WO2019165755A1 - 一种发光二极管芯片及其制备方法 - Google Patents

一种发光二极管芯片及其制备方法 Download PDF

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WO2019165755A1
WO2019165755A1 PCT/CN2018/098389 CN2018098389W WO2019165755A1 WO 2019165755 A1 WO2019165755 A1 WO 2019165755A1 CN 2018098389 W CN2018098389 W CN 2018098389W WO 2019165755 A1 WO2019165755 A1 WO 2019165755A1
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sub
pixel
quantum well
layer
regions
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French (fr)
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WO2019165755A8 (zh
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吕泉
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华为技术有限公司
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Priority to EP18908112.8A priority Critical patent/EP3748700A4/en
Publication of WO2019165755A1 publication Critical patent/WO2019165755A1/zh
Priority to US17/004,958 priority patent/US11296257B2/en
Publication of WO2019165755A8 publication Critical patent/WO2019165755A8/zh

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    • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
    • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
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    • H01L33/26—Materials of the light emitting region
    • H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
    • H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen
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    • H01L33/38—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape
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    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials

Definitions

  • the present application relates to the field of semiconductor technologies, and in particular, to a light emitting diode chip and a method for fabricating the same.
  • GaN-based light emitting diode As a kind of optoelectronic device, GaN-based light emitting diode (LED) is widely used in many display fields due to its long service life, good stability and low energy consumption, such as micro-projection display and head. Display areas such as wearable display, augmented reality (AR), virtual reality (VR), and wearable display.
  • LED gallium-based light emitting diode
  • GaN-based LED chips can be controlled on the order of micrometers. If micron-sized GaN-based LED chips are used as display pixels, a high-resolution, low-power, thin and light display system can be realized.
  • the embodiment of the present application provides an LED chip and a preparation method thereof for realizing full color display.
  • an LED chip comprising:
  • each of the three sub-pixel structures including a sequentially grown blue quantum well structure, an interface barrier layer, a green light quantum well structure, a charge blocking layer, and a P-type GaN doped layer;
  • Three P-type contact electrodes respectively formed over three sub-pixel structures, and N-type contact electrodes formed on regions other than the three sub-pixel regions on the first surface of the N-type GaN doped layer;
  • a red colloidal quantum dot structure formed on a second surface of the N-type GaN doped layer and corresponding to a first sub-pixel region of the three sub-pixel regions.
  • each of the three sub-pixel structures includes a blue quantum well structure and a green quantum well structure
  • the LED chip can pass through the other two of the three sub-pixel structures except the first sub-pixel structure.
  • the sub-pixel structure enables the LED chip to emit blue light and green light.
  • a red colloidal quantum dot structure can be coated on a corresponding region of the first sub-pixel structure including the blue quantum well structure and the green quantum well structure, thereby absorbing blue and green light through the red colloidal quantum dot structure and converting into red light.
  • the full color display can be realized by using the LED chip provided in the first aspect.
  • the N-type GaN doped layer may be a GaN layer doped with silicon
  • the P-type GaN doped layer may be a GaN layer doped with magnesium
  • the pixel shape can be circular or square. Therefore, the above three sub-pixel regions may be circular regions or square regions.
  • the size of the sub-pixel area may be set according to different requirements of the LED chip, which is not specifically limited in the embodiment of the present application.
  • the circular region may have a diameter of 5 um to 50 um.
  • the blue quantum well structure comprises: N blue quantum well layers, and N+1 isolation layers alternated with N blue quantum well layers for isolating N blue quantum well layers, N ⁇ 1.
  • the blue quantum well structure is formed by alternately growing the isolation layer and the blue quantum well layer.
  • a blue quantum well structure can be formed by a material growth process of 3 to 5 cycles.
  • a blue quantum well structure can include two blue quantum well layers and three isolation layers alternately formed with two blue quantum well layers.
  • the blue quantum well layer may be a GaN layer doped with an indium element.
  • the green quantum well structure comprises: M green quantum well layers, and M+1 isolation layers alternated with M green quantum well layers for isolating M green quantum well layers, M ⁇ 1.
  • the green light quantum well structure is formed by alternately growing the isolation layer and the green quantum well layer.
  • a green light quantum well structure can be formed by a material growth process of 3 to 5 cycles.
  • a green light quantum well structure can include two green light quantum well layers and three isolation layers alternately formed with two green light quantum well layers.
  • the green quantum well layer may be a GaN layer doped with an indium element; the proportion of the green quantum well layer doped with the indium element is different from the ratio of the blue quantum well layer doped with the indium element.
  • the LED chip may further include: a red filter placed on the red colloid quantum dot structure; a blue filter placed on a second surface of the N-type GaN doped layer and corresponding to a second sub-pixel region of the three sub-pixel regions; on a second surface of the N-type GaN doped layer And a green filter placed on a region corresponding to the third sub-pixel region of the three sub-pixel regions.
  • the red filter placed on the red colloidal quantum dot can filter out the color light (such as blue light and green light) other than red light in the first sub-pixel region; the corresponding region in the second sub-pixel region
  • the blue filter placed on the screen can filter out the color light (such as green light) other than blue light in the second sub-pixel area; the green filter placed on the corresponding area of the third sub-pixel area can be filtered out A color light (such as blue light) other than green light on the three sub-pixel regions.
  • the LED chip further includes: a driving circuit connected to the three P-type contact electrodes and the N-type contact electrodes.
  • the driving circuit can control the luminous intensity of each sub-pixel structure by using a pulse width modulation technology, so that the color brightness of the blue light, the green light, and the red light emitted by each sub-pixel structure in the LED chip is uniform.
  • the substrate and the buffer layer In the preparation of the LED chip provided in the first aspect, material growth on the substrate and the buffer layer is required. After the material growth is completed, the substrate and the buffer layer can be cleaved because the functions of the substrate and the buffer layer are completed. Of course, since the substrate and the buffer layer do not affect the light-emitting display of the LED chip, the substrate and the buffer layer may not be cleaved.
  • the LED chip further includes: a buffer layer and a substrate formed on the second surface of the N-type GaN doped layer, the buffer layer and the N-type The GaN doped layer is adjacent, and the substrate is adjacent to the buffer layer and the red colloidal quantum dot structure.
  • an embodiment of the present application provides a method for preparing an LED chip, the method comprising the following steps:
  • the mask pattern transfers onto the P-type GaN doped layer to form a second sample; wherein the mask pattern includes a plurality of sub-pixel regions and other regions than the plurality of sub-pixel regions;
  • At least one red colloidal quantum dot structure is respectively coated on the second side of the substrate and corresponding to at least one first sub-pixel region for emitting red light in the plurality of sub-pixel regions to form an LED chip.
  • the method further comprises: respectively placing at least one red filter on the at least one red colloidal quantum dot structure; on the second side of the substrate, and in the plurality of sub-pixel regions At least one blue color filter is respectively disposed on a region corresponding to the at least one second sub-pixel region emitting blue light; at least one third for emitting green light in the second surface of the substrate and in the plurality of sub-pixel regions At least one green filter is placed on each of the areas corresponding to the sub-pixel regions.
  • the method further includes: aligning the plurality of P-type contact electrodes and the N-type contact electrodes with the driving circuit by metal solder balls.
  • the substrate and the buffer layer may be cleaved with the LED chip by laser irradiation before coating the at least one red colloidal quantum dot structure separately; then, at this time, on the substrate And coating at least one red colloidal quantum dot structure on the second surface and corresponding to the at least one first sub-pixel region for emitting red light in the plurality of sub-pixel regions, which can be realized by: At least one red colloidal quantum dot structure is respectively coated on a surface of the GaN doped layer adjacent to the buffer layer and corresponding to the at least one first sub-pixel region.
  • etching is performed on the second sample according to the mask pattern to protect the structures on the plurality of sub-pixel regions, and exposing other regions of the mask pattern except the plurality of sub-pixel regions to the N-type
  • the GaN doped layer can be specifically realized by: passivating and protecting a side surface of the LED chip and a plurality of sub-pixel regions; and etching other regions by inductively coupled plasma ICP or reactive ion etching RIE to expose other regions to N Type GaN doped layer.
  • a plurality of P-type contact electrodes are respectively formed on a plurality of sub-pixel regions, and an N-type contact electrode is formed on other regions, which can be realized by: depositing a nickel-gold alloy by electron beam evaporation, After annealing at 200 ° C to 500 ° C, a plurality of P-type contact electrodes are respectively formed on the plurality of sub-pixel regions; and indium tin oxide ITO or graphite is sputtered on other regions to form an N-type contact electrode.
  • an embodiment of the present application provides an LED chip, where the LED chip includes:
  • the third sub-pixel structure on the third sub-pixel region of the three sub-pixel regions includes a sequentially grown green light quantum well structure, a charge blocking layer, and a P-type GaN doped layer;
  • Three P-type contact electrodes respectively formed over three sub-pixel structures, and N-type contact electrodes formed on regions other than the three sub-pixel regions on the first surface of the N-type GaN doped layer;
  • a red colloidal quantum dot structure formed on a second surface of the N-type GaN doped layer and a region corresponding to the first sub-pixel region.
  • the LED chip can emit blue light through the second sub-pixel structure; the third sub-pixel structure in the three sub-pixel structures includes the green quantum The well structure allows the LED chip to emit green light through the third sub-pixel structure.
  • the red colloidal quantum dot structure may be coated on the corresponding region of the first sub-pixel structure including the blue quantum well structure or the green quantum well structure, thereby absorbing blue or green light through the red colloidal quantum dot structure and converting into red light. To achieve red light from the LED chip. Therefore, the full color display can be realized by using the LED chip provided in the third aspect.
  • the N-type GaN doped layer may be a GaN layer doped with silicon, the P-type GaN doped layer in the first sub-pixel structure, and the P-type in the second sub-pixel structure
  • Both the GaN doped layer and the P-type GaN doped layer in the third sub-pixel structure may be a GaN layer doped with magnesium.
  • the pixel shape can be circular or square. Therefore, the three sub-pixel regions may be all circular regions or square regions.
  • the size of the sub-pixel area may be set according to different requirements of the LED chip, which is not specifically limited in the embodiment of the present application.
  • the circular region may have a diameter of 5 um to 50 um.
  • the blue quantum well structure in the second sub-pixel structure comprises: N blue quantum well layers, and alternating with the N blue quantum well layers for isolating the N blue quantum well layers.
  • the blue quantum well structure in the second sub-pixel structure is formed by alternately growing the isolation layer and the blue quantum well layer.
  • the blue quantum well structure in the second sub-pixel structure can be formed by a material growth process of 3 to 5 cycles.
  • the blue quantum well structure in the second sub-pixel structure may include two blue quantum well layers and three isolation layers alternately formed with two blue quantum well layers.
  • the blue quantum well layer in the second sub-pixel structure may be a GaN layer doped with an indium element.
  • the blue quantum well structure in the first sub-pixel structure may be the same as the structure of the blue quantum well structure in the second sub-pixel structure.
  • the green quantum well structure in the third sub-pixel structure comprises: M green quantum well layers, and alternating with the M green quantum well layers for isolating the M green quantum well layers.
  • the green quantum well structure in the third sub-pixel structure is formed by alternately growing the isolation layer and the green quantum well layer.
  • the green quantum well structure in the third sub-pixel structure can be formed by a material growth process of 3 to 5 cycles.
  • the green quantum well structure in the third sub-pixel structure may comprise two green light quantum well layers and three isolation layers alternately formed with two green light quantum well layers.
  • the green quantum well layer in the third sub-pixel structure may be a GaN layer doped with an indium element; the proportion of the green quantum well layer doped indium element in the third sub-pixel structure and the blue light in the second sub-pixel structure The proportion of the quantum well layer doped with indium elements is different.
  • the green quantum well structure in the first sub-pixel structure may be the same as the green quantum well structure in the third sub-pixel structure.
  • the LED chip may further include: a red filter placed on the red colloid quantum dot structure; a blue filter placed on a second surface of the N-type GaN doped layer and corresponding to the second sub-pixel region; on the second surface of the N-type GaN doped layer, and the third sub- A green filter placed on the area corresponding to the pixel area.
  • the red filter placed on the red colloidal quantum dot can filter out the color light (such as blue light and green light) other than red light in the first sub-pixel region; the corresponding region in the second sub-pixel region
  • the blue filter placed on the screen can filter out the color light (such as green light) other than blue light in the second sub-pixel area; the green filter placed on the corresponding area of the third sub-pixel area can be filtered out A color light (such as blue light) other than green light on the three sub-pixel regions.
  • the LED chip further includes: a driving circuit connected to the three P-type contact electrodes and the N-type contact electrodes.
  • the driving circuit can control the luminous intensity of each sub-pixel structure by using a pulse width modulation technology, so that the color brightness of the blue light, the green light, and the red light emitted by each sub-pixel structure in the LED chip is uniform.
  • the substrate and the buffer layer In the preparation of the LED chip provided in the third aspect, material growth on the substrate and the buffer layer is required. After the material growth is completed, the substrate and the buffer layer can be cleaved because the functions of the substrate and the buffer layer are completed. Of course, since the substrate and the buffer layer do not affect the light-emitting display of the LED chip, the substrate and the buffer layer may not be cleaved.
  • the LED chip further includes: a buffer layer and a substrate formed on the second surface of the N-type GaN doped layer, the buffer layer and the N-type The GaN doped layer is adjacent, and the substrate is adjacent to the buffer layer and the red colloidal quantum dot structure.
  • an embodiment of the present application provides a method for fabricating an LED chip, which includes the following steps:
  • a blue quantum well structure, a charge blocking layer, and a P-type GaN doped layer are sequentially grown on the blue quantum well growth region in the N-type GaN doped layer; and the blue quantum well growth region is removed in the N-type GaN doped layer a green light quantum well structure, a charge blocking layer, and a P-type GaN doped layer are sequentially grown on the outer green light quantum well growth region to form a first sample;
  • the mask pattern includes a plurality of sub-pixel regions and other regions than the plurality of sub-pixel regions, the plurality of sub-pixel regions including at least one first sub-pixel region for emitting red light, and at least one for emitting blue light a second sub-pixel region and at least one third sub-pixel region for emitting green light; at least one first sub-pixel region is aligned with the blue quantum well growth region or the green quantum well growth region, and at least one second sub-pixel region is aligned with the blue light a quantum well growth region, at least one third sub-pixel region aligned with the green light quantum well growth region;
  • At least one red colloidal quantum dot structure is respectively coated on the second surface of the substrate and corresponding to the at least one first sub-pixel region to form an LED chip.
  • a blue quantum well structure, a charge blocking layer, and a P-type GaN doped layer are sequentially grown on a blue quantum well growth region in the N-type GaN doped layer; and, in the N-type GaN doped layer
  • the green quantum well structure, the charge blocking layer and the P-type GaN doped layer are sequentially grown on the green quantum well growth region except the blue quantum well growth region, which can be realized by: forming on the N-type GaN doped layer a first mask, the first mask is for protecting the green quantum well growth region; the blue quantum well structure, the charge blocking layer and the P-type GaN doped layer are sequentially grown on the blue quantum well growth region; the first mask is removed; A second mask is formed on the growth region of the blue quantum well, and the second mask is used to protect the blue quantum well growth region; the green quantum well structure, the charge blocking layer and the P-type GaN doped layer are sequentially grown on the green quantum well growth region.
  • the method further comprises: respectively placing at least one red filter on the at least one red colloidal quantum dot structure; on the second side of the substrate, and with the at least one second sub-pixel region At least one blue color filter is respectively disposed on the corresponding area; at least one green color filter is respectively disposed on the second surface of the substrate and the area corresponding to the at least one third sub-pixel area.
  • the method further includes: aligning the plurality of P-type contact electrodes and the N-type contact electrodes with the driving circuit by metal solder balls.
  • the substrate and the buffer layer may be cleaved with the LED chip by laser irradiation before coating the at least one red colloidal quantum dot structure separately; then, at this time, on the substrate Applying at least one red colloidal quantum dot structure on the second surface and corresponding to the at least one first sub-pixel region, respectively, can be realized by: a side adjacent to the buffer layer in the N-type GaN doped layer At least one red colloidal quantum dot structure is coated on each of the regions corresponding to the at least one first sub-pixel region.
  • etching is performed on the second sample according to the mask pattern to protect the structures on the plurality of sub-pixel regions, and exposing other regions of the mask pattern except the plurality of sub-pixel regions to the N-type
  • the GaN doped layer can be specifically realized by: passivating and protecting a side surface of the LED chip and a plurality of sub-pixel regions; and etching other regions by inductively coupled plasma ICP or reactive ion etching RIE to expose other regions to N Type GaN doped layer.
  • a plurality of P-type contact electrodes are respectively formed on a plurality of sub-pixel regions, and an N-type contact electrode is formed on other regions, which can be realized by: depositing a nickel-gold alloy by electron beam evaporation, After annealing at 200 ° C to 500 ° C, a plurality of P-type contact electrodes are respectively formed on the plurality of sub-pixel regions; and indium tin oxide ITO or graphite is sputtered on other regions to form an N-type contact electrode.
  • FIG. 1 is a schematic structural diagram of a first GaN-based LED chip according to an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of a second GaN-based LED chip according to an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of a third GaN-based LED chip according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of region division on a first side of an N-type GaN doped layer according to an embodiment of the present application
  • FIG. 5 is a schematic structural diagram of a fourth GaN-based LED chip according to an embodiment of the present application.
  • FIG. 6 is a schematic structural diagram of a fifth GaN-based LED chip according to an embodiment of the present application.
  • FIG. 7 is a schematic structural diagram of a sixth GaN-based LED chip according to an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a seventh GaN-based LED chip according to an embodiment of the present application.
  • FIG. 9 is a schematic structural diagram of an eighth GaN-based LED chip according to an embodiment of the present application.
  • FIG. 10 is a flowchart of a method for preparing an LED chip according to an embodiment of the present application.
  • FIG. 11 is a schematic structural view of a fourth sample according to an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a ninth GaN-based LED chip according to an embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of a tenth GaN-based LED chip according to an embodiment of the present application.
  • 15 is a flowchart of a method for preparing another LED chip according to an embodiment of the present application.
  • 16 is a schematic structural view of another fourth sample according to an embodiment of the present application.
  • 17 is a schematic structural diagram of an eleventh GaN-based LED chip according to an embodiment of the present application.
  • FIG. 18 is a schematic structural diagram of a twelfth GaN-based LED chip according to an embodiment of the present application.
  • a method of sequentially growing a buffer layer, an N-type doped layer on a substrate, and then growing a sub-pixel structure on each sub-pixel region of the N-type doped layer is employed.
  • Each sub-pixel structure in turn includes a three-color quantum well structure (ie, a blue quantum well structure, a green quantum well structure, a red light quantum well structure), a charge blocking layer, and a P-type doped layer.
  • a three-color quantum well structure ie, a blue quantum well structure, a green quantum well structure, a red light quantum well structure
  • the structure of the LED chip prepared by the above method can be as shown in FIG. It should be noted that only three sub-pixel structures grown on three sub-pixel regions are shown in the LED chip shown in FIG. 1 , and the three sub-pixel structures are respectively used to emit blue light, green light, and red light.
  • the LED chip may comprise a plurality of sub-pixel structures, each sub-pixel structure may be used as a sub-pixel point of the full-color display LED chip, and each of the three sub-pixel structures in the plurality of sub-pixel structures may be used as one of the full-color display LED chips. pixel.
  • the emission wavelength of the quantum well structure is controlled by changing the ratio of the doped indium (In) element in the quantum well structure, thereby realizing the display of three colors of blue, green, and red.
  • the blue quantum well structure can emit blue light; by controlling the doping of the green quantum well structure
  • the proportion of the elements is such that when the emission wavelength of the green quantum well structure is 500 nm to 550 nm, the green quantum well structure can emit green light; by controlling the proportion of doped In elements in the red quantum well structure, the emission wavelength of the red quantum well structure is At 620 nm to 700 nm, the red quantum well structure emits red light.
  • the blue filter is covered on the area corresponding to the sub-pixel structure on the left side, and since the blue color filter can filter out other color lights other than the blue light, the area above the blue color filter can emit blue light;
  • the area corresponding to the middle sub-pixel structure is covered with a green color filter. Since the green color filter can filter out other color lights other than green light, the area above the green color filter can emit green light; the sub-pixel on the right side
  • the area corresponding to the structure is covered with a red color filter, and since the red color filter can filter out other color lights other than red light, the area above the red color filter can emit red light.
  • the red quantum well structure requires a high concentration of doped In elements. Excessive doping of In element causes defects and misalignment of the red quantum well structure, so that the resulting red quantum well structure has low luminous efficiency and large power consumption.
  • the embodiment of the present application provides an LED chip and a preparation method thereof, which are used to achieve full color display, improve luminous efficiency, and reduce power consumption.
  • the LED chip includes the following four parts:
  • GaN N-type gallium nitride
  • Each of the three sub-pixel structures includes a sequentially grown blue quantum well structure, an interface barrier layer, a green light quantum well structure, a charge blocking layer, and a P-type GaN doped layer.
  • Three P-type contact electrodes respectively formed over the three sub-pixel structures, and N-type contact electrodes formed on the first surface of the N-type GaN doped layer except for the three sub-pixel regions.
  • a red colloidal quantum dot structure formed on a second surface of the N-type GaN doped layer and corresponding to a first sub-pixel region of the three sub-pixel regions.
  • the colloidal quantum dots are inorganic nanomaterials having a quasi-zero-dimensional structure synthesized by chemical synthesis.
  • the colloidal quantum dot structure can realize the absorption and conversion of spectral energy: the colloidal quantum dot structure can absorb the spectral energy of various short-wavelength colored light when absorbing spectral energy; when controlling the spectral energy, by controlling the size of the colloidal quantum dot structure, The wavelength of the emission of the colloidal quantum dots is controlled, thereby realizing that the colloidal quantum dots emit light of different colors.
  • the red colloidal quantum dot structure can absorb the blue light emitted by the blue quantum well structure and/or the green light emitted by the green quantum well structure.
  • the emission wavelength of the red colloidal quantum dot structure can be the emission wavelength of red light (for example, it can be 620 nm to 700 nm), then the red colloidal quantum dot structure can emit red. Light.
  • the red colloidal quantum dot structure may comprise a plurality of colloidal quantum dots, and each colloidal quantum dot is composed of a core, a shell and a ligand.
  • the material of the core may be CdSe, CdTe, InP, ZnS, GaAs, HgTe, HgSe, InGaP, PbS, PbSe, PbTe, InSe, CuInGaS2, GuIn, GaSe2, etc.
  • the material of the shell may be CdS, ZnS, ZnSe
  • the material may be silicone, oleic acid or the like.
  • the red colloidal quantum dots may be encapsulated by an epoxy resin.
  • red light is emitted by the red colloidal quantum dot structure absorbing blue light and/or green light, so that there is no need to set a red light quantum well structure in the LED chip, and there is no existing GaN-based LED chip.
  • red quantum well structure caused by doping with a high concentration of In element.
  • the red light colloidal quantum dot structure absorbs blue light and/or green light to realize red light. The luminous efficiency of the LED chip can be improved, thereby reducing the power consumption of the LED chip.
  • the region corresponding to the first sub-pixel structure can emit red light.
  • the other two sub-pixel structures of the three sub-pixel structures except the first sub-pixel structure also include a blue quantum well structure and a green light quantum well structure, blue and green light can be realized by the other two sub-pixel structures respectively. display.
  • the filter may be placed in the corresponding light emitting area, that is, the LED chip shown in FIG. 2 may further include: a red filter placed over the red colloidal quantum dot structure; a blue filter placed on a second side of the N-type GaN doped layer and corresponding to a second sub-pixel region of the three sub-pixel regions a light patch; a green filter placed on a second surface of the N-type GaN doped layer and on a region corresponding to the third sub-pixel region of the three sub-pixel regions.
  • the second sub-pixel area can be used to emit blue light
  • the third sub-pixel area can be used to emit green light.
  • a red filter placed on the red colloidal quantum dot can filter out color light (such as blue light and green light) other than red light on the first sub-pixel area; blue placed on the corresponding area of the second sub-pixel area a color filter that filters out color light other than blue light (such as green light) on the second sub-pixel area; a green filter placed on a corresponding area of the third sub-pixel area can filter out the third sub-pixel area A color light other than green light (such as blue light).
  • the structure of the LED chip can be as shown in FIG.
  • the area above the red color filter can emit red light
  • the area above the green color filter can emit green light
  • the area above the blue color filter can emit blue light.
  • the charge blocking layer can reduce the charge leakage of the sub-pixel structure.
  • the charge blocking layer may be composed of Al 0.15 Ga 0.85 N and may have a thickness of 15 nm to 35 nm.
  • the N-type GaN doped layer may be a GaN layer doped with silicon, and may have a thickness of 2 um to 3 um;
  • the P-type GaN doped layer may be a GaN layer doped with magnesium, and may have a thickness of 150 nm to 300 nm.
  • the first face of the N-type GaN doped layer may be divided into three sub-pixel regions and other regions than the three sub-pixel regions.
  • the three sub-pixel regions are respectively used to form three sub-pixel structures, which are respectively used to emit blue light, green light, and red light, thereby realizing full color display of the LED chip.
  • the three sub-pixel structures can be formed by etching, that is, by forming a mask pattern that divides the sub-pixel region and other regions, and etching the structures on other regions according to the mask pattern, thereby forming a sub- Pixel structure.
  • the sub-pixel region is only a division of the region to form a sub-pixel structure, and does not represent any actual structure.
  • the region division on the first side of the N-type GaN doped layer may be as shown in FIG.
  • a light gray area represents a sub-pixel area
  • a dark gray area represents a region other than the three sub-pixel areas on the first surface of the N-type GaN doped layer. It is not difficult to imagine that the sub-pixel structure formed on the sub-pixel region shown in FIG. 4 has a cylindrical structure.
  • the pixel shape can be circular or square. Therefore, the three sub-pixel regions in the embodiment of the present application may all be circular regions, or may be square regions.
  • the size of the sub-pixel area may be set according to different requirements of the LED chip, which is not specifically limited in the embodiment of the present application.
  • the circular region may have a diameter of 5 um to 50 um.
  • the blue quantum well structure may include: N blue quantum well layers, and N+1 alternating with N blue quantum well layers for isolating N blue quantum well layers Isolation layer, N ⁇ 1.
  • the green light quantum well structure may include: M green light quantum well layers, and M+1 isolation layers alternately formed with M green light quantum well layers for isolating M green light quantum well layers, M ⁇ 1.
  • the quantum well structure is formed by alternately growing the isolation layer and the quantum well layer.
  • quantum well structures can be formed by a material growth process of 3 to 5 cycles.
  • a blue quantum well structure can include two blue quantum well layers and three isolation layers alternately formed with two blue quantum well layers.
  • the blue light quantum well layer may be composed of GaN doped with an In element, and specifically, may be represented by In x Ga 1-x N.
  • the green light quantum well layer may be composed of GaN doped with an In element, and specifically, may be represented by In x Ga 1-x N.
  • the difference is that the proportion of the blue quantum well layer and the green quantum well layer doped with the In element is different, that is, the value of x is different.
  • the quantum well layers have different emission wavelengths.
  • the emission wavelength of the quantum well layer can be controlled by controlling the ratio of doped In elements in the quantum well layer.
  • the thickness of the blue quantum well layer may be 2 nm to 5 nm, and the thickness of the green quantum well layer may also be 2 nm to 5 nm.
  • the spacer layer may be composed of GaN and may have a thickness of 7 nm to 15 nm.
  • a driving circuit connected to three P-type contact electrodes and N-type contact electrodes may be further included.
  • the precise alignment of the driving circuit and the contact electrode can be realized by the metal solder ball.
  • the driving circuit may include a thin film transistor (TFT), a low temperature poly-silicon (LTPS), a complementary metal oxide semiconductor (CMOS), or the like.
  • TFT thin film transistor
  • LTPS low temperature poly-silicon
  • CMOS complementary metal oxide semiconductor
  • the driving circuit can control the luminous intensity of each sub-pixel structure by using pulse width modulation (PWM) technology, so that the color brightness of blue light, green light and red light emitted by each sub-pixel structure in the LED chip is uniform.
  • PWM pulse width modulation
  • the substrate and the buffer layer can be cleaved, and the cleavable LED chip can be as shown in FIG. 2, FIG. 3, FIG.
  • the substrate and the buffer layer are not included in the chip; in addition, since the substrate and the buffer layer do not affect the light-emitting display of the LED chip, the substrate and the buffer layer may not be cleaved.
  • the LED chip further includes a buffer layer and a substrate formed on the second surface of the N-type GaN doped layer, the buffer layer is doped with the N-type GaN
  • the heterolayer is contiguous and the substrate is contiguous with the buffer layer and the red colloidal quantum dot structure, as shown in FIG.
  • the substrate may be any one of a sapphire substrate, a Si substrate, a SiC substrate or a GaN substrate; the buffer layer may be a GaN buffer layer, and the thickness thereof may be selected from 2 um to 3 um.
  • the LED chip shown in FIG. 2 only includes three sub-pixel structures, that is, the LED chip only contains one pixel.
  • the LED chip may include a plurality of sub-pixel structures, and each of the plurality of sub-pixel structures is a pixel of the LED chip, and the structure of each pixel may be as shown in FIG. 2 .
  • Each pixel is a basic unit of the full color display of the LED chip.
  • the LED chip shown in FIG. 2 since each of the three sub-pixel structures includes a blue quantum well structure and a green quantum well structure, the LED chip can be divided by three sub-pixel structures respectively.
  • the other two sub-pixel structures outside the first sub-pixel structure enable the LED chip to emit blue and green light.
  • a red colloidal quantum dot structure can be coated on the corresponding region of the first sub-pixel structure, thereby absorbing red light and green light through the red colloidal quantum dot structure and then converting into red light, thereby realizing red light emission from the LED chip. Therefore, the full color display can be realized by using the LED chip shown in FIG. 2.
  • the red colloidal quantum dot structure since the red colloidal quantum dot structure has the characteristics of narrow line width and high photoluminescence efficiency, the red light colloidal quantum dot structure absorbs blue light and green light to realize the scheme of emitting red light by the full color display LED chip.
  • the red light quantum structure of the LED chip is used to realize the red light emission of the LED chip, and the luminous efficiency of the LED chip can be improved, thereby reducing the power consumption of the LED chip.
  • the embodiment of the present application further provides another LED chip.
  • the LED chip includes the following four parts:
  • the first sub-pixel structure on the first sub-pixel region of the three sub-pixel regions includes a sequentially grown blue quantum well structure or a green quantum well structure, a charge blocking layer, and a P-type GaN doped layer; three sub-pixel regions
  • the second sub-pixel structure on the second sub-pixel region includes a sequentially grown blue quantum well structure, a charge blocking layer, and a P-type GaN doped layer; and a third sub-pixel region in the three sub-pixel regions
  • the sub-pixel structure includes a green light quantum well structure, a charge blocking layer, and a P-type GaN doped layer which are sequentially grown.
  • Three P-type contact electrodes respectively formed over the three sub-pixel structures, and N-type contact electrodes formed on the first surface of the N-type GaN doped layer except for the three sub-pixel regions.
  • a red colloidal quantum dot structure formed on a second surface of the N-type GaN doped layer and corresponding to the first sub-pixel region.
  • the structure, material, illuminating principle, illuminating effect, and size setting of the red colloidal quantum dot structure can be referred to the related description in the LED chip shown in FIG. 2, and details are not described herein again.
  • the first sub-pixel structure may include any one of a blue quantum well structure and a green light quantum well structure. That is, the red colloidal quantum dot structure emits red light by absorbing the spectral energy of blue light, and also emits red light by absorbing the spectral energy of green light. In actual implementation, the red colloidal quantum dot structure absorbs the spectral energy of blue light and has high conversion efficiency. Therefore, when the first sub-pixel structure of the LED chip shown in FIG. 7 includes a blue quantum well structure, the LED chip emits light. higher efficiency.
  • the region corresponding to the first sub-pixel structure can emit red light.
  • the second sub-pixel structure of the three sub-pixel structures includes a blue quantum well structure
  • the display of the blue light can be realized by the second sub-pixel structure, wherein the third sub-pixel structure of the three sub-pixel structures includes the green quantum
  • the well structure allows the display of green light to be achieved by the third sub-pixel structure.
  • the filter may be placed in the corresponding light emitting area, that is, the LED chip shown in FIG. 7 may further include: a red filter placed over the red colloidal quantum dot structure; a blue filter placed on a second surface of the N-type GaN doped layer and corresponding to the second sub-pixel region; A green filter placed on a second surface of the GaN doped layer and on a region corresponding to the third sub-pixel region.
  • a red filter placed on the red colloidal quantum dot can filter out color light (such as blue light or green light) other than red light on the first sub-pixel area; blue placed on the corresponding area of the second sub-pixel area a color filter that filters out color light other than blue light (such as green light) on the second sub-pixel area; a green filter placed on a corresponding area of the third sub-pixel area can filter out the third sub-pixel area A color light other than green light (such as blue light).
  • color light such as blue light or green light
  • blue placed on the corresponding area of the second sub-pixel area a color filter that filters out color light other than blue light (such as green light) on the second sub-pixel area
  • a green filter placed on a corresponding area of the third sub-pixel area can filter out the third sub-pixel area A color light other than green light (such as blue light).
  • the structure of the LED chip can be as shown in FIG. In the LED chip shown in FIG. 8, the area above the red filter can emit red light, the area above the green filter can emit green light, and the area above the blue filter can emit blue light.
  • the charge blocking layer can reduce the charge leakage of the sub-pixel structure.
  • the charge blocking layer may be composed of Al 0.15 Ga 0.85 N and may have a thickness of 15 nm to 35 nm.
  • the N-type GaN doped layer may be a GaN layer doped with silicon, and may have a thickness of 2 um to 3 um; a P-type GaN doped layer in the first sub-pixel structure and a P-type GaN doped in the second sub-pixel structure;
  • the P-type GaN doped layer in the impurity layer and the third sub-pixel structure may each be a GaN layer doped with magnesium, and may have a thickness of 150 nm to 300 nm.
  • the blue quantum well structure in the second sub-pixel structure may include: N blue quantum well layers, and N blue quantum well layers for isolating N blue quantum well layers N+1 isolation layers formed alternately, N ⁇ 1.
  • the green quantum well structure in the third sub-pixel structure may include: M green quantum well layers, and M+1 alternating with the M green quantum well layers for isolating the M green quantum well layers. Isolation layer, M ⁇ 1.
  • the structure thereof may be the same as the blue quantum well structure in the second sub-pixel structure; if the first sub-pixel structure includes a green quantum well structure, the structure may be the same The green light quantum well structure in the three sub-pixel structure is the same.
  • the specific internal structure of the blue quantum well structure and the green quantum well structure is not different from the LED chip shown in FIG. 2.
  • a driving circuit connected to three P-type contact electrodes and N-type contact electrodes may be further included.
  • the driving circuit can control the luminous intensity of each sub-pixel structure by using PWM technology, so that the color brightness of blue light, green light and red light emitted by each sub-pixel structure in the LED chip is uniform.
  • the LED chip further includes: a second surface formed on the N-type GaN doped layer
  • the buffer layer and the substrate are adjacent to the N-type GaN doped layer, and the substrate is adjacent to the buffer layer and the red colloidal quantum dot structure.
  • the LED chip shown in FIG. 7 only includes three sub-pixel structures, that is, the LED chip only contains one pixel.
  • the LED chip may comprise a plurality of sub-pixel structures, and each of the plurality of sub-pixel structures is a pixel of the LED chip, and the structure of each pixel may be as shown in FIG. 7 .
  • Each pixel is a basic unit of the full color display of the LED chip.
  • the LED chip shown in FIG. 7 since the second sub-pixel structure of the three sub-pixel structures includes a blue quantum well structure, the LED chip can emit blue light through the second sub-pixel structure;
  • the third sub-pixel structure includes a green light quantum well structure, so that the LED chip emits green light through the third sub-pixel structure.
  • the red colloidal quantum dot structure may be coated on the corresponding region of the first sub-pixel structure including the blue quantum well structure or the green quantum well structure, thereby absorbing blue or green light through the red colloidal quantum dot structure and converting into red light. To achieve red light from the LED chip. Therefore, the full color display can be realized by using the LED chip provided in the above scheme.
  • the red colloidal quantum dot structure since the red colloidal quantum dot structure has the characteristics of narrow line width and high photoluminescence efficiency, the red light colloidal quantum dot structure absorbs blue light and green light to realize the scheme of emitting red light by the full color display LED chip.
  • the red light quantum structure of the LED chip is used to realize the red light emission of the LED chip, and the luminous efficiency of the LED chip can be improved, thereby reducing the power consumption of the LED chip.
  • each sub-pixel structure includes a blue quantum well structure and a green quantum well structure.
  • the red light can be emitted by absorbing blue and green light by the first sub-pixel structure corresponding to the red colloidal quantum dot; and for the other two sub-pixel structures, which sub-pixel structure emits blue light and which sub-pixel structure emits green light,
  • the color of the placed filter is determined. That is, the sub-pixel structure corresponding to the blue color filter is used for emitting blue light, and the sub-pixel structure corresponding to the green color filter is used for emitting green light.
  • each sub-pixel structure is different, and the first sub-pixel structure includes one of a blue quantum well structure or a green quantum well structure, and the second sub-pixel structure includes a blue quantum The well structure, the third sub-pixel structure comprises a green light quantum well structure.
  • the second sub-pixel structure including the blue quantum well structure can be used to emit blue light by absorbing blue or green light by the first sub-pixel structure corresponding to the red colloidal quantum dot, and for the other two sub-pixel structures, for emitting blue light, including
  • the third sub-pixel structure of the green light quantum well structure is used to emit green light.
  • the LED chip shown in FIG. 2 or the LED chip shown in FIG. 7 can be selectively used.
  • the material growth process of the LED chip does not have to consider which sub-pixel structure is used for the color of the light, that is, it is not necessary for different sub-pixels.
  • the structure is separately grown for materials, and the operation flow of the material growth process can be simplified. Therefore, if it is desired to simplify the LED chip fabrication process, the LED chip shown in FIG. 2 can be used.
  • the structure of the LED chip prepared in this manner is simpler than that of the LED chip shown in FIG. 2, and can be applied to simplify the structure of the LED chip. The requirements for higher scenarios.
  • the LED chip shown in FIG. 2 and the LED chip shown in FIG. 7 are two typical LED chips provided by the embodiments of the present application.
  • the preparation methods of the two typical LED chips provided by the embodiments of the present application are introduced through two embodiments.
  • the embodiment of the present application provides a method for preparing an LED chip, which is used to prepare the LED chip shown in FIG. 2 .
  • the method includes the following steps:
  • S1001 sequentially growing a buffer layer, an N-type GaN doped layer, a blue quantum well structure, an interface barrier layer, a green quantum well structure, a charge blocking layer, and a P-type GaN doped layer on the first surface of the substrate to form a first A sample.
  • MOCVD metal organic chemical vapor deposition
  • the substrate may be any one of a sapphire substrate, a Si substrate, a SiC substrate, or a GaN substrate.
  • the buffer layer may be a GaN buffer layer, and the thickness thereof may be selected from 2 um to 3 um.
  • the N-type GaN doped layer may be a GaN layer doped with silicon, and may have a thickness of 2 um to 3 um;
  • the P-type GaN doped layer may be a GaN layer doped with magnesium, and may have a thickness of 150 nm to 300 nm.
  • the charge blocking layer may reduce charge leakage of the sub-pixel structure.
  • the charge blocking layer may be composed of Al 0.15 Ga 0.85 N, and may have a thickness of 15 nm to 35 nm.
  • S1002 Transfer the mask pattern onto the P-type GaN doped layer to form a second sample.
  • the mask pattern includes a plurality of sub-pixel regions and other regions than the plurality of sub-pixel regions.
  • the first sample grown in S1001 can be divided into a plurality of sub-pixel regions and other regions by a mask pattern.
  • S1003 etching on the second sample according to the mask pattern, protecting the structures on the plurality of sub-pixel regions, and exposing other regions to the N-type GaN doped layer to form a third sample.
  • etching is performed on the second sample according to the mask pattern to protect the structure on the plurality of sub-pixel regions, and the other regions except the plurality of sub-pixel regions in the mask pattern are exposed to the N-type GaN doping.
  • the impurity layer can be realized by: passivating and protecting the side surface of the LED chip and a plurality of sub-pixel regions; using inductive coupled plasma (ICP) or reactive ion etching (RIE) The regions are etched such that other regions are exposed to the N-type GaN doped layer.
  • S1004 forming a plurality of P-type contact electrodes on the plurality of sub-pixel regions in the third sample, and forming N-type contact electrodes on the other regions to form a fourth sample.
  • a plurality of P-type contact electrodes are respectively formed on a plurality of sub-pixel regions, and an N-type contact electrode is formed on other regions, which can be realized by depositing a nickel-gold alloy by electron beam evaporation, 200 ° C ⁇ After annealing at 500 ° C, a plurality of P-type contact electrodes are respectively formed on the plurality of sub-pixel regions; and indium tin oxide (ITO) or graphite is sputtered on other regions to form an N-type contact electrode.
  • ITO indium tin oxide
  • the plurality of sub-pixel structures share one N-type contact electrode, and the N-type contact electrode may also be referred to as a common cathode.
  • the structure of the formed fourth sample can be as shown in FIG. It should be noted that only the LED chip including three sub-pixel structures is shown in FIG.
  • the fourth sample obtained after executing S1004 may include a plurality of sub-pixel structures, and each of the three sub-pixel structures of the plurality of sub-pixel structures may serve as one pixel point for realizing full color display.
  • each convex cylindrical structure represents a sub-pixel structure, and each sub-pixel structure includes a p-contact (i.e., a P-type contact electrode).
  • the planar region other than the bumps in Fig. 12 can be regarded as other regions than the sub-pixel regions on which the N-type contact electrodes are formed.
  • S1005 coating at least one red colloidal quantum dot structure on a second surface of the substrate and corresponding to at least one first sub-pixel region for emitting red light in the plurality of sub-pixel regions to form an LED chip.
  • the LED chip fabricated by the method shown in FIG. 10 can be as shown in FIG. It should be noted that the LED chip shown in FIG. 13 includes only three sub-pixel structures. In actual implementation, the LED chip prepared by the method shown in FIG. 10 may include a plurality of sub-pixel structures, wherein each of the three sub-pixel structures may constitute one pixel, and each pixel point serves as a basic unit of the full color display of the LED chip.
  • the method shown in FIG. 10 may further include: respectively placing at least one red filter on at least one red colloid quantum dot structure; on the second side of the substrate and in the plurality of sub-pixel regions Having at least one blue color filter respectively on a region corresponding to at least one second sub-pixel region emitting blue light; at least one portion for emitting green light on the second surface of the substrate and in the plurality of sub-pixel regions At least one green filter is placed on each of the areas corresponding to the three sub-pixel regions.
  • the method shown in FIG. 10 may further include: aligning the plurality of P-type contact electrodes and the N-type contact electrodes with the driving circuit by metal solder balls.
  • the luminous intensity of each sub-pixel structure can be controlled such that the color brightness of blue, green and red light emitted by each sub-pixel structure in the LED chip is uniform.
  • the substrate and the buffer layer may be cleaved with the LED chip by laser irradiation before coating at least one red colloidal quantum dot structure, respectively.
  • the operation of coating at least one red colloidal quantum dot structure in S1005 can be realized by: on the side adjacent to the buffer layer in the N-type GaN doped layer, and with at least one first sub-pixel region At least one red colloidal quantum dot structure is coated on the corresponding regions.
  • the substrate and the buffer layer can be cleaved, thereby simplifying the structure of the LED chip.
  • one possible structure of the LED chip prepared in the manner shown in FIG. 10 can be as shown in FIG.
  • the LED chip shown in FIG. 14 can be regarded as a specific example of the LED chip shown in FIG. 2.
  • the method shown in FIG. 10 can be used to prepare the LED chip shown in FIG. 2.
  • the implementation method not described in detail in the method shown in FIG. 10 can be referred to the related description in the LED chip shown in FIG. 2.
  • the embodiment of the present application provides a method for preparing an LED chip, which can be used to prepare the LED chip shown in FIG. 7. Referring to Figure 15, the method includes the following steps:
  • S1501 sequentially growing a buffer layer and an N-type GaN doped layer on the first surface of the substrate.
  • the substrate may be any one of a sapphire substrate, a Si substrate, a SiC substrate, or a GaN substrate.
  • the buffer layer may be a GaN buffer layer, and the thickness thereof may be selected from 2 um to 3 um.
  • the N-type GaN doped layer may be a GaN layer doped with silicon, and may have a thickness of 2 um to 3 um.
  • S1502 sequentially growing a blue quantum well structure, a charge blocking layer, and a P-type GaN doped layer on the blue quantum well growth region in the N-type GaN doped layer; and, in addition to the blue quantum well growth in the N-type GaN doped layer A green light quantum well structure, a charge blocking layer, and a P-type GaN doped layer are sequentially grown on the green light quantum well growth region outside the region to form a first sample.
  • the N-type GaN doped layer is divided into a blue quantum well growth region and a green quantum well growth region during material growth, and different structures are grown on different quantum well growth regions.
  • the material growth process in S1502 can be achieved by: forming a first mask on the N-type GaN doped layer, the first mask for protecting the green quantum well growth region; and sequentially on the blue quantum well growth region Growing a blue light quantum well structure, a charge blocking layer, and a P-type GaN doped layer; removing the first mask; forming a second mask on the blue quantum well growth region, the second mask for protecting the blue quantum well growth region; A green quantum well structure, a charge blocking layer, and a P-type GaN doped layer are sequentially grown on the green quantum well growth region.
  • the mask pattern includes a plurality of sub-pixel regions and other regions than the plurality of sub-pixel regions, the plurality of sub-pixel regions including at least one first sub-pixel region for emitting red light, and at least one for emitting blue light a second sub-pixel region and at least one third sub-pixel region for emitting green light; at least one first sub-pixel region is aligned with the blue quantum well growth region or the green quantum well growth region, and at least one second sub-pixel region is aligned with the blue light In the quantum well growth region, at least one third sub-pixel region is aligned with the green quantum well growth region.
  • the first sample grown in S1502 can be divided into a plurality of sub-pixel regions and other regions by a mask pattern.
  • S1504 etching on the second sample according to the mask pattern, protecting the structures on the plurality of sub-pixel regions, and exposing other regions to the N-type GaN doped layer to form a third sample.
  • the structure is a structure grown on a blue quantum well growth region, that is, a blue quantum well structure, a charge blocking layer, and a P-type GaN doped layer. With this structure, the LED chip can emit blue light.
  • the corresponding structure on the etched at least one third sub-pixel region is grown on the green quantum well growth region.
  • the structure is a green quantum well structure, a charge blocking layer, and a P-type GaN doped layer. With this structure, the LED chip can be made to emit green light.
  • At least one first sub-pixel region is aligned with the blue quantum well growth region or the green quantum well growth region, and thus the corresponding structure on the first sub-pixel region after etching can be implemented by applying a red colloidal quantum dot to the LED chip. Red light.
  • etching is performed on the second sample according to the mask pattern to protect the structures on the plurality of sub-pixel regions, and the other regions except the plurality of sub-pixel regions in the mask pattern are exposed to the N-type GaN doping.
  • the impurity layer can be realized by: passivating and protecting a side surface of the LED chip and a plurality of sub-pixel regions; and etching other regions by ICP or RIE so that other regions are exposed to the N-type GaN doped layer.
  • S1505 forming a plurality of P-type contact electrodes on the plurality of sub-pixel regions in the third sample, and forming N-type contact electrodes on the other regions to form a fourth sample.
  • a plurality of P-type contact electrodes are respectively formed on a plurality of sub-pixel regions, and an N-type contact electrode is formed on other regions, which can be realized by depositing a nickel-gold alloy by electron beam evaporation, 200 ° C ⁇
  • a plurality of P-type contact electrodes are respectively formed on the plurality of sub-pixel regions; and indium tin oxide (ITO) or graphite is sputtered on other regions to form an N-type contact electrode.
  • ITO indium tin oxide
  • the plurality of sub-pixel structures share one N-type contact electrode, and the N-type contact electrode may also be referred to as a common cathode.
  • the structure of a fourth sample formed can be as shown in FIG. It should be noted that only the LED chip including three sub-pixel structures is shown in FIG.
  • the fourth sample obtained after executing S1505 may include a plurality of sub-pixel structures, and each of the three sub-pixel structures of the plurality of sub-pixel structures may serve as one pixel point for realizing full color display.
  • At least one first sub-pixel region is aligned with the blue quantum well growth region.
  • S1506 coating at least one red colloidal quantum dot structure on a second surface of the substrate and corresponding to the at least one first sub-pixel region to form an LED chip.
  • the LED chip shown in Fig. 17 can be obtained. It should be noted that the LED chip shown in FIG. 17 includes only three sub-pixel structures. In actual implementation, the LED chip prepared by the method shown in FIG. 15 may include a plurality of sub-pixel structures, wherein each of the three sub-pixel structures may constitute one pixel, and each pixel point serves as a basic unit of the full color display of the LED chip.
  • the method shown in FIG. 15 may further include: respectively placing at least one red filter on the at least one red colloidal quantum dot structure; on the second side of the substrate, and the at least one second sub-pixel At least one blue color filter is respectively disposed on the corresponding region of the region; at least one green color filter is respectively disposed on the second surface of the substrate and the region corresponding to the at least one third sub-pixel region.
  • the method shown in FIG. 15 may further include: aligning the plurality of P-type contact electrodes and the N-type contact electrodes with the driving circuit by metal solder balls.
  • the luminous intensity of each sub-pixel structure can be controlled such that the color brightness of blue, green and red light emitted by each sub-pixel structure in the LED chip is uniform.
  • the substrate and the buffer layer may be cleaved with the LED chip by laser irradiation before coating at least one red colloidal quantum dot structure, respectively.
  • the operation of coating at least one red colloidal quantum dot structure in S1506 can be realized by: on the side adjacent to the buffer layer in the N-type GaN doped layer, and with at least one first sub-pixel region. At least one red colloidal quantum dot structure is coated on the corresponding regions.
  • the substrate and the buffer layer can be cleaved, thereby simplifying the structure of the LED chip.
  • FIG. 15 After placing a three-color filter, connecting the driving circuit, and cleaving the substrate and the buffer layer, one possible structure of the LED chip prepared in the manner shown in FIG. 15 can be as shown in FIG.
  • the LED chip shown in Fig. 18 can be regarded as a specific example of the LED chip shown in Fig. 7.
  • the second embodiment and the first embodiment differ only in the material growth process (ie, S1001 in FIG. 10 and S1501 to S1502 in FIG. 15), and other preparation steps are similar or The same steps. It is because of the difference in material growth steps that the structure of the finally prepared LED chip is different.
  • the method shown in FIG. 15 can be used to prepare the LED chip shown in FIG. 7.
  • the implementation manner not described in detail in the method shown in FIG. 15 can be referred to the related description in the LED chip shown in FIG.
  • the embodiment of the present application provides an LED chip and a method for fabricating the same, and the full color display of the LED chip can be realized by using the solution provided by the embodiment of the present application.

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Abstract

一种发光二极管芯片及其制备方法，用以实现全彩显示。芯片包括：N型GaN掺杂层；分别在N型GaN掺杂层的第一面的三个子像素区域上形成的三个子像素结构，三个子像素结构中的每个子像素结构中均依次包含蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层和P型GaN掺杂层；在三个子像素结构之上分别形成的三个P型接触电极，以及在N型GaN掺杂层的第一面上除三个子像素区域之外的其他区域上形成的N型接触电极；在N型GaN掺杂层的第二面上、与三个子像素区域中的第一子像素区域对应的区域上形成的红光胶体量子点结构。

Description

一种发光二极管芯片及其制备方法
本申请要求于2018年02月28日提交中国专利局、申请号为201810168757.X、发明名称为“一种发光二极管芯片及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及半导体技术领域，尤其涉及一种发光二级管芯片及其制备方法。
背景技术
氮化镓(GaN)基发光二极管(light emitting diode，LED)作为一种光电子器件，因其使用寿命长、稳定性好、能耗低等优点在众多显示领域应用广泛，比如微投影显示、头戴式显示、增强现实(augmented reality，AR)、虚拟现实(virtual reality，VR)以及可穿戴显示等显示领域。
目前，GaN基LED芯片的尺寸可以控制在微米量级，若将微米量级的GaN基LED芯片作为显示的像素，可以实现高分辨率、低能耗、轻薄的显示系统。
随着显示技术的发展，对于显示器像素的分辨率、色彩等提出了新的诉求，如何通过GaN基LED芯片实现全彩显示成为亟需解决的问题。
发明内容
本申请实施例提供一种LED芯片及其制备方法，用以实现全彩显示。
第一方面，本申请实施例提供一种发光二极管LED芯片，该LED芯片包括：
N型氮化镓GaN掺杂层；
分别在N型GaN掺杂层的第一面的三个子像素区域上形成的三个子像素结构，三个子像素结构中的每个子像素结构中均包含依次生长的蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层；
在三个子像素结构之上分别形成的三个P型接触电极，以及在N型GaN掺杂层的第一面上除三个子像素区域之外的其他区域上形成的N型接触电极；
在N型GaN掺杂层的第二面上、且与三个子像素区域中的第一子像素区域对应的区域上形成的红光胶体量子点结构。
采用上述方案，由于三个子像素结构中的每个子像素结构中均包含蓝光量子阱结构和绿光量子阱结构，因而LED芯片可分别通过三个子像素结构中除第一子像素结构之外的另外两个子像素结构实现LED芯片发出蓝光和绿光。同时，可在包含蓝光量子阱结构和绿光量子阱结构的第一子像素结构对应区域上涂覆红光胶体量子点结构，从而通过红光胶体量子点结构吸收蓝光和绿光后转换为红光，实现LED芯片发出红光。因此，采用第一方面提供的LED芯片可以实现全彩显示。
在第一方面提供的LED芯片中，N型GaN掺杂层可以为掺杂有硅元素的GaN层，P型GaN掺杂层可以为掺杂有镁元素的GaN层。
对于微显示芯片，像素形状可以为圆形或方形。因此，上述三个子像素区域可以均为 圆形区域，也可以均为方形区域。此外，子像素区域的尺寸可依据LED芯片的不同需求设置，本申请实施例中对此不做具体限定。示例性地，圆形区域的直径可以为5um～50um。
在一种可能的设计中，蓝光量子阱结构包括：N个蓝光量子阱层，以及用于隔离N个蓝光量子阱层的、与N个蓝光量子阱层交替形成的N+1个隔离层，N≥1。
也就是说，蓝光量子阱结构是通过交替生长隔离层和蓝光量子阱层形成的。通常，蓝光量子阱结构可通过3～5个周期的材料生长过程形成。例如，蓝光量子阱结构可以包两个蓝光量子阱层以及与两个蓝光量子阱层交替形成的三个隔离层。
其中，蓝光量子阱层可以为掺杂有铟元素的GaN层。
在一种可能的设计中，绿光量子阱结构包括：M个绿光量子阱层，以及用于隔离M个绿光量子阱层的、与M个绿光量子阱层交替形成的M+1个隔离层，M≥1。
也就是说，绿光量子阱结构是通过交替生长隔离层和绿光量子阱层形成的。通常，绿光量子阱结构可通过3～5个周期的材料生长过程形成。例如，绿光量子阱结构可以包两个绿光量子阱层以及与两个绿光量子阱层交替形成的三个隔离层。
其中，绿光量子阱层可以为掺杂有铟元素的GaN层；绿光量子阱层掺杂铟元素的比例与蓝光量子阱层掺杂铟元素的比例不同。
为了更好地实现LED芯片三种色光(即红光、蓝光和绿光)的显示、提高色纯度，该LED芯片还可以包括：在红光胶体量子点结构之上放置的红色滤光片；在N型GaN掺杂层的第二面上、且与三个子像素区域中的第二子像素区域对应的区域上放置的蓝色滤光片；在N型GaN掺杂层的第二面上、且与三个子像素区域中的第三子像素区域对应的区域上放置的绿色滤光片。
采用上述方案，在红光胶体量子点上放置的红色滤光片，可以滤除第一子像素区域上除红光以外的色光(比如蓝光和绿光)；在第二子像素区域对应的区域上放置的蓝色滤光片，可以滤除第二子像素区域上除蓝光以外的色光(比如绿光)；在第三子像素区域对应的区域上放置的绿色滤光片，可以滤除第三子像素区域上除绿光以外的色光(比如蓝光)。
在一种可能的设计中，该LED芯片还包括：与三个P型接触电极和N型接触电极连接的驱动电路。
其中，驱动电路可采用脉冲宽度调制技术控制每个子像素结构的发光强度，使得LED芯片中每个子像素结构所发出的蓝光、绿光和红光的色亮度均一。
在制备第一方面提供的LED芯片时，需要在衬底和缓冲层上进行材料生长。而在材料生长完成以后，由于衬底和缓冲层的功能已完成，因此可以将衬底和缓冲层解理。当然，由于衬底和缓冲层对LED芯片的发光显示不会产生影响，因此也可以不对衬底和缓冲层进行解理。
若不对衬底和缓冲层进行解理，在一种可能的设计中，该LED芯片还包括：形成于N型GaN掺杂层的第二面上的缓冲层和衬底，缓冲层与N型GaN掺杂层邻接，衬底与缓冲层和红光胶体量子点结构邻接。
第二方面，本申请实施例提供一种LED芯片的制备方法，该方法包括如下步骤：
在衬底的第一面上依次生长缓冲层、N型GaN掺杂层、蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层，以形成第一样品；
将掩膜图形转移到P型GaN掺杂层上，以形成第二样品；其中，该掩膜图形上包含多个子像素区域以及除多个子像素区域之外的其他区域；
根据该掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得其他区域露出至N型GaN掺杂层，以形成第三样品；
在第三样品中的多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，以形成第四样品；
在衬底的第二面上、且与多个子像素区域中用于发红光的至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，以形成LED芯片。
在一种可能的设计中，该方法还包括：在至少一个红光胶体量子点结构上分别放置至少一个红色滤光片；在衬底的第二面上、且与多个子像素区域中用于发蓝光的至少一个第二子像素区域对应的区域上分别放置至少一个蓝色滤光片；在衬底的第二面上、且与多个子像素区域中用于发绿光的至少一个第三子像素区域对应的区域上分别放置至少一个绿色滤光片。
在一种可能的设计中，该方法还包括：将多个P型接触电极和N型接触电极通过金属焊球与驱动电路对位连接。
在一种可能的设计中，在分别涂覆至少一个红光胶体量子点结构之前，还可采用激光辐照方式将衬底和缓冲层，与LED芯片解理；那么此时，在衬底的第二面上、且与多个子像素区域中用于发红光的至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，具体可通过如下方式实现：在N型GaN掺杂层中与缓冲层邻接的一面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构。
在一种可能的设计中，根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得掩膜图形中除多个子像素区域之外的其他区域露出至N型GaN掺杂层，具体可通过如下方式实现：钝化保护LED芯片的侧面以及多个子像素区域；采用电感耦合等离子体ICP或反应离子刻蚀RIE对其他区域进行刻蚀，使得其他区域露出至N型GaN掺杂层。
在一种可能的设计中，在多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，具体可通过如下方式实现：采用电子束蒸发沉积镍金合金，200℃～500℃退火后在多个子像素区域上分别形成多个P型接触电极；并在其他区域上溅射氧化铟锡ITO或石墨，以形成N型接触电极。
第三方面，本申请实施例提供一种发光二极管LED芯片，该LED芯片包括：
N型氮化镓GaN掺杂层；
分别在N型GaN掺杂层的第一面的三个子像素区域上形成的三个子像素结构，三个子像素区域中的第一子像素区域上的第一子像素结构中包含依次生长的蓝光量子阱结构或绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层；三个子像素区域中的第二子像素区域上的第二子像素结构中包含依次生长的蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；三个子像素区域中的第三子像素区域上的第三子像素结构中包含依次生长的绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层；
在三个子像素结构之上分别形成的三个P型接触电极，以及在N型GaN掺杂层的第一面上除三个子像素区域之外的其他区域上形成的N型接触电极；
在N型GaN掺杂层的第二面上、且与第一子像素区域对应的区域上形成的红光胶体量子点结构。
采用上述方案，由于三个子像素结构中的第二子像素结构包含蓝光量子阱结构，因而 可通过第二子像素结构实现LED芯片发出蓝光；三个子像素结构中的第三子像素结构包含绿光量子阱结构，因而可通过第三子像素结构实现LED芯片发出绿光。同时，可在包含蓝光量子阱结构或绿光量子阱结构的第一子像素结构对应区域上涂覆红光胶体量子点结构，从而通过红光胶体量子点结构吸收蓝光或绿光后转换为红光，实现LED芯片发出红光。因此，采用第三方面提供的LED芯片可以实现全彩显示。
在第三方面提供的LED芯片中，N型GaN掺杂层可以为掺杂有硅元素的GaN层，第一子像素结构中的P型GaN掺杂层、第二子像素结构中的P型GaN掺杂层和第三子像素结构中的P型GaN掺杂层均可以为掺杂有镁元素的GaN层。
对于微显示芯片，像素形状可以为圆形或方形。因此，上述三个子像素区域可以均为圆形区域，也可以均为方形区域。此外，子像素区域的尺寸可依据LED芯片的不同需求设置，本申请实施例中对此不做具体限定。示例性地，圆形区域的直径可以为5um～50um。
在一种可能的设计中，第二子像素结构中的蓝光量子阱结构包括：N个蓝光量子阱层，以及用于隔离N个蓝光量子阱层的、与N个蓝光量子阱层交替形成的N+1个隔离层，N≥1。
也就是说，第二子像素结构中的蓝光量子阱结构是通过交替生长隔离层和蓝光量子阱层形成的。通常，第二子像素结构中的蓝光量子阱结构可通过3～5个周期的材料生长过程形成。例如，第二子像素结构中的蓝光量子阱结构可以包两个蓝光量子阱层以及与两个蓝光量子阱层交替形成的三个隔离层。
其中，第二子像素结构中的蓝光量子阱层可以为掺杂有铟元素的GaN层。
此外，若第一子像素结构中包含蓝光量子阱结构，第一子像素结构中的蓝光量子阱结构可以与第二子像素结构中的蓝光量子阱结构的结构相同。
在一种可能的设计中，第三子像素结构中的绿光量子阱结构包括：M个绿光量子阱层，以及用于隔离M个绿光量子阱层的、与M个绿光量子阱层交替形成的M+1个隔离层，M≥1。
也就是说，第三子像素结构中的绿光量子阱结构是通过交替生长隔离层和绿光量子阱层形成的。通常，第三子像素结构中的绿光量子阱结构可通过3～5个周期的材料生长过程形成。例如，第三子像素结构中的绿光量子阱结构可以包两个绿光量子阱层以及与两个绿光量子阱层交替形成的三个隔离层。
其中，第三子像素结构中的绿光量子阱层可以为掺杂有铟元素的GaN层；第三子像素结构中的绿光量子阱层掺杂铟元素的比例与第二子像素结构中的蓝光量子阱层掺杂铟元素的比例不同。
此外，若第一子像素结构中包含绿光量子阱结构，第一子像素结构中的绿光量子阱结构可以与第三子像素结构中的绿光量子阱结构的结构相同。
为了更好地实现LED芯片三种色光(即红光、蓝光和绿光)的显示、提高色纯度，该LED芯片还可以包括：在红光胶体量子点结构之上放置的红色滤光片；在N型GaN掺杂层的第二面上、且与第二子像素区域对应的区域上放置的蓝色滤光片；在N型GaN掺杂层的第二面上、且与第三子像素区域对应的区域上放置的绿色滤光片。
采用上述方案，在红光胶体量子点上放置的红色滤光片，可以滤除第一子像素区域上除红光以外的色光(比如蓝光和绿光)；在第二子像素区域对应的区域上放置的蓝色滤光片，可以滤除第二子像素区域上除蓝光以外的色光(比如绿光)；在第三子像素区域对应 的区域上放置的绿色滤光片，可以滤除第三子像素区域上除绿光以外的色光(比如蓝光)。
在一种可能的设计中，该LED芯片还包括：与三个P型接触电极和N型接触电极连接的驱动电路。
其中，驱动电路可采用脉冲宽度调制技术控制每个子像素结构的发光强度，使得LED芯片中每个子像素结构所发出的蓝光、绿光和红光的色亮度均一。
在制备第三方面提供的LED芯片时，需要在衬底和缓冲层上进行材料生长。而在材料生长完成以后，由于衬底和缓冲层的功能已完成，因此可以将衬底和缓冲层解理。当然，由于衬底和缓冲层对LED芯片的发光显示不会产生影响，因此也可以不对衬底和缓冲层进行解理。
若不对衬底和缓冲层进行解理，在一种可能的设计中，该LED芯片还包括：形成于N型GaN掺杂层的第二面上的缓冲层和衬底，缓冲层与N型GaN掺杂层邻接，衬底与缓冲层和红光胶体量子点结构邻接。
第四方面，本申请实施例提供一种发光二极管LED芯片的制备方法，该方法包括如下步骤：
在衬底的第一面上依次生长缓冲层、N型GaN掺杂层；
在N型GaN掺杂层中的蓝光量子阱生长区域上依次生长蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；并，在N型GaN掺杂层中除蓝光量子阱生长区域之外的绿光量子阱生长区域上依次生长绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层，以形成第一样品；
将掩膜图形转移到P型GaN掺杂层上，以形成第二样品；
其中，掩膜图形上包含多个子像素区域以及除多个子像素区域之外的其他区域，多个子像素区域包含用于发红光的至少一个第一子像素区域、用于发蓝光的至少一个第二子像素区域以及用于发绿光的至少一个第三子像素区域；至少一个第一子像素区域对准蓝光量子阱生长区域或者绿光量子阱生长区域，至少一个第二子像素区域对准蓝光量子阱生长区域，至少一个第三子像素区域对准绿光量子阱生长区域；
根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得其他区域露出至N型GaN掺杂层，以形成第三样品；
在第三样品中的多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，以形成第四样品；
在衬底的第二面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，以形成LED芯片。
在一种可能的设计中，在N型GaN掺杂层中的蓝光量子阱生长区域上依次生长蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；并，在N型GaN掺杂层中除蓝光量子阱生长区域之外的绿光量子阱生长区域上依次生长绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层，具体可通过如下方式实现：在N型GaN掺杂层上制作第一掩膜，第一掩膜用于保护绿光量子阱生长区域；在蓝光量子阱生长区域上依次生长蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；去除第一掩膜；在蓝光量子阱生长区域上制作第二掩膜，第二掩膜用于保护蓝光量子阱生长区域；在绿光量子阱生长区域上依次生长绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层。
在一种可能的设计中，该方法还包括：在至少一个红光胶体量子点结构上分别放置至 少一个红色滤光片；在衬底的第二面上、且与至少一个第二子像素区域对应的区域上分别放置至少一个蓝色滤光片；在衬底的第二面上、且与至少一个第三子像素区域对应的区域上分别放置至少一个绿色滤光片。
在一种可能的设计中，该方法还包括：将多个P型接触电极和N型接触电极通过金属焊球与驱动电路对位连接。
在一种可能的设计中，在分别涂覆至少一个红光胶体量子点结构之前，还可以采用激光辐照方式将衬底和缓冲层，与LED芯片解理；那么此时，在衬底的第二面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，可通过如下方式实现：在N型GaN掺杂层中与缓冲层邻接的一面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构。
在一种可能的设计中，根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得掩膜图形中除多个子像素区域之外的其他区域露出至N型GaN掺杂层，具体可通过如下方式实现：钝化保护LED芯片的侧面以及多个子像素区域；采用电感耦合等离子体ICP或反应离子刻蚀RIE对其他区域进行刻蚀，使得其他区域露出至N型GaN掺杂层。
在一种可能的设计中，在多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，具体可通过如下方式实现：采用电子束蒸发沉积镍金合金，200℃～500℃退火后在多个子像素区域上分别形成多个P型接触电极；并，在其他区域上溅射氧化铟锡ITO或石墨，以形成N型接触电极。
另外，需要说明的是，第二方面中任一种可能设计方式所带来的技术效果可参见第一方面中不同设计方式所带来的技术效果，第四方面中任一种可能设计方式所带来的技术效果可参见第三方面中不同设计方式所带来的技术效果，此处不再赘述。
附图说明
图1为本申请实施例提供的第一种GaN基LED芯片的结构示意图；
图2为本申请实施例提供的第二种GaN基LED芯片的结构示意图；
图3为本申请实施例提供的第三种GaN基LED芯片的结构示意图；
图4为本申请实施例提供的一种N型GaN掺杂层的第一面上的区域划分的示意图；
图5为本申请实施例提供的第四种GaN基LED芯片的结构示意图；
图6为本申请实施例提供的第五种GaN基LED芯片的结构示意图；
图7为本申请实施例提供的第六种GaN基LED芯片的结构示意图；
图8为本申请实施例提供的第七种GaN基LED芯片的结构示意图；
图9为本申请实施例提供的第八种GaN基LED芯片的结构示意图；
图10为本申请实施例提供的一种LED芯片的制备方法的流程图；
图11为本申请实施例提供的一种第四样品的结构示意图；
图12为本申请实施例提供的一种第四样品的SEM图像；
图13为本申请实施例提供的第九种GaN基LED芯片的结构示意图；
图14为本申请实施例提供的第十种GaN基LED芯片的结构示意图；
图15为本申请实施例提供的另一种LED芯片的制备方法的流程图；
图16为本申请实施例提供的另一种第四样品的结构示意图；
图17为本申请实施例提供的第十一种GaN基LED芯片的结构示意图；
图18为本申请实施例提供的第十二种GaN基LED芯片的结构示意图。
具体实施方式
通常，在制备全彩显示的GaN基LED时，采用如下方法：在衬底上依次生长缓冲层、N型掺杂层，然后在N型掺杂层的每个子像素区域上生长子像素结构，每个子像素结构依次包含三色量子阱结构(即蓝光量子阱结构、绿光量子阱结构、红光量子阱结构)、电荷阻挡层以及P型掺杂层。然后，制备N型接触电极和P型接触电极。
采用上述方法制备的LED芯片的结构可以如图1所示。需要说明的是，图1所示的LED芯片中仅示出了三个子像素区域上生长的三个子像素结构，这三个子像素结构分别用于发出蓝光、绿光和红光。实际实现时，LED芯片可以包含多个子像素结构，每个子像素结构均可以作为全彩显示LED芯片的一个子像素点，多个子像素结构中每三个子像素结构可以作为全彩显示LED芯片的一个像素点。
下面，对图1所示的LED芯片实现全彩显示的原理进行介绍。
首先，通过改变量子阱结构中掺杂铟(In)元素的比例来控制该量子阱结构的发光波长，从而实现蓝、绿、红三种色彩的显示。示例性地，通过控制蓝光量子阱结构中掺杂In元素的比例，使得蓝光量子阱结构的发光波长为450nm～480nm时，蓝光量子阱结构可发出蓝光；通过控制绿光量子阱结构中掺杂In元素的比例，使得绿光量子阱结构的发光波长为500nm～550nm时，绿光量子阱结构可发出绿光；通过控制红光量子阱结构中掺杂In元素的比例，使得红光量子阱结构的发光波长为620nm～700nm时，红光量子阱结构可发出红光。
然后，通过在LED芯片上覆盖不同颜色的滤光片，从而实现通过每个子像素结构发出不同颜色的光。例如，在左侧的子像素结构对应的区域上覆盖蓝色滤光片，由于蓝色滤光片可以滤掉蓝光以外的其他色光，因而蓝色滤光片之上的区域可以发出蓝光；在中间的子像素结构对应的区域上覆盖绿色滤光片，由于绿色滤光片可以滤掉绿光以外的其他色光，因而绿色滤光片之上的区域可以发出绿光；在右侧的子像素结构对应的区域上覆盖红色滤光片，由于红色滤光片可以滤掉红光以外的其他色光，因而红色滤光片之上的区域可以发出红光。
在图1所示的LED芯片中，红光量子阱结构需要高浓度掺杂In元素。而掺杂In元素过多会导致红光量子阱结构的缺陷和错位，使得最终得到的红光量子阱结构的发光效率低、功耗大。
为了使本申请实施例的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
本申请实施例提供一种LED芯片及其制备方法，用以实现全彩显示的同时，提高发光效率、降低功耗。
需要说明的是，本申请实施例中所涉及的多个，是指两个或两个以上。另外，需要理解的是，在本申请实施例的描述中，“第一”、“第二”等词汇，仅用于区分描述的目的，而不能理解为指示或暗示相对重要性，也不能理解为指示或暗示顺序。
下面结合附图对本申请实施例提供的方案进行具体说明。
参见图2，为本申请实施例提供的LED芯片的结构示意图。该LED芯片包括如下四个部分：
一、N型氮化镓(GaN)掺杂层。
二、分别在N型GaN掺杂层的第一面的三个子像素区域上形成的三个子像素结构。
其中，三个子像素结构中的每个子像素结构中均包含依次生长的蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层。
三、在三个子像素结构之上分别形成的三个P型接触电极，以及在N型GaN掺杂层的第一面上除三个子像素区域之外的其他区域上形成的N型接触电极。
四、在N型GaN掺杂层的第二面上、且与三个子像素区域中的第一子像素区域对应的区域上形成的红光胶体量子点结构。
本申请实施例中，胶体量子点是通过化学合成的具有准零维结构的无机纳米材料。胶体量子点结构可以实现光谱能量的吸收和转换：胶体量子点结构在吸收光谱能量时，可以吸收各种短波长色光的光谱能量；在转换光谱能量时，通过控制胶体量子点结构的尺寸，可以控制胶体量子点的发光波长，从而实现胶体量子点发出不同颜色的光。
红光胶体量子点结构可以吸收蓝光量子阱结构发出的蓝光，和/或，绿光量子阱结构发出的绿光。通过控制红光胶体量子点结构的尺寸，可以使得红光胶体量子点结构的发光波长为红光的发光波长(例如可以是为620nm～700nm)，那么，红光胶体量子点结构即可发出红光。
具体实现时，红光胶体量子点结构中可以包含多个胶体量子点，每个胶体量子点由核、壳和配体三部分组成。核的材料可以为CdSe、CdTe、InP、ZnS、GaAs、HgTe、HgSe、InGaP、PbS、PbSe、PbTe、InSe、CuInGaS2、GuIn、GaSe2等；壳的材料可以为CdS、ZnS、ZnSe；配体的材料可以为硅氧烷、油酸等。此外，为了提高红光胶体量子点结构的阻隔水氧能力并防止胶体量子点被玷污，本申请实施例中，还可以用环氧树脂对红光胶体量子点进行封装。
本申请实施例中，通过红光胶体量子点结构吸收蓝光和/或绿光的方式来发出红光，因而LED芯片中无需设置红光量子阱结构，也就不存在现有的GaN基LED芯片中存在的、掺杂高浓度In元素而导致的红光量子阱结构缺陷和错位的问题。此外，由于胶体量子点的发射光谱具有线宽窄、光致荧光效率高等特点，因而在全彩显示LED芯片中，采用红光胶体量子点结构吸收蓝光和/或绿光的方式来实现红光，可以提高LED芯片的发光效率，从而降低LED芯片的功耗。
图2所示的LED芯片中，通过设置的红光胶体量子点，第一子像素结构对应的区域可以发出红光。此外，由于三个子像素结构中除第一子像素结构之外的另外两个子像素结构中也包含蓝光量子阱结构和绿光量子阱结构，因而可分别通过另外两个子像素结构实现蓝光和绿光的显示。
为了更好地实现LED芯片三种色光(即红光、蓝光和绿光)的显示、提高色纯度，可以在相应发光区域放置滤光片，即图2所示的LED芯片还可以包括：在红光胶体量子点结构之上放置的红色滤光片；在N型GaN掺杂层的第二面上、且与三个子像素区域中的第二子像素区域对应的区域上放置的蓝色滤光片；在N型GaN掺杂层的第二面上、且与三个子像素区域中的第三子像素区域对应的区域上放置的绿色滤光片。
其中，第二子像素区域可用于发出蓝光，第三子像素区域可用于发出绿光。在红光胶 体量子点上放置的红色滤光片，可以滤除第一子像素区域上除红光以外的色光(比如蓝光和绿光)；在第二子像素区域对应的区域上放置的蓝色滤光片，可以滤除第二子像素区域上除蓝光以外的色光(比如绿光)；在第三子像素区域对应的区域上放置的绿色滤光片，可以滤除第三子像素区域上除绿光以外的色光(比如蓝光)。
放置红色滤光片、蓝色滤光片和绿色滤光片后，该LED芯片的结构可以如图3所示。在图3所示的LED芯片中，红色滤光片之上的区域可以发出红光，绿色滤光片之上的区域可以发出绿光，蓝色滤光片之上的区域可以发出蓝光。
在图2所示的LED芯片中，电荷阻挡层可以减小子像素结构的电荷泄露。示例性地，电荷阻挡层可以由Al 0.15Ga 0.85N组成，其厚度可以是15nm～35nm。N型GaN掺杂层可以是掺杂有硅元素的GaN层，其厚度可以是2um～3um；P型GaN掺杂层可以是掺杂有镁元素的GaN层，其厚度可以是150nm～300nm。
此外，在N型GaN掺杂层的第一面可以划分为三个子像素区域和除三个子像素区域之外的其他区域。三个子像素区域分别用于形成三个子像素结构，三个子像素结构分别用于发出蓝光、绿光和红光，从而实现该LED芯片的全彩显示。其中，三个子像素结构的形成可通过刻蚀方式实现，即通过制作划分出子像素区域和其他区域的掩膜图形，并根据该掩膜图形将其他区域上的结构刻蚀掉，从而形成子像素结构。
需要说明的是，本申请实施例中，子像素区域仅仅是为了形成子像素结构而对区域进行的划分，并不代表任何实际结构。示例性地，当子像素区域为圆形区域时，N型GaN掺杂层的第一面上的区域划分可以如图4所示。图4中，浅灰色区域代表子像素区域，深灰色区域代表N型GaN掺杂层的第一面上除三个子像素区域之外的其他区域。不难想象，在图4所示的子像素区域上形成的子像素结构为圆柱形结构。
对于微显示芯片，像素形状可以为圆形或方形。因此，本申请实施例中的三个子像素区域可以均为圆形区域，也可以均为方形区域。此外，子像素区域的尺寸可依据LED芯片的不同需求进行设置，本申请实施例中对此不做具体限定。示例性地，圆形区域的直径可以为5um～50um。
在图2所示的LED芯片中，蓝光量子阱结构可以包括：N个蓝光量子阱层，以及用于隔离N个蓝光量子阱层的、与N个蓝光量子阱层交替形成的N+1个隔离层，N≥1。同样地，绿光量子阱结构可以包括：M个绿光量子阱层，以及用于隔离M个绿光量子阱层的、与M个绿光量子阱层交替形成的M+1个隔离层，M≥1。
也就是说，量子阱结构是通过交替生长隔离层和量子阱层形成的。通常，量子阱结构可通过3～5个周期的材料生长过程形成。例如，蓝光量子阱结构可以包两个蓝光量子阱层以及与两个蓝光量子阱层交替形成的三个隔离层。
蓝光量子阱层可以由掺杂有In元素的GaN组成，具体地，可以用In xGa 1-xN表示。同样地，绿光量子阱层可以由掺杂有In元素的GaN组成，具体地，可以用In xGa 1-xN表示。不同的是，蓝光量子阱层和绿光量子阱层掺杂In元素的比例不同，即x的取值不同。当量子阱层中掺杂的In元素的比例不同时，该量子阱层的发光波长不同。通过控制量子阱层中掺杂In元素的比例，可以控制该量子阱层的发光波长。例如，当x＝0.15时，量子阱层的发光波长为460nm，此时该量子阱层可发出蓝光，即该量子阱层为蓝光量子阱层；当x＝0.25时，量子阱层的发光波长为5300nm，此时该量子阱层可发出绿光，即该量子阱层为绿光量子阱层。
本申请实施例中，蓝光量子阱层的厚度可以是2nm～5nm，绿光量子阱层的厚度也可以是2nm～5nm。隔离层可以由GaN组成，其厚度可以是7nm～15nm。
此外，如图5所示，在图2所示的LED芯片中，还可以包含与三个P型接触电极和N型接触电极连接的驱动电路。
其中，可以通过金属焊球实现驱动电路和接触电极的精准对位连接。示例性地，驱动电路中可以包含薄膜晶体管(thin film transistor，TFT)、低温多晶硅(low temperature poly-silicon，LTPS)、互补金属氧化物半导体(complementary metal oxide semiconductor，CMOS)等。驱动电路可采用脉冲宽度调制(pulse width modulation，PWM)技术控制每个子像素结构的发光强度，使得LED芯片中每个子像素结构所发出的蓝光、绿光和红光的色亮度均一。
众所周知，在制备LED芯片时，需要在衬底和缓冲层上进行材料生长。而在材料生长完成以后，由于衬底和缓冲层的功能已完成，因此可以将衬底和缓冲层解理，解理后的LED芯片可以如图2、图3、图5所示，即LED芯片中不包含衬底和缓冲层；此外，由于衬底和缓冲层对LED芯片的发光显示不会产生影响，因此也可以不对衬底和缓冲层进行解理。
若在材料生长完成后不对衬底和缓冲层进行解理，则该LED芯片还包括形成于N型GaN掺杂层的第二面上的缓冲层和衬底，该缓冲层与N型GaN掺杂层邻接，该衬底与该缓冲层和红光胶体量子点结构邻接，如图6所示。
本申请实施例中，衬底可以为蓝宝石衬底、Si衬底、SiC衬底或者GaN衬底中的任一种；缓冲层可以是GaN缓冲层，其厚度可以选为2um～3um。
需要说明的是，图2所示LED芯片仅包含三个子像素结构，即该LED芯片仅包含一个像素点。实际实现时，LED芯片可包含多个子像素结构，多个子像素结构中每三个为一组作为LED芯片的一个像素点，每个像素点的结构均可以如图2所示。每个像素点为LED芯片全彩显示的一个基本单元。
综上，在图2所示的LED芯片中，由于三个子像素结构中的每个子像素结构中均包含蓝光量子阱结构和绿光量子阱结构，因而该LED芯片可分别通过三个子像素结构中除第一子像素结构之外的另外两个子像素结构实现LED芯片发出蓝光和绿光。同时，可在第一子像素结构对应区域上涂覆红光胶体量子点结构，从而通过红光胶体量子点结构吸收蓝光和绿光后转换为红光，实现LED芯片发出红光。因此，采用图2所示的LED芯片可以实现全彩显示。
此外，由于红光胶体量子点结构具有线宽窄、光致荧光效率高等特点，因而采用红光胶体量子点结构吸收蓝光和绿光的方式来实现全彩显示LED芯片发出红光的方案，与现有技术中通过红光量子阱结构实现LED芯片发出红光的方案相比，可以提高LED芯片的发光效率，从而降低LED芯片的功耗。
此外，本申请实施例还提供另一种LED芯片，如图7所示，该LED芯片包括如下四个部分：
一、N型氮化镓GaN掺杂层。
二、分别在N型GaN掺杂层的第一面的三个子像素区域上形成的三个子像素结构。
其中，三个子像素区域中的第一子像素区域上的第一子像素结构中包含依次生长的蓝光量子阱结构或绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层；三个子像素区域中的 第二子像素区域上的第二子像素结构中包含依次生长的蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；三个子像素区域中的第三子像素区域上的第三子像素结构中包含依次生长的绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层。
三、在三个子像素结构之上分别形成的三个P型接触电极，以及在N型GaN掺杂层的第一面上除三个子像素区域之外的其他区域上形成的N型接触电极。
四、在N型GaN掺杂层的第二面上、且与第一子像素区域对应的区域上形成的红光胶体量子点结构。
其中，红光胶体量子点结构的结构、材料、发光原理、发光效果、尺寸设置等可参见图2所示LED芯片中的相关描述，此处不再赘述。
需要说明的是，在图7所示的LED芯片中，第一子像素结构中包含蓝光量子阱结构和绿光量子阱结构中的任一种即可。即，红光胶体量子点结构可通过吸收蓝光的光谱能量发出红光，也可以通过吸收绿光的光谱能量发出红光。实际实现时，红光胶体量子点结构吸收蓝光的光谱能量后的转换效率较高，因此，图7所示的LED芯片的第一子像素结构中包含蓝光量子阱结构时，该LED芯片的发光效率更高。
图7所示的LED芯片中，通过设置的红光胶体量子点结构，第一子像素结构对应的区域可以发出红光。此外，由于三个子像素结构中的第二子像素结构中包含蓝光量子阱结构，因而可通过第二子像素结构实现蓝光的显示，由于三个子像素结构中的第三子像素结构中包含绿光量子阱结构，因而可通过第三子像素结构实现绿光的显示。
为了更好地实现LED芯片三种色光(即红光、蓝光和绿光)的显示、提高色纯度，可以在相应发光区域放置滤光片，即图7所示的LED芯片还可以包括：在红光胶体量子点结构之上放置的红色滤光片；在N型GaN掺杂层的第二面上、且与第二子像素区域对应的区域上放置的蓝色滤光片；在N型GaN掺杂层的第二面上、且与第三子像素区域对应的区域上放置的绿色滤光片。
在红光胶体量子点上放置的红色滤光片，可以滤除第一子像素区域上除红光以外的色光(比如蓝光或绿光)；在第二子像素区域对应的区域上放置的蓝色滤光片，可以滤除第二子像素区域上除蓝光以外的色光(比如绿光)；在第三子像素区域对应的区域上放置的绿色滤光片，可以滤除第三子像素区域上除绿光以外的色光(比如蓝光)。
放置红色滤光片、蓝色滤光片和绿色滤光片后，该LED芯片的结构可以如图8所示。在图8所示的LED芯片中，红色滤光片之上的区域可以发出红光，绿色滤光片之上的区域可以发出绿光，蓝色滤光片之上的区域可以发出蓝光。
在图7所示的LED芯片中，电荷阻挡层可以减小子像素结构的电荷泄露。示例性地，电荷阻挡层可以由Al 0.15Ga 0.85N组成，其厚度可以是15nm～35nm。N型GaN掺杂层可以是掺杂有硅元素的GaN层，其厚度可以是2um～3um；第一子像素结构中的P型GaN掺杂层、第二子像素结构中的P型GaN掺杂层和第三子像素结构中的P型GaN掺杂层均可以是掺杂有镁元素的GaN层，其厚度可以是150nm～300nm。
此外，在图7所示的LED芯片中，关于三个子像素区域的解释可参见图2所示的LED芯片中的相关描述，此处不再赘述。
在图7所示的LED芯片中，第二子像素结构中的蓝光量子阱结构可以包括：N个蓝光量子阱层，以及用于隔离N个蓝光量子阱层的、与N个蓝光量子阱层交替形成的N+1个隔离层，N≥1。同样地，第三子像素结构中的绿光量子阱结构可以包括：M个绿光量子阱 层，以及用于隔离M个绿光量子阱层的、与M个绿光量子阱层交替形成的M+1个隔离层，M≥1。
此外，若第一子像素结构中包含蓝光量子阱结构，其结构可与第二子像素结构中的蓝光量子阱结构相同；若第一子像素结构中包含绿光量子阱结构，其结构可与第三子像素结构中的绿光量子阱结构相同。
也就是说，在图7所示的LED芯片中，蓝光量子阱结构和绿光量子阱结构的具体内部结构与图2所示的LED芯片并无不同。其具体实现方式可参见图2所示LED芯片中的相关描述。
此外，如图9所示，在图7所示的LED芯片中，还可以包含与三个P型接触电极和N型接触电极连接的驱动电路。驱动电路可采用PWM技术控制每个子像素结构的发光强度，使得LED芯片中每个子像素结构所发出的蓝光、绿光和红光的色亮度均一。
同样地，若在制备图7所示的LED芯片时，在材料生长完成后不对衬底和缓冲层进行解理，则该LED芯片还包括：形成于N型GaN掺杂层的第二面上的缓冲层和衬底，缓冲层与N型GaN掺杂层邻接，衬底与缓冲层和红光胶体量子点结构邻接。
需要说明的是，图7所示LED芯片仅包含三个子像素结构，即该LED芯片仅包含一个像素点。实际实现时，LED芯片可包含多个子像素结构，多个子像素结构中每三个为一组作为LED芯片的一个像素点，每个像素点的结构均可以如图7所示。每个像素点为LED芯片全彩显示的一个基本单元。
综上，采用图7所示的LED芯片，由于三个子像素结构中的第二子像素结构包含蓝光量子阱结构，因而可通过第二子像素结构实现LED芯片发出蓝光；三个子像素结构中的第三子像素结构包含绿光量子阱结构，因而可通过第三子像素结构实现LED芯片发出绿光。同时，可在包含蓝光量子阱结构或绿光量子阱结构的第一子像素结构对应区域上涂覆红光胶体量子点结构，从而通过红光胶体量子点结构吸收蓝光或绿光后转换为红光，实现LED芯片发出红光。因此，采用上述方案中提供的LED芯片可以实现全彩显示。
此外，由于红光胶体量子点结构具有线宽窄、光致荧光效率高等特点，因而采用红光胶体量子点结构吸收蓝光和绿光的方式来实现全彩显示LED芯片发出红光的方案，与现有技术中通过红光量子阱结构实现LED芯片发出红光的方案相比，可以提高LED芯片的发光效率，从而降低LED芯片的功耗。
通过以上对图7所示LED芯片的介绍不难看出，图7所示的LED芯片与图2所示的LED芯片的主要区别点在于三个子像素结构的内部结构不同。
在图2所示的LED芯片中，每个子像素结构的内部结构均相同，每个子像素结构中均包含蓝光量子阱结构和绿光量子阱结构。通过对应放置红光胶体量子点的第一子像素结构吸收蓝光和绿光后可以发出红光；而对于另外两个子像素结构，哪个子像素结构发蓝光、哪个子像素结构发绿光，则由放置的滤光片的颜色决定。即，对应放置蓝色滤光片的子像素结构用于发蓝光，对应放置绿色滤光片的子像素结构用于发绿光。
在图7所示的LED芯片中，每个子像素结构的内部结构有所不同，第一子像素结构中包含蓝光量子阱结构或绿光量子阱结构中的一种，第二子像素结构包含蓝光量子阱结构，第三子像素结构包含绿光量子阱结构。通过对应放置红光胶体量子点的第一子像素结构吸收蓝光或绿光后可以发出红光，而对于另外两个子像素结构，包含蓝光量子阱结构的第二 子像素结构用于发蓝光，包含绿光量子阱结构的第三子像素结构用于发绿光。
具体实现时，可选择性地采用图2所示的LED芯片或者图7所示的LED芯片。
在制备图2所示的LED芯片时，由于每个子像素结构的结构均相同，因而该LED芯片的材料生长过程不必考虑哪个子像素结构用于发什么颜色的光，即不必针对不同的子像素结构分别进行材料生长，材料生长过程的操作流程可以得到简化。因此，若希望LED芯片制备工艺简化，则可以采用图2所示的LED芯片。
在制备图7所示的LED芯片时，在材料生长时需要先生长部分材料；通过掩膜保护已生长的材料后，再生长其他部分的材料。虽然材料生长过程的工艺较为复杂，但是采用这种方式制备的LED芯片(即图7所示的LED芯片)的结构比图2所示LED芯片的结构简单，可适用于对LED芯片结构简单化的要求较高的场景。
基于以上介绍，图2所示的LED芯片和图7所示的LED芯片为本申请实施例提供的两个典型的LED芯片。下面，通过两个实施例对本申请实施例提供的这两个典型LED芯片的制备方法进行介绍。
实施例一
本申请实施例提供一种LED芯片的制备方法，该方法用于制备图2所示的LED芯片。参见图10，该方法包括如下步骤：
S1001：在衬底的第一面上依次生长缓冲层、N型GaN掺杂层、蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层，以形成第一样品。
S1001中，可采用金属有机化学气相外延(metal organic chemical vapor deposition，MOCVD)的方式进行材料的生长。
其中，衬底可以为蓝宝石衬底、Si衬底、SiC衬底或者GaN衬底中的任一种。缓冲层可以是GaN缓冲层，其厚度可以选为2um～3um。N型GaN掺杂层可以是掺杂有硅元素的GaN层，其厚度可以是2um～3um；P型GaN掺杂层可以是掺杂有镁元素的GaN层，其厚度可以是150nm～300nm。电荷阻挡层可以减小子像素结构的电荷泄露，示例性地，电荷阻挡层可以由Al 0.15Ga 0.85N组成，其厚度可以是15nm～35nm。
S1002：将掩膜图形转移到P型GaN掺杂层上，以形成第二样品。
其中，掩膜图形上包含多个子像素区域以及除多个子像素区域之外的其他区域。
也就是说，通过掩膜图形可以将S1001中生长的第一样品划分成多个子像素区域和其他区域。
S1003：根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得其他区域露出至N型GaN掺杂层，以形成第三样品。
具体地，S1003中，根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得掩膜图形中除多个子像素区域之外的其他区域露出至N型GaN掺杂层，可通过如下方式实现：钝化保护LED芯片的侧面以及多个子像素区域；采用电感耦合等离子体(inductive coupled plasma，ICP)或反应离子刻蚀(reactive ion etching，RIE)的方式对其他区域进行刻蚀，使得其他区域露出至N型GaN掺杂层。
S1004：在第三样品中的多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，以形成第四样品。
具体地，S1004中，在多个子像素区域上分别形成多个P型接触电极，并在其他区域 上形成N型接触电极，可以通过如下方式实现：采用电子束蒸发沉积镍金合金，200℃～500℃退火后在多个子像素区域上分别形成多个P型接触电极；并，在其他区域上溅射氧化铟锡(ITO)或石墨，以形成N型接触电极。本申请实施例中，多个子像素结构共用一个N型接触电极，该N型接触电极又可以称为共阴极。
执行S1004后，形成的第四样品的结构可以如图11所示。需要说明的是，图11中仅示出了包含三个子像素结构的LED芯片。实际实现时，执行S1004后得到的第四样品中可包含多个子像素结构，多个子像素结构中每三个子像素结构可作为一个像素点，用以实现全彩显示。
此外，第四样品的扫描电子显微镜(scanning electron microscopy，SEM)图像可以如图12所示。图12中，每个凸起的圆柱形结构代表一个子像素结构，每个子像素结构上包含p-contact(即P型接触电极)。图12中除凸起之外的平面区域可以视为除子像素区域之外的其他区域，在该区域上形成有N型接触电极。
S1005：在衬底的第二面上、且与多个子像素区域中用于发红光的至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，以形成LED芯片。
采用图10所示方法制成的LED芯片可以如图13所示。需要说明的是，图13所示的LED芯片中仅包含三个子像素结构。实际实现时，采用图10所示方法制备出的LED芯片中可以包含多个子像素结构，其中每三个子像素结构可以构成一个像素点，每个像素点作为LED芯片全彩显示的一个基本单元。
可选地，图10所示的方法还可以包括：在至少一个红光胶体量子点结构上分别放置至少一个红色滤光片；在衬底的第二面上、且与多个子像素区域中用于发蓝光的至少一个第二子像素区域对应的区域上分别放置至少一个蓝色滤光片；在衬底的第二面上、且与多个子像素区域中用于发绿光的至少一个第三子像素区域对应的区域上分别放置至少一个绿色滤光片。
通过在衬底的第二面上加盖不同颜色的滤光片，可以滤除该颜色的色光以外的其他色光，从而可以提高LED芯片用于全彩显示时的色纯度。
可选地，图10所示的方法还可以包括：将多个P型接触电极和N型接触电极通过金属焊球与驱动电路对位连接。
通过控制驱动电路的PWM电流，可以控制每个子像素结构的发光强度，使得LED芯片中每个子像素结构所发出的蓝光、绿光和红光的色亮度均一。
可选地，在图10所示的方法中，在分别涂覆至少一个红光胶体量子点结构之前，还可以采用激光辐照方式将衬底和缓冲层，与LED芯片解理。那么此时，S1005中涂覆至少一个红光胶体量子点结构的操作，可通过如下方式实现：在N型GaN掺杂层中与缓冲层邻接的一面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构。
在材料生长完成以后，由于衬底和缓冲层的功能已完成，因此可以将衬底和缓冲层解理，从而使得LED芯片的结构得到简化。
在放置三色滤光片、连接驱动电路并将衬底和缓冲层解理后，采用图10所示方式制备的LED芯片的一种可能的结构可以如图14所示。图14所示的LED芯片可视为图2所示LED芯片的一个具体示例。
需要说明的是，图10所示方法可用于制备图2所示的LED芯片，图10所示方法中未 详尽描述的实现方式可参见图2所示LED芯片中的相关描述。
实施例二
本申请实施例提供一种LED芯片的制备方法，该方法可用于制备图7所示的LED芯片。参见图15，该方法包括如下步骤：
S1501：在衬底的第一面上依次生长缓冲层、N型GaN掺杂层。
其中，衬底可以为蓝宝石衬底、Si衬底、SiC衬底或者GaN衬底中的任一种。缓冲层可以是GaN缓冲层，其厚度可以选为2um～3um。N型GaN掺杂层可以是掺杂有硅元素的GaN层，其厚度可以是2um～3um。
S1502：在N型GaN掺杂层中的蓝光量子阱生长区域上依次生长蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；并，在N型GaN掺杂层中除蓝光量子阱生长区域之外的绿光量子阱生长区域上依次生长绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层，以形成第一样品。
S1502中，在进行材料生长时将N型GaN掺杂层划分为蓝光量子阱生长区域和绿光量子阱生长区域，并在不同的量子阱生长区域上生长不同的结构。
具体地，S1502中的材料生长过程可通过如下方式实现：在N型GaN掺杂层上制作第一掩膜，第一掩膜用于保护绿光量子阱生长区域；在蓝光量子阱生长区域上依次生长蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层；去除第一掩膜；在蓝光量子阱生长区域上制作第二掩膜，第二掩膜用于保护蓝光量子阱生长区域；在绿光量子阱生长区域上依次生长绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层。
S1503：将掩膜图形转移到P型GaN掺杂层上，以形成第二样品。
其中，掩膜图形上包含多个子像素区域以及除多个子像素区域之外的其他区域，多个子像素区域包含用于发红光的至少一个第一子像素区域、用于发蓝光的至少一个第二子像素区域以及用于发绿光的至少一个第三子像素区域；至少一个第一子像素区域对准蓝光量子阱生长区域或者绿光量子阱生长区域，至少一个第二子像素区域对准蓝光量子阱生长区域，至少一个第三子像素区域对准绿光量子阱生长区域。
也就是说，通过掩膜图形可以将S1502中生长的第一样品划分成多个子像素区域和其他区域。
S1504：根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得其他区域露出至N型GaN掺杂层，以形成第三样品。
根据该掩膜图形对第二样品进行刻蚀时，由于该掩膜图形上的至少一个第二子像素区域对准蓝光量子阱生长区域，因此刻蚀后的至少一个第二子像素区域上对应的结构为蓝光量子阱生长区域上生长的结构，即蓝光量子阱结构、电荷阻挡层以及P型GaN掺杂层。通过该结构，可以使得LED芯片发出蓝光。
同样地，由于该掩膜图形上的至少一个第三子像素区域对准绿光量子阱生长区域，因此刻蚀后的至少一个第三子像素区域上对应的结构为绿光量子阱生长区域上生长的结构，即绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层。通过该结构，可以使得LED芯片发出绿光。
此外，至少一个第一子像素区域对准蓝光量子阱生长区域或者绿光量子阱生长区域，因而刻蚀后第一子像素区域上对应的结构可以通过涂覆红光胶体量子点来实现LED芯片 发出红光。
具体地，S1504中，根据掩膜图形在第二样品上进行刻蚀，保护多个子像素区域上的结构，并使得掩膜图形中除多个子像素区域之外的其他区域露出至N型GaN掺杂层，可通过如下方式实现：钝化保护LED芯片的侧面以及多个子像素区域；采用ICP或RIE的方式对其他区域进行刻蚀，使得其他区域露出至N型GaN掺杂层。
S1505：在第三样品中的多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，以形成第四样品。
具体地，S1505中，在多个子像素区域上分别形成多个P型接触电极，并在其他区域上形成N型接触电极，可以通过如下方式实现：采用电子束蒸发沉积镍金合金，200℃～500℃退火后在多个子像素区域上分别形成多个P型接触电极；并，在其他区域上溅射氧化铟锡(ITO)或石墨，以形成N型接触电极。本申请实施例中，多个子像素结构共用一个N型接触电极，该N型接触电极又可以称为共阴极。
执行S1505后，形成的一种第四样品的结构可以如图16所示。需要说明的是，图16中仅示出了包含三个子像素结构的LED芯片。实际实现时，执行S1505后得到的第四样品中可包含多个子像素结构，多个子像素结构中每三个子像素结构可作为一个像素点，用以实现全彩显示。
此外，在图16所示的第四样品中，至少一个第一子像素区域对准蓝光量子阱生长区域。
S1506：在衬底的第二面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，以形成LED芯片。
通过对图16所示的第四样品执行S1506，可以得到图17所示的LED芯片。需要说明的是，图17所示的LED芯片中仅包含三个子像素结构。实际实现时，采用图15所示方法制备出的LED芯片中可以包含多个子像素结构，其中每三个子像素结构可以构成一个像素点，每个像素点作为LED芯片全彩显示的一个基本单元。
可选地，图15所示的方法还可以包括：在至少一个红光胶体量子点结构上分别放置至少一个红色滤光片；在衬底的第二面上、且与至少一个第二子像素区域对应的区域上分别放置至少一个蓝色滤光片；在衬底的第二面上、且与至少一个第三子像素区域对应的区域上分别放置至少一个绿色滤光片。
通过在衬底的第二面上加盖不同颜色的滤光片，可以滤除该颜色的色光以外的其他色光，从而可以提高LED芯片用于全彩显示时的色纯度。
可选地，图15所示的方法还可以包括：将多个P型接触电极和N型接触电极通过金属焊球与驱动电路对位连接。
通过控制驱动电路的PWM电流，可以控制每个子像素结构的发光强度，使得LED芯片中每个子像素结构所发出的蓝光、绿光和红光的色亮度均一。
可选地，在图15所示的方法中，在分别涂覆至少一个红光胶体量子点结构之前，还可以采用激光辐照方式将衬底和缓冲层，与LED芯片解理。那么此时，S1506中涂覆至少一个红光胶体量子点结构的操作，可通过如下方式实现：在N型GaN掺杂层中与缓冲层邻接的一面上、且与至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构。
在材料生长完成以后，由于衬底和缓冲层的功能已完成，因此可以将衬底和缓冲层解 理，从而使得LED芯片的结构得到简化。
在放置三色滤光片、连接驱动电路并将衬底和缓冲层解理后，采用图15所示方式制备的LED芯片的一种可能的结构可以如图18所示。图18所示的LED芯片可视为图7所示LED芯片的一个具体示例。
通过如上对实施例二的介绍不难看出，实施例二和实施一仅在材料生长过程(即图10中的S1001和图15中的S1501～S1502)有所差别，其他制备步骤均为相似或相同的步骤。而正是因为材料生长步骤的不同，导致最终制备得到的LED芯片的结构有所不同。
需要说明的是，图15所示方法可用于制备图7所示的LED芯片，图15所示方法中未详尽描述的实现方式可参见图7所示LED芯片中的相关描述。
综上，本申请实施例提供一种LED芯片及其制备方法，采用本申请实施例提供的方案可以实现LED芯片的全彩显示。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (15)

  1. 一种发光二极管LED芯片，其特征在于，包括：
    N型氮化镓GaN掺杂层；
    分别在所述N型GaN掺杂层的第一面的三个子像素区域上形成的三个子像素结构，所述三个子像素结构中的每个子像素结构中均包含依次生长的蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层；
    在所述三个子像素结构之上分别形成的三个P型接触电极，以及在所述N型GaN掺杂层的第一面上除所述三个子像素区域之外的其他区域上形成的N型接触电极；
    在所述N型GaN掺杂层的第二面上、且与所述三个子像素区域中的第一子像素区域对应的区域上形成的红光胶体量子点结构。
  2. 如权利要求1所述的芯片，其特征在于，所述蓝光量子阱结构包括：N个蓝光量子阱层，以及用于隔离所述N个蓝光量子阱层的、与所述N个蓝光量子阱层交替形成的N+1个隔离层，N≥1。
  3. 如权利要求1或2所述的芯片，其特征在于，所述绿光量子阱结构包括：M个绿光量子阱层，以及用于隔离所述M个绿光量子阱层的、与所述M个绿光量子阱层交替形成的M+1个隔离层，M≥1。
  4. 如权利要求1～3任一项所述的芯片，其特征在于，还包括：
    在所述红光胶体量子点结构之上放置的红色滤光片；
    在所述N型GaN掺杂层的第二面上、且与所述三个子像素区域中的第二子像素区域对应的区域上放置的蓝色滤光片；
    在所述N型GaN掺杂层的第二面上、且与所述三个子像素区域中的第三子像素区域对应的区域上放置的绿色滤光片。
  5. 如权利要求1～4任一项所述的芯片，其特征在于，还包括：
    与所述三个P型接触电极和所述N型接触电极连接的驱动电路。
  6. 如权利要求1～5任一项所述的芯片，其特征在于，还包括：
    形成于所述N型GaN掺杂层的第二面上的缓冲层和衬底，所述缓冲层与所述N型GaN掺杂层邻接，所述衬底与所述缓冲层和所述红光胶体量子点结构邻接。
  7. 如权利要求1～6任一项所述的芯片，其特征在于，所述三个子像素区域均为圆形区域，或者所述三个子像素区域均为方形区域。
  8. 如权利要求1～7任一项所述的芯片，其特征在于，所述N型GaN掺杂层为掺杂有硅元素的GaN层，所述P型GaN掺杂层为掺杂有镁元素的GaN层。
  9. 如权利要求3～8任一项所述的芯片，其特征在于，所述蓝光量子阱层为掺杂有铟元素的GaN层；所述绿光量子阱层为掺杂有铟元素的GaN层；所述绿光量子阱层掺杂铟元素的比例与所述蓝光量子阱层掺杂铟元素的比例不同。
  10. 一种发光二极管LED芯片的制备方法，其特征在于，包括：
    在衬底的第一面上依次生长缓冲层、N型GaN掺杂层、蓝光量子阱结构、界面阻挡层、绿光量子阱结构、电荷阻挡层以及P型GaN掺杂层，以形成第一样品；
    将掩膜图形转移到所述P型GaN掺杂层上，以形成第二样品；所述掩膜图形上包含多个子像素区域以及除所述多个子像素区域之外的其他区域；
    根据所述掩膜图形在所述第二样品上进行刻蚀，保护所述多个子像素区域上的结构，并使得所述其他区域露出至所述N型GaN掺杂层，以形成第三样品；
    在所述第三样品中的所述多个子像素区域上分别形成多个P型接触电极，并在所述其他区域上形成N型接触电极，以形成第四样品；
    在所述衬底的第二面上、且与所述多个子像素区域中用于发红光的至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，以形成LED芯片。
  11. 如权利要求10所述的方法，其特征在于，还包括：
    在所述至少一个红光胶体量子点结构上分别放置至少一个红色滤光片；
    在所述衬底的第二面上、且与所述多个子像素区域中用于发蓝光的至少一个第二子像素区域对应的区域上分别放置至少一个蓝色滤光片；
    在所述衬底的第二面上、且与所述多个子像素区域中用于发绿光的至少一个第三子像素区域对应的区域上分别放置至少一个绿色滤光片。
  12. 如权利要求10或11所述的方法，其特征在于，还包括：
    将所述多个P型接触电极和所述N型接触电极通过金属焊球与驱动电路对位连接。
  13. 如权利要求10～12任一项所述的方法，其特征在于，在分别涂覆至少一个红光胶体量子点结构之前，还包括：
    采用激光辐照方式将所述衬底和所述缓冲层，与所述LED芯片解理；
    在所述衬底的第二面上、且与所述多个子像素区域中用于发红光的至少一个第一子像素区域对应的区域上分别涂覆至少一个红光胶体量子点结构，包括：
    在所述N型GaN掺杂层中与所述缓冲层邻接的一面上、且与所述至少一个第一子像素区域对应的区域上分别涂覆所述至少一个红光胶体量子点结构。
  14. 如权利要求10～13任一项所述的方法，其特征在于，根据所述掩膜图形在所述第二样品上进行刻蚀，保护所述多个子像素区域上的结构，并使得所述掩膜图形中除所述多个子像素区域之外的其他区域露出至所述N型GaN掺杂层，包括：
    钝化保护所述LED芯片的侧面以及所述多个子像素区域；
    采用电感耦合等离子体ICP或反应离子刻蚀RIE对所述其他区域进行刻蚀，使得所述其他区域露出至所述N型GaN掺杂层。
  15. 如权利要求10～14任一项所述的方法，其特征在于，在所述多个子像素区域上分别形成多个P型接触电极，并在所述其他区域上形成N型接触电极，包括：
    采用电子束蒸发沉积镍金合金，200℃～500℃退火后在所述多个子像素区域上分别形成多个P型接触电极；并
    在所述其他区域上溅射氧化铟锡ITO或石墨，以形成所述N型接触电极。
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