of aluminum gallium indium phosphide with a high doping concentration. The composition of the aluminum gallium indium phosphide is also Al x Ga 0.5-x In 0.5 P (x = 0-0.5). Similarly, silicon or tellurium is used as the doping element, and the doping concentration is about 0.9-3.5E18 / cm 3 Similarly, the doping concentration of the odd-numbered current spreading layers, such as the third current spreading layer 230 in the following stacks, is the same as the doping concentration of the first current spreading layer 210. The third current spreading layer 230 also has a doping concentration of 0.9 to 3.5E17 / cm 3 The even-numbered current spreading layers, such as the fourth current spreading layer 240, have the same doping concentration as the second current spreading layer 220. The fourth current spreading layer 240 also has a doping concentration of 0.9 to 3.5E18 / cm3 In the present invention, the odd-numbered layers are epitaxial layers of aluminum gallium indium phosphide having a high doping concentration. Meanwhile, in another embodiment, the odd-numbered layers may be epitaxial layers of aluminum gallium indium phosphide having a high doping concentration, and the even-numbered layers may be epitaxial layers of aluminum gallium indium phosphide having a low doping concentration, but the description thereof will be omitted. In practical applications, in the semiconductor epitaxial structure 20 of the light-emitting diode according to the present invention, the number of layers of the current spreading layer 200 can be determined according to the actual diffusion effect. Note that the values ​​of the low doping concentration or high doping concentration in each layer of the current spreading layer described above are merely examples, and are not limited thereto. In the present invention, there is no particular limitation on the doping element or doping concentration, and in order to generate a difference in the actual resistance value, it is sufficient that there is a difference in doping concentration between the adjacent diffusion layers above and below.

[0019] As mentioned above, a low doping concentration leads to a high resistance. Conversely, a high doping concentration leads to a low resistance. In the multiple current spreading layers 200, current spreading layers with high doping concentrations and current spreading layers with low doping concentrations are alternately stacked. As a result, the lateral current is enhanced in the layer with a high doping concentration with a low resistance. However, when the current flows downward, it encounters a layer with a low doping concentration with a high resistance, and the vertical current is hindered, and the current flows laterally. Therefore, when the current is injected downward from the upper electrode structure 30 into the current spreading layer, the current spreading layers with high doping concentrations and current spreading layers with low doping concentrations are alternately stacked, resulting in a "vertical hinderance, lateral enhancement" diffusion effect. This allows the current to be effectively and uniformly spread after passing through the current spreading layers before being injected into the light emitting layer 120.

[0020] The above-mentioned aluminum gallium indium phosphide current spreading layer is only an example, and in practical application, it can be adjusted according to different epitaxial structures of light emitting diodes. The material of each current spreading layer is one selected from the group consisting of indium gallium phosphide (InGaP), aluminum gallium indium phosphide (AlGaInP), aluminum indium phosphide (AlInP), indium gallium arsenide (InGaAs), aluminum indium gallium arsenide (AlInGaAs), aluminum gallium arsenide (AlGaAsP), gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), and indium gallium arsenide phosphide (InGaAsP).

[0021] Furthermore, in order to realize effective uniform current diffusion, in addition to the above technical means of alternately stacking current diffusion layers with high and low doping concentrations, the thickness of each current diffusion layer 200 can be adjusted to obtain a similar effect of uniform current diffusion. Specifically, in the epitaxial stacking of the current diffusion layers, the thickness of the lower current diffusion layer of two adjacent current diffusion layers is greater than the thickness of the adjacent upper current diffusion layer. In other words, the current diffusion layer 200 "becomes gradually thicker, denser at the top and sparser at the bottom". The closer to the light emitting layer 120 from above, the thicker the current diffusion layer 200 becomes. As the thickness of the current diffusion layer increases, the substantial resistance of the current diffusion layer also gradually increases. As a result, when the current is injected from above to below, a diffusion effect of "vertical interference, lateral enhancement" is obtained. In detail, in the so-called "dense at the top and sparse at the bottom" of the present invention, the part of the current diffusion layer close to the light emitting layer becomes the "lower part", and the part away from the light emitting layer becomes the "upper part". The thickness of the current spreading layer closer to the light emitting layer is thicker, i.e. "sparser", than the thickness of the current spreading layer farther from the light emitting layer. On the other hand, the current spreading layer farther from the light emitting layer is thinner, i.e. "dense". According to the principle of current spreading, a thin and thick epitaxial layer has a high resistance value, which hinders the vertical flow of current. On the other hand, a layer with a low resistance value enhances the lateral flow of current. Since it is desired that the diffusion effect is higher near the light emitting layer compared to the top, the lower part near the light emitting layer is designed to be thicker.

[0022] Specifically, in actual applications, among the plurality of current diffusion layers, the thickness of the Nth current diffusion layer is b + a×(N - 1). N is the total number of current diffusion layers, which is a positive integer from 1 to 1000, but not limited to 1000. b is the thickness of the first current diffusion layer 210, where 0 < b < 10 micrometers, but not limited to this. a is the increasing thickness of each layer of the current diffusion layer, where 0 < a < 10 micrometers, but not limited to this. Table 1 below shows that in the embodiments of the present invention, when the total number of current diffusion layers is 16, the thickness of the first current diffusion layer 210 is b, and the increasing thickness of each layer is a, the thickness of the current diffusion layer gradually changes, and the current diffusion layers with high doping concentration and those with low doping concentration are alternately stacked. [Table 1]

[0023] As described above, the design principle of the diffusion structure adopted in the present invention is as follows. (1) Each current diffusion layer has a dopant, and the current diffusion layers with high doping concentration and those with low doping concentration are alternately stacked. (2) There is no particular limitation as long as there is a difference in doping concentration. (3) The present invention adopts the design of gradually thickening current diffusion layers and does not require the use of the inter-lattice piezoelectric field effect. To a certain extent, a diffusion effect can be obtained whether the thickness of the diffusion layer is too thick or too thin. (4) In the epitaxial layer of the diffusion layer of the present invention, it is not limited to the use of superlattice pairs with a certain thickness, but has technical features such as a gradually changing thickness (dense at the top and sparse at the bottom), and / or a structure in which the current diffusion layers with high doping concentration and those with low doping concentration are alternately stacked.

[0024] The above embodiments illustrate the embodiments of the present invention and explain the characteristic configurations of the present invention. The present invention is not limited to the above embodiments. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention shall be based on the scope of the claims. [Explanation of Reference Signs]

[0025] 10 Substrate 20 Semiconductor epitaxial structure 30 Electrode structure 100 Semiconductor composite layer 110 P-type semiconductor layer 120 Light-emitting layer 130 N-type semiconductor lower layer 140 N-type semiconductor upper layer 200 Current Diffusion Layer 210 First current spreading layer 220 Second current spreading layer 230 Third current spreading layer 240 4th current spreading layer N Nth current spreading layer

Claims

1. A light emitting diode, A substrate; a semiconductor epitaxial structure disposed on the substrate, the semiconductor epitaxial structure having a semiconductor composite layer and a plurality of current spreading layers disposed within the semiconductor composite layer; In the plurality of current spreading layers, the current spreading layers having a high doping concentration and the current spreading layers having a low doping concentration are alternately stacked.

2. 2. The light-emitting diode of claim 1, wherein the material of the current spreading layer is one selected from the group consisting of indium gallium phosphide (InGaP), aluminum gallium indium phosphide (AlGaInP), aluminum indium phosphide (AlInP), indium gallium arsenide (InGaAs), aluminum indium gallium arsenide (AlInGaAs), aluminum gallium arsenide (AlGaAs), aluminum gallium arsenide phosphide (AlGaAsP), gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), and indium gallium arsenide phosphide (InGaAsP).

3. 3. The light emitting diode according to claim 2, wherein the doping material of the current spreading layer comprises silicon or tellurium.

4. One of the two current spreading layers adjacent to each other has a thickness of about 0.9 to 3.5E18 / cm ３ and the other has a high doping concentration of about 0.9-3.5E17 / cm ３ 4. The light emitting diode of claim 3, having a low doping concentration of .

5. 2. The light-emitting diode according to claim 1, wherein, in the plurality of current spreading layers, a thickness of the lower current spreading layer is greater than a thickness of the adjacent upper current spreading layer.

6. 6. The light emitting diode of claim 5, wherein the thickness of the current spreading layer is b+a×(N−1), where N is the total number of the current spreading layers, N being a positive integer from 1 to 1000, b is the thickness of a first layer of the plurality of current spreading layers, 0<b<10 micrometers, a is the incremental thickness of each current spreading layer, 0<a<10 micrometers.

7. A light emitting diode, A substrate; a semiconductor epitaxial structure disposed on the substrate, the semiconductor epitaxial structure having a semiconductor composite layer and a plurality of current spreading layers disposed within the semiconductor composite layer; A light emitting diode, wherein, among the plurality of current spreading layers, a thickness of a lower current spreading layer is greater than a thickness of an adjacent upper current spreading layer.

8. 8. The light emitting diode of claim 7, wherein the thickness of the current spreading layer is b+a×(N−1), where N is the total number of the current spreading layers, N is a positive integer from 1 to 1000, b is the thickness of a first layer of the plurality of current spreading layers, 0<b<10 micrometers, a is the incremental thickness of each current spreading layer, 0<a<10 micrometers.

9. 8. The light-emitting diode of claim 7, wherein the material of the current spreading layer is one selected from the group consisting of indium gallium phosphide (InGaP), aluminum gallium indium phosphide (AlGaInP), aluminum indium phosphide (AlInP), indium gallium arsenide (InGaAs), aluminum indium gallium arsenide (AlInGaAs), aluminum gallium arsenide (AlGaAs), aluminum gallium arsenide phosphide (AlGaAsP), gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), and indium gallium arsenide phosphide (InGaAsP).

10. 8. The light emitting diode according to claim 7, wherein the current spreading layers are formed by alternating stacking of the current spreading layers having a high doping concentration and the current spreading layers having a low doping concentration.

11. 11. The light emitting diode of claim 10, wherein the doping material of the current spreading layer comprises silicon or tellurium.

12. One of the two current spreading layers adjacent to each other has a thickness of about 0.9 to 3.5E18 / cm ３ and the other has a high doping concentration of about 0.9-3.5E17 / cm ３ 12. The light emitting diode of claim 11, having a low doping concentration of

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