CN114927601B - Light emitting diode and preparation method thereof - Google Patents

Light emitting diode and preparation method thereof Download PDF

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Publication number
CN114927601B
CN114927601B CN202210856078.8A CN202210856078A CN114927601B CN 114927601 B CN114927601 B CN 114927601B CN 202210856078 A CN202210856078 A CN 202210856078A CN 114927601 B CN114927601 B CN 114927601B
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layer
light
quantum dot
semiconductor layer
emitting diode
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CN114927601A (en
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程龙
郑文杰
曾家明
高虹
刘春杨
胡加辉
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Jiangxi Zhao Chi Semiconductor Co Ltd
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Jiangxi Zhao Chi Semiconductor 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
    • H01L33/02—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
    • H01L33/20—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 particular shape, e.g. curved or truncated substrate
    • H01L33/24—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 particular shape, e.g. curved or truncated substrate of the light emitting region, e.g. non-planar junction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound 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
    • H01L33/02—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
    • H01L33/04—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 quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—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 quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • 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
    • 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
    • H01L33/325—Materials of the light emitting region containing only elements of group III and group V of the periodic system containing nitrogen characterised by the doping materials

Abstract

The invention provides a light-emitting diode and a preparation method thereof, wherein the light-emitting diode comprises a substrate, and a first semiconductor layer, a light-emitting layer and a second semiconductor layer which are sequentially grown on the substrate; wherein a V-shaped pit is formed on the light-emitting layer by epitaxial process, and a Mg quantum dot layer are sequentially grown in the V-shaped pit from the inner wall surface of the V-shaped pit 3 N 2 Quantum dot layer and MgGaN layer. By sequentially growing Mg quantum dot layer and Mg in the V-shaped pits 3 N 2 Quantum dot layer and MgGaN layer have promoted the injection efficiency of hole on the luminescent layer, have solved the poor technical problem of emitting diode luminous efficiency among the prior art.

Description

Light emitting diode and preparation method thereof
Technical Field
The invention relates to the technical field of photoelectricity, in particular to a light-emitting diode and a preparation method thereof.
Background
Third generation semiconductor materials of V-III group represented by GaN have larger width so that they have higher breakdown voltage, better thermal stability, higher saturated electron drift rate, and LEDs (light emitting diodes) from ultraviolet to infrared bands can be manufactured by doping elements such as Al, In, etc. to form different forbidden band widths.
GaN epitaxial layers are typically grown on foreign substrates (e.g., sapphire, SiC, silicon substrates, etc.) that produce many dislocations or defects by heteroepitaxial growth on the foreign substrate via a Metal Organic Chemical Vapor Deposition (MOCVD) system. These dislocations and defects include threading dislocations, stacking faults, inversion domains, etc., and these defects may cause the generation of "V-pits". In conventional semiconductor physics, defects are generally considered to be a detrimental factor to device performance. Therefore, in the early stage of developing the gallium nitride thin film growth technology, V-pits were regarded as defects, affecting the internal quantum efficiency of the light emitting diode, but recent studies have shown that V-pits have a shielding effect on defects and also have a large influence on the injection efficiency of holes.
GaN epitaxy, because it is heteroepitaxy, produces many dislocations and defects and thus V-pits. Although V-type pit can improve the hole injection quantum efficiency and thus improve the light emission efficiency, in the epitaxial structure of GaN light emitting diode, the hole injection efficiency of V-type pit is greatly affected by the material in the V-type pit itself. Generally, the V-type pit is made of GaN material and lacks P-type doping, so that the injection efficiency of holes into the quantum well is low, and the light emitting efficiency of the light emitting diode is poor.
Disclosure of Invention
Based on this, the present invention provides a light emitting diode and a method for manufacturing the same, which are used to solve the technical problem of poor light emitting efficiency of the light emitting diode in the prior art.
The invention provides a light-emitting diode which comprises a substrate, a first semiconductor layer, a light-emitting layer and a second semiconductor layer, wherein the first semiconductor layer, the light-emitting layer and the second semiconductor layer are sequentially grown on the substrate;
wherein a V-shaped pit is formed on the light-emitting layer by an epitaxial process, and a Mg quantum dot layer are sequentially grown in the V-shaped pit from the inner wall surface of the V-shaped pit 3 N 2 Quantum dot layer and MgGaN layer.
Further, in the light emitting diode, the thickness of the Mg quantum dot layer is 1-10 nm, and Mg 3 N 2 The quantum dot layer is 1-20 nm thick, and the MgGaN layer is 5-50 nm thick.
Further, the light emitting diode, wherein the depth of the V-shaped pit is 50-500 nm, and the width of the opening of the V-shaped pit is 60-600 nm.
Further, the light emitting diode, wherein the first semiconductor layer comprises a buffer layer, a non-doped GaN layer and an N-type semiconductor layer which are grown on the substrate in sequence; the second semiconductor layer includes an electron blocking layer and a P-type semiconductor layer sequentially grown on the light emitting layer.
In another aspect, the present invention provides a method for manufacturing a light emitting diode, including:
providing a substrate;
sequentially growing a first semiconductor layer and a light-emitting layer on the substrate, wherein the light-emitting layer is provided with a V-shaped pit formed by an epitaxial process;
sequentially growing a Mg quantum dot layer and Mg on the inner wall surface of the V-shaped pit 3 N 2 A quantum dot layer and a MgGaN layer;
and growing a second semiconductor layer on the light emitting layer.
Further, the preparation method of the light emitting diode epitaxial wafer comprises the step of growing a Mg quantum dot layer and Mg on the inner wall surface of the V-shaped pit in sequence 3 N 2 The quantum dot layer and the MgGaN layer specifically comprise the following steps:
in the first stage, N is introduced 2 、H 2 And a magnesium source, and controlling said N 2 、H 2 And the reaction temperature of the magnesium source is within a first preset temperature range until a Mg quantum dot layer with a first preset thickness grows on the inner wall surface of the V-shaped pit;
second stage, NH is introduced 3 And controlling said N 2 、H 2 、NH 3 And the reaction temperature of the magnesium source is in a first preset temperature range until the Mg with a second preset thickness grows on the Mg quantum dot layer 3 N 2 A quantum dot layer;
in the third stage, gallium source is introduced and the N is controlled 2 、H 2 、NH 3 The reaction temperature of the magnesium source and the gallium source is in a first preset temperature range until the reaction temperature is in the range of the Mg 3 N 2 Quantum dot layerAnd growing a MgGaN layer with a third preset thickness.
Further, according to the preparation method of the light emitting diode epitaxial wafer, MOCVD equipment is adopted from the first stage to the third stage, and the growth pressure of a reaction cavity in the MOCVD equipment is 100-500 torr in the first stage to the third stage.
Further, the preparation method of the light emitting diode epitaxial wafer is characterized in that the first preset temperature range is 700-850 ℃.
Further, the preparation method of the light emitting diode epitaxial wafer is characterized in that the Mg doping concentration in the MgGaN layer is 1E + 19-1E +20atoms/cm 3 。
Further, the method for preparing the light emitting diode epitaxial wafer, wherein the step of sequentially growing the first semiconductor layer and the light emitting layer on the substrate specifically comprises:
sequentially growing a buffer layer, a non-doped GaN layer, an N-type semiconductor layer and a light-emitting layer on the substrate;
the step of growing a second semiconductor layer on the light-emitting layer specifically includes:
and sequentially growing an electron blocking layer and a P-type semiconductor layer on the light emitting layer.
Compared with the prior art, the invention has the beneficial effects that: sequentially growing Mg quantum dot layer and Mg in the V-shaped pit 3 N 2 The quantum dot layer and the MgGaN layer improve the injection efficiency of holes on the light-emitting layer and solve the technical problem of poor light-emitting efficiency of the light-emitting diode in the prior art.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic view of a layered structure of a light emitting diode according to a first embodiment of the present invention;
FIG. 2 is a partial three-dimensional physical image of a light-emitting layer in a first embodiment of the invention;
FIG. 3 is a flow chart of a method for fabricating a light emitting diode according to an eleventh embodiment of the present invention;
the following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Example one
Referring to fig. 1, a light emitting diode according to a first embodiment of the invention is shown, which includes a substrate 100, and a first semiconductor layer, a light emitting layer 500 and a second semiconductor layer sequentially grown on the substrate 100;
wherein, a V-shaped pit is formed on the light-emitting layer 500 by epitaxial process, and a Mg quantum dot layer 610 and a Mg quantum dot layer are sequentially grown in the V-shaped pit from the inner wall surface 3 N 2 Quantum dot layer 620, and MgGaN layer 630.
Specifically, in this embodiment, the first semiconductor layer includes a buffer layer 200, an undoped GaN layer 300, and an N-type semiconductor layer 400 sequentially grown on the substrate 100; the second semiconductor layer includes an electron blocking layer 700 and a P-type semiconductor layer 800 sequentially grown on the light emitting layer 500.
Preferably, In this embodiment, the depth of the V-pit between the light emitting layer 500 and the electron blocking layer 700 is 200nm, the width of the opening of the V-pit is 250nm, the Mg quantum dot layer 610 is deposited on the light emitting layer 500 with the V-pit, the thickness of the Mg quantum dot layer 610 is 3nm, wherein the In component of the sidewall quantum well of the V-pit is lower, and the width of the well is thinner, which results In that the forbidden bandwidth of the sidewall quantum well is higher than that of the mesa quantum well by several hundred meV, the higher barrier can block the migration of carriers from the mesa quantum well to the sidewall quantum well, so that the carriers are far away from the dislocations at the bottom of the V-pit, and the Mg quantum dot layer 610 can more effectively improve the hole injection efficiency at the sidewall.
Wherein Mg is deposited on the Mg Quantum dot layer 610 3 N 2 Quantum dot layer 620, Mg 3 N 2 The quantum dot layer 620 has a thickness of 7nm, and the introduction of the Mg quantum dot layer 610 can effectively improve Mg 3 N 2 In addition, due to Mg 3 N 2 Quantum dot layer 620 is an ionic compound and thus more susceptible to ionization of Mg 2+ Therefore, the transmission efficiency and the hole injection efficiency of the P layer are improved, and the luminous efficiency of the LED device is improved.
In the presence of Mg 3 N 2 A MgGaN layer 630 is deposited on the quantum dot layer 620, the thickness of the MgGaN layer 630 is 15nm, and the doping concentration of Mg in the MgGaN layer 630 is 5E +19atoms/cm 3 The MgGaN layer 630 provides enough holes for the quantum well to emit light, and ensures the electron and hole recombination efficiency of the quantum well.
It should be explained that under proper growth conditions, each threading dislocation in the material forms a V-shaped pit when the quantum well grows, the quantum well grows in the V-shaped pit to form a sidewall quantum well, the thickness of the sidewall quantum well is thinner than that of the c-plane quantum well, the forbidden bandwidth is larger, because the sidewall quantum well with the larger forbidden bandwidth grows at the periphery of the threading dislocation, a physical image as shown in fig. 2 is formed, barriers are formed around the threading dislocation for carriers, the barrier height is the forbidden bandwidth difference between the sidewall quantum well and the c-plane quantum well, and the barriers block carriers from approaching the dislocation, thereby avoiding being captured by the dislocation and improving the efficiency of radiative recombination.
P-type doping of GaN is relatively difficult, with P-type doping concentrations much lower than N-type doping concentrations. Meanwhile, the effective mass of the holes is much larger than that of the electrons, resulting in much smaller mobility of the holes than that of the electrons. Due to the two factors, the injection rate of holes into the multiple quantum well region is far smaller than that of electrons, so that the mismatching of the injection of the electrons and the holes is caused, the luminous efficiency of the LED is limited, and the luminous efficiency is attenuated under large current. The P-type semiconductor layer 800 enables Mg to better replace Ga sites, reduces the formation of Mg-H bonds, improves the activation performance and doping concentration of Mg of a P-type layer, and improves the activation efficiency and doping efficiency of Mg.
In summary, in the light emitting diode of the above embodiments of the invention, the Mg quantum dot layer and the Mg layer are sequentially grown in the V-shaped pit 3 N 2 Quantum dot layer and MgGaN layer have promoted the injection efficiency of hole on the luminescent layer, have solved the poor technical problem of emitting diode luminous efficiency among the prior art.
Example two
This example is substantially the same as example 1 except that the doping concentration of Mg in the MgGaN layer 630 was 1E +19atoms/cm 3 。
EXAMPLE III
This example is substantially the same as example 1 except that the doping concentration of Mg in the MgGaN layer 630 was 1E +20atoms/cm 3 。
Example four
This example is substantially the same as example 1 except that the MgGaN layer 630 has a thickness of 20 nm.
EXAMPLE five
This embodiment is substantially the same as embodiment 1 except that the Mg quantum dot layer 610 has a thickness of 1 nm.
EXAMPLE six
This embodiment is substantially the same as embodiment 1 except that the Mg quantum dot layer 610 has a thickness of 10 nm.
EXAMPLE seven
This example is substantially the same as example 1 except that Mg 3 N 2 Quantum dot layer 620 is 1nm thick.
Example eight
This example is substantially the same as example 1 except that Mg 3 N 2 Quantum dot layer 620 is 20nm thick.
Example nine
This example is substantially the same as example 1 except that the MgGaN layer 630 has a thickness of 5 nm.
Example ten
This example is substantially the same as example 1 except that the MgGaN layer 630 has a thickness of 50 nm.
In summary, the light efficiency improvement of the product obtained in the above embodiment is measured, and the result is shown in table 1.
If the sample A and the sample B are prepared into 10 mil by 24 mil chips by using the same chip process conditions, wherein the sample A is a chip prepared by mass production at present, the sample B is a chip prepared by the scheme, 300 LED chips are respectively extracted from the two samples, and as can be seen from table 1, the photoelectric efficiency is improved by 1-2% when the chip is tested under the current of 120 mA/60 mA, and other electrical properties are good.
TABLE 1
Figure 791592DEST_PATH_IMAGE001
EXAMPLE eleven
A method for manufacturing a light emitting diode according to an eleventh embodiment of the present invention includes:
step S101, providing a substrate;
specifically, the substrate can be sapphire substrate or SiO 2 One of a sapphire composite substrate, a silicon carbide substrate, a gallium nitride substrate and a zinc oxide substrate.
In the embodiment, the substrate is a sapphire substrate, sapphire is the most common GaN-based LED substrate material at present, and most GaN-based LEDs in the market use sapphire as the substrate material. The sapphire substrate has the biggest advantages of mature technology, good stability and low production cost.
Step S102, sequentially growing a first semiconductor layer and a light-emitting layer on the substrate, wherein the light-emitting layer is provided with a V-shaped pit formed by an epitaxial process;
specifically, the first semiconductor layer comprises a buffer layer, a non-doped GaN layer and an N-type semiconductor layer which are sequentially grown on the substrate.
Optionally, the growth temperature of the N-type semiconductor layer is 1050-1200 ℃, the pressure is 100-600 torr, the thickness is 2-3 um, and the Si doping concentration is 1E 19-5E 19atoms/cm 3 。
In this embodiment, the growth temperature of the N-type semiconductor layer is 1120 ℃, the growth pressure is 100torr, the growth thickness is 2-3 um, and the Si doping concentration is 2.5E19atoms/cm 3 Firstly, the N-type semiconductor layer provides sufficient electrons for LED luminescence, secondly, the resistivity of the N-type semiconductor layer is higher than that of the transparent electrode on the P-type semiconductor layer, therefore, sufficient Si doping can effectively reduce the resistivity of the N-type semiconductor layer, and finally, the sufficient thickness of the N-type semiconductor layer can effectively release the luminous efficiency of the stress light-emitting diode.
Optionally, the light emitting layer is an In-GaN quantum well layer and an Al-GaN quantum barrier layer which are alternately stacked, the number of stacking cycles is 6-12, wherein the growth temperature of the In-GaN quantum well layer is 790-810 ℃, the thickness of the In-GaN quantum well layer is 2-5 nm, the growth pressure is 50-300 torr, the growth temperature of the Al-GaN quantum barrier layer is 800-900 ℃, the thickness of the Al-GaN quantum barrier layer is 5-15 nm, the growth pressure is 50-300 torr, and the Al component is 0.01-0.1.
Specifically, the light emitting layer is an In-GaN quantum well layer and an Al-GaN quantum barrier layer which are alternately stacked, the number of stacking cycles is 10, the growth temperature of the In-GaN quantum well is 795 ℃, the thickness of the In-GaN quantum well is 3.5nm, the pressure is 200torr, the In component is 0.22, the growth temperature of the Al-GaN quantum barrier layer is 855 ℃, the thickness of the Al-GaN quantum barrier layer is 9.8nm, the growth pressure is 200torr, the Al component is 0.05, the multi-quantum well active region is a region where electrons and holes are compounded, the overlapping degree of wave functions of the electrons and the holes can be obviously increased through reasonable structural design, and therefore the light emitting efficiency of the LED device is improved.
Step S103, growing a Mg quantum dot layer and Mg in sequence from the inner wall surface of the V-shaped pit 3 N 2 A quantum dot layer and a MgGaN layer;
step S104, growing a second semiconductor layer on the light emitting layer.
Specifically, the second semiconductor layer includes an electron blocking layer and a P-type semiconductor layer sequentially grown on the light emitting layer.
Optionally, the growth temperature of the P-type semiconductor layer is 900-The growth pressure is 100-600 torr, the Mg doping concentration is 1E + 19-1E +21atoms/cm 3 。
In this embodiment, the growth temperature of the P-type semiconductor layer is 985 deg.C, the thickness is 15nm, the growth pressure is 200torr, and the Mg doping concentration is 2E +20atoms/cm 3 Too high a doping concentration of Mg will deteriorate the crystal quality, while lower doping concentrations will affect the hole concentration. Meanwhile, for the LED structure containing the V-shaped pit, the higher growth temperature of the P-type semiconductor layer is also beneficial to combining the V-shaped pit, and the LED epitaxial wafer with the smooth surface is obtained.
In summary, in the method for manufacturing the light emitting diode according to the above embodiment of the invention, the Mg quantum dot layer and the Mg layer are sequentially grown in the V-shaped pit 3 N 2 Quantum dot layer and MgGaN layer have promoted the injection efficiency of hole on the luminescent layer, have solved the poor technical problem of emitting diode luminous efficiency among the prior art.
Example twelve
A method for manufacturing a light emitting diode according to a twelfth embodiment of the present invention includes:
step S11, providing a substrate;
specifically, the substrate can be sapphire substrate or SiO 2 One of a sapphire composite substrate, a silicon carbide substrate, a gallium nitride substrate and a zinc oxide substrate.
In the embodiment, the substrate is a sapphire substrate, sapphire is the most common GaN-based LED substrate material at present, and most GaN-based LEDs in the market use sapphire as the substrate material. The sapphire substrate has the biggest advantages of mature technology, good stability and low production cost.
Step S12, sequentially growing a first semiconductor layer and a light-emitting layer on the substrate, wherein the light-emitting layer is provided with a V-shaped pit formed by an epitaxial process;
specifically, the first semiconductor layer comprises a buffer layer, a non-doped GaN layer and an N-type semiconductor layer which are sequentially grown on the substrate.
Optionally, the growth temperature of the N-type semiconductor layer is 1050-1200 ℃, the pressure is 100-600 torr, the thickness is 2-3 um, the Si doping concentration is 1E 19-5E 19atoms/cm 3 。
In this embodiment, the growth temperature of the N-type semiconductor layer is 1120 ℃, the growth pressure is 100torr, the growth thickness is 2-3 um, and the Si doping concentration is 2.5E19atoms/cm 3 Firstly, the N-type semiconductor layer provides sufficient electrons for LED luminescence, secondly, the resistivity of the N-type semiconductor layer is higher than that of the transparent electrode on the P-type semiconductor layer, therefore, sufficient Si doping can effectively reduce the resistivity of the N-type semiconductor layer, and finally, the sufficient thickness of the N-type semiconductor layer can effectively release the luminous efficiency of the stress light-emitting diode.
Optionally, the light emitting layer is an In-GaN quantum well layer and an Al-GaN quantum barrier layer which are alternately stacked, the number of stacking cycles is 6-12, wherein the growth temperature of the In-GaN quantum well layer is 790-810 ℃, the thickness of the In-GaN quantum well layer is 2-5 nm, the growth pressure is 50-300 torr, the growth temperature of the Al-GaN quantum barrier layer is 800-900 ℃, the thickness of the Al-GaN quantum barrier layer is 5-15 nm, the growth pressure is 50-300 torr, and the Al component is 0.01-0.1.
Specifically, the light emitting layer is an In-GaN quantum well layer and an Al-GaN quantum barrier layer which are alternately stacked, the number of stacking cycles is 10, the growth temperature of the In-GaN quantum well is 795 ℃, the thickness of the In-GaN quantum well is 3.5nm, the pressure is 200torr, the In component is 0.22, the growth temperature of the Al-GaN quantum barrier layer is 855 ℃, the thickness of the Al-GaN quantum barrier layer is 9.8nm, the growth pressure is 200torr, the Al component is 0.05, the multi-quantum well active region is a region where electrons and holes are compounded, the overlapping degree of wave functions of the electrons and the holes can be obviously increased through reasonable structural design, and therefore the light emitting efficiency of the LED device is improved.
Step S13, growing Mg quantum dot layer and Mg in sequence from the inner wall surface of the V-shaped pit 3 N 2 A quantum dot layer and a MgGaN layer;
step S14, growing a second semiconductor layer on the light emitting layer.
Specifically, the second semiconductor layer includes an electron blocking layer and a P-type semiconductor layer sequentially grown on the light emitting layer. Optionally, the growth temperature of the P-type semiconductor layer is 900- 3 。
In this example, the growth temperature of the P-type semiconductor layer was 985 ℃ and the thickness was 15nmThe growth pressure is 200torr, the Mg doping concentration is 2E +20atoms/cm 3 Too high a doping concentration of Mg will deteriorate the crystal quality, while lower doping concentrations will affect the hole concentration. Meanwhile, for the LED structure containing the V-shaped pit, the higher growth temperature of the P-type semiconductor layer is also beneficial to combining the V-shaped pit, and the LED epitaxial wafer with the smooth surface is obtained.
Further, the Mg quantum dot layer and the Mg are grown on the inner wall surface of the V-shaped pit in sequence 3 N 2 The quantum dot layer and the MgGaN layer specifically comprise the following steps:
in the first stage, N is introduced 2 、H 2 And a magnesium source, and controlling said N 2 、H 2 And the reaction temperature of the magnesium source is within a first preset temperature range until a Mg quantum dot layer with a first preset thickness grows on the inner wall surface of the V-shaped pit;
second stage, NH is introduced 3 And controlling said N 2 、H 2 、NH 3 And the reaction temperature of the magnesium source is in a first preset temperature range until the Mg with a second preset thickness grows on the Mg quantum dot layer 3 N 2 A quantum dot layer;
in the third stage, gallium source is introduced and the N is controlled 2 、H 2 、NH 3 The reaction temperature of the magnesium source and the gallium source is in a first preset temperature range until the reaction temperature is in the range of the Mg 3 N 2 And growing a MgGaN layer with a third preset thickness on the quantum dot layer.
Specifically, MOCVD equipment is adopted from the first stage to the third stage, and the growth pressure of a reaction cavity in the MOCVD equipment is 100-500 torr in the first stage to the third stage.
Preferably, in this embodiment, the first predetermined thickness of the Mg quantum dot layer is 3nm, which can further effectively improve the hole injection efficiency at the sidewall. Mg (magnesium) 3 N 2 The second thickness of the quantum dot layer is 7nm, which can effectively increase Mg 3 N 2 The crystal quality of (a); the third thickness of the MgGaN layer is 15nm, so that enough holes are provided for the quantum well to emit light, and the electron and hole recombination efficiency of the quantum well is ensured.
Further, the first preset temperature range is 700-850 ℃, and the Mg doping concentration in the MgGaN layer is 1E + 19-1E +20atoms/cm 3 。
In the embodiment, the depth of a V-shaped pit between a multiple quantum well and an electron barrier layer is 200nm, the width of an opening of the V-shaped pit is 250nm, an Mg quantum dot layer is firstly deposited on the multiple quantum well layer with the V-shaped pit, the thickness is 3nm, the pressure of a reaction cavity is controlled to be 200torr, and the first preset temperature is 760 ℃;
deposition of Mg on Mg Quantum dot layers 3 N 2 The quantum dot layer is 7nm in thickness, the pressure of the reaction cavity is controlled to be 200torr, and the first preset temperature is 760 ℃;
in the presence of Mg 3 N 2 Depositing a MgGaN layer on the quantum dot layer, wherein the Mg doping concentration is 5E +19atoms/cm 3 The thickness is 15nm, the pressure of the reaction cavity is controlled to be 200torr, and the first preset temperature is 760 ℃.
Further, the step of sequentially growing the first semiconductor layer and the light emitting layer on the substrate specifically includes:
sequentially growing a buffer layer, a non-doped GaN layer, a first semiconductor layer and a light-emitting layer on the substrate;
the step of growing a second semiconductor layer on the light-emitting layer specifically includes:
and sequentially growing an electron blocking layer and a P-type semiconductor layer on the light emitting layer.
In this example, medium-micro A7MOCVD (Metal-organic Chemical Vapor Deposition, MOCVD for short) equipment is used for high-purity H 2 (Hydrogen gas), high purity N 2 (Nitrogen), high purity H 2 And high purity N 2 One of the mixed gases of (1) is used as a carrier gas, high-purity NH is added 3 As the N source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) as gallium sources, trimethyl indium (TMIn) as indium sources, trimethyl aluminum (TMAl) as aluminum sources, Silane (SiH) 4 ) As N-type dopant, magnesium dicocene (CP) 2 Mg) as a P-type dopant.
In this embodiment, the buffer layer is specifically an AlN buffer layer, the thickness of which is 15nm, and the AlN buffer layer is used to control crystal defects, improve the quality of subsequently grown crystals, and relieve stress between the substrate and the epitaxial layer due to lattice mismatch and thermal mismatch.
Transferring the sapphire substrate plated with the AlN buffer layer into MOCVD, and performing annealing at H 2 And (3) pretreating the sapphire substrate for 1-10 min at the temperature of 1000-1200 ℃ in the atmosphere, and then nitriding the sapphire substrate, so that the crystal quality of the AlN buffer layer is improved, and the crystal quality of the post-deposition GaN epitaxial layer can be effectively improved.
Optionally, the growth temperature of the non-doped GaN layer is 1050-1200 ℃, the pressure is 100-600 torr, and the thickness is 1-5 um.
In the embodiment, the growth temperature of the undoped GaN layer is 1100 ℃, the growth pressure is 150torr, the growth thickness is 2-3 um, the growth temperature of the undoped GaN layer is higher, the pressure is lower, the crystal quality of the prepared GaN is better, meanwhile, the thickness is increased along with the thickness of the GaN, the compressive stress can be released through stacking faults, the line defects are reduced, the crystal quality is improved, the reverse leakage is reduced, the consumption of the GaN layer thickness on Ga source materials is higher, the epitaxial cost of the LED is greatly improved, therefore, the LED epitaxial wafer is usually grown by 2-3 um in the undoped GaN, the production cost is saved, and the GaN material has higher crystal quality.
Optionally, the thickness of the electron blocking layer is 10-40 nm for AlInGaN, the growth temperature is 900-.
Specifically, the electron blocking layer is AlInGaN with the thickness of 15nm, wherein the concentration of Al components gradually changes from 0.01 to 0.05 along the growth direction of the epitaxial layer, the concentration of In components is 0.01, the growth temperature is 965 ℃, the growth pressure is 200torr, the electron overflow can be effectively limited, the blocking of holes can be reduced, the injection efficiency of the holes to a quantum well is improved, the auger recombination of carriers is reduced, and the light emitting efficiency of the light emitting diode is improved.
In summary, in the method for manufacturing the light emitting diode according to the above embodiment of the invention, the Mg quantum dot layer and the Mg layer are sequentially grown in the V-shaped pit 3 N 2 The quantum dot layer and the MgGaN layer improve the injection efficiency of the holes on the light-emitting layer, and solve the problem of poor light-emitting efficiency of the light-emitting diode in the prior artTo solve the technical problem of (1).
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The light-emitting diode is characterized by comprising a substrate, and a first semiconductor layer, a light-emitting layer and a second semiconductor layer which are sequentially grown on the substrate;
wherein a V-shaped pit is formed on the light-emitting layer by an epitaxial process, and a Mg quantum dot layer are sequentially grown in the V-shaped pit from the inner wall surface of the V-shaped pit 3 N 2 Quantum dot layer and MgGaN layer.
2. The LED of claim 1 wherein the Mg quantum dot layer has a thickness of 1-10 nm, and Mg 3 N 2 The quantum dot layer is 1-20 nm thick, and the MgGaN layer is 5-50 nm thick.
3. The light-emitting diode according to claim 1, wherein the depth of the V-shaped pit is 50to 500nm, and the width of the V-shaped pit opening is 60 to 600 nm.
4. The light-emitting diode according to claim 1, wherein the first semiconductor layer comprises a buffer layer, an undoped GaN layer and an N-type semiconductor layer sequentially grown on the substrate; the second semiconductor layer includes an electron blocking layer and a P-type semiconductor layer sequentially grown on the light emitting layer.
5. A method for preparing a light-emitting diode, the method comprising:
providing a substrate;
sequentially growing a first semiconductor layer and a light-emitting layer on the substrate, wherein the light-emitting layer is provided with a V-shaped pit formed by an epitaxial process;
sequentially growing a Mg quantum dot layer and Mg on the inner wall surface of the V-shaped pit 3 N 2 A quantum dot layer and a MgGaN layer;
and growing a second semiconductor layer on the light emitting layer.
6. The method of claim 5, wherein the growing of the Mg quantum dot layer, the Mg quantum dot layer and the Mg quantum dot layer from the inner wall surface of the V-shaped pit in sequence 3 N 2 The quantum dot layer and the MgGaN layer specifically comprise the following steps:
in the first stage, N is introduced 2 、H 2 And a magnesium source, and controlling said N 2 、H 2 And the reaction temperature of the magnesium source is within a first preset temperature range until a Mg quantum dot layer with a first preset thickness grows on the inner wall surface of the V-shaped pit;
second stage, NH is introduced 3 And controlling said N 2 、H 2 、NH 3 And the reaction temperature of the magnesium source is in a first preset temperature range until the Mg with a second preset thickness grows on the Mg quantum dot layer 3 N 2 A quantum dot layer;
in the third stage, gallium source is introduced and the N is controlled 2 、H 2 、NH 3 The reaction temperature of the magnesium source and the gallium source is in a first preset temperature range until the reaction temperature is in the range of Mg 3 N 2 And growing a MgGaN layer with a third preset thickness on the quantum dot layer.
7. The method for preparing the light-emitting diode according to claim 6, wherein MOCVD equipment is adopted in the first stage to the third stage, and the growth pressure of a reaction chamber in the MOCVD equipment is 100-500 torr in the first stage to the third stage.
8. The method for preparing the light-emitting diode according to claim 6, wherein the first predetermined temperature range is 700-850 ℃.
9. The method for preparing the light-emitting diode according to claim 6, wherein the Mg doping concentration in the MgGaN layer is 1E + 19-1E +20atoms/cm 3 。
10. The method for preparing a light-emitting diode according to claim 5, wherein the step of sequentially growing the first semiconductor layer and the light-emitting layer on the substrate specifically comprises:
sequentially growing a buffer layer, a non-doped GaN layer, an N-type semiconductor layer and a light-emitting layer on the substrate; the step of growing a second semiconductor layer on the light-emitting layer specifically includes:
and sequentially growing an electron blocking layer and a P-type semiconductor layer on the light emitting layer.
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