TWI495161B - Light-emitting diode - Google Patents

Description

Light-emitting diode

The invention relates to a light-emitting diode, in particular to a light-emitting diode based on a carbon nanotube.

High-efficiency blue, green and white light-emitting diodes made of gallium nitride semiconductor materials have longevity, energy saving, green environmental protection and other remarkable features, and have been widely used in large screen color display, automobile lighting, traffic signals, multimedia display. In the field of optical communication, especially in the field of lighting, it has broad potential for development.

The prior light-emitting diode generally includes an N-semiconductor layer, a P-semiconductor layer, an active layer disposed between the N-semiconductor layer and the P-semiconductor layer, and a P-type electrode (usually a transparent electrode) disposed on the P-semiconductor layer. And an N-type electrode disposed on the N-semiconductor layer. When the light-emitting diode is in operation, positive and negative voltages are applied to the P-semiconductor layer and the N-semiconductor layer, respectively, so that holes existing in the P-semiconductor layer and electrons existing in the N-semiconductor layer are active. Recombination occurs in the layer to generate light which is emitted from the light-emitting diode through the transparent electrode.

However, the light-emitting efficiency of the previous light-emitting diode (the light extraction efficiency generally refers to the efficiency of the light wave generated in the active layer being released from the inside of the light-emitting diode) is low, and the main reasons are as follows: First, due to the refraction of the semiconductor The rate is greater than the refractive index of the air, and the light from the active layer is totally reflected at the interface between the semiconductor and the air, so that most of the light waves are It is limited to the inside of the light-emitting diode until it is completely absorbed by the material in the light-emitting diode. Second, the operating current of the light-emitting diode is easily limited to the P-type electrode and its lateral dispersion distance is large, and the current is improperly dispersed, resulting in low light extraction efficiency of the light-emitting diode. The low light extraction efficiency causes a large amount of heat to be generated inside the light-emitting diode, and the heat generated inside the light-emitting diode is hard to be dissipated due to the limitation of the structure and material of the light-emitting diode, so that the performance of the semiconductor material changes. The service life of the light-emitting diode is reduced, which in turn affects the large-scale application of the light-emitting diode.

In order to solve the above problems, various means are used to improve the light extraction efficiency of the light emitting diode, such as roughening the surface of the semiconductor layer, photon recycling method, and adding a reflective layer, etc., but the above method destroys the semiconductor layer to varying degrees. Crystal structure; moreover, its light extraction efficiency is limited. To this end, RH Horng et al. studied a light-emitting diode provided with a transparent conductive layer to improve the light extraction efficiency of the light-emitting diode. For details, please refer to the title "GaN-based light-emitting diodes with indium tin oxide textureing window". Layers using natural lithography" RHHorng et al., Applied Physics Letters, vol. 86, 221101 (2005).

The document discloses a light-emitting diode 10, see Figure 1. The light-emitting diode 10 is provided with a substrate 110, a buffer layer 120, an N-type semiconductor layer 132, a light-emitting layer 134, a P-type semiconductor layer 136, and a transparent contact layer 140 in this order from the bottom to the top; The 10 further includes a transparent conductive layer 150, a first electrode 142, and a second electrode 144. The first electrode 142 is disposed on a surface of the N-type semiconductor layer 132. The transparent conductive layer 150 and the second electrode 144 are disposed on the surface of the transparent contact layer 140 and collectively cover the transparent contact layer 140. Wherein, the buffer layer 120 and the N-type semi-conductive An undoped gallium nitride layer 122 is disposed between the bulk layers 132, and the undoped gallium nitride layer 122 also serves as a buffer for facilitating the growth of the N-type semiconductor and reducing the lattice mismatch of the N-type semiconductor; The hetero-GaN layer 122 is an optional structure. The transparent contact layer 140 completely covers the P-type semiconductor layer 136, and the transparent contact layer 140 has a function of electrically connecting the second electrode 144 and the P-type semiconductor layer 136. The transparent conductive layer 150 forms an ohmic contact with the transparent contact layer 140, and the light generated by the light emitting diode 10 can be emitted from the layer.

Although the transparent conductive layer 150 is a mesh structure, the mesh structure can make the lateral distribution of the working current uniform, and the light extraction efficiency can be increased. However, since the transparent conductive layer 150 is made of indium tin oxide (ITO) material, the ITO material has disadvantages such as insufficient mechanical properties and uneven distribution of resistance values. In addition, the transparency of the ITO material gradually decreases in moist air. In addition, the transparent contact layer 140 completely covers the P-type semiconductor layer 136, and the transparent contact layer 140 can absorb part of the light. Therefore, the light extraction efficiency of the light-emitting diode 10 is still low, and the performance is unstable.

In view of the above, it is necessary to provide a light-emitting diode to solve the problem of low light extraction efficiency of the light-emitting diode.

A light emitting diode comprising: a substrate; an active layer disposed on a surface of the substrate, the active layer comprising a first semiconductor layer, a second semiconductor layer and an active layer The active layer is disposed between the first semiconductor layer and the second semiconductor layer; a first electrode, the first electrode and the first semiconductor layer; a second electrode, the second electrode is electrically connected to the second semiconductor layer; At least one transparent conductive layer covering at least a portion of the active layer and the first electrode And at least one of the second electrodes is electrically connected. Wherein, the transparent conductive layer comprises a carbon nanotube structure.

Compared with the prior art, the use of the carbon nanotube structure as the transparent conductive layer has the following advantages: First, since the carbon nanotube has excellent electrical conductivity, the nanometer is composed of a carbon nanotube. The carbon tube structure also has excellent electrical conductivity. Therefore, by using the above-mentioned carbon nanotube structure as a transparent conductive layer, the effective working current of the light-emitting diode can be correspondingly improved, and current loss can be reduced. Secondly, since the carbon nanotubes have good transparency under humid conditions, the carbon nanotube structure is used as the transparent conductive layer of the light-emitting diode, so that the light-emitting diode can have better transparency and avoid the light-emitting two. The light extraction efficiency of the polar body is lowered, and the performance of the light-emitting diode is further stabilized.

20, 30, 40‧‧‧Lighting diodes

210, 310, 410‧‧‧ base

220, 320, 420‧‧‧ buffer layer

242, 342, 442‧‧‧ first electrode

244, 344, 444‧‧‧ second electrode

250, 350‧‧‧ transparent conductive layer

230, 330, 430‧‧‧ active layer

240, 340‧‧‧ fixed electrode

232, 332, 432‧‧‧ first semiconductor layer

234, 334, 434‧‧‧ active layer

236, 336, 436‧‧‧ second semiconductor layer

262, 362, 462‧‧‧ first surface

264, 364, 464‧‧‧ second surface

450‧‧‧First transparent conductive layer

452‧‧‧Second transparent conductive layer

446‧‧‧First fixed electrode

440‧‧‧Second fixed electrode

1 is a cross-sectional view showing the structure of a conventional light-emitting diode.

2 is a perspective exploded view of a light-emitting diode according to a first embodiment of the present invention.

3 is a schematic structural view of a light-emitting diode according to a first embodiment of the present invention.

Fig. 4 is a scanning electron micrograph of a carbon nanotube film as a transparent conductive layer in the first embodiment of the present invention.

FIG. 5 is a schematic structural view of a light emitting diode according to a second embodiment of the present invention.

Fig. 6 is a schematic view showing the structure of a light-emitting diode according to a third embodiment of the present invention.

The illuminating diode provided by the present invention will be further described in detail below with reference to the accompanying drawings.

Referring to FIG. 2 and FIG. 3 together, a first embodiment of the present invention provides a light emitting diode 20, which mainly includes a substrate 210, a buffer layer 220, an active layer 230, a first electrode 242, and a first The second electrode 244, a transparent conductive layer 250 and a fixed electrode 240. The substrate 210, the buffer layer 220, the active layer 230, the fixed electrode 240, the transparent conductive layer 250, and the second electrode 244 are sequentially stacked. The first electrode 242 is disposed on a surface of the active layer 230. The second electrode 244 is electrically connected to the transparent conductive layer 250.

The substrate 210 has a supporting role. The substrate 210 has a thickness of 300-500 micrometers and is made of materials such as sapphire, gallium arsenide, indium phosphide, lithium metaaluminate, lithium gallate, aluminum nitride, tantalum, tantalum carbide and tantalum nitride. One. In this embodiment, the substrate 210 has a thickness of 400 microns and the material is sapphire.

The buffer layer 220 is disposed on a surface of the substrate 210. The buffer layer 220 is advantageous for improving the growth quality of the material and reducing the lattice mismatch. The buffer layer 220 has a thickness of 10-300 nm, and the material thereof is gallium nitride or aluminum nitride. In this embodiment, the buffer layer 220 has a thickness of 20-50 nm, and the material is gallium nitride. The buffer layer 220 is an optional structure.

The active layer 230 is disposed on the surface of the buffer layer 220 opposite to the substrate 210 , that is, the buffer layer 220 is located between the substrate 210 and the active layer 230 . It can be understood that when there is no buffer layer 220, the active layer 230 is directly disposed on the surface of the substrate 210. The active layer 230 includes a first semiconductor layer 232, an active layer 234, and a second semiconductor layer 236. The active layer 234 is disposed between the first semiconductor layer 232 and the second semiconductor layer 236.

Specifically, the first semiconductor layer 232 is disposed adjacent to the substrate 210. It can be understood that when there is no buffer layer 220, the first semiconductor layer 232 is directly disposed on the surface of the substrate 210. The active layer 230 is a stepped structure, and the active layer 234 and the second semiconductor layer 236 are sequentially disposed on the surface of the first semiconductor layer 232. The first semiconductor layer 232 includes a first surface 262 and a second surface 264. The first surface 262 and the second surface 264 of the first semiconductor layer 232 have different heights. The active layer 234 and the second semiconductor Layers 236 are disposed in sequence on first surface 262. It can be understood that the first surface 262 and the second surface 264 of the first semiconductor layer 232 can be located in the same plane. In this case, the active layer 234 and the second semiconductor layer 236 are sequentially disposed on the first semiconductor layer 232. Part of the surface.

The first semiconductor layer 232 and the second semiconductor layer 236 are of an N-type semiconductor layer or a P-type semiconductor layer. Specifically, when the first semiconductor layer 232 is an N-type semiconductor layer, the second semiconductor layer 236 is a P-type semiconductor layer; when the first semiconductor layer 232 is a P-type semiconductor layer, the second semiconductor layer 236 is an N-type Semiconductor layer. The N-semiconductor layer serves to provide electrons, and the P-semiconductor layer functions to provide holes. The material of the N-type semiconductor layer is one of materials such as N-gallium nitride, N-GaAs and N-phosphorus. The material of the P-type semiconductor layer is one of materials such as P-gallium nitride, P-GaAs and P-phosphorus phosphide. The first semiconductor layer 232 has a thickness of 1-5 microns. The second semiconductor layer 236 has a thickness of 0.1 to 3 μm. In this embodiment, the first semiconductor layer 232 is an N-type semiconductor layer, and the first semiconductor layer 232 has a thickness of 2 μm and the material is N-GaN. The second semiconductor layer 236 is a P-type semiconductor layer having a thickness of 0.3 μm and a material of P-GaN.

The active layer 234 is a quantum well structure including one or more quantum well layers (Quantum Well). The active layer 234 is used to provide photons. The material of the active layer 234 is one of gallium nitride, indium gallium nitride, indium gallium aluminum nitride, arsenic oxide, aluminum arsenide, indium gallium phosphide, indium phosphide, and indium gallium arsenide. Any combination thereof has a thickness of 0.01 to 0.6 μm. In this embodiment, the active layer 234 has a two-layer structure including an indium gallium nitride layer and a gallium nitride layer; the thickness of the layer is 0.3 micrometers.

The fixed electrode 240 is disposed on a surface of the active layer 230 and covers at least a portion of the active layer 230. Specifically, the fixed electrode 240 is disposed on a surface of the second semiconductor layer 236 and at least partially in contact with the transparent conductive layer 250. In this embodiment, the fixed electrode 240 is disposed between the second semiconductor layer 236 and the transparent conductive layer 250. The fixed electrode 240 is at least one layer structure, and the material thereof comprises one of titanium, aluminum, nickel and gold or any combination thereof. In this embodiment, the fixed electrode 240 has a two-layer structure including a nickel layer having a thickness of 150 angstroms and a gold layer having a thickness of 1000 angstroms. The arrangement of the fixed electrode 240 is advantageous for enhancing the adhesion between the transparent conductive layer 250 and the second semiconductor layer 236, and facilitating the electrical connection between the second electrode 244 and the transparent conductive layer 250 and the second semiconductor layer 236. The fixed electrode 240 is of an alternative construction.

The first electrode 242 and the second electrode 244 are electrically connected to the active layer 230, respectively. Specifically, the first electrode 242 is electrically connected to the first semiconductor layer 232. The second electrode 244 is electrically connected to the second semiconductor layer 236. The first electrode 242 and the second electrode 244 may have two polarities of an N-type electrode or a P-type electrode. The polarities of the first electrode 242 and the second electrode 244 are the same as the polarities of the first semiconductor layer 232 and the second semiconductor layer 236, respectively. The first electrode 242 and the second electrode 244 are at least one layer structure and have a thickness of 0.01 to 2 micrometers. The first electrode 242 and the second electricity The material of the pole 244 includes one of titanium, aluminum, nickel, and gold, or any combination thereof. In this embodiment, the first electrode 242 is an N-type electrode, and the first electrode 242 has a two-layer structure including a titanium layer having a thickness of 150 angstroms and a gold layer having a thickness of 2000 angstroms. The second electrode 244 is a P-type electrode, and the second electrode 238 has a two-layer structure including a nickel layer having a thickness of 150 angstroms and a gold layer having a thickness of 1000 angstroms.

The transparent conductive layer 250 is disposed between the second electrode 244 and the second semiconductor layer 236 and covers at least a portion of the surface of the second semiconductor layer 236. The transparent conductive layer 250 includes a carbon nanotube structure. The carbon nanotube structure includes at least one carbon nanotube film, a plurality of nanocarbon line structures, or a combination thereof. The carbon nanotubes in the carbon nanotube film are ordered or disorderly arranged. The ordered arrangement means that the carbon nanotubes are regularly arranged. The disordered arrangement refers to a random arrangement of carbon nanotubes. The carbon nanotube membrane comprises one of a carbon nanotube membrane, a carbon nanotube membrane, a flocculation membrane, and a long carbon nanotube membrane. The plurality of nanocarbon line-like structures are disposed in parallel or intersecting each other. The nanocarbon line-like structure includes at least one nanocarbon line including a non-twisted nano carbon line or a carbon nanotube strand.

Referring to FIG. 4, the carbon nanotube film is a carbon nanotube film. The carbon nanotube film comprises a plurality of carbon nanotubes arranged in a preferred orientation. The carbon nanotubes are connected end to end by Van der Valli. Specifically, the carbon nanotube film comprises a plurality of continuous and aligned carbon nanotube segments, the plurality of carbon nanotube segments being connected end to end by Van der Waals force. Each of the carbon nanotube segments includes a plurality of carbon nanotubes that are parallel to each other, and the plurality of mutually parallel carbon nanotubes are tightly coupled by a van der Waals force. The carbon nanotube segments have any length, thickness, uniformity, and shape. The carbon nanotube film can be obtained by directly stretching an array of carbon nanotubes, wherein the nano tube in the carbon nanotube film The carbon tubes are arranged in the same direction as the stretching direction. The width of the carbon nanotube film is related to the size of the substrate on which the carbon nanotube array is grown. The length of the carbon nanotube film is not limited and can be obtained according to actual needs. Further, the carbon nanotube structure comprises at least two carbon nanotube membranes arranged in an overlapping manner, and the carbon nanotubes in the adjacent two layers of carbon nanotube membranes have an intersection angle α, and 0°≦ α≦90°. For the structure of the carbon nanotubes and the preparation method thereof, please refer to the disclosure of CN101239712A, entitled "Nano Carbon Tube Film Structure", published on February 13, 2008, which was applied by Fan Shoushan et al. on February 9, 2007. Continental patent application for its preparation method.

Alternatively, the carbon nanotube membrane is a carbon nanotube rolled membrane. The carbon nanotube film comprises a plurality of uniformly distributed carbon nanotubes, and the carbon nanotubes are isotropic and arranged in a preferred orientation in the same direction or in different directions. The carbon nanotubes in the carbon nanotube film overlap each other. The carbon nanotube film can be obtained by rolling an array of carbon nanotubes. The length and width of the carbon nanotube structure are not limited. The carbon nanotube film has a thickness of from 1 micrometer to 1000 micrometers. For the structure of the carbon nanotube rolled film and the preparation method thereof, please refer to the mainland patent filed on June 1, 2007 by Fan Shoushan et al., application number 200710074699.6, entitled "Preparation method of carbon nanotube film" Application.

Alternatively, the carbon nanotube membrane is a carbon nanotube flocculation membrane. The carbon nanotube film comprises a plurality of intertwined carbon nanotubes which are attracted to each other by a van der Waals force to form a grid-like structure. The carbon nanotube film is isotropic, wherein the carbon nanotubes are uniformly distributed and arranged irregularly. The length and width of the carbon nanotube film are not limited. For the structure and preparation method of the carbon nanotube film, please refer to the mainland patent application entitled "Preparation Method of Nano Carbon Tube Film", which is filed on Apr. 13, 2007, to the application No. 200710074027.5.

Alternatively, the carbon nanotube membrane is a long carbon nanotube membrane. The carbon nanotube film comprises a plurality of carbon nanotubes arranged in a preferred orientation. The plurality of carbon nanotubes are parallel to each other, arranged side by side and tightly coupled by Van der Waals force. The plurality of carbon nanotubes have substantially equal lengths and may be of the order of millimeters in length. The length of the carbon nanotube film may be equal to the length of the carbon nanotube. The length of the carbon nanotube film is limited by the length of the carbon nanotube. For the structure of the carbon nanotube film and the preparation method thereof, please refer to the mainland patent filed on February 1, 2008 by Fan Shoushan et al., application No. 200810066048.7, entitled "Nano Carbon Tube Film Structure and Preparation Method" Application.

The nanocarbon line-like structure includes at least one non-twisted nanocarbon line. The non-twisted nanocarbon pipeline includes a plurality of carbon nanotubes arranged along the length of the nanocarbon pipeline. Preferably, the non-twisted nanocarbon pipeline comprises a plurality of carbon nanotube segments, the plurality of carbon nanotube segments being connected end to end by a van der Waals force, each of the carbon nanotube segments comprising a plurality of mutually parallel and by Van der Valli is tightly integrated with the carbon nanotubes. The carbon nanotube segments have any length, thickness, uniformity, and shape. The length of the non-twisted nanocarbon pipeline is not limited, and the diameter is from 0.5 nm to 100,000 nm. The non-twisted nano carbon pipeline and the preparation method thereof are referred to the application of Fan Shoushan et al., which was filed on September 16, 2002 and announced on August 20, 2008, and the announcement number is CN100411979C, entitled "A Nano Carbon Pipe Rope" And its preparation method" of the mainland patent.

Optionally, the nanocarbon line-like structure comprises at least one carbon nanotube strand. The carbon nanotube stranded wire further includes a plurality of carbon nanotubes spirally arranged in a longitudinal direction around the carbon nanotube line. Preferably, the carbon nanotube strand comprises a plurality of carbon nanotube segments, the plurality of carbon nanotube segments are connected end to end by Van der Waals force, and each of the carbon nanotube segments comprises a plurality of parallel and borrowed Nano carbon tube tightly combined by Van der Valli . The carbon nanotube segments have any length, thickness, uniformity, and shape. The length of the nano carbon pipeline is not limited, and the diameter is from 0.5 nm to 100,000 nm. The carbon nanotube strand is obtained by twisting both ends of a carbon nanotube film in a reverse direction by a mechanical force.

It can be understood that the carbon nanotube structure is not limited to the above-mentioned nano carbon tube film and a plurality of nano carbon line-like structures, and any other carbon nanotube structure has a transparent conductive property and can improve the light-emitting diode. The light extraction efficiency is within the protection scope of the present invention.

The carbon nanotubes include one or more of a single-walled carbon nanotube, a double-walled carbon nanotube, and a multi-walled carbon nanotube. The single-walled carbon nanotube has a diameter of 0.5 nm to 50 nm, the double-walled carbon nanotube has a diameter of 1 nm to 50 nm, and the multi-walled carbon nanotube has a diameter of 1.5 nm to 50 nm. Nano.

In this embodiment, the transparent conductive layer 250 includes a carbon nanotube structure, the nano carbon tube structure is a two-layer carbon nanotube film, and the carbon nanotube film includes a plurality of carbon nanotubes connected end to end. And the preferred orientation is arranged. Specifically, the carbon nanotube membrane comprises a plurality of continuous and aligned carbon nanotube segments. The plurality of carbon nanotube segments are connected end to end by Van der Valli. Each of the carbon nanotube segments includes a plurality of carbon nanotubes that are parallel to each other, and the plurality of mutually parallel carbon nanotubes are tightly coupled by a van der Waals force. The two layers of carbon nanotube films are arranged in an overlapping manner, and the carbon nanotubes in each layer of the carbon nanotube film are arranged in a preferred orientation in the same direction. Specifically, the two layers of the carbon nanotube film in the transparent conductive layer 250 are overlapped with each other, and the carbon nanotubes in the adjacent two layers of carbon nanotube film have an intersection angle α, wherein α is 90 degrees. The carbon nanotubes are multi-walled carbon nanotubes, and the multi-walled carbon nanotubes have a diameter of 1.5 nm to 50 nm.

When the light emitting diode 20 is in an operating state, the second electrode 244 has a small amount of holes generated, and the first electrode 242 has a small amount of electrons generated. The second electrode 244 generates a portion of the holes passing through the transparent conductive layer 250 to the second semiconductor layer 236, and induces the second semiconductor layer 236 to generate a large number of holes; meanwhile, the second electrode 244 generates another portion of the cavity from the second The two electrodes 244 sequentially pass through the transparent conductive layer 250 and the fixed electrode 240 to reach the second semiconductor layer 236, and induce the second semiconductor layer 236 to generate a large amount of holes; afterwards, the holes move to the active layer 234. The transparent conductive layer 250 and the second semiconductor layer 236 are directly electrically connected to each other, which facilitates lateral dispersion and uniform distribution of current, thereby improving the light extraction efficiency of the light-emitting diode 20 . Electrons move from the first electrode 242 to the first semiconductor layer 232, and induce the first semiconductor layer 232 to generate a large amount of electrons; thereafter, the electrons move to the active layer 234. These holes and electrons meet the active layer 234 and collide to generate photons.

Most of the photons pass through the second semiconductor layer 236 to the transparent conductive layer 250. When the light of this portion is directly refracted from the transparent conductive layer 250 without passing through the fixed electrode 240, the fixed electrode 240 can be prevented from absorbing light and reducing the light extraction efficiency. At the same time, a portion of the photons pass from the active layer 234 to the first semiconductor layer 232 and are refracted from the second surface 264 of the first semiconductor layer 232. A part of the photons are refracted and emitted a plurality of times inside the light-emitting diode 20. Therefore, the light emitting diode 20 has a higher light extraction efficiency.

Referring to FIG. 5, a second embodiment of the present invention provides a light emitting diode 30, which mainly includes a substrate 310, a buffer layer 320, an active layer 330, a first electrode 342, and a second electrode 344. The transparent conductive layer 350 and a fixed electrode 340; wherein the active layer 330 includes a first semiconductor layer 332, an active layer 334, and a second half The conductor layer 336 is disposed between the first semiconductor layer 332 and the second semiconductor layer 336. The first semiconductor layer 332 includes a first surface 362 and a second surface 364. The first surface 362 and the second surface 364 have different heights. The active layer 334 and the second semiconductor layer 336 are sequentially stacked on the second surface. First surface 362. It can be understood that the first surface 362 and the second surface 364 may be in the same plane, and the active layer 334 and the second semiconductor layer 336 are sequentially stacked on a part of the surface of the first semiconductor layer 332.

The structure of the light-emitting diode 30 of the second embodiment is substantially the same as that of the light-emitting diode 20 of the first embodiment. The difference is that in the light-emitting diode 30, the transparent conductive layer 350 covers at least part of the second semiconductor layer 332. Surface 364 is electrically coupled to first electrode 342. The structure of the transparent conductive layer 350 is the same as that of the transparent conductive layer 250 in the first embodiment. The fixed electrode 340 is disposed between the second surface 364 of the first semiconductor layer 332 and the transparent conductive layer 350. The first electrode 342 is disposed on a surface of the transparent conductive layer 350 and disposed opposite to the fixed electrode 340. The second electrode 344 is disposed on a surface of the second semiconductor layer 336.

When the light-emitting diode 30 provided in this embodiment is in an operating state, the second electrode 344 has a small amount of holes generated, and the first electrode 342 has a small amount of electrons generated. The small amount of holes generated by the second electrode 344 moves to the second semiconductor layer 336, and induces the second semiconductor layer 336 to generate a large number of holes; afterwards, the holes move the active layer 334. At the same time, the small amount of electrons move from the first electrode 342 to the first semiconductor layer 332, and induces the first semiconductor layer 332 to generate a large amount of electrons; thereafter, the electrons move to the active layer 334. These holes and electrons meet at the active layer 334 and collide to generate photons. A portion of the photons are moved to the second semiconductor layer 336 and from the surface of the second semiconductor layer 336 At the same time, most of the photons pass through the first semiconductor layer 332 to reach the transparent conductive layer 350, and most of the light is directly refracted from the transparent conductive layer 350; and a part of the photons are emitted from the light-emitting diode 30. The interior is refracted multiple times and shot.

Referring to FIG. 6, a third embodiment of the present invention provides a light emitting diode 40. The structure of the LED body 40 mainly includes a substrate 410, a buffer layer 420, an active layer 430, a first electrode 442, a second electrode 444, a first transparent conductive layer 450, and a second transparent conductive layer. The layer 452, the first fixed electrode 446 and the second fixed electrode 440; wherein the active layer 430 includes a first semiconductor layer 432, an active layer 434, and a second semiconductor layer 436, and the active layer 434 The first semiconductor layer 432 is disposed between the first semiconductor layer 432 and the second semiconductor layer 436. The first semiconductor layer 432 includes a first surface 462 and a second surface 464. The first surface 462 and the second surface 464 have different heights. The active layer 434 and the second semiconductor layer 436 are sequentially stacked on the second semiconductor layer 436. First surface 462. It can be understood that the first surface 462 and the second surface 464 may be in the same plane, and the active layer 434 and the second semiconductor layer 436 are sequentially stacked on a part of the surface of the first semiconductor layer 432. The second transparent conductive layer 452 covers at least a portion of the surface of the second semiconductor layer 436 and is electrically connected to the second electrode 444. The second fixed electrode 440 is disposed between the second semiconductor layer 436 and the second transparent conductive layer 452. The second electrode 444 is disposed on a surface of the second transparent conductive layer 452.

The structure of the light-emitting diode 40 of the third embodiment is substantially the same as that of the light-emitting diode 20 of the first embodiment. The difference is that in the light-emitting diode 40, the first transparent conductive layer 450 covers the first semiconductor layer. At least a portion of the surface of the second surface 464 of 432, and The first electrode 442 is electrically connected. The first fixed electrode 446 is disposed between the first transparent conductive layer 450 and the second surface 464 of the first semiconductor layer 432 . The first electrode is disposed on a surface of the first transparent conductive layer 450 and disposed opposite to the first fixed electrode 446. The first transparent conductive layer 450 and the second transparent conductive layer 452 are electrically connected to the first electrode 442 and the second electrode 444, respectively, so that the light generated by the light emitting diode 40 can be generated from the first semiconductor layer 432 and the second The semiconductor layer 436 is emitted. The first transparent conductive layer 450 and the second transparent conductive layer 452 have at least one transparent conductive layer which is a carbon nanotube structure. The other transparent conductive layer of the first transparent conductive layer 450 and the second transparent conductive layer 452 is one of an indium lanthanum oxide, a zinc oxide, a nickel gold alloy, a tin oxide, and a carbon nanotube structure. The carbon nanotube structure is the same as that of the first embodiment.

The light-emitting diode provided by the embodiment of the invention has the advantages that the use of the carbon nanotube structure as the transparent conductive layer has the following advantages: First, since the carbon nanotube has excellent electrical conductivity, the carbon nanotube composed of the carbon nanotube is composed of carbon nanotubes. The structure also has excellent electrical conductivity. Therefore, by using the above-mentioned nano carbon tube structure as a transparent conductive layer, the effective working current of the light-emitting diode can be correspondingly improved, and current loss can be reduced. Secondly, since the carbon nanotube has good transparency in a humid environment, the carbon nanotube structure is used as a transparent conductive layer of the light-emitting diode, so that the light-emitting diode has better transparency and avoids light-emitting. In a humid environment, the light extraction efficiency is lowered. Third, when the carbon nanotubes in the carbon nanotube film are arranged in an orderly manner, the pores of the carbon nanotubes are arranged in an orderly manner, so that the carbon nanotube film has the characteristics of a photonic crystal structure, and the light can be from Nye The pores between the carbon nanotubes are emitted, thereby improving the light extraction efficiency, reducing the heat generation inside the light-emitting diode, and prolonging the service life of the light-emitting diode. Fourth, the nanotube in the carbon nanotube film The carbon nanotubes are arranged in an orderly manner, so that the working current distribution of the light-emitting diodes is uniform, and the light extraction efficiency is reduced due to uneven current distribution. In addition, the transparent conductive layer and the semiconductor layer are directly electrically connected, which reduces the working current loss, increases the luminous efficiency of the light emitting diode, reduces the absorption of light by the fixed electrode, and improves the light extraction efficiency of the light emitting diode. Therefore, the light-emitting diode provided by the embodiment of the invention has the characteristics of long service life, high light extraction efficiency and stable performance.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

20‧‧‧Lighting diode

210‧‧‧Base

220‧‧‧buffer layer

242‧‧‧First electrode

244‧‧‧second electrode

250‧‧‧Transparent conductive layer

230‧‧‧Active layer

240‧‧‧Fixed electrode

232‧‧‧First semiconductor layer

234‧‧‧Active layer

236‧‧‧Second semiconductor layer

262‧‧‧ first surface

264‧‧‧ second surface

Claims (18)

A light emitting diode comprising: a substrate; an active layer disposed on a surface of the substrate, the active layer comprising a first semiconductor layer, a second semiconductor layer and an active layer The active layer is disposed between the first semiconductor layer and the second semiconductor layer; a first electrode, the first electrode is electrically connected to the first semiconductor layer; a second electrode, the second electrode is The second semiconductor layer is electrically connected; and at least one transparent conductive layer directly covering at least a portion of the active layer and electrically connected to at least one of the first electrode and the second electrode; The improvement is that the at least one transparent conductive layer comprises a carbon nanotube structure, further comprising a fixed electrode disposed between a portion of the carbon nanotube structure and the active layer for fixing the nano Carbon tube structure. The light-emitting diode of claim 1, wherein the carbon nanotube structure comprises at least one carbon nanotube film, a plurality of nanocarbon line-like structures, or a combination thereof. The light-emitting diode according to claim 2, wherein the carbon nanotube structure comprises at least two layers of carbon nanotube films arranged in an overlapping manner, the carbon nanotube film comprising a plurality of ordered arrays of naphthalene a carbon nanotube, and the carbon nanotubes in the adjacent two carbon nanotube membranes in the at least two overlapping carbon nanotube membranes have an intersection angle between the carbon nanotubes, and the intersection angle is greater than or equal to 0 degrees, and Less than or equal to 90 degrees. The light-emitting diode of claim 2, wherein the carbon nanotube film comprises A plurality of carbon nanotubes are connected end to end and arranged in a preferred orientation in the same direction, and the adjacent carbon nanotubes are tightly coupled by van der Waals force. The light-emitting diode according to claim 2, wherein the carbon nanotube film comprises a plurality of carbon nanotubes parallel to a surface of the carbon nanotube film. The light-emitting diode according to claim 2, wherein the carbon nanotube film comprises a plurality of carbon nanotubes overlapping each other and arranged in a preferred orientation in one direction or in a plurality of directions. The light-emitting diode of claim 2, wherein the nanocarbon line-like structure comprises at least one nanocarbon pipeline, the nanocarbon pipeline comprising a plurality of carbon nanotubes along the nanocarbon pipeline The length direction is preferably oriented or spirally arranged around the length of the nanocarbon line. The light-emitting diode of claim 2, wherein the plurality of nanocarbon line-like structures are disposed in parallel or intersecting each other. The light-emitting diode of claim 1, wherein the active layer has a stepped structure, and the active layer and the second semiconductor layer are stacked on a portion of the surface of the first semiconductor layer, and a portion is exposed a first semiconductor layer; the first electrode is disposed on a surface of the exposed portion of the first semiconductor layer, and the second electrode is disposed on a surface of the second semiconductor layer. The light-emitting diode according to claim 1, wherein the first semiconductor layer is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer. The light-emitting diode according to claim 1, wherein the fixed electrode is disposed opposite to at least one of the first electrode and the second electrode through the carbon nanotube structure. The light-emitting diode of claim 11, wherein the fixed electrode is disposed between the active layer and the at least one transparent conductive layer. The light-emitting diode of claim 1, further comprising a buffer layer disposed between the substrate and the active layer. The light-emitting diode of claim 1, wherein the substrate is one of sapphire, gallium arsenide, indium phosphide, antimony, antimony carbide, and tantalum nitride, or any combination thereof. The light-emitting diode of claim 1, wherein the material of the first semiconductor layer is N-gallium nitride, N-GaAs or N-phosphorus. The light-emitting diode of claim 15, wherein the material of the second semiconductor layer is P-gallium nitride, P-gallium arsenide or P-phosphorus phosphide. The light-emitting diode according to Item 1, wherein the material of the active layer is gallium nitride, indium gallium nitride, indium gallium nitride, arsenic, aluminum arsenide, indium phosphide. One of gallium, indium phosphide, and indium gallium arsenide or any combination thereof. The light-emitting diode of claim 1, wherein the material of the first electrode and the second electrode comprises one of titanium, aluminum, nickel and gold or any combination thereof.