CN211858672U

CN211858672U - Micro light-emitting diode

Info

Publication number: CN211858672U
Application number: CN202020604177.3U
Authority: CN
Inventors: 杨顺贵; 黄国栋; 林雅雯; 黄嘉宏
Original assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Current assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Priority date: 2020-04-21
Filing date: 2020-04-21
Publication date: 2020-11-03
Anticipated expiration: 2030-04-21

Abstract

The utility model relates to a light emitting diode field especially relates to a little emitting diode, and it is including the first semiconductor layer, active layer and the second semiconductor layer that stack gradually the setting, first semiconductor layer with the second semiconductor layer is the semiconductor layer of different grade type, the active layer is including the first quantum well layer and the second quantum well layer that stack gradually the second quantum well layer reaches be formed with the nanoring structure on the second semiconductor layer, the light of first colour of first quantum well layer transmission, second quantum well layer with the light of the part transmission second colour that the nanoring lateral wall corresponds, first colour with the second colour is inequality, first semiconductor layer electric connection has first electrode, second semiconductor layer electric connection has the second electrode. The nanoring will release the original quantum well stress and reduce the quantum confined stark effect to produce blue light.

Description

Micro light-emitting diode

Technical Field

The utility model relates to a LED display device makes technical field, especially relates to a little emitting diode.

Background

A typical Light-Emitting Diode (LED) chip includes a substrate and an epitaxial layer, and has a thickness of about 100 to 500 μm and a size of 100 to 1000 μm. Further, the research on micro LED display panels is carried out by peeling off an epitaxial layer having a thickness of about 4 to 5 μm on the surface of an LED by a physical or chemical mechanism (Lift-off), and then transferring the peeled epitaxial layer onto a circuit board. The micro LED display combines two technical features of a Thin film transistor liquid crystal display (TFT-LCD) and an LED, has mature development of materials, processes and equipment, has a product specification far higher than that of the current TFT-LCD or organic light-Emitting Diode (OLED), and more widely includes a flexible and transparent display in the application field, and is a secondary flat panel display technology with high feasibility.

At present, the micro LED chip is applied to a full-color AR micro display and a mobile/large display by two methods, one is natural color mixing by using a three-primary-color (Red Green Blue, RGB) micro LED; the other is Quantum dot (Quantum Dots, QDs) + blue micro LED chip, if the natural color mixing of the RGB micro LED chip is used, the red is GaAs material, the green and blue are InGaN material, the design difficulty of the display panel circuit will be caused, if the Quantum dot + blue micro LED chip is used, the green light Quantum dot color conversion efficiency is not high, and the full-color efficiency is low.

Disclosure of Invention

Based on above problem, the utility model relates to a little emitting diode can be in the spontaneous white light of three-colour mixture department, and its concrete structure is as follows:

a micro light emitting diode comprising:

the semiconductor device comprises a first semiconductor layer, an active layer and a second semiconductor layer which are sequentially stacked, wherein the first semiconductor layer and the second semiconductor layer are different types of semiconductor layers, and the active layer comprises a first quantum well layer and a second quantum well layer which are sequentially stacked;

a nanoring structure is formed on the second quantum well layer and the second semiconductor layer, the first quantum well layer emits light of a first color, and the second quantum well layer emits light of a second color at a position corresponding to the sidewall of the nanoring;

the cross section of the nano ring is in the shape of a circle, a square, a rectangle or any closed loop;

the nanoring is internally filled with a color conversion material, the color conversion material converts light of a first color emitted by the first quantum well layer into light of a third color, and the first color, the second color and the third color are different;

the first semiconductor layer is electrically connected with a first electrode;

the second semiconductor layer is electrically connected with a second electrode.

Furthermore, the first semiconductor layer is an N-type semiconductor layer and comprises a low-temperature GaN layer, an undoped GaN layer and an N-type GaN layer which are sequentially stacked, and the second semiconductor layer is a P-type semiconductor layer. GaN is a compound of nitrogen and gallium, a direct bandgap semiconductor compound.

Furthermore, the first quantum well layer and the second quantum well layer are green light quantum well layers, and the materials of the first quantum well layer and the second quantum well layer comprise InGaN and GaN.

Further, the color conversion material is a red light quantum dot material.

Furthermore, the pair of quantum wells is formed by sequentially laminating an InGaN well layer/low-temperature GaN/high-temperature GaN layer, the first quantum well layer comprises 10 pairs of green light quantum wells, and the second quantum well layer comprises 10 pairs of green light quantum wells. InGaN is an indium gallium nitride compound, is a third-generation semiconductor material, and is applied to photoelectric devices in many ways.

Furthermore, the outer diameter of the nanoring is 10-2000 nm.

Furthermore, the outer diameter of the nanoring is 100-900 nm.

Furthermore, a current diffusion layer is formed on the second semiconductor layer, the current diffusion layer is made of ITO, and the second electrode is formed on the surface, away from the second semiconductor layer, of the current diffusion layer. ITO is an N-type oxide semiconductor, indium tin oxide, which has excellent conductivity and mechanical properties for use on semiconductor chips.

Further, the first electrode is formed on a surface of the first semiconductor layer facing the second semiconductor layer, and the first electrode is flush with a surface of the second electrode.

Further, the first electrode is formed on a surface of the first semiconductor layer, which faces away from the second semiconductor layer.

The beneficial effects of the utility model reside in that:

the method has the advantages that the green light quantum well is partially arranged into the nanoring structure, and the red light quantum dots are filled in the nanoring structure, so that the part of the quantum well structure which is not arranged into the nanoring structure can emit green light, the luminescent wavelength of the part of the nanoring structure is changed due to the release of material stress, blue light is emitted, and the red light quantum dots emit red light, so that the self-white light is emitted at the three-color mixed part of the quantum well structure; the application can relieve the problem that the recombination efficiency of electrons and holes is reduced due to bending of energy bands in a quantum well because of the spontaneous built-in electric field generated by different electron affinities by using the nanoring structure, so that the recombination efficiency of the electrons and the holes is improved; the structure of the application is a micro LED chip, the size is 10-80 um, and the AR micro display and the mobile/large display have ultrahigh resolution characteristics.

In the present application, Silicon Dioxide (SiO 2) nanospheres are used as a mask, and a yellow photolithography etching is used to form nanorings, which can release the original Quantum well stress to reduce the Quantum Confined Stark Effect (QCSE) and generate blue light. The red quantum dots are placed in the nano-structure in a spraying mode, the interior of the nano-ring is uniformly covered, and the color conversion efficiency is improved due to the surface area effect of the nano-structure.

Drawings

Fig. 1 is a micro light emitting diode according to the present invention;

FIG. 2 is a schematic plan view of a nanoring on a first quantum well layer;

FIG. 3 is another micro LED of the present invention;

FIG. 4 is a flow chart of a method of fabricating a micro LED;

FIG. 5 is a schematic diagram of a structure for forming a first semiconductor layer on a substrate;

FIG. 6 is a structural diagram of an active layer and a second semiconductor layer formed on a first semiconductor layer;

FIG. 7 is a schematic diagram of a structure for forming nanorings;

FIG. 8 is a schematic structural view of disposing a color converting material within a nanoring;

FIG. 9 is a schematic structural diagram of a current diffusion layer formation;

FIG. 10 is a schematic diagram of a structure for forming a second electrode;

FIG. 11 is a schematic diagram of a structure for forming a first electrode;

fig. 12 is a schematic view of a structure for bonding a light emitting diode to a display panel.

The reference numbers in the figures illustrate:

the light emitting diode comprises a substrate 10, a first semiconductor layer 11, a low-temperature GaN layer 111, an undoped GaN layer 112, an N-type GaN layer 113, an active layer 12, a first quantum well layer 121, a second quantum well layer 122, a second semiconductor layer 13, a nanoring 14, a first electrode 114, a color conversion material 15, a second electrode 16, a current diffusion layer 17, a display panel 20 and a third electrode 18.

Detailed Description

The technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the drawings in the embodiments of the present application, and the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments.

The terms "first", "second" and "third" in this application are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicit to the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of the feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Example 1

Fig. 1 shows a micro light emitting diode according to the present invention.

The structure of the semiconductor device is shown in fig. 1, and includes a first semiconductor layer 11, an active layer 12 and a second semiconductor layer 13.

The first semiconductor layer 11 is an N-type semiconductor, preferably GaN, which is a new generation energy material and is widely used in light emitting diodes.

The first semiconductor layer 11 includes a low temperature GaN layer 111, and an undoped GaN layer 112, an N-type GaN layer 113, and an N-type GaN layer 113 are sequentially stacked on the low temperature GaN layer 11.

The active layer 12 is a quantum well layer, and the active layer 12 is composed of a plurality of pairs of quantum wells. The active layer 12 includes a first quantum well layer 121 level second quantum well layer 122. The quantum well layer in this embodiment is a green light quantum well layer, i.e., emits green light after being energized.

In this embodiment, the pair of quantum wells are formed by sequentially stacking an InGaN well layer, a low temperature GaN layer, and a high temperature GaN layer, the first quantum well layer 121 is formed by 10 pairs of quantum wells, the thickness of the 10 pairs of quantum wells is better in adaptability during application and manufacturing, and the manufacturing difficulty is not increased on the premise of reasonably controlling the size of the micro light emitting diode. In other embodiments, the first quantum well layer 121 may also be formed by stacking other numbers of quantum wells, depending on the chip design.

The first semiconductor layer 11 is further formed with a first electrode 114, and the first electrode 114 is partially embedded in the first semiconductor layer 11 or located on the first semiconductor layer 11 and connected to the first semiconductor layer 11.

The nanoring 14 is formed on the first quantum well layer 121, and the outer diameter R of the nanoring 14 is 10 to 2000nm, and more preferably 100 to 900 nm. The nanoring 14 with the size is easy to realize in process, and the uniformity of mixed light emitting of three colors can be well controlled.

As shown in fig. 1 and 2, in the present embodiment, the nano 14 ring is formed on the first quantum well layer 121 in a hollow cylindrical shape. In other embodiments, the nanoring 14 may have other three-dimensional shapes as long as the hollow structure is satisfied, for example, the cross section of the nanoring 14 may be in the shape of any polygon such as a square, a rectangle, or other closed loop. The nanoring structure can alleviate the problem that spontaneous built-in electric fields are generated due to different electron affinities, so that the recombination efficiency of electrons and holes is reduced due to bending of energy bands in the quantum well, and the recombination efficiency of the electrons and the holes is improved.

The sidewall of nanoring 14 includes second quantum well layer 122 and second semiconductor layer 13. The second quantum well layer 122 is located between the first quantum well layer 121 and the second semiconductor layer 13.

A color conversion material 15 is disposed within the nanoring 14, the color conversion material 15 being a red quantum dot. The red quantum dots may convert green light emitted from the first quantum well layer into red light. Red quantum dots are filled in the nanorings, so that the parts of the quantum well structure, which are not formed with the nanorings 14, can emit green light, the parts of the second green light quantum well layers 121 on the nanorings 14 release light emitting wavelength change due to material stress, and accordingly blue light is emitted, and red light is emitted by the red quantum dots, so that the quantum well structure can emit spontaneous white light after three colors are mixed.

A second electrode 16 is also formed on the second semiconductor layer 13. The second electrode 16 is an external electrode, and is preferably an ITO conductive film.

The pair of quantum wells has an InGaN well layer/low temperature GaN/high temperature GaN stacked in sequence, and in this embodiment, each of the first quantum 121 well layer and the second quantum well layer 122 includes 10 pairs of quantum wells. The thickness of the lamination can be easily controlled in process, and the light-emitting efficiency is high, and the thickness of the epitaxial layer can not be too large.

A current diffusion layer 17 is further formed on the nanoring 14 and the first quantum well layer 121, and the current diffusion layer 17 completely covers the nanoring 14 and the first quantum well layer 121. The material of the current diffusion layer 17 is a transparent oxide, and ITO is more preferable.

At least one second electrode 16 is formed on the current diffusion layer 17. The upper surfaces of the first electrode 14 and the second electrode 16 are at the same level, so that the package can be performed by flip chip packaging.

Example 2

This embodiment is another structure of micro-led.

The structure of the semiconductor device is shown in fig. 3, and includes a first semiconductor layer 11, an active layer 12 and a second semiconductor layer 13.

As shown in fig. 2 and 3, in the present embodiment, the nano 14 ring is formed on the first quantum well layer 121 in a hollow cylindrical shape. In other embodiments, the nanoring 14 may have other three-dimensional shapes as long as the hollow structure is satisfied, for example, the cross section of the nanoring 14 may be in the shape of any polygon such as a square, a rectangle, or other closed loop. The nanoring structure can alleviate the problem that spontaneous built-in electric fields are generated due to different electron affinities, so that the recombination efficiency of electrons and holes is reduced due to bending of energy bands in the quantum well, and the recombination efficiency of the electrons and the holes is improved.

A color converting material 15 is provided within nanoring 14. The color conversion material 15 in this embodiment is a red quantum dot that can convert green light emitted from the first quantum well layer 121 into red light. Red light quantum dots are filled in the nanorings, so that the parts of the quantum well structure, which are not formed with the nanorings 14, can emit green light, the parts of the second green light quantum well layers 121 on the nanorings 14 release light emitting wavelength change due to material stress, and accordingly blue light is emitted, and red light is emitted by the red quantum dots, so that the quantum well structure can emit spontaneous white light after three colors are mixed.

The third electrode 18 is formed on the surface of the first semiconductor layer 11 opposite to the active layer 12, and the third electrode 18 is preferably made of an ITO thin film material, specifically, the ITO material is deposited on the first semiconductor layer 11 to form a thin film, and then the thin film is etched to form the third electrode. The ITO material is used as an electrode applied to the light-emitting diode and has excellent mechanical property and conductivity.

Example 3

Fig. 4 shows a method for manufacturing a micro light emitting diode according to the present application. The method comprises the following specific steps:

s10 provides a substrate 10, and forms a first semiconductor layer 11 on the substrate 10.

As shown in fig. 5, the first semiconductor layer 11 includes a low-temperature GaN layer 111, an undoped GaN layer 112, and an N-type GaN layer 113, which are stacked at one time, and the substrate 10 is a sapphire substrate.

S11 forms an active layer 12 and a second semiconductor layer 13 on the first semiconductor layer 11.

As shown in fig. 6, the active layer 12 is a quantum well layer, and is composed of a first quantum well layer 121 and a second quantum well layer 122 on which the second semiconductor layer 13 is formed. The first semiconductor layer 11 and the second semiconductor layer 13 are different types of semiconductors, in this embodiment, the first semiconductor layer 11 is an N-type semiconductor, the second semiconductor layer is a P-type semiconductor, and the specific second semiconductor layer 13 is a P-type GaN layer.

The pair of quantum wells has an InGaN well layer/low temperature GaN/high temperature GaN stacked in sequence, and each of the first and second quantum well layers 121 and 122 preferably includes 10 pairs of green quantum wells. The thicknesses of the first quantum well layer 121 and the second quantum well layer 122 provided in this embodiment are favorable for controlling the process difficulty, and too thin is more demanding on the process and affects the light emitting effect, but too thick is not favorable for the light and thin of the display panel.

S12 the second semiconductor layer 13 and the second quantum well layer 121 are etched by photolithography to form a plurality of nanoring structures 14, as shown in fig. 7.

The photolithography etching process comprises forming a patterned mask on the second semiconductor layer 13 with nano-silica particles, and etching by dry etching to form the nano-ring 14. If only plane epitaxy is stressed to emit green light without using nano-silica particles by photolithography, the stress of the original Quantum well is released to reduce the Quantum Confined Stark Effect (QCSE) and generate blue light after the nano-ring 14 is formed by using SiO2 nanospheres and photolithography.

S13 sets a color conversion material 15 within the nanoring 14.

As shown in fig. 8, in the present embodiment, the color conversion material 15 is a red quantum dot, and the red quantum dot is sprayed into the nanoring 14 by spraying. Red light quantum dots are filled in the nanorings, green light can be emitted from the parts of the quantum well structure, which are not formed with the nanorings 14, the second green light quantum well layer 121 on the nanorings 14 releases light emitting wavelength change due to material stress, so that blue light is emitted, and the red light quantum dots convert the green light emitted by the first quantum well layer 122 into red light, so that spontaneous white light is emitted from the three-color mixed part of the quantum well structure.

S14 forms a current diffusion layer 17 on the first quantum well layer 121 and the nanoring 14.

As shown in fig. 9, the current diffusion layer 17 is preferably a transparent oxide layer, more preferably an ITO film, formed by depositing an ITO material.

S15 forms at least one second electrode 16 on the current diffusion layer 17.

As shown in fig. 10. The second electrode 16 is preferably an ITO film formed by depositing an ITO material onto the current spreading layer 17 and then selectively etching.

S16 removes a portion of the current diffusion layer 17, the nanoring 14, and the first quantum well layer 121 to expose a portion of the first semiconductor layer 11, and forms the first electrode 114 on the exposed first semiconductor layer 11.

Preferably, the upper surface of the first electrode 114 is flush with the upper surface of the second electrode 16, as shown in fig. 11. The upper surface of the first electrode 114 is flush with the upper surface of the second electrode 16, which is advantageous for packaging the light emitting diode by using a flip chip packaging method.

S17 removes the substrate 10 and transfers the resulting structure to a display panel 20.

The first electrode 114 and the second electrode 16 are bonded to the electrodes on the display panel 30, as shown in fig. 12.

In this embodiment, the color of the light emitted from the active layer 12 and the color of the color conversion material are selected only by this embodiment as the selection in the description, and in other structures, when other materials are applied as the quantum well layer, the nanoring and the color conversion material, it is only necessary to ensure that the colors emitted from the first quantum well layer 121, the sidewall of the nanoring and the color conversion material are different, and the concept of the present invention can be realized.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The foregoing describes the general principles of the present disclosure in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present disclosure are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.

Claims

1. A micro light emitting diode, comprising:

the first semiconductor layer is electrically connected with a first electrode;

2. The micro light-emitting diode according to claim 1, wherein the first semiconductor layer is an N-type semiconductor layer including a low-temperature GaN layer, an undoped GaN layer, and an N-type GaN layer, which are sequentially stacked, and the second semiconductor layer is a P-type semiconductor layer.

3. The micro light emitting diode of claim 1, wherein the first and second quantum well layers are green quantum well layers, and the first and second quantum well layers are made of InGaN and GaN.

4. The micro light-emitting diode of claim 1, wherein the color conversion material is a red light quantum dot material.

5. The micro light emitting diode of claim 3, wherein a pair of quantum wells are sequentially stacked as an InGaN well layer/low temperature GaN/high temperature GaN layer, the first quantum well layer includes 10 pairs of the green quantum wells, and the second quantum well layer includes 10 pairs of the green quantum wells.

6. The micro led of claim 1, wherein the nanoring has an outer diameter of 10 to 2000 nm.

7. The micro led of claim 6, wherein the nanoring has an outer diameter of 100 to 900 nm.

8. The micro light-emitting diode of claim 1, wherein a current diffusion layer is formed on the second semiconductor layer, the current diffusion layer is made of ITO, and the second electrode is formed on a surface of the current diffusion layer facing away from the second semiconductor layer.

9. The micro light-emitting diode of claim 8, wherein the first electrode is formed on a surface of the first semiconductor layer facing the second semiconductor layer, and the first electrode is flush with a surface of the second electrode.

10. The micro light-emitting diode of claim 8, wherein the first electrode is formed on a surface of the first semiconductor layer facing away from the second semiconductor layer.