CN113488566A - Red light diode chip with reflection structure and preparation method thereof - Google Patents
Red light diode chip with reflection structure and preparation method thereof Download PDFInfo
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- 230000007704 transition Effects 0.000 claims description 12
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 claims description 6
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- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 9
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- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 2
- RGGPNXQUMRMPRA-UHFFFAOYSA-N triethylgallium Chemical compound CC[Ga](CC)CC RGGPNXQUMRMPRA-UHFFFAOYSA-N 0.000 description 2
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- IBEFSUTVZWZJEL-UHFFFAOYSA-N trimethylindium Chemical compound C[In](C)C IBEFSUTVZWZJEL-UHFFFAOYSA-N 0.000 description 2
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—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
- H01L33/02—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 bodies
- H01L33/10—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 bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—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
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
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Abstract
The disclosure provides a red light diode chip with a reflection structure and a preparation method thereof, belonging to the field of red light diode manufacturing. The reflection structure is additionally arranged between the substrate and the n-type AlInP limiting layer, the wavelength range of light reflected by the reflection structure is 600-900 nm, the reflection structure can comprise n Bragg reflectors which are sequentially stacked, the wavelength of the light reflected by each Bragg reflector is gradually increased, all light in the wavelength range of almost red light is reflected, and the light extraction efficiency of the red light diode is effectively guaranteed. Under the condition that the number of the Bragg reflectors is large, the reflectivity of light rays which are not vertically incident can be greatly improved, and finally the external quantum efficiency of the red light diode is effectively improved so as to improve the light extraction efficiency of the red light diode.
Description
Technical Field
The disclosure relates to the field of manufacturing of red light diodes, in particular to a red light diode chip with a reflection structure and a preparation method thereof.
Background
The red light diode is an important light source device and is widely applied to the aspects of outdoor illumination, automobile tail lamps and the like, and the red light diode chip is a basic structure for preparing the red light diode. The red diode chip generally includes a substrate, and a bragg reflector, an n-type AlInP confining layer, a light emitting layer, a p-type AlInP confining layer, a p-type AlGaInP transition layer, and a p-type GaP ohmic contact layer sequentially stacked on the substrate.
However, the bragg reflector has a high reflectivity only for vertically incident light, and only reflects light rays with the same wavelength, and the emergent light of the light-emitting layer has an isotropic characteristic and uniformly emits light in the whole solid angle, so that a considerable part of the light emitted by the light-emitting layer cannot be reflected by the bragg reflector and absorbed by the substrate, which causes a problem of low photoelectric conversion efficiency. The external quantum efficiency of the red light diode chip is low, and the luminous efficiency of the red light diode chip is not ideal.
Disclosure of Invention
The embodiment of the disclosure provides a red light diode chip with a reflection structure and a preparation method thereof, which can improve the external quantum efficiency of a red light diode so as to improve the light extraction efficiency of the red light diode. The technical scheme is as follows:
the embodiment of the disclosure provides a red light diode chip with a reflection structure, which comprises an epitaxial wafer, a p electrode and an n electrode,
the epitaxial wafer comprises a substrate, a reflecting structure, an n-type AlInP limiting layer, a light emitting layer, a p-type AlInP limiting layer, a p-type AlGaInP transition layer and a p-type GaP ohmic contact layer which are sequentially stacked on the substrate, the wavelength range of light reflected by the reflecting structure is 600-900 nm,
the reflecting structure comprises n Bragg reflectors which are sequentially stacked, n is an integer and is not less than 3, in the growth direction of the reflecting structure, the wavelength of light reflected by each Bragg reflector is gradually increased,
the p electrode is positioned on the p-type GaP ohmic contact layer, and the n electrode is positioned on one surface of the substrate far away from the p electrode.
Optionally, in the growth direction of the reflective structure, the wavelengths of the light reflected by each bragg mirror are increased in an arithmetic progression.
Optionally, the difference between the wavelengths of the light reflected by two adjacent bragg reflectors is 25nm to 115 nm.
Optionally, each of the bragg mirrors includes AlAs reflective layers and AlGaAs reflective layers that are alternately stacked, and of the n bragg mirrors, the number of AlAs reflective layers in the first bragg mirror is larger than that in the second bragg mirror,
the first Bragg reflector is the Bragg reflector which is farthest from the light-emitting layer, and the second Bragg reflector is the Bragg reflector except the first Bragg reflector in the n Bragg reflectors.
Optionally, the number of AlAs reflective layers in n-1 second bragg mirrors is the same.
Optionally, the number of AlAs reflective layers in the first bragg reflector is 8 to 24.
Optionally, the number of AlAs reflecting layers in the second bragg reflector is 4 to 22.
Optionally, the epitaxial wafer further comprises an anti-reflection structure, the anti-reflection structure is positioned between the p-electrode and the p-type GaP ohmic contact layer,
the anti-reflection structure comprises Ti3O5Layer and indium tin oxide layer, the Ti3O5A layer laminated on part of the surface of the p-type GaP ohmic contact layer, and an indium tin oxide layer laminated on the Ti3O5The p-type GaP ohmic contact layer is arranged on the substrate, the p-electrode is positioned on the indium tin oxide layer, and the orthographic projection of the p-electrode on the surface of the substrate is completely coincided with the orthographic projection of the indium tin oxide layer on the surface of the substrate.
Alternatively, the Ti3O5The thickness of the layer is (55 nm-75 nm, and the thickness of the indium tin oxide layer is 80 nm-100 nm.
The embodiment of the disclosure provides a preparation method of a red light diode chip with a reflection structure, which comprises the following steps:
providing a substrate;
a reflecting structure, an n-type AlInP limiting layer, a light emitting layer, a p-type AlInP limiting layer, a p-type AlGaInP transition layer and a p-type GaP ohmic contact layer are sequentially grown on the substrate, the wavelength range of light reflected by the reflecting structure is 600-900 nm,
the reflecting structure comprises n Bragg reflectors which are sequentially stacked, n is an integer and is not less than 3, and the wavelength of light reflected by each Bragg reflector is gradually increased in the growth direction of the reflecting structure;
forming a p-electrode on the p-type GaP ohmic contact layer;
and forming an n electrode on one surface of the substrate far away from the p electrode.
The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure include:
a reflection structure is added between the substrate and the n-type AlInP limiting layer, the wavelength range of light reflected by the reflection structure is 600-900 nm, most red light and part infrared light can be reflected, and the light emitting efficiency of the red light emitting diode is effectively guaranteed. The reflective structure may include n bragg mirrors sequentially stacked, n being an integer greater than or equal to 3. And in the growth direction of the reflecting structure, the wavelength of the light reflected by each Bragg reflector is gradually increased, so that each Bragg reflector can mainly reflect red light in a part of wavelength range, and the n Bragg reflectors are matched to reflect all light in almost red light wavelength range, thereby effectively ensuring the light-emitting efficiency of the red light diode. And because n Bragg reflectors are arranged, the main wavelengths of the light rays reflected by each Bragg reflector are different, even if the reflectivity of each Bragg reflector to the light rays which are vertically incident is higher, the reflectivity of the light rays which are not vertically incident can be greatly improved under the condition that the number of the Bragg reflectors is more, and finally, the external quantum efficiency of the red light diode is effectively improved so as to improve the light extraction efficiency of the red light diode.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a red light diode chip having a reflection structure according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a first bragg reflector provided in an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of another red led chip having a reflective structure according to an embodiment of the present disclosure;
fig. 4 is a flowchart of a method for manufacturing a red light diode chip having a reflective structure according to an embodiment of the present disclosure;
fig. 5 is a flowchart of another method for manufacturing a red led chip having a reflective structure according to an embodiment of the present disclosure.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of a red light diode chip provided in an embodiment of the present disclosure, and as can be seen from fig. 1, the embodiment of the present disclosure provides a red light diode chip including an epitaxial wafer 1, a p electrode 2, and an n electrode 3.
The epitaxial wafer 1 comprises a substrate 11, and a reflecting structure 12, an n-type AlInP limiting layer 13, a light emitting layer 14, a p-type AlInP limiting layer 15, a p-type AlGaInP transition layer 16 and a p-type GaP ohmic contact layer 17 which are sequentially laminated on the substrate 11, wherein the wavelength range of light reflected by the reflecting structure 12 is 600-900 nm. The reflective structure 12 includes n bragg reflectors 121 sequentially stacked, n is an integer and n is greater than or equal to 3, and the wavelength of the light reflected by each bragg reflector 121 gradually increases in the growth direction of the reflective structure 12.
The p-electrode 2 is positioned on the p-type GaP ohmic contact layer 17, and the n-electrode 3 is positioned on one surface of the substrate 11 far away from the p-electrode 2.
The reflection structure 12 is added between the substrate 11 and the n-type AlInP limiting layer 13, the wavelength range of light reflected by the reflection structure 12 is 600-900 nm, most red light and part infrared light can be reflected, and the light emitting efficiency of the red light emitting diode is effectively guaranteed. The reflective structure 12 may include n bragg mirrors 121 sequentially stacked, n being an integer greater than or equal to 3. In the growth direction of the reflective structure 12, the wavelength of the light reflected by each bragg reflector 121 is gradually increased, so that each bragg reflector 121 can mainly reflect a part of red light in the wavelength range, and the n bragg reflectors 121 cooperate to reflect all light in almost the red light wavelength range, thereby effectively ensuring the light extraction efficiency of the red light diode. And because there are n bragg reflectors 121, the main wavelength of the light reflected by each bragg reflector 121 is different, even if each bragg reflector 121 has a high reflectivity only for the light with vertical incidence, under the condition that the number of the bragg reflectors 121 is large, the reflectivity for the light with non-vertical incidence can be greatly improved, and finally, the external quantum efficiency of the red light diode is effectively improved to improve the light extraction efficiency of the red light diode.
In the growth direction of the reflective structure 12, the wavelength of the light reflected by each bragg reflector 121 is gradually increased, the light with shorter wavelength can be reflected to the light-emitting surface first, the light with longer wavelength is gradually reflected to the light-emitting surface by other bragg reflectors 121, the propagation rule of the light is further met, more light can be effectively reflected to the light-emitting surface, and the light-emitting efficiency of the red light diode can be improved.
It should be noted that in the implementation provided in the present disclosure, n may be 6, and a better quality of the reflective structure 12 may be obtained. In other implementation manners provided by the present disclosure, n can also be selected within a range of 3-10, the cost is reasonable, and the overall quality is also good. n may also be selected to be a number greater than 10, 11, 15, or even greater, as the present disclosure is not limited in this respect.
Alternatively, the wavelengths of the light reflected by each bragg mirror 121 are increased in an arithmetic progression in the growth direction of the reflective structure 12.
The wavelength of the light reflected by each bragg reflector 121 is increased in an arithmetic progression, so that the cost of the bragg reflector 121 can be reasonably controlled, most of the light can be effectively reflected to the light-emitting surface, the light-emitting efficiency of the red light diode is effectively improved, and the overall cost is reasonably controlled.
Illustratively, the difference between the wavelengths of the light reflected by the two adjacent bragg mirrors 121 is 25nm to 115 nm.
When the wavelength difference between the light beams reflected by two adjacent bragg reflectors 121 is within the above range, the light beams that the bragg reflectors 121 will leak are less, the red light diode can emit most of the light beams, and the light emitting efficiency of the red light diode can be improved.
In one implementation provided by the present disclosure, the difference between the wavelengths of the light reflected by two adjacent bragg mirrors 121 may be 50 nm. The resulting red diode also emits most of the light.
In one implementation manner provided by the present disclosure, n is 6, the difference between the wavelengths of the light reflected by two adjacent bragg mirrors 121 is 50nm, and the wavelength of the light reflected by the bragg mirrors 121 may gradually increase from 620nm to 870nm in the growth direction of the reflective structure 12. Most of the light of the red diode can be reflected.
Note that, in each bragg mirror 121, the thickness of the high-reflectivity reflective layer and the thickness of the low-reflectivity reflective layer both satisfy the following formula:
d is λ/4n, D is the thickness of the reflective layer, λ is the wavelength of reflection, and n is the refractive index of the material on which the light is incident. Substituting the wavelength of the light and the refractive index of the high-reflectivity reflecting layer into the formula to obtain the thickness of the high-reflectivity reflecting layer; the thickness of the low-reflectance reflective layer is obtained in the same manner as the thickness of the high-reflectance reflective layer.
Alternatively, each bragg mirror 121 includes an AlAs reflective layer 1211 and an AlGaAs reflective layer 1212 which are alternately stacked.
The high-reflectivity reflective layer and the low-reflectivity reflective layer constituting each bragg reflector 121 are made of the same material, which facilitates control of the wavelength of light reflected by each bragg reflector 121. And the materials of the AlAs reflecting layer 1211 and the AlGaAs reflecting layer 1212 can also realize good matching and transition with other infrared materials, so that the quality of the finally obtained reflecting structure 12 can be ensured to be better.
Illustratively, the number of layers of the AlAs reflective layer 1211 in the first bragg mirror 121 is greater than the number of layers of the AlAs reflective layer 1211 in the second bragg mirror 121 among the n bragg mirrors 121. The first bragg reflector 121 is a bragg reflector 121 farthest from the light emitting layer 14, and the second bragg reflector 121 is a bragg reflector 121 of the n bragg reflectors 121 except for the first bragg reflector 121.
The first bragg reflector 121 that reflects light with a shorter wavelength has a large number of layers and a large thickness, and can reflect most of the light that the red light diode can emit, and the number of layers of the reflective layer in the second bragg reflector 121 behind the first bragg reflector 121 can be appropriately reduced, and is mainly used for reflecting part of the light that the red light diode can emit. The light extraction efficiency of the finally obtained red light diode can be controlled to be high, and the cost of the reflecting structure 12 is not too high.
Alternatively, the number of layers of the AlAs reflective layers 1211 in the n-1 second bragg mirrors is the same.
The number of the AlAs reflecting layers 1211 in the n-1 second Bragg reflectors is the same, so that the quality of the n-1 second Bragg reflectors can be controlled to be uniform, and the stress can be effectively released to obtain the Bragg reflector with better quality. And the n-1 second Bragg reflectors can effectively reflect most of red light, and the overall cost is not high.
It should be noted that, among the n bragg mirrors 121, one bragg mirror 121 farthest from the light emitting layer 14 is a first bragg mirror 121, and all bragg mirrors 121 except the first bragg mirror 121 among the n bragg mirrors 121 are second bragg mirrors 121, so that n-1 second bragg mirrors 121 are remained except the first bragg mirror 121.
Illustratively, the number of layers of the AlAs reflective layer 1211 in the first Bragg reflector 121 is 8 to 24.
The number of the AlAs reflective layers 1211 in the first bragg reflector 121 is within the above range, so that the first bragg reflector 121 having a good quality can be obtained, and most of the low-band red light can be reflected.
Optionally, the number of the AlAs reflective layers 1211 in the second bragg reflector is 4 to 22.
The number of the AlAs reflecting layers 1211 in the second bragg reflector is in the above range, so that the quality is good, and most of the low-band red light can be reflected.
In one implementation manner provided by the present disclosure, the number of the AlAs reflective layers 1211 in the first bragg reflector 121 may be 15, the number of the AlAs reflective layers 1211 in the second bragg reflector may be 3, and the quality of the resulting reflective structure 12 is also better. The number of the AlAs reflective layers 1211 in the first bragg reflector 121 and the second bragg reflector 121 may be selected from other numbers, which is not limited in the disclosure.
Note that, in the bragg mirror 121, since the high-reflectance reflective layer and the low-reflectance reflective layer are both provided in pairs, the number of layers of the AlAs reflective layer 1211 is merely used as an example, and the number of layers of the AlGaAs reflective layer 1212 in each bragg mirror 121 is the same as the number of layers of the AlAs reflective layer 1211 in the bragg mirror 121.
Since the number of reflective layers in the bragg mirror 121 in the reflective structure 12 is large, and it is not easy to observe, a specific reflective layer structure of the bragg mirror 121 is not shown in fig. 1. The structure of the bragg mirror 121 can be specifically referred to in fig. 2.
Fig. 2 is a schematic structural diagram of a first bragg reflector according to an embodiment of the disclosure, and referring to fig. 2, it can be seen that the first bragg reflector shown in fig. 2 has 15 AlAs reflective layers 1211, and the bragg reflector has overlapping AlAs reflective layers 1211 and AlGaAs reflective layers 1212. The hierarchical arrangement of the second bragg reflector can refer to the hierarchical arrangement of the first bragg reflector in fig. 2, and is not described herein again.
Fig. 3 is a schematic structural diagram of another red led chip according to an embodiment of the disclosure, and referring to fig. 3, the red led chip includes an epitaxial wafer 1, a p-electrode 2, and an n-electrode 3.
The epitaxial wafer 1 comprises a substrate 11, and a GaAs buffer layer 18, a reflection structure 12, an n-type AlInP limiting layer 13, an n-type AlGaInP waveguide layer 19, a light-emitting layer 14, a p-type AlGaInP waveguide layer 20, a p-type AlInP limiting layer 15, a p-type AlGaInP transition layer 16, a p-type GaP current spreading layer 21, a p-type GaP ohmic contact layer 17 and an anti-reflection structure 22 which are sequentially stacked on the substrate 11, wherein the anti-reflection structure 22 is positioned between the p-type GaP ohmic contact layer 17 and the p-electrode 2. The n-electrode 3 is located on a side of the substrate 11 remote from the p-electrode 2.
The reflective structure 12 of fig. 3 is described above, and therefore will not be described in detail here.
For ease of understanding, some of the hierarchical structures in the red diode chip epitaxial wafer 1 are described in detail below.
Optionally, the material of the substrate 11 is gallium arsenide. Is convenient for obtaining and preparing.
Illustratively, GaAs buffer layer 18 may have a thickness of 150-300 nm. The obtained red light diode chip has better quality.
Optionally, the thickness of the n-type AlInP limiting layer 13 is 250-350 nm. The obtained red light diode chip has better quality.
Optionally, the n-type AlGaInP waveguide layer 19 has a thickness of 3-3.5 um. The obtained red light diode chip has better quality.
Optionally, the light emitting layer 14 includes a first AlGaInP well layer and a second AlGaInP well layer which are alternately stacked, the Al composition in the first AlGaInP well layer is different from the Al composition in the second AlGaInP well layer, and the quality of the red light diode chip obtained by the light emitting layer 14 having a thickness of 150 to 200nm is good.
Optionally, the p-type AlGaInP waveguide layer 20 has a thickness of 3-3.5 um. The obtained red light diode chip has better quality.
Optionally, the thickness of the p-type AlInP limiting layer 15 is 350-450 nm. The obtained red light diode chip has better quality.
Optionally, the thickness of the p-type GaP current spreading layer 21 is 4-5 um. The obtained red light diode chip has better quality.
Illustratively, the thickness of the p-type GaP ohmic contact layer 17 is 500-1000 nm. The obtained red light diode chip has better quality.
Optionally, antireflective structure 22 comprises Ti3O5Layer 221 and ITO layer 222, Ti3O5The layer 221 is laminated on a part of the surface of the p-type GaP ohmic contact layer 17, and the ITO layer 222 is laminated on Ti3O5The layer 221 is on the p-type GaP ohmic contact layer 17, the p-electrode 2 is on the ITO layer 222, and the orthographic projection of the p-electrode 2 on the surface of the substrate 11 is completely overlapped with the orthographic projection of the ITO layer 222 on the surface of the substrate 11.
Ti3O5The layer 221 can block current, thereby preventing the current from being injected under the p-electrode 2 and improving the uniformity of the light emitted from the red diode. And Ti3O5Layer 221 prevents light refracted or exiting through ITO layer 222 from entering Ti3O5In the layer 221, there is no light absorption effect, so that most of the light can exit through the ito layer 222, thereby improving the light-emitting efficiency of the red led.
Alternatively, Ti3O5The thickness of layer 221 can be 55nm to 75nm, and the thickness of ITO layer 222 can be 80nm to 100 nm. The light emitting efficiency of the red light diode can be effectively improved.
In one implementation provided by the present disclosure, Ti3O5The thickness of layer 221 can be 63nm, the refractive index can be 2.4, and the thickness of ito layer 222 can be 90 nm.
Note that Ti3O5The thickness of layer 221 is Ti3O5The maximum thickness of layer 221.
Illustratively, the material of the p-electrode 2 may include a Cr metal layer and an Au metal layer which are sequentially stacked, and the thicknesses of the Cr metal layer and the Au metal layer are 20-50 nm and 3000-4500 nm, respectively. The p-electrode 2 can be guaranteed to have good quality, and the p-electrode 2 can be well connected with the transparent conducting layer.
Illustratively, the n-electrode 3 is made of a supporting Au metal layer, an AuGeNi metal layer and a second Au metal layer which are sequentially laminated, and the thicknesses of the supporting Au metal layer, the AuGeNi metal layer and the second Au metal layer are respectively 10-30 nm, 120-200 nm and 160-300 nm. The good quality of the n-electrode 3 can be ensured, and the n-electrode 3 can realize good connection with the substrate 11 made of gallium arsenide material.
Compared with the structure of the red light diode chip shown in fig. 1, the structure of the red light diode chip shown in fig. 3 has the advantages that the GaAs buffer layer 18 is added between the substrate 11 and the reflective structure 12, the corresponding waveguide layer is added between the light emitting layer 14 and the limiting layer, and the anti-reflection structure 22 is added on the p-type GaP ohmic contact layer 17, so that lattice mismatch can be relieved, and the light extraction efficiency of the red light diode chip can be further improved.
It should be noted that fig. 3 is only used for example, and in other implementations provided by the present disclosure, the red light diode may also have other different hierarchical structures, which is not limited by the present disclosure.
Fig. 4 is a flowchart of a method for manufacturing a red light diode chip according to an embodiment of the present disclosure, and referring to fig. 4, the method for manufacturing a red light diode chip includes:
s101: a substrate is provided.
S102: a reflecting structure, an n-type AlInP limiting layer, a light emitting layer, a p-type AlInP limiting layer, a p-type AlGaInP transition layer and a p-type GaP ohmic contact layer are sequentially grown on a substrate, and the wavelength range of light reflected by the reflecting structure is 600-900 nm. The reflecting structure comprises n Bragg reflectors which are sequentially stacked, n is an integer and is not less than 3, and the wavelength of light reflected by each Bragg reflector is gradually increased in the growth direction of the reflecting structure.
S103: and forming a p-electrode on the p-type GaP ohmic contact layer.
S104: and forming an n electrode on one surface of the substrate far away from the p electrode.
The technical effect of the method for manufacturing a red light diode chip shown in fig. 4 can refer to the technical effect of the structure of the red light diode chip shown in fig. 1, and therefore, the technical effect of the method for manufacturing a red light diode chip in fig. 3 is not described herein again.
The structure of the red led chip after the step S104 is executed can refer to fig. 1.
Fig. 5 is a flowchart of another method for manufacturing a red light diode chip according to an embodiment of the present disclosure, and referring to fig. 5, the method for manufacturing a red light diode chip includes:
s201: a substrate is provided.
In step S201, the material of the substrate may be gallium arsenide.
S202: a GaAs buffer layer is grown on the substrate.
Optionally, the growth conditions of the GaAs buffer layer include: the growth temperature is 650-670 ℃, the thickness is 150-300 nm, the V/III is 20-30, and the growth rate is 0.5-0.8 nm/s.
S203: and growing a reflecting structure on the GaAs buffer layer.
Optionally, the growth conditions of the reflective structure include: the growth temperature is 650-670 ℃, the thickness is 150-300 nm, the V/III is 20-30, and the growth rate is 0.5-0.8 nm/s. A reflecting structure of better quality can be obtained.
S204: an n-type AlInP confinement layer is grown on the reflective structure.
Optionally, the n-type AlInP confinement layer growth conditions include: the growth temperature is 670-680 ℃, the thickness is 350-450 nm, the V/III is 40-50, the growth rate is 1.2-1.7 nm/s, and the concentration of the doped impurities is 1-2 e18 cm-3。
S205: an n-type AlGaInP waveguide layer is grown on the n-type AlInP limiting layer.
Optionally, the n-type AlGaInP waveguide layer growth conditions include: the growth temperature is 670-680 ℃, the thickness is 3-3.5 um, the V/III is 40-50, the growth rate is 1.2-1.7 nm/s, and the concentration of the doped impurities is 1-2 e18 cm-3。
S206: a light emitting layer is grown on the n-type AlGaInP waveguide layer.
Optionally, the growth conditions of the light emitting layer include: the growth temperature is 660-670 ℃, the thickness is 150-200 nm, the V/III is 20-30, and the growth rate is 0.4-0.6 nm/s. A light emitting layer with good quality can be obtained.
S207: a p-type AlGaInP waveguide layer is grown on the light-emitting layer.
Alternatively, the growth conditions for the p-type AlGaInP waveguide layer 20 include: the growth temperature is 660-670 ℃, the thickness is 150-200 nm, the V/III is 20-30, and the growth rate is 0.4-0.6 nm/s. A p-type AlGaInP waveguide layer 20 of good quality can be obtained.
S208: a p-type AlInP confinement layer is grown on the p-type AlGaInP waveguide layer.
Optionally, the growth conditions of the p-type AlInP confinement layer include: the growth temperature is 670-680 ℃, the thickness is 350-450 nm, the V/III is 40-50, the growth rate is 1.2-1.7 nm/s, and the concentration of the doped impurities is 1-2 e18 cm-3。
S209: and growing a p-type AlGaInP transition layer on the p-type AlInP limiting layer.
Alternatively, the p-type AlGaInP transition layer growth conditions include: the growth temperature is 670-680 ℃, the thickness is 3-3.5 um, the V/III is 40-50, the growth rate is 1.2-1.7 nm/s, and the concentration of the doped impurities is 1-2 e18 cm-3。
S210: a p-type GaP current spreading layer is grown on the p-type AlGaInP transition layer.
Optionally, the growth conditions of the p-type GaP current spreading layer include: the growth temperature is 670-680 ℃, the thickness is 4-5 um, the V/III is 20-30, the growth rate is 1.2-2 nm/s, and the concentration of magnesium doped impurities is 1-3 e18 cm-3。
S211: and growing a p-type GaP ohmic contact layer on the p-type GaP current spreading layer.
Optionally, the growth conditions of the p-type GaP ohmic contact layer include: the growth temperature is 600-640 ℃, the thickness is 20-30 nm, the V/III is 20-30, the growth rate is 0.45-0.55 nm/s, and the concentration of magnesium doped impurities is 1-5 e18 cm-3。
S212: and growing an anti-reflection structure on the p-type GaP ohmic contact layer. The anti-reflection structure comprises Ti sequentially laminated on the p-type GaP ohmic contact layer3O5A layer and an ITO layer.
Optionally, in S212, before the anti-reflection structure is grown on the p-type GaP ohmic contact layer, the p-type GaP ohmic contact layer may be cleaned by hydrogen peroxide; acid cleaning is carried out on the p-type GaP ohmic contact layer, and the acid cleaning solution comprises H2SO4、H2O2And H2A solution of O.
The cleanness of the p-type GaP ohmic contact layer can be ensured by hydrogen peroxide and acid washing, the p-type GaP ohmic contact layer is in a rough state, and the total reflection at the interface of the p-type GaP ohmic contact layer can be reduced to improve the light extraction efficiency.
In step S212, Ti3O5The growing of the layer includes: depositing a layer of Ti3O5A film; for Ti3O5Etching the film to obtain Ti3O5And (3) a layer. Indium tin oxide layers may also be deposited.
Alternatively, the antireflective structure is obtained by physical vapor deposition, and Ti3O5The deposition temperature of the layer is 200-400 ℃, Ti3O5The deposition pressure of the layer is 1E-4Pa to 5E-4 Pa; the deposition temperature of the ITO layer is 250-350 ℃, and the deposition pressure of the ITO layer is 1E-6 Torr-5E-6 Torr. A relatively dense anti-reflection structure with good quality can be obtained.
S213: and forming a p electrode on the anti-reflection structure, wherein the orthographic projection of the p electrode on the surface of the substrate is completely overlapped with the orthographic projection of the indium tin oxide layer on the surface of the substrate.
Illustratively, the p-electrode may be obtained by evaporation. The acquisition and preparation of the p electrode are easy.
Note that the p-electrode growth may also include: firstly, coating photoresist on a transparent conducting layer and forming a hole pattern on the photoresist; growing a p electrode in the hole; and removing the photoresist.
S214: and forming an n electrode on one surface of the substrate far away from the p electrode.
Alternatively, the n-electrode is obtained by evaporation. The obtained p-electrode and n-electrode have good quality.
In the two-material epitaxial structure with the alternate stacking, the two-material epitaxial structure with the alternate stacking can be obtained by alternately introducing the growth sources corresponding to the two materials into the reaction chamber.
It should be noted that, in the examples of the present disclosure, VeecoK 465i or C4 or RB MOCVD (Metal Organic Chemical Vapor deposition) was usedDeposition, metal organic chemical vapor Deposition) apparatus implements a method of growing LEDs. By using high-purity H2(Hydrogen) or high purity N2(Nitrogen) or high purity H2And high purity N2The mixed gas of (2) is used as a carrier gas, high-purity NH3As the N source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) as the gallium source, trimethyl indium (TMIn) as the indium source, disilane (Si) as the indium source2H6) As N-type dopant, trimethylaluminum (TMAl) as aluminum source, magnesium diclomentate (CP)2Mg) as a P-type dopant.
Although the present disclosure has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure.
Claims (10)
1. A red light diode chip with a reflection structure is characterized in that the red light diode chip comprises an epitaxial wafer, a p electrode and an n electrode,
the epitaxial wafer comprises a substrate, a reflecting structure, an n-type AlInP limiting layer, a light emitting layer, a p-type AlInP limiting layer, a p-type AlGaInP transition layer and a p-type GaP ohmic contact layer which are sequentially stacked on the substrate, the wavelength range of light reflected by the reflecting structure is 600-900 nm,
the reflecting structure comprises n Bragg reflectors which are sequentially stacked, n is an integer and is not less than 3, in the growth direction of the reflecting structure, the wavelength of light reflected by each Bragg reflector is gradually increased,
the p electrode is positioned on the p-type GaP ohmic contact layer, and the n electrode is positioned on one surface of the substrate far away from the p electrode.
2. The red led chip of claim 1, wherein the wavelengths of the light reflected by each of the bragg mirrors increase in an arithmetic progression in a growth direction of the reflective structure.
3. The red diode chip of claim 1, wherein the difference between the wavelengths of the light reflected by two adjacent bragg reflectors is 25nm to 115 nm.
4. The red diode chip as claimed in any one of claims 1 to 3, wherein each of said Bragg reflectors comprises AlAs reflective layers and AlGaAs reflective layers which are alternately stacked, and of the n Bragg reflectors, the number of AlAs reflective layers in a first Bragg reflector is greater than the number of AlAs reflective layers in a second Bragg reflector,
the first Bragg reflector is the Bragg reflector which is farthest from the light-emitting layer, and the second Bragg reflector is the Bragg reflector except the first Bragg reflector in the n Bragg reflectors.
5. The red diode chip of claim 4, wherein n-1 said second Bragg reflector mirrors have the same number of AlAs reflective layers.
6. The red light diode chip of claim 4, wherein the number of AlAs reflecting layers in the first Bragg reflector is 8-24.
7. The red light diode chip of claim 4, wherein the number of AlAs reflecting layers in the second Bragg reflector is 4-22.
8. The red diode chip of any one of claims 1 to 3, wherein the epitaxial wafer further comprises an anti-reflection structure, the anti-reflection structure is located between the p-type GaP ohmic contact layers and the p-electrode,
the anti-reflection structure comprises Ti3O5Layer and indium tin oxide layer, the Ti3O5A layer laminated on part of the surface of the p-type GaP ohmic contact layer, and an indium tin oxide layer laminated on the Ti3O5The p-type GaP ohmic contact layer is arranged on the substrate, the p-electrode is positioned on the indium tin oxide layer, and the orthographic projection of the p-electrode on the surface of the substrate is completely coincided with the orthographic projection of the indium tin oxide layer on the surface of the substrate.
9. The red diode chip of claim 8, wherein the Ti3O5The thickness of the layer is 55 nm-75 nm, and the thickness of the indium tin oxide layer is 80 nm-100 nm.
10. A preparation method of a red light diode chip with a reflection structure is characterized by comprising the following steps:
providing a substrate;
a reflecting structure, an n-type AlInP limiting layer, a light emitting layer, a p-type AlInP limiting layer, a p-type AlGaInP transition layer and a p-type GaP ohmic contact layer are sequentially grown on the substrate, the wavelength range of light reflected by the reflecting structure is 600-900 nm,
the reflecting structure comprises n Bragg reflectors which are sequentially stacked, n is an integer and is not less than 3, and the wavelength of light reflected by each Bragg reflector is gradually increased in the growth direction of the reflecting structure;
forming a p-electrode on the p-type GaP ohmic contact layer;
and forming an n electrode on one surface of the substrate far away from the p electrode.
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| CN114975708A (en) * | 2022-08-02 | 2022-08-30 | 江西兆驰半导体有限公司 | Front-mounted red and yellow light LED chip and preparation method thereof |
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Cited By (1)
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| CN114975708A (en) * | 2022-08-02 | 2022-08-30 | 江西兆驰半导体有限公司 | Front-mounted red and yellow light LED chip and preparation method thereof |
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Application publication date: 20211008 |