CN109979959B - Micro light emitting diode chip and display device - Google Patents
Micro light emitting diode chip and display device Download PDFInfo
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- H10H29/00—Integrated devices, or assemblies of multiple devices, comprising at least one light-emitting semiconductor element covered by group H10H20/00
- H10H29/10—Integrated devices comprising at least one light-emitting semiconductor component covered by group H10H20/00
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Abstract
本发明公开了一种微发光二极管芯片和显示装置，涉及芯片设计技术领域，主要目的是在通过电流控制微发光二极管芯片的灰阶的过程中，使得微发光二极管芯片波长稳定，能够实现灰阶的正常显示和切换。本发明的主要技术方案为：微发光二极管芯片，包括：多个子芯片，多个所述子芯片并联设置，每个所述子芯片具有一个启亮电压，至少两个所述子芯片的所述启亮电压不同。本申请提供的微发光二极管芯片，在通过电流控制微发光二极管芯片的灰阶的过程中，使得在不同的驱动电压驱动的情况下，逐步改变芯片的亮度，且能够保证微发光二极管芯片的电流密度不变，从而在逐步改变芯片亮度的同时，保证了波长的稳定性，达到较好地切换和显示灰阶的目的。
The invention discloses a micro-light-emitting diode chip and a display device, and relates to the technical field of chip design. The main purpose is to stabilize the wavelength of the micro-light-emitting diode chip and realize the gray-scale during the process of controlling the gray-scale of the micro-light-emitting diode chip through current. normal display and switching. The main technical scheme of the present invention is: a micro-LED chip, comprising: a plurality of sub-chips, a plurality of the sub-chips are arranged in parallel, each of the sub-chips has a turn-on voltage, at least two of the sub-chips The ignition voltage is different. In the micro-LED chip provided by the present application, in the process of controlling the gray scale of the micro-LED chip by current, the brightness of the chip can be gradually changed under the driving condition of different driving voltages, and the current of the micro-LED chip can be guaranteed. The density remains unchanged, so that while the brightness of the chip is gradually changed, the stability of the wavelength is ensured, and the purpose of better switching and displaying gray scales is achieved.
Description
Technical Field
The invention relates to the technical field of chip design, in particular to a micro light-emitting diode chip and a display device.
Background
With the development of the display industry, the display technology field is dedicated to realizing micro led and MiniLED display with a lower relative technical threshold.
In order to advance the display technology, except for the transfer and the back plate, effort needs to be invested to break through, the chip end needs to be improved to adjust the gray scale of a screen by a display picture, in order to save cost, an active TFT driving mode is selected, the gray scale of the chip needs to be directly controlled through current, but due to the effects of quantum well growth and a polarization field, the wavelength value of the existing LED chip can shift under different current densities, the quantum confinement Stark effect can be caused, the wavelength of the chip is unstable, and therefore display and switching of the gray scale are limited.
Therefore, how to stabilize the wavelength of the chip and realize the normal display and switching of the gray scale becomes an urgent problem to be solved.
Disclosure of Invention
In view of this, embodiments of the present invention provide a micro led chip and a display device, and mainly aim to stabilize the wavelength of the micro led chip and enable normal display and switching of gray scales in the process of controlling the gray scales of the micro led chip through current.
In order to achieve the purpose, the invention mainly provides the following technical scheme:
in one aspect, an embodiment of the present invention provides a micro light emitting diode chip, including:
the display device comprises a plurality of sub-chips, wherein the plurality of sub-chips are arranged in parallel, each sub-chip is provided with a lighting voltage, and the lighting voltages of at least two sub-chips are different.
In the technical scheme, each of the sub-chips comprises an N-type layer and a P-type layer, the product of the doping concentration of the N-type layer and the doping concentration of the P-type layer is a doping concentration product, and the doping concentration products of at least two of the sub-chips are different.
In the technical scheme, a plurality of the sub-chips are uniformly distributed.
In the technical scheme, each sub-chip is of an annular structure, the centers of the plurality of sub-chips are located at the same position, and the sub-chip far away from the center is sleeved outside the sub-chip close to the center.
In this technical solution, a plurality of the sub-chips are integrally formed.
In the technical scheme, the lighting voltages of the sub-chips are all different.
On the other hand, the embodiment of the invention also provides a display device, which comprises a plurality of chips as described above.
In the technical scheme, the chip is in a flip-chip or vertical or forward-mounted structure.
The micro light emitting diode chip and the display device provided by the embodiment of the invention are characterized in that the micro light emitting diode chip comprises a plurality of sub-chips which are arranged in parallel, each sub-chip is provided with a starting voltage, the starting voltages of at least two sub-chips are different, the starting voltages are voltages capable of starting the corresponding sub-chips, when the driving voltage reaches the starting voltage of a certain sub-chip, the sub-chip with the starting voltage can be started, each sub-chip is provided with a starting voltage, and under the condition that the starting voltages of at least two sub-chips are different, the brightness of the chip can be gradually changed through the change of the driving voltage to achieve the purpose of switching gray scales, in the process of the change of the driving voltage, only the sub-chip with the starting voltage reaching the driving voltage can be started, so that in the process of the change of the driving voltage, the number of the sub-chips which can be turned on is increased, namely the area through which current can pass is increased, so that more sub-chip areas share the current, the current density cannot be changed greatly, and the micro light-emitting diode chip can integrally work under the same current density. Therefore, even if the driving voltage of the micro light-emitting diode chip is different, the current density of the micro light-emitting diode chip cannot be changed greatly, and the wavelength of the micro light-emitting diode chip is determined by the current density of the chip, so that the wavelength of the chip is basically unchanged, the wavelength is stable, and the normal display and switching of gray scales of the chip can be realized. Therefore, the micro light emitting diode chip provided by the application is provided with the plurality of sub-chips, each sub-chip is provided with the starting voltage, the starting voltages of the at least two sub-chips are different, namely, the gray scale of the chip is controlled through the current, so that the brightness of the chip is gradually changed under the driving condition of different driving voltages, the current density of the chip is unchanged, the brightness of the chip is gradually changed, the stability of the wavelength is guaranteed, and the purpose of better switching and displaying the gray scale is achieved.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Fig. 1 is a schematic structural diagram of a chip according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of another chip according to an embodiment of the present invention;
FIG. 3 is a voltage-current characteristic diagram of a plurality of sub-chips according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a mask according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a process of forming a mask according to an embodiment of the present invention;
fig. 6 is a current flow diagram of a chip according to an embodiment of the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description will be made on the specific implementation, structure, features and effects of the micro-led chip 1 and the display device according to the present invention with reference to the accompanying drawings and preferred embodiments.
As shown in fig. 1 to 6, an embodiment of the invention provides a micro light emitting diode chip 1, which includes a plurality of sub-chips 12, the plurality of sub-chips 12 are arranged in parallel, each sub-chip 12 has a lighting voltage, and the lighting voltages of at least two sub-chips 12 are different.
The micro light emitting diode chip 1 provided by the embodiment of the invention comprises a plurality of sub-chips 12, wherein the plurality of sub-chips 12 are arranged in parallel, each sub-chip 12 is provided with a lighting voltage, the lighting voltages of at least two sub-chips 12 are different, the lighting voltage is a voltage at which the corresponding sub-chip 12 can be used for lighting, the sub-chip 12 can be used for passing current when the sub-chip 12 works, when the driving voltage reaches the lighting voltage of a certain sub-chip 12, the sub-chip 12 with the lighting voltage can be used for lighting, under the condition that each sub-chip 12 is provided with a lighting voltage and the lighting voltages of at least two sub-chips 12 are different, the micro light emitting diode chip 1 provided by the application can gradually change the brightness of the micro light emitting diode chip 1 through the change of the driving voltage to achieve the purpose of gray scale switching, and in the process of the change of the driving voltage, only the sub-chip 12 with the lighting voltage reaching the driving voltage can be used for lighting, in the process of changing the driving voltage, the number of the sub-chips 12 capable of being turned on is increased, the area capable of passing current is increased while the number of the sub-chips 12 capable of being turned on is increased, so that more sub-chip areas share the current, the current density is not greatly changed, the whole micro light emitting diode chip 1 can work at the same current density, the current density of the micro light emitting diode chip 1 is not greatly changed even if the driving voltage of the micro light emitting diode chip 1 is different, the wavelength of the micro light emitting diode chip 1 is determined by the current density of the micro light emitting diode chip 1, the wavelength of the micro light emitting diode chip 1 is basically unchanged, the wavelength is stable, and the normal display and switching of gray scales of the chip 1 can be realized. In the prior art, the LED chip 1 can cause quantum confinement Stark effect due to the polarization effect in the multi-quantum well region, so that the wavelength of the chip 1 is unstable. Taking blue-green chip 1 as an example, the prior art mainly uses a quantum well system of GaN/InGaN, and the wavelength of the quantum well system is blue-shifted with the current. Compared with the prior art, the LED driving circuit has the advantages that the plurality of sub-chips 12 with the lighting voltage are arranged in the structure of the same micro LED chip 1, the lighting voltage of at least two sub-chips 12 is different, so that the sub-chips 12 corresponding to different sub-chips are lighted under the driving condition of different driving voltages, current is shared, the current density of the micro LED chip 1 is guaranteed to be unchanged, the brightness of the micro LED chip 1 is gradually changed, the stability of wavelength is guaranteed, and the purpose of better switching and displaying gray scales is achieved.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
In the embodiment of the present invention, each of the sub-chips includes an N-type layer 124 and a P-type layer 128, a product of a doping concentration of the N-type layer 124 and a doping concentration of the P-type layer 128 is a doping concentration product, and the doping concentration products of at least two of the sub-chips are different.
In this embodiment, each of the sub-chips 12 includes an N-type layer 124 and a P-type layer 128, the sub-chips 12 emit light by means of the N-type layer 124 and the P-type layer 128 being co-current and then being combined in the light emitting layer, thereby completing the light emission of the sub-chip 12, wherein the product of the doping concentration of the N-type layer 124 and the doping concentration of the P-type layer 128 represents the energy level of the sub-chip 12, wherein the N-type layer 124 is doped with other elements, the mass ratio of the other elements to the N-type layer 124 is the doping concentration of the N-type layer 124, the mass ratio of the other elements may be Si, i.e. the mass ratio of Si to the N-type layer 124 is the doping concentration of the N-type layer 124, the P-type layer 128 is doped with other elements, the doping concentration of the P-type layer 128 is the mass ratio of the P-type layer 128, when the products of the doping concentrations of the N-type layer 124 and the P-type, that is, the structure of the sub-chip 12 is changed, the energy level position of the sub-chip 12 is different, and the turn-on voltage of the sub-chip 12 is different. After the micro light emitting diode chip 1 starts to operate, the driving voltage drives to enable a current to pass through the sub-chip 12, and when the current passing through the sub-chip 12 can enable the sub-chip 12 to be turned on, the voltage corresponding to the current is the turning-on voltage of the sub-chip 12, and the current passing through the sub-chip 12 when the sub-chip 12 starts to operate is generally 0.1A or 1A. As shown in fig. 3, when the current reaches the level that the micro led chip 1 can operate, the voltages corresponding to the lines representing the sub-chips 12 are different, so that the micro led chip 1 provided by the present application directly controls the luminance and chromaticity of the chip 1 through the current, and at least two sub-chip structures with different doping concentration products are disposed in the same micro led chip 1, so that at least two sub-chips 12 have different lighting voltages therein, thereby gradually changing the luminance of the micro led chip 1 without changing the current density of the micro led chip 1, so that the wavelength of the micro led chip 1 is stable, and the purpose of switching and displaying gray scales is achieved.
In addition, the turn-on voltage is Vth，
Wherein, VDIs the diffusion voltage; n is a radical ofAIs the doping concentration of the N-type layer; n is a radical ofDThe doping concentration of the P type layer; n isiIs the intrinsic carrier concentration of the semiconductor; k is Boltzmann constant, K is 1.3806505(24) x 10^ (-23) J/K; t is the temperature of the micro light-emitting diode chip; e is the electron charge, e is 1.6021892 × 10^ (-19) C. Starting voltage VthAnd a diffusion voltage VDBoth are approximately equal in value, and the diffusion voltage
In this formula, K is Boltzmann's constant, T is the temperature of the micro-LED chip 1, e is the electronic charge, niThe intrinsic carrier concentration of the semiconductor is the equilibrium concentration of free electrons and free holes in the intrinsic semiconductor material, and other factors capable of influencing the diffusion voltage are the product of the doping concentration of the N-type layer and the doping concentration of the P-type layer, so that the magnitude of the diffusion voltage is influenced by the product of the doping concentrations of the N-type layer and the P-type layer in the sub-chip, and the turn-on voltage is approximately equal to the diffusion voltage, so that the magnitude of the turn-on voltage is influenced by the product of the doping concentrations of the N-type layer and the P-type layer in the sub-chip, and the turn-on voltage of the sub-chip 12 can be changed by changing the product of the doping concentrations of the N-type layer and the P-type layer in the sub-chip. Therefore, the difference of the turn-on voltages of the plurality of sub-chips can be controlled by controlling the difference of the product of the doping concentrations of the N-type layer and the P-type layer in the plurality of sub-chips. Therefore, when the micro light-emitting diode chip 1 is used, the size of the starting voltage of the sub-chip 12 can be changed by changing the product of the doping concentrations of the N-type layer and the P-type layer, and then different sub-chips 12 can be started gradually according to the driving voltage which is increased gradually in the working process, so that the purpose of gradually changing the brightness of the micro light-emitting diode chip 1 and achieving gray scale switching is achieved.
As shown in fig. 1, in the embodiment of the present invention, a plurality of sub-chips 12 are uniformly arranged.
In this embodiment, the plurality of sub-chips 12 are uniformly arranged, and the positive and negative electrodes of the plurality of sub-chips 12 are connected together and arranged in parallel to form one chip 1, each sub-chip 12 has a lighting voltage, the micro light emitting diode chip 1 is driven by different driving voltages, the sub-chip 12 having the lighting voltage smaller than the driving voltage is used for lighting, when in operation, the lighting small chip 1 can share current through the expansion effect of the current, so that the current density change of the whole chip 1 is small when in operation, thereby ensuring that the wavelength of the chip 1 does not have too large offset, and further the plurality of sub-chips 12 are gradually lighted according to the lighting voltage of the sub-chips 12, so as to gradually change the brightness of the micro light emitting diode chip 1 and achieve the purpose of gray scale switching.
The gaps between the plurality of sub-chips 12 are reduced as much as possible, so that errors due to the gaps between the plurality of sub-chips 12 are reduced, and the current density variation can be minimized.
As shown in fig. 2, in the embodiment of the present invention, each sub-chip 12 is a ring structure, centers of the plurality of sub-chips 12 are located at the same position, and the sub-chip 12 far away from the center is sleeved outside the sub-chip 12 near the center.
In this embodiment, as shown in fig. 2, A, B, C, D, E, F and G in the figure respectively represent sub-chips from the center to two sides, each sub-chip 12 is in a ring structure, the centers of the sub-chips 12 in the ring structure are overlapped, the distance from the outer edge of the sub-chip 12 close to the center is smaller than the distance from the outer edge of the sub-chip 12 far from the center to the center, so that the sub-chip 12 far from the center can be sleeved outside the sub-chip 12 close to the center, the sub-chips 12 are sequentially sleeved and arranged, and the sub-chips 12 are arranged in parallel, each ring sub-chip 12 has a turn-on voltage, the sub-chip 12 with the turn-on voltage smaller than the drive voltage is turned on by the micro light emitting diode chip 1 under the drive of different drive voltages, and in operation, the turned-on small chip 1 can share current through the expansion effect of the current, so that the current density change is smaller when the whole micro light emitting diode chip 1, therefore, the wavelength of the chip 1 can be ensured not to be greatly deviated, and then the plurality of sub-chips 12 are gradually turned on according to the turn-on voltage of the sub-chips, so that the brightness of the chip 1 is gradually changed, and the purpose of gray scale switching is achieved.
Preferably, the ring structure is a circular ring structure, that is, each sub-chip 12 is a circular ring structure, and the cross section of the micro light emitting diode chip 1 is circular.
Optionally, the lighting voltage of the sub-chip 12 far from the center is greater than that of the sub-chip 12 near the center, so that the brightness of the chip 1 is gradually lit from the middle to the edge, thereby achieving the gray scale switching.
Optionally, the arrangement of the sub-chips 12 is not limited to uniform arrangement and annular sleeve arrangement, and as long as the requirement that the sub-chips 12 are arranged in parallel is met, the arrangement mode of the sub-chips 12 can be set according to the requirement.
In the embodiment of the present invention, the plurality of sub-chips 12 are integrally formed.
In this embodiment, the sub-chips 12 are integrally formed, that is, gaps between the sub-chips 12 may also pass through current or there is no gap between the sub-chips, so that stability of current density can be ensured to a greater extent, and the wavelength of the chip 1 is substantially unchanged, and further the sub-chips 12 are gradually turned on according to their own lighting voltage, so as to gradually change the brightness of the chip 1, thereby achieving the purpose of gray scale switching.
In this embodiment, the lighting voltages of the plurality of sub-chips 12 are all different.
In the embodiment of the invention, the lighting voltages of the plurality of sub-chips 12 are all different, so that the plurality of sub-chips 12 can be sequentially lighted under the driving of different driving voltages, the core micro light-emitting diode segment 1 can have various brightness, and the requirements of users are met.
In this embodiment, fig. 6 shows a chip 1 in a flip-chip structure, in which the product of the doping concentration of the N-type layer 124 and the doping concentration of the P-type layer 128 of the plurality of sub-chips in the structure of the micro light emitting diode chip 1 is different, wherein the turn-on voltage of the sub-chip 12 near the center of the micro led chip 1 is lower than the turn-on voltage of the sub-chip 12 far from the center, the N pole of the micro light emitting diode chip 1 structure is positioned at the center of the micro light emitting diode chip 1, the P pole is positioned at the annular position around the micro light emitting diode chip 1, in the low voltage driving, the current inside the micro led chip 1 mainly flows at the sub-chip 12 at the center where the lighting voltage has reached the low voltage, wherein the main flow channel of the current is the solid line part in the figure, that is, the current is only diffused to the annular area near the sub-chip where the lighting voltage at the center is smaller than the driving voltage; when the high voltage is used for driving, the lighting voltage of the sub-chip 12 in the micro light-emitting diode chip 1 is smaller than the high voltage, the current in the micro light-emitting diode chip 1 can be expanded to the position with a larger annular area, the current can circulate in the whole chip 1, the circulation channel of the current is a dotted line part in a figure, and because the expanded area of the current is increased, the whole current density of the chip 1 can be kept at the same level, so that the wavelength consistency of the chip 1 can be ensured.
Optionally, the turn-on voltage of the sub-chip 12 close to the center of the micro light emitting diode chip 1 is greater than the turn-on voltage of the sub-chip 12 far from the center; certainly, the arrangement of the sub-chips is not limited to the above two manners, and the lighting voltages of the sub-chips in the micro light emitting diode chip 1 may be arranged according to other requirements, and in the arrangement process of the sub-chips, the respective lighting voltages are determined according to the product of the doping concentrations of the P-type layer and the N-type layer, that is, the lighting voltages of the sub-chips are changed by changing the product of the doping concentrations of the P-type layer and the N-type layer in the sub-chips.
In this embodiment, the N-type layer 124 and the P-type layer 128 of the chiplet 12 are P-type GaN and N-type GaN, respectively.
The embodiment of the invention also provides a display device, which comprises the chip 1;
the chip 1 is in a flip-chip structure, a vertical structure or a forward structure.
In this embodiment, the front-mounted structure of the chip uses sapphire as the substrate as the lower surface, the electrode is on the upper surface, and the materials from top to bottom are: the structure of the LED comprises a P-GaN layer, a light emitting layer, an N-GaN layer and a sapphire substrate layer, the LED is simple in structure, but current is crowded, and the sapphire substrate is poor in heat conductivity, so that heat dissipation is seriously hindered. The flip chip structure is shown in fig. 6, and the materials from top to bottom are: the LED chip comprises a sapphire layer 122, an N-GaN layer 124, a multi-quantum well layer 126 and a P-GaN layer 128, wherein the multi-quantum well layer is used for emitting light when a driving voltage reaches a starting voltage, in addition, an insulating layer (not shown in the figure) is arranged below the P-GaN layer 128 in the flip chip structure, the P-GaN layer is connected with electrodes through a through hole process after being separated by the insulating layer, and the heat dissipation effect is greatly improved through the structure. The vertical structure of the chip adopts a high-heat substrate to replace a sapphire substrate, two electrodes of the chip of the vertical structure are respectively arranged on two sides of an epitaxial layer, the current almost completely vertically flows through the epitaxial layer through an N electrode, the current flowing transversely is extremely little, the current congestion problem of a normally installed structure can be avoided, and the luminous efficiency is improved.
In the embodiment of the present invention, as shown in fig. 2 and fig. 6, a plurality of sub-chips including A, B, C, D, E, F and G are provided, each sub-chip 12 has an annular structure, and each sub-chip 12 has a lighting voltage, optionally, the lighting voltages of the sub-chips are all different, that is, the products of the doping concentrations of the N-type layer and the P-type layer of each sub-chip are all different, so that the micro light emitting diode chip 1 is driven by different driving voltages, and the plurality of sub-chips are sequentially lighted according to the lighting voltages, so as to gradually change the brightness of the chip 1, thereby achieving the purpose of gray scale switching. In the low-voltage driving, the current inside the micro light-emitting diode chip 1 flows at the sub-chip 12 where the lighting voltage has reached the low voltage; when the driving voltage is gradually increased, the sub-chips which can be turned on are also gradually increased, the current flowing area in the micro light-emitting diode chip 1 is also increased, and the whole current density of the chip 1 can be kept at the same level due to the increase of the current expanding area, so that the wavelength consistency of the chip 1 can be ensured.
As shown in fig. 4 and 5, in this embodiment, in the manufacturing process of the chip 1, each sub-chip 12 needs to use a different mask 14 to correspond to each other, the mask 14 uses different annular masks 14 according to the positions of the corresponding sub-chips 12, and by controlling the gas ratio and the temperature of MOCVD, electron and hole transport layers with different concentrations can be grown at the corresponding annular positions. It can grow from the center outwards, but the material grown in the back Mask will cover the material grown in the front end during the growth process, and the specific appearance can be referred to fig. 5. The excess material may be removed by etching to form a planarized film. Portion a of fig. 4 is an embodiment of a method of reticle formation that requires etching of reticle 14. pGaN and nGaN may be grown using the same method, so that an epitaxial wafer as shown in fig. 2 may be formed, and then the growth of the rear electrode and the extension layer may be performed at the corresponding positions to form a single chip 1.
As shown in fig. 4, in this embodiment, another structure of the mask 14 is further provided, a position to be grown is reserved on the mask 14, and the position of a single sub-chip 12 needs to be rotated during the growth of the mask 14, so as to ensure that the ring-shaped grown material can grow uniformly. Part b of fig. 4 is an embodiment of another method for forming reticles, in which each reticle 14 corresponding to one sub-chip needs to be formed by rotation simultaneously with the corresponding sub-chip, so that etching is not needed during the growth of the material of the reticle 14, and the formed device is a planarized structure.
In the embodiment, the stability of the wavelength can be improved by weakening the piezoelectric field, adopting a quaternary structure, optimizing the growth condition of the epitaxial material, the total strain and other measures.
The micro light emitting diode chip 1 and the display device provided by the embodiment of the invention, wherein the micro light emitting diode chip 1 comprises a plurality of sub-chips 12, the plurality of sub-chips 12 are arranged in parallel, each sub-chip 12 has a lighting voltage, the lighting voltages of at least two sub-chips 12 are different, the lighting voltages are voltages at which the corresponding sub-chips 12 can be lighted, the sub-chips 12 can be lighted when the driving voltage reaches the lighting voltage of a certain sub-chip 12, the current passes when the sub-chips 12 are in operation, the sub-chips 12 with the lighting voltages can be lighted, under the condition that each sub-chip 12 has a lighting voltage and the lighting voltages of at least two sub-chips 12 are different, the micro light emitting diode chip 1 provided by the application can gradually change the brightness of the micro light emitting diode chip 1 through the change of the driving voltage, so as to achieve the purpose of switching gray scales, in the process of the change of the driving voltage, only the sub-chip 12 with the lighting voltage reaching the driving voltage is lighted, and in the process of the change of the driving voltage, the number of the sub-chips 12 capable of being lighted is increased, the area for passing current is increased while the number of the sub-chips 12 which can be turned on is increased, so that more area is provided for sharing current, further, the current density will not change greatly, so that the micro light emitting diode chip 1 can work under the same current density as a whole, therefore, even if the driving voltage of the micro light emitting diode chip 1 is different, the current density of the micro light emitting diode chip 1 will not change greatly, and the wavelength of the micro led chip 1 is determined by the current density of the micro led chip 1, therefore, the wavelength of the micro light-emitting diode chip 1 is basically unchanged, the wavelength is stable, and the micro light-emitting diode chip 1 can realize normal display and switching of gray scales. In the prior art, the LED chip 1 can cause quantum confinement Stark effect due to the polarization effect in the multi-quantum well region, so that the wavelength of the chip 1 is unstable. Taking blue-green chip 1 as an example, the wavelength of the existing quantum well system mainly using GaN/InGaN is blue shifted with the current. Compared with the prior art, the LED driving circuit has the advantages that the plurality of sub-chips 12 with the lighting voltage are arranged in the structure of the same micro LED chip 1, the lighting voltage of at least two sub-chips 12 is different, so that the sub-chips 12 corresponding to different sub-chips are lighted under the driving condition of different driving voltages, current is shared, the current density of the micro LED chip 1 is guaranteed to be unchanged, the brightness of the micro LED chip 1 is gradually changed, the stability of wavelength is guaranteed, and the purpose of better switching and displaying gray scales is achieved.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (6)
1. A micro light emitting diode chip, comprising:
the plurality of sub-chips are arranged in parallel, each sub-chip is provided with a lighting voltage, and the lighting voltages of at least two sub-chips are different;
each sub-chip comprises an N-type layer and a P-type layer, the product of the doping concentration of the N-type layer and the doping concentration of the P-type layer is a doping concentration product, and the doping concentration products of at least two sub-chips are different;
each sub-chip is of an annular structure, the centers of the plurality of sub-chips are located at the same position, and the sub-chip far away from the center is sleeved outside the sub-chip close to the center;
the starting voltage of the sub-chip far away from the center is larger than that of the sub-chip close to the center.
2. The micro light-emitting diode chip of claim 1,
the plurality of sub-chips are uniformly arranged.
3. The micro light-emitting diode chip of claim 1,
and a plurality of the sub-chips are integrally formed.
4. The micro light-emitting diode chip of claim 3,
the lighting voltages of the sub-chips are all different.
5. A display device comprising the micro light-emitting diode chip as claimed in any one of claims 1 to 4.
6. The display device according to claim 5,
the chip is of a flip-chip or vertical or face-up structure.
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| CN115019675A (en) * | 2022-05-31 | 2022-09-06 | 武汉天马微电子有限公司 | Display panel and display device |
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| US9281298B2 (en) * | 2014-02-10 | 2016-03-08 | Nthdegree Technologies Worldwide Inc. | Process for forming ultra-micro LEDS |
| EP3270429B1 (en) * | 2015-03-13 | 2020-03-04 | Sharp Kabushiki Kaisha | Light-emitting device |
| TWI645394B (en) * | 2018-02-06 | 2018-12-21 | 友達光電股份有限公司 | Display apparatus and driving method thereof |
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Effective date of registration: 20220126 Address after: 100015 No. 10, Jiuxianqiao Road, Beijing, Chaoyang District Patentee after: BOE TECHNOLOGY GROUP Co.,Ltd. Patentee after: BOE crystal core technology Co., Ltd Address before: 100015 No. 10, Jiuxianqiao Road, Beijing, Chaoyang District Patentee before: BOE TECHNOLOGY GROUP Co.,Ltd. Patentee before: BOE Optoelectronics Technology |