CN113540294B - Preparation method of low-ohmic contact ultraviolet light-emitting diode epitaxial wafer - Google Patents

Preparation method of low-ohmic contact ultraviolet light-emitting diode epitaxial wafer Download PDF

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CN113540294B
CN113540294B CN202110593081.0A CN202110593081A CN113540294B CN 113540294 B CN113540294 B CN 113540294B CN 202110593081 A CN202110593081 A CN 202110593081A CN 113540294 B CN113540294 B CN 113540294B
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ohmic contact
algan
layer
contact layer
ultraviolet light
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CN113540294A (en
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葛永晖
刘旺平
梅劲
刘春杨
陈张笑雄
王慧
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HC Semitek Zhejiang Co Ltd
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HC Semitek Zhejiang Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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
    • H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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
    • H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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
    • H01L33/0095—Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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 with at least one potential-jump barrier or surface barrier 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
    • H01L33/14—Semiconductor devices with at least one potential-jump barrier or surface barrier 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 carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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 with at least one potential-jump barrier or surface barrier 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
    • H01L33/26—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 system
    • H01L33/32—Materials of the light emitting region containing only elements of group III and group V of the periodic system containing nitrogen

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Abstract

The disclosure provides a preparation method of a low-ohmic contact ultraviolet light-emitting diode epitaxial wafer, and belongs to the technical field of light-emitting diodes. The AlGaN ohmic contact layer made of the intrinsic AlGaN material has good quality and high transmittance to ultraviolet light, and reduces the absorption to the ultraviolet light so as to improve the light extraction rate. Cl to ionize chlorine ‑ Acting on the surface of AlGaN ohmic contact layer, Cl ‑ The metal electrode has a covalent bond effect with Ga in the AlGaN ohmic contact layer, a chlorine monomolecular layer is formed on the surface of the ohmic contact layer, and the effect of obviously reducing the surface work function of the ohmic contact layer is achieved, so that the ohmic contact layer and a subsequent electrode metal conducting layer are favorably in good ohmic contact, the ohmic contact between the electrode metal and the AlGaN ohmic contact layer is low, the working voltage required by the ultraviolet light-emitting diode is low, and the service life of the ultraviolet light-emitting diode can be prolonged.

Description

Preparation method of low-ohmic contact ultraviolet light-emitting diode epitaxial wafer
Technical Field
The disclosure relates to the technical field of light emitting diodes, in particular to a preparation method of a low-ohmic contact ultraviolet light emitting diode epitaxial wafer.
Background
The ultraviolet light emitting diode is a light emitting product for photocuring, is commonly used for sterilization, disinfection, food sealing material curing, medical adhesive curing and the like, and the low-ohmic contact ultraviolet light emitting diode epitaxial wafer is a basic structure for preparing the ultraviolet light emitting diode. The low-ohmic contact ultraviolet light emitting diode epitaxial wafer generally comprises a substrate, and an n-type AlGaN layer, a GaN/AlGaN multi-quantum well layer, a p-type AlGaN layer and a p-type GaN ohmic contact layer which are grown on the substrate.
The p-type impurities in the p-type GaN ohmic contact layer are usually heavily doped to ensure that good ohmic contact can be formed between the p-type GaN ohmic contact layer and the electrode metal. However, the quality of the p-type GaN ohmic contact layer is reduced due to the highly doped p-type impurities, and the ultraviolet light is seriously absorbed by the p-type GaN ohmic contact layer, so that the light emitting efficiency of the finally obtained ultraviolet light emitting diode is not high.
Disclosure of Invention
The embodiment of the disclosure provides a preparation method of a low-ohmic-contact ultraviolet light emitting diode epitaxial wafer, which can ensure that good ohmic contact is formed with an electrode and effectively improve the light emitting efficiency of an ultraviolet light emitting diode.
The technical scheme is as follows:
the embodiment of the present disclosure provides a low-ohmic contact ultraviolet light emitting diode epitaxial wafer, and a preparation method of the low-ohmic contact ultraviolet light emitting diode epitaxial wafer includes:
providing a substrate;
growing an n-type AlGaN layer on the substrate;
growing a GaN/AlGaN multi-quantum well layer on the n-type AlGaN layer;
growing a P-type AlGaN layer on the GaN/AlGaN multi-quantum well layer;
growing an AlGaN ohmic contact layer on the P-type AlGaN layer, wherein the AlGaN ohmic contact layer is made of intrinsic AlGaN material;
cl ionizing chlorine gas - Acting on the surface of the AlGaN ohmic contact layer to reduce the work function of the surface of the AlGaN ohmic contact layer.
Optionally Cl ionizing said chlorine gas - The time length of acting on the surface of the AlGaN ohmic contact layer is 10-30 min.
Optionally Cl for ionizing the chlorine gas at the temperature of 200-300 DEG C - Acting on the surface of the AlGaN ohmic contact layer.
Optionally, Cl ionizing the chlorine gas under a pressure of 1-15 mTorr - Acting on the surface of the AlGaN ohmic contact layer.
Optionally, the thickness of the AlGaN ohmic contact layer is 10-100 nm.
Optionally, said Cl ionizing chlorine gas - Acting on the surface of the AlGaN ohmic contact layer, and comprising:
putting the substrate into radio frequency sputtering equipment or magnetron sputtering equipment;
introducing chlorine into the chamber of the radio frequency sputtering equipment or the magnetron sputtering equipment;
the radio frequency sputtering apparatus or the magnetron sputtering apparatus ionizes the chlorine gas and Cl that ionizes the chlorine gas - Acting on the surface of the AlGaN ohmic contact layer.
Optionally, the flow rate of the chlorine gas introduced into the chamber is 30-300 sccm.
Optionally, the power of ionizing the chlorine gas by the radio frequency sputtering equipment or the magnetron sputtering equipment is 500-800 w.
Optionally, after the substrate is placed in a radio frequency sputtering apparatus or a magnetron sputtering apparatus, before chlorine is introduced into the radio frequency sputtering apparatus or the chamber of the magnetron sputtering apparatus, the preparation method includes:
heating the substrate while vacuumizing the chamber until the vacuum degree of the chamber is lower than a pressure threshold and the temperature of the substrate reaches a temperature threshold; and maintaining the vacuum degree of the chamber at the pressure threshold and the temperature of the substrate at the temperature threshold for 2-12 minutes.
Optionally, the pressure threshold is equal to or less than 1 × 10 -7 Torr; the temperature threshold is 100-200 ℃.
The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure include:
the AlGaN ohmic contact layer made of the intrinsic AlGaN material has less impurities and better quality, and can form good lattice matching with the P-type AlGaN layer, so that the quality of the AlGaN ohmic contact layer on the P-type AlGaN layer can be further improved. And the AlGaN ohmic contact layer has larger broadband gap and very high transmittance to ultraviolet rays, and can reduce the absorption of the AlGaN ohmic contact layer to the ultraviolet rays so as to improve the light-emitting rate of the ultraviolet light-emitting diode. Cl to ionize chlorine - Acting on the surface of AlGaN ohmic contact layer, Cl - The chlorine monomolecular layer is formed on the surface of the ohmic contact layer and can play a role in modifying the surface of the ohmic contact layer, and ionized Cl - The nucleophilic substitution effect is carried out, a covalent bond exists between the nucleophilic substitution effect and Ga in the AlGaN ohmic contact layer, so that the effect of obviously reducing the surface work function of the ohmic contact layer is achieved, good ohmic contact between the ohmic contact layer and a subsequent electrode metal conducting layer is favorably formed, the ohmic contact between the electrode metal and the AlGaN ohmic contact layer is low, the working voltage required by the ultraviolet light-emitting diode is low, and the service life of the ultraviolet light-emitting diode can be prolonged.
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 flowchart of a method for manufacturing a low-ohmic contact ultraviolet light emitting diode epitaxial wafer according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a low-ohmic contact ultraviolet light emitting diode epitaxial wafer according to an embodiment of the present disclosure;
fig. 3 is a flowchart of another method for manufacturing an epitaxial wafer of a low-ohmic-contact ultraviolet light emitting diode according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of another low-ohmic-contact ultraviolet light emitting diode epitaxial wafer provided by an embodiment of the 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 flowchart of a method for manufacturing a low-ohmic contact ultraviolet light emitting diode epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 1, the method for manufacturing a low-ohmic contact ultraviolet light emitting diode epitaxial wafer includes:
s101: a substrate is provided.
S102: an n-type AlGaN layer is grown on a substrate.
S103: and growing a GaN/AlGaN multi-quantum well layer on the n-type AlGaN layer.
S104: and growing a P-type AlGaN layer on the GaN/AlGaN multi-quantum well layer.
S105: and growing an AlGaN ohmic contact layer on the P-type AlGaN layer, wherein the material of the AlGaN ohmic contact layer is an intrinsic AlGaN material.
S106: cl ionizing chlorine gas - Acting on the surface of the AlGaN ohmic contact layer to reduce the work function of the surface of the AlGaN ohmic contact layer.
The AlGaN ohmic contact layer made of the intrinsic AlGaN material has less impurities and better quality, and can form good lattice matching with the P-type AlGaN layer, so that the quality of the AlGaN ohmic contact layer on the P-type AlGaN layer can be further improved. And the AlGaN ohmic contact layer has larger broadband gap and very high transmittance to ultraviolet rays, and can reduce the absorption of the AlGaN ohmic contact layer to the ultraviolet rays so as to improve the light-emitting rate of the ultraviolet light-emitting diode. Cl to ionize chlorine - Acting on the surface of AlGaN ohmic contact layer, Cl - The chlorine monomolecular layer is formed on the surface of the ohmic contact layer and can play a role in modifying the surface of the ohmic contact layer, and ionized Cl - The nucleophilic substitution effect is carried out, a covalent bond exists between the nucleophilic substitution effect and Ga in the AlGaN ohmic contact layer, so that the effect of obviously reducing the surface work function of the ohmic contact layer is achieved, good ohmic contact between the ohmic contact layer and a subsequent electrode metal conducting layer is favorably formed, the ohmic contact between the electrode metal and the AlGaN ohmic contact layer is low, the working voltage required by the ultraviolet light-emitting diode is low, and the service life of the ultraviolet light-emitting diode can be prolonged.
Illustratively, in step S105, the thickness of the AlGaN ohmic contact layer is 10to 100 nm.
When the thickness of the AlGaN ohmic contact layer is within the range of 10-100 nm, the AlGaN ohmic contact layer has good quality, and can realize good adhesion with subsequent electrode metals, thereby ensuring the stable connection and use of the electrode metals.
Optionally, in step S105, the growth temperature of the P-type AlGaN layer is 950 to 1050 ℃, and the growth pressure of the P-type AlGaN layer is 100to 600 Torr.
When the growth temperature and the growth pressure of the P-type AlGaN layer are respectively in the above ranges, the quality of the obtained P-type AlGaN layer is better. And the growth rate of the P-type AlGaN layer is higher, so that the quality of the P-type AlGaN layer is effectively improved, the growth rate of the P-type AlGaN layer is improved, the quality of an ultraviolet light-emitting diode epitaxial wafer is improved, and the time cost is effectively controlled.
Optionally, in step S106, Cl ionized chlorine gas - The time length of acting on the surface of the AlGaN ohmic contact layer is 10-30 min.
Cl ionized by chlorine - The time for acting on the surface of the AlGaN ohmic contact layer is 10-30 min, so that the surface of the AlGaN ohmic contact layer and Cl can be ensured - The metal electrode layer is fully acted, a chlorine monomolecular layer can be stably formed, the ohmic contact between the AlGaN ohmic contact layer and the electrode metal is effectively reduced, and the working voltage of the ultraviolet light-emitting diode is reduced so as to prolong the service life of the ultraviolet light-emitting diode.
Optionally Cl for ionizing chlorine gas at the temperature of 200-300 DEG C - Acting on the surface of the AlGaN ohmic contact layer.
Can ensure the surface of the AlGaN ohmic contact layer and Cl - The metal electrode layer is fully acted, a chlorine monomolecular layer can be stably formed, the ohmic contact between the AlGaN ohmic contact layer and the electrode metal is effectively reduced, and the working voltage of the ultraviolet light-emitting diode is reduced so as to prolong the service life of the ultraviolet light-emitting diode.
Illustratively, Cl ionized with chlorine gas under a pressure of 1-15 mTorr - Acting on the surface of the AlGaN ohmic contact layer.
Under the condition that the pressure is 1-15 mTorr, Cl - The ultraviolet light-emitting diode can stably act on the surface of the AlGaN ohmic contact layer to form a chlorine monomolecular layer in a definite mode, and finally, the ohmic contact between the AlGaN ohmic contact layer and electrode metal is effectively reduced, and the working voltage of the ultraviolet light-emitting diode is reduced so as to prolong the service life of the ultraviolet light-emitting diode.
In step S106, Cl ionized by chlorine gas - Acting on the surface of the AlGaN ohmic contact layer, the AlGaN ohmic contact layer can comprise:
putting the substrate into radio frequency sputtering equipment or magnetron sputtering equipment; introducing chlorine into a chamber of radio frequency sputtering equipment or magnetron sputtering equipment; cl for ionizing chlorine gas by radio frequency sputtering equipment or magnetron sputtering equipment and ionizing chlorine gas - Acting on the surface of the AlGaN ohmic contact layer.
The radio frequency sputtering equipment or the magnetron sputtering equipment can quickly and effectively ionize the introduced chlorine and control the Cl ionized by the chlorine - The AlGaN ohmic contact layer is acted on the surface of the AlGaN ohmic contact layer, and the work function of the surface of the AlGaN ohmic contact layer is effectively ensured to be reduced.
It should be noted that after the chamber of the radio frequency sputtering apparatus or the magnetron sputtering apparatus is filled with chlorine gas, the metal target of the radio frequency sputtering apparatus or the magnetron sputtering apparatus may serve as a negative electrode, the surface of the AlGaN ohmic contact layer may serve as a positive electrode, and an electric field for ionizing chlorine gas is formed between the metal target and the AlGaN ohmic contact layer. Cl in chlorine 2 Under the combined action of Lorentz force of horizontal magnetic field and Coulomb force of vertical electric field, plasma is formed and makes circular motion in the cavity, in Cl 2 Ionized into Cl under the action of electric field coulomb force + And Cl - After ionization of Cl - Moving to the positive electrode of AlGaN ohmic contact layer, Cl - And then the work function of the surface of the AlGaN ohmic contact layer is effectively reduced by the action of the Ga in the AlGaN ohmic contact layer. The metal target is used as a cathode, the surface of the AlGaN ohmic contact layer is used as an anode, and the metal target can be realized by respectively connecting the cathode and the anode which are used for providing an electric field and are of a radio frequency sputtering device or a magnetron sputtering device.
Illustratively, the flow rate of the chlorine gas introduced into the chamber is 30-300 sccm.
The flow of the chlorine gas introduced into the cavity is 30-300 sccm, the flow of the introduced chlorine gas is stable, effective ionization of the chlorine gas can be supported, and the environment in the cavity is guaranteed to be stable and normal.
Optionally, the time for introducing the chlorine gas into the chamber is 1-2 hours. Can ensure that the chamber is filled with chlorine gas, more chlorine gas can meet the effective ionization of chlorine gas, ensure the environment in the chamber to be stable and normal, and is favorable for Cl - Stable reaction with the AlGaN ohmic contact layer.
Illustratively, the power of ionizing the chlorine gas by the radio frequency sputtering equipment or the magnetron sputtering equipment is 500-800 w.
The power of the radio frequency sputtering equipment or the magnetron sputtering equipment for ionizing the chlorine is 500-800 w, the chlorine can be stably ionized, and Cl is ensured - The source of the AlGaN ohmic contact layer is sufficient, and the AlGaN ohmic contact layer can be in full and comprehensive contact and reaction with the surface of the AlGaN ohmic contact layer, so that the work function of the surface of the finally obtained AlGaN ohmic contact layer is ensured to be small.
In one implementation manner provided by the present disclosure, after the substrate is placed in the radio frequency sputtering apparatus or the magnetron sputtering apparatus, before the chlorine gas is introduced into the chamber of the radio frequency sputtering apparatus or the magnetron sputtering apparatus, the preparation method may include:
heating the substrate while vacuumizing the chamber until the vacuum degree of the chamber is lower than a pressure threshold and the temperature of the substrate reaches a temperature threshold; and maintaining the vacuum degree of the chamber at a pressure threshold and the temperature of the substrate at a temperature threshold for 2-12 minutes.
The substrate is heated while the chamber is vacuumized, and heating and vacuuming are performed simultaneously, so that the preorder work for processing the AlGaN ohmic contact layer can be shortened, and the time cost of the ultraviolet light-emitting diode is reduced. Until the vacuum degree of the chamber is lower than the pressure threshold, and the temperature of the substrate reaches the temperature threshold, impurities on the surface of the AlGaN ohmic contact layer can be effectively removed, and the surface of the AlGaN ohmic contact layer and Cl are ensured - And stable reaction is carried out, so that the work function of the surface of the AlGaN ohmic contact layer can be effectively reduced. Maintaining the vacuum degree of the chamber at the pressure threshold and the temperature of the substrate at the temperature threshold for 2-12 minutesImpurities can be effectively removed, and the work function of the surface of the AlGaN ohmic contact layer can be effectively reduced.
Optionally, the pressure threshold is equal to or less than 1 × 10 -7 Torr; the temperature threshold is in the range of 100-200 ℃.
Pressure threshold value equal to or less than 1 x 10 -7 Torr; the temperature threshold range is 100-200 ℃, impurities can be effectively removed, and the preparation cost of the ultraviolet light-emitting diode cannot be excessively increased.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a low-ohmic contact ultraviolet light emitting diode epitaxial wafer provided in an embodiment of the present disclosure, and as shown in fig. 2, the embodiment of the present disclosure provides a low-ohmic contact ultraviolet light emitting diode epitaxial wafer, which includes a substrate 1, and an n-type AlGaN layer 2, a GaN/AlGaN multiple quantum well layer 3, a p-type AlGaN layer 4, and an AlGaN ohmic contact layer 5 sequentially stacked on the substrate 1.
Fig. 3 is a flowchart of a method for manufacturing another low-ohmic contact ultraviolet light emitting diode epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 3, the method for manufacturing the low-ohmic contact ultraviolet light emitting diode epitaxial wafer includes:
s201: a substrate is provided.
Alternatively, the substrate may be a sapphire substrate.
S202: and growing a buffer layer on the substrate, wherein the buffer layer is an AlN layer.
The AlN layer in step S202 may be obtained by magnetron sputtering.
Optionally, the AlN layer is sputtered at 400-700 deg.C under 3000-5000W and 1-10 torr. A buffer layer of better quality can be obtained.
Optionally, step S202 further includes: and carrying out in-situ annealing treatment on the buffer layer, wherein the temperature is 1000-1200 ℃, the pressure range is 150-500 Torr, and the time is 5-10 minutes. The crystal quality of the buffer layer can be further improved.
S203: and growing an undoped AlGaN layer on the buffer layer.
Optionally, the growth temperature of the undoped AlGaN layer is 1000-1200 ℃, and the pressure is 50-200 torr. The obtained undoped AlGaN layer has better quality, and the crystal quality of the finally obtained ultraviolet light-emitting diode can be improved.
Optionally, the undoped AlGaN layer is grown to a thickness of between 0.1 and 3.0 microns. The crystal quality of the finally obtained ultraviolet light emitting diode can be improved.
S204: and growing an n-type AlGaN layer on the undoped AlGaN layer.
Optionally, the n-type layer is a Si-doped n-type AlGaN layer. Easy preparation and acquisition.
Optionally, the growth temperature of the n-type AlGaN layer is 1000-1200 ℃, and the pressure is 50-200 torr. The obtained n-type AlGaN layer has better quality, and the crystal quality of the finally obtained ultraviolet light-emitting diode can be improved.
Illustratively, the n-type AlGaN layer is grown to a thickness of between 1 and 4.0 microns. The crystal quality of the finally obtained ultraviolet light emitting diode can be improved.
Illustratively, in the n-type AlGaN layer, the doping concentration of Si is 10 18 cm -3 -10 20 cm -3 In the meantime.
S205: and growing a GaN/AlGaN multi-quantum well layer on the n-type AlGaN layer.
Alternatively, the GaN/AlGaN multi quantum well layer may include a multi quantum well structure. The GaN/AlGaN multi-quantum well layer includes a plurality of alternately stacked GaN layers and Al x Ga 1-x N layer 0<x<0.3。
Illustratively, the growth temperature of the GaN layer ranges between 850 ℃ and 950 ℃, and the pressure ranges between 100Torr and 300 Torr; al (Al) x Ga 1-x The growth temperature of the N layer is 900-1000 ℃, and the growth pressure is 50-200 Torr. The GaN/AlGaN multi-quantum well layer with better quality can be obtained.
Optionally, the well thickness of the GaN layer is around 3nm and the barrier thickness is between 8nm and 20 nm. The obtained GaN/AlGaN multi-quantum well layer has good quality and reasonable cost.
S206: and growing an electron barrier layer on the GaN/AlGaN multi-quantum well layer.
Alternatively, the electron blocking layer may be p-type Al y Ga 1-y N layer 0.2<y<0.5。
Alternatively, p-type Al y Ga 1-y The growth temperature of the N layer is 900-1050 ℃, and the pressure is 50-200 torr. The obtained p-type doped AlGaN layer has better quality, and the crystal quality of the finally obtained ultraviolet light-emitting diode can be improved.
Illustratively, the p-type doped AlGaN layer is grown to a thickness of between 15 and 60 nanometers. The crystal quality of the finally obtained ultraviolet light emitting diode can be improved.
S207: and growing a p-type AlGaN layer on the electron blocking layer.
Optionally, the growth temperature of the p-type AlGaN layer is 850-1050 ℃, and the pressure is 50-200 torr. The obtained p-type AlGaN layer has better quality, and the crystal quality of the finally obtained ultraviolet light-emitting diode can be improved.
Illustratively, the p-type AlGaN layer is grown to a thickness of between 100 and 300 nanometers. The crystal quality of the finally obtained ultraviolet light emitting diode can be improved.
S208: and growing an AlGaN ohmic contact layer on the P-type AlGaN layer, wherein the material of the AlGaN ohmic contact layer is an intrinsic AlGaN material.
Step S208 can refer to step S105 of the preparation method shown in fig. 1, and therefore step S208 is not described herein again.
S209: and annealing the AlGAN ohmic contact layer.
Optionally, in step S209, the annealing temperature is 650 ℃ to 850 ℃, the annealing time is 5 to 15 minutes, and the temperature of the reaction chamber is reduced to 20 ℃ to 30 ℃ after annealing. The stress of the AlGAN ohmic contact layer can be effectively released, and the quality of the finally obtained low-ohmic contact ultraviolet light-emitting diode epitaxial wafer is improved.
The annealing here can improve the quality of the AlGAN ohmic contact layer, and can also improve the quality of the transparent conductive layer grown on the AlGAN ohmic contact layer. Heating in the subsequent transparent conducting layer forming process can further release stress existing in the low-ohmic contact ultraviolet light emitting diode epitaxial wafer, and the quality of the ultraviolet low-ohmic contact ultraviolet light emitting diode epitaxial wafer obtained finally is effectively improved.
S210: cl ionizing chlorine gas - Acting on the surface of the AlGaN ohmic contact layer to reduce the work function of the surface of the AlGaN ohmic contact layer.
Step S210 can refer to step S106 of the preparation method shown in fig. 1, and therefore step S210 is not described herein again.
The structure of the low ohmic contact uv led epitaxial wafer after step S210 is performed can be seen in fig. 4.
It should be noted that, in the embodiment of the present disclosure, a VeecoK 465i or C4 or RB MOCVD (Metal Organic Chemical Vapor Deposition) apparatus is adopted to implement the growth method of the LED. By using high-purity H 2 (Hydrogen) or high purity N 2 (Nitrogen) or high purity H 2 And high purity N 2 The mixed gas of (2) is used as a carrier gas, high-purity NH 3 As an N source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) as gallium sources, trimethyl indium (TMIn) as indium sources, silane (SiH4) as an N-type dopant, trimethyl aluminum (TMAl) as an aluminum source, and magnesium dicylocene (CP) 2 Mg) as a P-type dopant.
Fig. 4 is a schematic structural diagram of another low-ohmic contact ultraviolet light emitting diode epitaxial wafer according to an embodiment of the present disclosure, and as can be seen from fig. 4, in another implementation manner provided by an embodiment of the present disclosure, the low-ohmic contact ultraviolet light emitting diode epitaxial wafer having a transparent conductive layer 5 may include a substrate 1, and a buffer layer 6, an undoped AlGaN layer 7, an n-type AlGaN layer 2, a GaN/AlGaN multi-quantum well layer 3, an electron blocking layer 8, a p-type AlGaN layer 4, and an AlGaN ohmic contact layer 5, which are sequentially stacked on the substrate 1.
Illustratively, the buffer layer 6 is an AlN layer. The lattice mismatch of the structure behind the substrate 1 and the buffer layer 6 can be effectively alleviated.
Optionally, the thickness of the buffer layer 6 is 15-35 nm. The lattice mismatch can be effectively mitigated without unduly increasing the manufacturing cost.
Alternatively, the thickness of the undoped AlGaN layer 7 may be 0.1 to 3.0 micrometers.
The thickness of the undoped AlGaN layer 7 is proper, the cost is reasonable, and the quality of the ultraviolet light-emitting diode can be effectively improved.
Alternatively, the thickness of the n-type AlGaN layer 2 can be between 1.5 and 3.5 micrometers.
The n-type AlGaN layer 2 can provide carriers reasonably, and the quality of the n-type AlGaN layer 2 itself is also good.
Illustratively, the n-type element doped in the n-type AlGaN layer 2 may be a Si element.
Exemplarily, the GaN/AlGaN multi quantum well layer 3 may be a multi quantum well structure. The GaN/AlGaN multi quantum well layer 3 includes GaN layers 31 and AlxGa1-xN layers 32 alternately stacked, where 0< x < 0.3. The luminous efficiency is better.
The number of layers of the GaN layer 31 and the AlxGa1-xN layer 32 may be the same, and the number of layers may be 4 to 12. The obtained GaN/AlGaN multi-quantum well layer 3 has better quality and more reasonable cost.
Alternatively, the thickness of the GaN layer 31 may be around 3nm, and the thickness of the AlxGa1-xN layer 32 may be between 8nm and 20 nm. Carriers can be efficiently trapped and light can be emitted.
Illustratively, the electron blocking layer 8 may be P-type Al y Ga 1-y N layer 0.2<y<0.5, P type Al y Ga 1-y The thickness of the N layer may be between 15nm and 60 nm. The effect of blocking electrons is better.
Illustratively, the P-type AlGaN layer 4 may be a P-type doped AlGaN layer. Is convenient for preparation and acquisition.
Optionally, the thickness of the p-type AlGaN layer 4 is 50-300 nm. The obtained p-type AlGaN layer 4 has good quality as a whole.
It should be noted that the structure of the AlGAN ohmic contact layer 5 shown in fig. 4 is the same as the structure of the AlGAN ohmic contact layer 5 shown in fig. 2, and therefore, the description thereof is omitted.
Compared with the low-ohmic contact ultraviolet light emitting diode epitaxial wafer shown in fig. 2, the low-ohmic contact ultraviolet light emitting diode epitaxial wafer shown in fig. 4 has the advantages that the buffer layer 6, the undoped AlGaN layer 7, the electron blocking layer 8 and other hierarchical structures are added, and the quality of the finally obtained ultraviolet light emitting diode can be further improved.
Fig. 4 is only one implementation of the ultraviolet light emitting diode provided by the embodiment of the present disclosure, and in other implementations provided by the present disclosure, the ultraviolet light emitting diode may also be other forms of ultraviolet light emitting diodes including a reflective layer, which is not limited by the present disclosure.
It should be noted that, during the preparation of the electrode, the electrode can be prepared on the AlGAN ohmic contact layer 5, and the electrode is shown with Cl in FIG. 4 - The resulting layer of chlorine molecules 100 on the surface of the AlGAN ohmic contact layer 5 reacted with the AlGAN ohmic contact layer 5, and an electrode metal 200 forming an ohmic contact with the AlGAN ohmic contact layer 5 is also shown in FIG. 4. It should be noted that in practical situations the chlorine molecule layer 100 is difficult to detect, and fig. 4 illustrates the chlorine molecule layer 100 only for the sake of understanding. And the structure of the n-electrode that is normally present in the chip is omitted in fig. 4.
The invention is not to be considered as limited to the particular embodiments shown and described, but is to be understood that various modifications, equivalents, improvements and the like can be made without departing from the spirit and scope of the invention.

Claims (10)

1. A preparation method of a low-ohmic contact ultraviolet light emitting diode epitaxial wafer is characterized by comprising the following steps:
providing a substrate;
growing an n-type AlGaN layer on the substrate;
growing a GaN/AlGaN multi-quantum well layer on the n-type AlGaN layer;
growing a P-type AlGaN layer on the GaN/AlGaN multi-quantum well layer;
growing an AlGaN ohmic contact layer on the P-type AlGaN layer, wherein the AlGaN ohmic contact layer is made of intrinsic AlGaN material;
cl ionizing chlorine gas - Acting on the surface of the AlGaN ohmic contact layer to reduce the work function of the surface of the AlGaN ohmic contact layer.
2. The method of claim 1, wherein Cl ionized the chlorine gas - The time length of acting on the surface of the AlGaN ohmic contact layer is 10-30 min.
3. The method according to claim 1, wherein Cl ionized by the chlorine gas is generated at a temperature of 200to 300 ℃ - Acting on the surface of the AlGaN ohmic contact layer.
4. The method according to any one of claims 1 to 3, wherein Cl is ionized by chlorine gas under a pressure of 1 to 15mTorr - Acting on the surface of the AlGaN ohmic contact layer.
5. The method according to any one of claims 1 to 3, wherein the AlGaN ohmic contact layer has a thickness of 10to 100 nm.
6. A method according to any one of claims 1 to 3, wherein said Cl ionized by chlorine gas is - Acting on the surface of the AlGaN ohmic contact layer, and comprising:
putting the substrate into radio frequency sputtering equipment or magnetron sputtering equipment;
introducing chlorine into the chamber of the radio frequency sputtering equipment or the magnetron sputtering equipment;
the radio frequency sputtering apparatus or the magnetron sputtering apparatus ionizes the chlorine gas and Cl that ionizes the chlorine gas - Acting on the surface of the AlGaN ohmic contact layer.
7. The method according to claim 6, wherein the flow rate of the chlorine gas introduced into the chamber is 30 to 300 sccm.
8. The preparation method of claim 6, wherein the power for ionizing the chlorine gas by the radio frequency sputtering device or the magnetron sputtering device is 500-800 w.
9. The preparation method according to claim 6, wherein after the substrate is placed in a radio frequency sputtering device or a magnetron sputtering device, before chlorine gas is introduced into a chamber of the radio frequency sputtering device or the magnetron sputtering device, the preparation method comprises the following steps:
heating the substrate while vacuumizing the chamber until the vacuum degree of the chamber is lower than a pressure threshold and the temperature of the substrate reaches a temperature threshold; and maintaining the vacuum degree of the chamber at the pressure threshold and the temperature of the substrate at the temperature threshold for 2-12 minutes.
10. The method of claim 9, wherein the pressure threshold is equal to or less than 1 x 10 - 7 Torr; the temperature threshold is 100-200 ℃.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000223741A (en) * 1999-01-29 2000-08-11 Sharp Corp Nitride semiconductor light emitting element
JP2001308381A (en) * 2000-04-21 2001-11-02 Showa Denko Kk Group iii nitride semiconductor light-emitting element and manufacturing method thereof

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Publication number Priority date Publication date Assignee Title
US6936863B2 (en) * 2002-11-18 2005-08-30 Showa Denko K.K. Boron phosphide-based semiconductor light-emitting device, production method thereof and light-emitting diode

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000223741A (en) * 1999-01-29 2000-08-11 Sharp Corp Nitride semiconductor light emitting element
JP2001308381A (en) * 2000-04-21 2001-11-02 Showa Denko Kk Group iii nitride semiconductor light-emitting element and manufacturing method thereof

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