CN113451466B

CN113451466B - LED chip, preparation method, backlight module and display screen

Info

Publication number: CN113451466B
Application number: CN202011184532.7A
Authority: CN
Inventors: 杨顺贵; 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: 2020-10-29
Filing date: 2020-10-29
Publication date: 2022-08-05
Anticipated expiration: 2040-10-29
Also published as: CN113451466A

Abstract

The invention relates to an LED chip, a preparation method, a backlight module and a display screen. Because a plurality of raised conical island structures are formed in the first region of the surface of the N-type semiconductor layer close to the quantum well layer, the existence of the conical island structures reduces QCSE in the quantum well layer in the region, improves the recombination efficiency of electrons and holes, enhances the luminous efficiency of the LED chip, and is beneficial to improving the quality of the backlight module manufactured based on the LED chip. On the other hand, reduced the intraformational stress of quantum well, promoted the content of In the first region quantum well layer, so the quantum well layer itself just can send blue light and green glow, if obtain white light, can only need set up red light conversion material can, need not set up green light conversion material, avoided because of the not high problem that full-color inefficiency that brings of green light conversion material color conversion efficiency, be favorable to promoting backlight unit's display effect.

Description

LED chip, preparation method, backlight module and display screen

Technical Field

The invention relates to the technical field of display, in particular to an LED chip, a preparation method, a backlight module and a display screen.

Background

A large number of white LED (light emitting diode) chips are required in a backlight module of a display screen, and it is a common practice to obtain white light by mixing red, green and blue light by providing a red quantum dot layer and a green quantum dot layer on a blue LED chip. However, the quantum well layer of the blue LED chip is usually formed by InGaN (indium gallium nitride), and a spontaneous built-in electric field is easily generated in the material due to different electron affinities of Ga (gallium) and N (nitrogen), which further causes bending of the energy band in the quantum well layer, reduces the recombination efficiency of electrons and holes, affects the light emitting efficiency of the blue LED chip, and limits the display effect of the backlight module.

Therefore, how to improve the display effect of the backlight module is an urgent problem to be solved.

Disclosure of Invention

In view of the above deficiencies of the related art, an object of the present application is to provide an LED chip, a manufacturing method thereof, a backlight module, and a display screen, which aim to solve the problem that the display effect is affected due to the low luminous efficiency of the LED chip in the related backlight module.

The application provides a LED chip, includes:

an N-type semiconductor layer;

a P-type semiconductor layer; and

a quantum well layer interposed between the N-type semiconductor layer and the P-type semiconductor layer;

the N electrode and the P electrode are respectively and electrically connected with the N-type semiconductor layer and the P-type semiconductor layer;

the surface of the N-type semiconductor layer close to the quantum well layer comprises a first area and a second area, the first area comprises a plurality of convex conical island structures, and the second area is a flat structure.

In the LED chip, since the plurality of convex tapered island structures are formed in the first region of the N-type semiconductor layer near the surface of the quantum well layer, the quantum well layer formed on the N-type semiconductor layer is also divided into two parts: the Quantum well layer is located in the first region, due to the existence of the cone-shaped island structure, QCSE (Quantum Confined Stark Effect) in the Quantum well layer of the region is reduced, the recombination efficiency of electrons and holes is improved, the luminous efficiency of the LED chip is enhanced, and the quality of the backlight module manufactured based on the LED chip is improved. On the other hand, due to the existence effect of the conical island structure, the stress In the quantum well layer is reduced, the content of In (indium) In the quantum well layer In the first region is improved, so that the quantum well layer In the first region emits green light, the second region is flat, the quantum well layer In the region emits blue light, and the multi-wavelength emission of the LED chip is realized. On this basis, if obtain white light, can only need set up ruddiness conversion material can, need not set up green light conversion material, avoided because of the not high problem of full-color inefficiency that brings of green light conversion material color conversion efficiency, be favorable to promoting backlight unit's display effect.

Optionally, a red quantum dot material is disposed between the quantum well layer and the P-type semiconductor layer.

In the LED chip, the red quantum dot material is directly arranged between the quantum well layer and the P-type semiconductor layer for wavelength conversion to prepare the LED chip capable of emitting white light, so that the complex process caused by arranging the light conversion layer on the surface of the LED chip after the preparation of the LED chip is finished is avoided, and the problem that the quality of the LED chip is unreliable due to the fact that the light conversion layer is arranged on the surface of the LED chip and is easy to damage is also avoided. More importantly, the red quantum dot material is attached to the quantum well layer, so that the color conversion efficiency of the LED chip can be improved.

Optionally, the shapes of the upper surface and the lower surface of the quantum well layer are consistent; the red quantum dot material is filled in the region of the quantum well layer corresponding to the first region.

In the LED chip, because the forms of the upper surface and the lower surface of the quantum well layer are consistent, the first region of the upper surface of the quantum well layer is also provided with the conical island structures, and the grooves among the conical island structures provide enough accommodating space for the red quantum dot material, so that the amount of the red quantum dot material filled in the region is increased, and the color conversion efficiency is improved.

Optionally, the N-type semiconductor layer is made of gan, and the crystal orientation of the tapered island structure is semipolar or nonpolar.

Optionally, the P-type semiconductor layer comprises a transparent conductive layer.

Optionally, the pyramidal island structures are tetrahedral structures or conical structures.

Based on the same inventive concept, the application also provides a backlight module, which comprises a driving substrate and a plurality of LED chips of any one of the LED chips, wherein the LED chips are arranged on the driving substrate, and the N electrode and the P electrode are respectively and electrically connected with a driving circuit in the driving substrate.

The backlight module is manufactured by adopting the LED chip with the plurality of convex conical island structures in the first region on the upper surface of the N-type semiconductor layer, so that the quantum well layer formed on the N-type semiconductor layer can be divided into two parts: the LED chip is positioned in the first area due to the existence of the conical island structure, so that the QCSE effect in the quantum well layer of the area is reduced, the recombination efficiency of electrons and holes is improved, the luminous efficiency of the LED chip is enhanced, and the quality of the backlight module manufactured based on the LED chip is improved. On the other hand, due to the existence effect of the conical island structure, the stress In the quantum well layer is reduced, the content of In the quantum well layer In the first region is improved, so that the quantum well layer In the first region emits green light, the second region is flat, the quantum well layer In the region emits blue light, and the multi-wavelength emission of the LED chip is realized. In order to obtain the required white light of backlight unit on this basis, only need set up ruddiness conversion material can, need not set up green light conversion material, avoided because of the not high problem of full-color inefficiency that brings of green light conversion material color conversion efficiency, be favorable to promoting backlight unit's display effect.

Based on the same inventive concept, the application also provides a display screen, and the display screen comprises the backlight module.

The QCSE effect in the LED chip quantum well layer in the display screen is improved, the recombination efficiency of electrons and holes is improved, the luminous efficiency of the LED chip is enhanced, and the display effect of the display screen is improved.

Based on the same inventive concept, the application also provides a preparation method of the LED chip, which comprises the following steps:

providing a substrate, and forming an N-type semiconductor layer on the substrate, wherein the upper surface of the N-type semiconductor layer, which is far away from the substrate, comprises a first region and a second region;

etching a first region of the N-type semiconductor layer to form a plurality of raised conical island structures in the first region;

forming a quantum well layer on the upper surface of the N-type semiconductor layer;

a P-type semiconductor layer is arranged on the quantum well layer;

and arranging an N electrode and a P electrode which are respectively and electrically connected with the N-type semiconductor layer and the P-type semiconductor layer to obtain the LED chip.

In the above method for manufacturing an LED chip, since the plurality of convex conical island structures are formed in the first region of the N-type semiconductor layer near the surface of the quantum well layer, the quantum well layer formed on the N-type semiconductor layer is also divided into two parts: because of the existence of the cone-shaped island structure, the quartz crystal quantum well structure is positioned in the first region, the QCSE in the quantum well layer of the region is reduced, the recombination efficiency of electrons and holes is improved, the luminous efficiency of an LED chip is enhanced, and the improvement of the quality of a backlight module manufactured based on the LED chip is facilitated. On the other hand, due to the existence effect of the conical island structure, the stress In the quantum well layer is reduced, the content of In the quantum well layer In the first region is improved, so that the quantum well layer In the first region emits green light, the second region is flat, the quantum well layer In the region emits blue light, and the multi-wavelength emission of the LED chip is realized. On this basis, if obtain white light, can only need set up ruddiness conversion material can, need not set up green light conversion material, avoided because of the not high problem of full-color inefficiency that brings of green light conversion material color conversion efficiency, be favorable to promoting backlight unit's display effect.

Optionally, after forming the quantum well layer on the upper surface of the N-type semiconductor layer and before disposing the P-type semiconductor layer on the quantum well layer, the method further includes:

and arranging red quantum dot material on the upper surface of the quantum well layer in a region corresponding to the first region.

According to the LED chip preparation method, the red quantum dot material is directly arranged between the quantum well layer and the P-type semiconductor layer for wavelength conversion, so that the LED chip capable of emitting white light is prepared, the complex process caused by arranging the light conversion layer on the surface of the LED chip after the LED chip is prepared is avoided, and the problem that the quality of the LED chip is unreliable due to the fact that the light conversion layer is arranged on the surface of the LED chip and is easy to damage is also avoided. More importantly, the red quantum dot material is attached to the quantum well layer, so that the color conversion efficiency of the LED chip can be improved.

Drawings

FIG. 1 is a schematic diagram illustrating an implementation principle of a backlight scheme in the related art according to the present invention;

FIG. 2 is a schematic diagram illustrating an implementation principle of another backlight scheme in the related art according to the present invention;

FIG. 3 is a schematic diagram of an LED chip according to an alternative embodiment of the present invention;

fig. 4 is a schematic diagram of another structure of an LED chip provided in an alternative embodiment of the present invention;

FIG. 5 is a schematic diagram of another structure of an LED chip provided in an alternative embodiment of the present invention;

FIG. 6 is a schematic diagram of another structure of an LED chip provided in an alternative embodiment of the present invention;

FIG. 7 is a flow chart of a method for fabricating an LED chip according to an alternative embodiment of the present invention;

FIG. 8 is a schematic diagram illustrating a state change of each process in an LED chip manufacturing flow according to another alternative embodiment of the present invention;

FIG. 9 is a flow chart of a method for fabricating an LED chip according to yet another alternative embodiment of the present invention;

fig. 10 is a schematic diagram illustrating a state change of each process in an LED chip manufacturing flow according to another alternative embodiment of the present invention.

Description of reference numerals:

101-red LED chip; 102-green LED chip; 103-and blue light LED chips; 200-blue light LED chip; 201-green conversion layer; 202-a red light conversion layer; 30-LED chips; a 31-N type semiconductor layer; 310-pyramidal island structures; 32-quantum well layer; a 33-P type semiconductor layer; 341-N electrode; 342-P electrode; 35-red light conversion material; 36-undoped gallium nitride layer; 60-LED chips; a 61-N type gallium nitride layer; 62-quantum well layer 63-P type TCO layer; 64-red quantum dot material; 651-N electrode; 652-P electrode 652; 66-undoped gallium nitride layer; 80-a substrate; 81-N type semiconductor layer; 810-pyramidal island structures; 82-quantum well layer; 83-P type semiconductor layer; 84-red light converting material; 851-N electrodes; 852-a P electrode; 100-LED chips; 1000-sapphire substrate; a 1001-LT-GaN layer; 1002-unopened GaN layer; 1003-N type GaN layer; 1003 a-tetrahedral microstructure; 1004-a photoresist layer; 1005-a quantum well layer; 1006-red quantum dot material; 1007-P type TCO layer; 1008-P electrode; 1009-N electrodes.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

In the backlight module, white light is obtained by mixing red light, green light and blue light, and at present, two main backlight schemes exist: one is to directly manufacture a red LED chip 101, a green LED chip 102 and a blue LED chip 103, as shown in FIG. 1, so that the red light, the green light and the blue light naturally emitted by the three LED chips are mixed; in another example, a green light conversion layer 201 and a red light conversion layer 202 are disposed on the blue LED chip 200, the green light conversion layer 201 and the red light conversion layer 202 are used to perform wavelength conversion on light emitted by the blue LED chip 200 to obtain red light and green light, and then white light is obtained by combining with blue light naturally emitted by the blue LED chip 200, please refer to fig. 2.

However, in the first backlight scheme, the red LED chip 101 includes GaAs (gallium arsenide) material, and the blue LED chip 103 and the green LED chip 102 include InGaN material, which causes difficulty in designing the driving circuit. In the second backlight scheme, on one hand, the light extraction efficiency of the blue LED chip 200 is not high due to the QCSE effect, and on the other hand, the light conversion efficiency of the green light conversion layer 201 is not high due to the fact that the green light conversion layer is usually formed by the green light quantum dot material, which easily affects the full color effect of the display screen.

Based on this, the present application intends to provide a solution to the above technical problem, the details of which will be explained in the following embodiments.

An alternative embodiment of the invention:

the present embodiment first provides an LED chip, please refer to a schematic structural diagram of the LED chip shown in fig. 3:

the LED chip 30 includes an N-type semiconductor layer 31, a P-type semiconductor layer 33, and a quantum well layer 32, wherein the quantum well layer 32 is interposed between the N-type semiconductor layer 31 and the P-type semiconductor layer 33. In addition, the LED chip 30 further includes electrodes: an N electrode 341 electrically connected to the N-type semiconductor layer 31, and a P electrode 342 electrically connected to the P-type semiconductor layer 33.

The surface of the N-type semiconductor layer 31 close to the quantum well layer 32 includes a first region including a plurality of convex pyramidal island structures 310 and a second region which is flat. These pyramidal island structures 310 are nano-scale microstructures that can be used to improve stress in the quantum well layers formed thereon.

In some examples of the present embodiment, the crystal orientation of the pyramidal island structures 310 is non-polar. In other examples of the present embodiment, the crystal orientation of the pyramidal island structures 310 may also be semipolar. For example, the crystal orientation of the pyramidal island structures 310 may be (1-100), (11-20), (1-102), (10-11), (11-22), and so forth. Optionally, the conical island structure 310 may be conical, and in some other examples of the present embodiment, the conical island structure 310 may also be a tetrahedral structure, that is, a triangular pyramid structure, or an N-pyramid, where a value of N is greater than or equal to 4, for example, the conical island structure 310 is a rectangular pyramid, a pentagonal pyramid, or the like.

In this embodiment, the quantum well layer 32 is made of indium gallium nitride. In some examples, the upper surface of the quantum well layer 32 (i.e., the surface of the quantum well layer away from the N-type semiconductor layer 31) both the first region and the second region are flat. In an example of the present embodiment, the upper surfaces of the quantum well layers in the two regions are level in height, as shown in fig. 4. In other examples of the present embodiment, the upper surface of the quantum well layer 32 has a shape corresponding to the shape of the lower surface thereof (i.e., the surface of the quantum well layer close to the N-type semiconductor layer 31), in other words, the second region of the upper surface of the quantum well layer 32 is flat, and the first region also includes a plurality of tapered island structures, as shown in fig. 3.

It can be understood that, since the plurality of tapered island structures 310 are provided In the first region of the upper surface of the N-type semiconductor layer 31, the QCSE effect In the quantum well layer formed In the region is reduced, the stress is improved, and it is advantageous to increase the In content In the quantum well layer In the region, so that the quantum well layer In the region emits green light, and the quantum well layer corresponding to the second region of the upper surface of the N-type semiconductor layer 31 emits blue light.

In this case, the quantum well layer 32 itself already realizes multiband emission, and can emit blue light and green light at the same time, and if white light is to be obtained, the white light can be obtained by only performing wavelength conversion using a red light conversion material to obtain red light, and then mixing the blue light and the green light emitted by the quantum well layer 32 itself. In some examples of the present embodiment, the LED chip 30 itself may not have the red light conversion material, for example, a red quantum dot layer is formed with the photo-red quantum dot material and then disposed on the light emitting surface of the LED chip to realize light conversion. In some examples, the LED chip 30 includes a red light conversion material, and the LED chip 30 obtains red light through the red light conversion material and emits white light after mixing with blue light and green light, so the LED chip 30 is a white LED chip, for example, the red light conversion material may be directly sprayed on the surface of the P-type semiconductor layer 33 away from the quantum well layer 32.

In some examples of this embodiment, after the quantum well layer 32 is formed, a red light conversion material may be disposed on the quantum well layer 32, that is, the red light conversion material is disposed between the quantum well layer 32 and the P-type semiconductor layer 33, and the red light conversion material is used to perform wavelength conversion on the light emitting electrode emitted by the quantum well layer 32 to obtain red light, so that the red light, the green light, and the blue light are mixed in the LED chip, and the LED chip can emit white light spontaneously, without additionally disposing a light conversion layer outside the LED chip. On the other hand, the closer the red light conversion material is to the quantum well layer 32, the better the color conversion efficiency is, and therefore, the red light conversion material is arranged to be attached to the quantum well layer 32, which is beneficial to improving the light conversion efficiency of the red light conversion material.

In some examples of the present embodiment, the red light conversion material may be disposed only in the first region of the quantum well layer 32, for example, please continue to refer to fig. 3: in the case where the shapes of the upper and lower surfaces of the quantum well layer 32 are the same, there will be a plurality of grooves between the plurality of conical island structures in the first region of the upper surface of the quantum well layer 32, and these grooves can provide accommodation spaces for the red light conversion material 35. Of course, it will be understood by those skilled in the art that the red light conversion material 35 may also be disposed in the second region on the upper surface of the quantum well layer 32, or in both the first region and the second region.

In some examples of the present embodiment, the red light conversion material 35 may be a red quantum dot material. However, it is understood that the red light conversion material may also be a red phosphor in case the LED chip size is relatively large, etc.

In some examples of the present embodiment, the P-type semiconductor layer 33 may have a layer structure made of gallium nitride, and typically, the P-type gallium nitride layer contains a doping element, such as magnesium (Mg), zinc (Zn), and the like. When the red quantum dot material is disposed between the quantum well layer 32 and the P-type semiconductor layer 33, in order to avoid damage to the red quantum dot material caused by a high-temperature environment required for forming the P-type gallium nitride layer and influence the effectiveness of the red quantum dot material, a TCO (Transparent conductive Oxide) layer, that is, a Transparent conductive layer, may be used as the P-type semiconductor layer 33.

In the present embodiment, the N-type semiconductor layer 31 may be a gallium nitride (GaN) layer, and usually the N-type GaN layer contains doping elements, such as silicon (Si), boron (B), germanium (Ge), and the like. It is to be understood that the N-type semiconductor layer 31 may be formed over a substrate, such as a sapphire substrate.

It is understood that, in order to improve the quality of the N-type semiconductor layer 31 and the quantum well layer 32, in this embodiment, an undoped gallium nitride layer 36 may be formed before the N-type semiconductor layer 31 is formed, as shown in fig. 5: the undoped gallium nitride layer 36 is provided in contact with the surface of the N-type semiconductor layer 31 remote from the quantum well layer 32.

The LED chips shown in fig. 3 to 5 are all of a forward mounting structure: for example, in fig. 3, the N electrode 341 is disposed below the N-type semiconductor layer 31 and is attached to the surface of the N-type semiconductor layer 31 remote from the quantum layer 32, and the P electrode 342 is disposed on the upper surface of the P-type semiconductor layer 33. In fig. 5, the N electrode 341 and the undoped gallium nitride layer 36 are attached to the surface of the N-type semiconductor layer 31, the N electrode 341 is electrically connected to the N-type semiconductor layer 31 through the undoped gallium nitride layer 36, and the P electrode 342 is disposed on the upper surface of the P-type semiconductor layer 33. However, it can be understood by those skilled in the art that in some other examples of the present embodiment, the LED chip may also be in a flip-chip structure, for example, please refer to the LED chip 60 shown in fig. 6, where the LED chip 60 includes an N-type gallium nitride layer 61, a quantum well layer 62, a P-type TCO layer 63, a red quantum dot material 64, an N electrode 651 disposed on a side of the N-type gallium nitride layer 61 facing the quantum well layer 62, and a P electrode 652 disposed on a surface of the P-type TCO layer 63 away from the quantum well layer 62. The LED chip 60 also comprises an undoped gallium nitride layer 66 arranged on the side of the N-type gallium nitride layer 61 facing away from the quantum well layer 62.

The embodiment further provides a backlight module, which includes a driving substrate and a plurality of LED chips, where the LED chip may be any one of the LED chips, and the N electrode and the P electrode of the LED chip are electrically connected to a driving circuit in the driving substrate respectively.

The embodiment further provides a display screen, and the display screen comprises the backlight module.

In addition, the present embodiment also provides an electronic device, which may be a mobile terminal such as a mobile phone, a tablet computer, a notebook computer, a palm computer, a Personal Digital Assistant (PDA), a Portable Media Player (PMP), a navigation device, a wearable device, a smart band, a pedometer, and a fixed terminal such as a Digital TV, a desktop computer, and the like. In this embodiment, the electronic device includes the backlight module.

According to the LED chip, the backlight module, the display screen and the electronic device, because the tapered island structure is formed in the partial region of the upper surface of the N-type semiconductor layer of the LED chip, the QCSE effect in the quantum well layer is improved by utilizing the nano structure, the recombination efficiency of electrons and holes is improved, the luminous efficiency of the LED chip is improved, and the display effect is enhanced. Moreover, because this LED chip need not to be used green glow quantum dot material when providing the required white light of backlight unit, can not receive the poor influence of green glow quantum dot material color conversion efficiency, is favorable to further promoting the full-color level of display screen.

Moreover, the red quantum dot material can be directly attached to the quantum well layer, so that the light conversion efficiency of the red light conversion material is further improved.

Another alternative embodiment of the invention:

in this embodiment, a method for manufacturing the LED chip is provided, please refer to a flowchart of a method for manufacturing an LED chip shown in fig. 7 and a schematic diagram of a state change of each process of the method for manufacturing an LED chip shown in fig. 8:

s702: a substrate is provided, and an N-type semiconductor layer is formed on the substrate.

In this embodiment, the N-type semiconductor layer 81 may be a gallium nitride layer, and is typically an N-type gallium nitride layer containing a dopant, such as an N-type gallium nitride layer doped with at least one of several elements, such as silicon, boron, and germanium. It is to be understood that the N-type semiconductor layer 81 is formed over a substrate 80, for example, a sapphire substrate, as shown in fig. 8 (a).

Considering that the substrate needs to be peeled off in the subsequent process, for example, when the LED chip is in a flip-chip structure, the LED chip needs to be peeled off from the substrate after the LED chip is prepared, or when the LED chip is in a normal-mount structure, the epitaxial layer of the LED chip needs to be peeled off from the substrate before the electrode is prepared. Since Laser Lift Off (LLO) is generally used for peeling Off the substrate, the principle of Laser decomposition of GaN, GaN → Ga + N is utilized ₂ In order to avoid the damage of the N-type semiconductor layer by the process, in this embodiment, a buffer layer may be formed on the substrate before the N-type semiconductor layer is formed on the substrate, and the buffer layer may be decomposed during the process of peeling off the substrate, so as to prevent the N-type semiconductor layer from being damaged. In some examples of the present embodiment, the buffer layer may also be made of gan.

In order to improve the quality of the N-type semiconductor layer 81 and the quantum well layer to be subsequently formed on the N-type semiconductor layer 81, in some examples of the present embodiment, an Undoped gallium nitride layer may be formed before the N-type semiconductor layer 81 is formed, for example, in an example of the present embodiment, an LT-GaN layer, an Undoped gallium nitride (Undoped GaN) layer, and an N-type gallium nitride layer are sequentially formed on a sapphire substrate from bottom to top.

S704: and etching a first region on the upper surface of the N-type semiconductor layer to form a plurality of raised conical island structures in the first region.

Since the N-type semiconductor layer 81 is formed on the substrate 80, the upper surface of the N-type semiconductor layer 81 is actually the surface of the N-type semiconductor layer 81 away from the substrate 80, and is also the interface between the N-type semiconductor layer 81 and the quantum well layer. In this embodiment, the upper surface of the N-type semiconductor layer 81 includes a first region and a second region, after the N-type semiconductor layer 81 is formed, the first region may be etched, and a plurality of raised conical island structures 810 are formed in the first region, as shown in fig. 8(b), and these conical island structures 810 belong to a nano-scale microstructure, and may be used to improve the stress in the quantum well layer formed thereon.

In some examples of the present embodiment, the crystal orientation of the pyramidal island structures 810 may be non-polar or semi-polar. For example, in some examples of the present embodiment, the crystal orientation of the pyramidal island structures 810 may be (1-100), (11-20), (1-102), (10-11), (11-22), and so on. Optionally, during the etching process, the crystal orientation of the pyramidal island structures 810 can be confirmed by X-ray diffraction analysis (XRD) measurement using an XRD machine to ensure that the crystal orientation is non-polar or semi-polar.

In some examples of the present embodiment, the conical island structures 810 may be at least one of conical, tetrahedral, rectangular pyramid, pentagonal pyramid, and the like. It should be understood that the present embodiment does not require that the conical island structures 810 be very standard conical shapes, triangular pyramids, rectangular pyramids, etc., for example, the edges of the conical island structures 810 may have slight curvature, etc.

It should be understood that, since only the first region of the upper surface of the N-type semiconductor layer 81 is etched while the second region is continuously kept flat, in the present embodiment, in order to prevent the second region of the upper surface of the N-type semiconductor layer 81 from being etched, a barrier layer may be provided in the second region of the upper surface of the N-type semiconductor layer 81 before the etching process is performed. In some examples of this embodiment, the blocking layer disposed in the second region may be a photoresist layer.

S706: a quantum well layer is formed on an upper surface of the N-type semiconductor layer.

After the etching of the first region on the upper surface of the N-type semiconductor layer 81 is completed, a quantum well layer 82 may be disposed on the N-type semiconductor layer 81, in this embodiment, the quantum well layer 82 is made of an indium gallium nitride material. In some examples, the upper surface of the quantum well layer 82 is flat, for example, any two points on the surface of the quantum well layer away from the N-type semiconductor layer 81 are in the same plane. In other examples of the present embodiment, the morphology of the upper surface of the quantum well layer 82 is consistent with that of the lower surface thereof (i.e., the surface of the quantum well layer close to the N-type semiconductor layer 81), in other words, the upper surface of the quantum well layer 82 is also divided into a flat second region and a first region including a plurality of tapered island structures, as shown in fig. 8 (c).

It can be understood that, since the plurality of tapered island structures 810 are provided In the first region of the upper surface of the N-type semiconductor layer 81, the QCSE effect In the quantum well layer formed In the region is improved, the stress is reduced, and the In content In the quantum well layer In the region is increased, so that the quantum well layer In the region emits green light, and the quantum well layer disposed In the second region of the upper surface of the N-type semiconductor layer 81 emits blue light.

S708: a P-type semiconductor layer is disposed on the quantum well layer.

In some examples of this embodiment, after the quantum well layer 82 is formed, the P-type semiconductor layer 83 may be provided on the quantum well layer 82, and the P-type semiconductor layer 83 may be provided directly in contact with the quantum well layer 82.

In other examples of this embodiment, after the quantum well layer 82 is formed, a red light conversion material may be disposed on the quantum well layer 82, and the red light conversion material is utilized to perform wavelength conversion on a light emitting electrode emitted by the quantum well layer 82 to obtain red light, so that the red light, the green light, and the blue light are mixed in the LED chip, and the LED chip may emit white light, without additionally disposing a light conversion layer outside the LED chip, and the epitaxial structure of the LED chip is utilized to protect the red light conversion material, thereby avoiding the occurrence of a situation that the light conversion layer disposed on the outer surface of the LED chip or outside the LED chip is damaged due to an external force factor. Moreover, the red light conversion material is attached to the quantum well layer 82, so that the light conversion efficiency of the red light conversion material is improved.

In some examples of the present embodiment, the red light conversion material may be disposed only in the first region of the quantum well layer 82, for example, in the case where the morphology of the upper and lower surfaces of the quantum well layer 82 is consistent, there will be a plurality of grooves between the plurality of tapered island structures of the first region of the upper surface of the quantum well layer 82, and these grooves may provide accommodation spaces for the red light conversion material, so after the quantum well layer 82 is formed, the red light conversion material 84 may be disposed in the first region of the upper surface of the quantum well layer 82, as shown in fig. 8 (d). Of course, it will be understood by those skilled in the art that the red light conversion material may be disposed in the second region of the upper surface of the quantum well layer 82, or in both the first and second regions.

In some examples of the present embodiment, the red light conversion material 84 may be a red quantum dot material. However, it is understood that the red light-converting material 84 may also be a red phosphor in the case where the LED chip size is relatively large, or the like.

After the red light conversion material 84 is disposed, a P-type semiconductor layer 83 may be further disposed, the P-type semiconductor layer 83 and the quantum well layer 82 sandwiching the red light conversion material 84, as in fig. 8 (e). In some examples of the embodiment, if the red light conversion material 84 is a red quantum dot material, in order to avoid the red quantum dot material being damaged by high temperature generated during the process of disposing the P-type semiconductor layer 83, which results in the red quantum dot material being failed and affecting the performance thereof, a P-type TCO layer with a low temperature may be selected as the P-type semiconductor layer 83 in the embodiment. Of course, if the red quantum dot material is not disposed directly under the P-type semiconductor layer 83, or the performance of the red light conversion material 84 is not affected by temperature, the P-type semiconductor layer 83 may be made of other materials, such as P-type gallium nitride.

S710: and arranging an N electrode and a P electrode which are respectively and electrically connected with the N-type semiconductor layer and the P-type semiconductor layer to obtain the LED chip.

After the P-type semiconductor layer 83 is formed, the epitaxial layers of the LED chip are prepared, and electrodes electrically connected to two semiconductor layers in the epitaxial layers may be provided. Alternatively, the LED chip may be a flip chip, in which case, the N electrode setting region of the N type semiconductor layer 81 may be exposed by etching the P type semiconductor layer 83 and the quantum well layer 82, and then the N electrode may be set; since the P electrode formation region on the P-type semiconductor layer 83 is exposed, the P electrode can be directly formed. After the electrode preparation is completed, the prepared LED chip may be peeled off from the substrate 80, and the substrate 80 may be removed, for example, by laser peeling. Alternatively, if a buffer layer, for example, an LT-GaN layer, is provided between the N-type semiconductor layer 81 and the substrate 80, the buffer layer may be decomposed by laser light to break the bond between the N-type semiconductor layer 81 and the substrate 80, so that the LED chip is detached from the substrate 80.

In other examples of this embodiment, the prepared LED chip is a forward-mounted LED chip, and although the P electrode installation region is exposed and the P electrode can be directly installed on the P-type semiconductor layer 83, because the N electrode installation region is hidden between the N-type semiconductor layer 81 and the substrate 80, the already formed epitaxial layer needs to be stripped off the substrate 80 before the N electrode is formed, and a laser stripping process can still be used to strip off the substrate 80 as shown in fig. 8(f), and similarly, in the case where a buffer layer is provided between the N-type semiconductor layer 81 and the substrate 80, the buffer layer can be directly decomposed by the laser. After removing the substrate 80, a metal layer may be formed on the surface of the N-type semiconductor layer 81 away from the quantum well layer 82, and then the metal layer may be patterned to form the N electrode 851. In some examples of the present embodiment, the P-electrode 852 is formed before peeling the substrate 80, and in other examples of the present embodiment, the P-electrode 852 and the N-electrode 851 are both formed after peeling the substrate 80, as shown in fig. 8 (g).

It will be appreciated that if the side of the N-type semiconductor layer 81 remote from the quantum well layer 82 is provided with an undoped gallium nitride layer, the N-electrode 851 of the LED chip being mounted is provided on the surface of the undoped gallium nitride layer, as shown in fig. 1, for example.

According to the LED chip preparation method provided by the embodiment, after the N-type semiconductor layer of the LED chip is formed, partial area of the upper surface of the N-type semiconductor layer can be etched firstly, so that a plurality of conical island structures are formed, QCSE in a quantum well layer in the area is reduced by using the conical island structures, the electron and hole recombination efficiency is improved, the luminous efficiency of the LED chip is enhanced, and the improvement of the quality of the backlight module manufactured based on the LED chip is facilitated. Moreover, because the quantum well layer formed by the method can emit green light and blue light, and the green quantum dot material is not needed when white light is obtained, the problem of low full-color efficiency caused by low color conversion efficiency of the green quantum dot material is avoided, and the display effect of the backlight module is favorably improved.

Yet another alternative embodiment of the invention:

in order to make the advantages and details of the LED chip and the LED chip manufacturing method more clear to those skilled in the art, the present embodiment will further describe the foregoing scheme with reference to examples, please refer to a flow chart of the LED chip manufacturing method shown in fig. 9 and a state change diagram of each process in fig. 9 shown in fig. 10:

s902: a sapphire substrate is provided.

Referring to fig. 10(a), it can be understood that the sapphire substrate 1000 is a growth substrate of a common blue and green LED chip, but this embodiment can not limit the growth substrate of the LED chip to only be a sapphire substrate.

S904: an LT-GaN layer is formed on a sapphire substrate.

Referring to fig. 10(b), the LT-GaN layer 1001 is a buffer layer in the above embodiment, and since it is decomposed during the process of peeling off the sapphire substrate, the LT-GaN layer 1001 is actually a sacrificial layer.

S906: an unopened GaN layer is formed on the LT-GaN layer.

Referring to fig. 10(c), the unopened GaN layer 1002 formed on the surface of the LT-GaN layer 1001 away from the sapphire substrate 1000 can be used to improve the quality of the N-type GaN layer 1003 and the quantum well layer 1004 which are grown subsequently.

S908: and forming an N-type GaN layer on the unopened GaN layer.

The N-type GaN layer 1003 is formed on the surface of the unopened GaN layer 1002 away from the LT-GaN layer 1001, as shown in FIG. 10 (d).

S910: and forming a photoresist layer in the second region on the upper surface of the N-type GaN layer.

As shown in fig. 10(e), the photoresist layer 1004 is mainly used to protect the second region on the upper surface of the N-type GaN layer 1003, so as to prevent the N-type GaN layer 1003 in the second region from being etched. In some examples of this embodiment, a photoresist may be coated on the second region of the upper surface of the N-type GaN layer 1003, and a photoresist layer 1004 may be formed after the photoresist is cured.

S912: and etching the first region on the upper surface of the N-type GaN layer to form a plurality of tetrahedral microstructures.

As shown in fig. 10(f), in the present embodiment, the tetrahedral microstructure 1003a is one form of the conical island structure in the foregoing example, but in some other examples of the present embodiment, the conical island structure formed by etching the first region on the upper surface of the N-type GaN layer 1003 may also be another structure.

In addition, the crystal orientation of the tetrahedral microstructure 1003a formed by etching in this embodiment is nonpolar or semipolar.

S914: the photoresist layer is removed.

After the etching is completed, the photoresist layer 1004 is not necessary to be continued, so that the photoresist layer 1004 may be removed, as shown in fig. 10 (g).

S916: a quantum well layer is formed on the N-type GaN layer.

It is needless to say that the interface morphology of the quantum well layer 1005 and the N-type GaN layer 1003 is determined by the upper surface of the N-type GaN layer 1003, but in this embodiment, the morphology of the upper surface of the quantum well layer 1005, that is, the surface of the quantum well layer 1005 away from the N-type GaN layer 1003 also coincides with the morphology of the upper surface of the N-type GaN layer 1003, as shown in fig. 10 (h).

S918: and filling the red quantum dot material in the first region of the quantum well layer.

After the quantum well layer 1005 is formed, a red quantum dot material 1006 may be filled in a first region of the quantum well layer 1005 by spray coating, as shown in fig. 10 (i).

S920: a P-type TCO layer is disposed.

The red quantum dot material 1006 is prevented from being damaged by high temperature generated in the process of setting the P-type semiconductor layer, so that the red quantum dot material 1006 fails, and therefore, the P-type TCO layer 1007 is set as the P-type semiconductor layer in this embodiment. The P-type TCO layer 1007 covers both the first and second regions of the quantum well layer 1005, as shown in fig. 10 (j).

S922: and arranging a P electrode on the P type TCO layer.

In this embodiment, before the sapphire substrate 1000 is peeled off, a metal layer may be formed on the P-type TCO layer 1007 to prepare the P-electrode 1008, as shown in fig. 10 (k).

S924: the laser decomposes the LT-GaN layer to peel off the sapphire substrate.

The LED chip prepared in this embodiment is a normal-mount LED chip, and therefore, two electrodes thereof are respectively distributed on different sides, and in order to prepare an N electrode, the sapphire substrate 1000 needs to be peeled off first. In the present embodiment, the LT-GaN layer 1001 may be irradiated with laser light from the sapphire substrate 1000 side, so that the LT-GaN layer 1001 is decomposed to separate the sapphire substrate 1000 from the LED chip body, as shown in fig. 10 (l).

S926: and arranging an N electrode on the surface of the unopened GaN layer far away from the N-type GaN layer.

After the sapphire substrate 1000 is peeled off, the unopened GaN layer 1002 is exposed, so in this embodiment, the N-electrode 1009 can be disposed on the surface of the unopened GaN layer 1002 away from the N-type GaN layer 1003, and the N-electrode 1009 can be electrically connected to the N-type GaN layer 1003 through the unopened GaN layer 1002, as shown in fig. 10 (m).

After the LED chip 100 is manufactured, the LED chip 100 may be transferred to a driving substrate to electrically connect the LED chip 100 and the driving substrate, so as to form a backlight module and a display screen, and then the backlight module and the display screen are applied to an electronic device.

According to the LED chip preparation method provided by the embodiment, the tetrahedral microstructure is formed in the partial region of the upper surface of the N-type GaN layer, the QCSE effect in the quantum well layer is improved by utilizing the nano microstructure, the electron and hole recombination efficiency is improved, the light emitting efficiency of the LED chip is improved, and the display effect is enhanced. Moreover, because this LED chip need not to be used green light quantum dot material when providing the required white light of backlight unit, can not receive the poor influence of green light quantum dot material color conversion efficiency, is favorable to further promoting the full-color level of display screen.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. An LED chip, comprising:

an N-type semiconductor layer;

a P-type semiconductor layer; and

the surface of the N-type semiconductor layer, which is close to the quantum well layer, comprises a first region and a second region, wherein the first region comprises a plurality of raised conical island structures formed by etching, and the second region is an unetched flat structure; the quantum well layer covers both the first region and the second region of the N-type semiconductor layer, and a portion of the quantum well layer corresponding to the first region is configured to emit green light and a portion corresponding to the second region is configured to emit blue light.

2. The LED chip of claim 1, wherein a red quantum dot material is disposed between the quantum well layer and the P-type semiconductor layer.

3. The LED chip of claim 2, wherein the quantum well layers have uniform morphology on both upper and lower surfaces; the red quantum dot material is filled in a region of the quantum well layer corresponding to the first region.

4. The LED chip of claim 1, wherein the N-type semiconductor layer is gan, and the pyramidal island structures have a semipolar or nonpolar crystal orientation.

5. The LED chip of claim 1, wherein said P-type semiconductor layer comprises a transparent conductive layer.

6. The LED chip of any of claims 1-5, wherein the pyramidal island structures are tetrahedral structures or conical structures.

7. A backlight module, comprising a driving substrate and a plurality of LED chips as claimed in any one of claims 1 to 6, wherein the LED chips are disposed on the driving substrate, and the N electrode and the P electrode are electrically connected to a driving circuit in the driving substrate respectively.

8. A display screen comprising the backlight module of claim 7.

9. A preparation method of an LED chip is characterized by comprising the following steps:

etching only a first region of the N-type semiconductor layer, forming a plurality of raised conical island structures in the first region, and keeping the second region flat;

forming a quantum well layer on the upper surface of the N-type semiconductor layer, wherein the quantum well layer covers the first region and the second region of the N-type semiconductor layer at the same time, and a part of the quantum well layer corresponding to the first region is configured to emit green light and a part corresponding to the second region is configured to emit blue light;

providing a P-type semiconductor layer on the quantum well layer;

10. The method for manufacturing an LED chip according to claim 9, wherein after forming a quantum well layer on the upper surface of the N-type semiconductor layer and before disposing a P-type semiconductor layer on the quantum well layer, the method further comprises: