CN117790649A - LED structure and preparation method thereof - Google Patents
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- CN117790649A CN117790649A CN202311820137.7A CN202311820137A CN117790649A CN 117790649 A CN117790649 A CN 117790649A CN 202311820137 A CN202311820137 A CN 202311820137A CN 117790649 A CN117790649 A CN 117790649A
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- 229910002601 GaN Inorganic materials 0.000 claims description 80
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 claims description 65
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- UOSXPFXWANTMIZ-UHFFFAOYSA-N cyclopenta-1,3-diene;magnesium Chemical compound [Mg].C1C=CC=C1.C1C=CC=C1 UOSXPFXWANTMIZ-UHFFFAOYSA-N 0.000 description 2
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Abstract
The invention provides an LED structure and a preparation method thereof, wherein in the preparation process of the LED structure, P-type Al is formed under the conditions that the growth pressure is 100-300 torr, the growth temperature is 850-1050 ℃ and the growth rate is 5-30A/s x Ga 1‑x An N layer; p-type Al formed under the above growth conditions x Ga 1‑x The N layer has higher quality, can be used as an electron blocking layer for blocking electron leakage, limits electrons to the quantum well active layer for compound luminescence, and overcomes the defects of P-type Al x Ga 1‑x The problems of low doping efficiency of the N layer and insufficient hole injection are solved, and the output optical power of the InGaN/GaN-based LED structure is improved; and by increasing the growth temperature and slowing downThe growth rate and other measures can enhance the migration capacity of the atomic surface, and are favorable for combining V-shaped pits, so that the antistatic capacity of the LED is improved.
Description
Technical Field
The invention relates to the technical field of semiconductor photoelectrons, in particular to an LED structure and a preparation method thereof.
Background
GaN and its series materials (including AlN, alGaN, inGaN, inN materials) called third generation semiconductor, its forbidden band width changes from 0.7eV to 6.2eV, cover from infrared to ultraviolet band, have important application value in the field of photoelectronic device, wherein AlGaN material is widely used in preparing ultraviolet detector, luminescent diode, laser, field effect transistor, power device and high-temperature electronic component, etc.; in the InGaN/GaN-based LED material structure, a P-type AlGaN layer is usually positioned between a quantum well and P-type GaN, and the P-type AlGaN layer serves as an electron blocking layer to limit electrons in a quantum well region so as to overcome the problems that under the condition of high current density injection, electrons overflow the quantum well to cause the reduction of luminous efficiency and the like; secondly, the injection path of the holes is regulated and controlled through the action of the V-shaped pits, so that the luminous efficiency is improved; the AlGaN material is combined with the V-shaped pit to provide a high potential barrier, so that dislocation is shielded, a leakage channel is reduced, and the antistatic capability of the LED is improved.
However, in the epitaxial growth process of the substrate surface, al atoms show a lot of different properties compared with Ga atoms, so that AlGaN material growth is obviously different from GaN material growth, for example, parasitic reaction of Al atoms and ammonia gas is more serious in the MOCVD growth process, and the surface diffusion length of Al atoms is very small; thus, alGaN materials have many difficulties in the growth process, such as poor material crystal quality, lattice mismatch, low activation rate of Mg dopants, and the like.
Therefore, how to improve the growth quality of the P-AlGaN layer is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the above, the present invention provides an LED structure and a method for manufacturing the same, which can improve the growth quality of a P-AlGaN layer, and the technical scheme is as follows:
the application provides a preparation method of an LED structure, which comprises the following steps:
providing a substrate;
forming a low-temperature gallium nitride layer on one side of the substrate, wherein the low-temperature gallium nitride layer is provided with a first V-shaped pit;
sequentially forming a stress buffer layer, a quantum well active layer and P-type Al on one side of the low-temperature gallium nitride layer, which is away from the substrate x Ga 1-x An N layer, the stress buffer layer has a second V-shaped pit, the quantum well active layer has a third V-shaped pit, and the P-shaped Al x Ga 1-x The surface of one side of the N layer, which faces away from the substrate, is a flat surface;
wherein the P-type Al is formed x Ga 1-x The N layer comprises: forming the P-type Al under the conditions that the growth pressure is 100-300 torr, the growth temperature is 850-1050 ℃ and the growth rate is 5-30A/s x Ga 1-x And N layers.
Preferably, in the method for manufacturing an LED structure, in a first direction, the opening sizes of the first V-shaped pit, the second V-shaped pit and the third V-shaped pit gradually increase, and the first direction is perpendicular to the plane of the substrate and is directed from the substrate to the low-temperature gallium nitride layer.
Preferably, in the method for manufacturing an LED structure, before forming the low-temperature gallium nitride layer, the method for manufacturing an LED structure further includes:
and forming an AlN buffer layer, a three-dimensional nucleation layer, a two-dimensional merging layer and an N-type gallium nitride layer on one side of the substrate facing the low-temperature gallium nitride layer in sequence.
Preferably, in the method for manufacturing an LED structure, the method for manufacturing an LED structure further includes:
at the P-type Al x Ga 1-x And forming a P-type gallium nitride layer on one side of the N layer, which is away from the substrate.
Preferably, in the method for manufacturing an LED structure, the P-type Al x Ga 1-x In the N layer, x is more than or equal to 0 and less than or equal to 0.5.
Preferably, in the method for manufacturing an LED structure, the P-type Al is formed x Ga 1-x The N layer further includes:
the P-type Al is formed by adopting a metal organic chemical vapor deposition method x Ga 1-x And N layers.
Preferably, in the method for manufacturing an LED structure, the P-type Al x Ga 1-x The doping element of the N layer is Mg, and the P-type Al is formed x Ga 1-x When the N layer is formed, the doping concentration of Mg is 1E19/cm 3 -2E20/cm 3 。
Preferably, in the method for manufacturing an LED structure, the P-type Al x Ga 1-x The thickness of the N layer is 150nm-250nm.
Preferably, in the method for manufacturing an LED structure, the providing a substrate includes:
a Si substrate or PSS sapphire substrate or SiC substrate is provided.
The application also provides an LED structure, the LED structure is prepared based on the preparation method of the LED structure described in any one of the above, and the LED structure comprises:
a substrate;
the low-temperature gallium nitride layer is positioned on one side of the substrate and is provided with a first V-shaped pit;
in a first direction, a stress buffer layer, a quantum well active layer and a P-type Al layer which are sequentially positioned on one side of the low-temperature gallium nitride layer, which is away from the substrate x Ga 1-x The N layer is perpendicular to the plane of the substrate in the first direction and is directed to the low-temperature gallium nitride layer by the substrate, the stress buffer layer is provided with a second V-shaped pit, the quantum well active layer is provided with a third V-shaped pit, and the P-shaped Al x Ga 1-x The surface of the N layer, which faces away from one side of the substrate, is a flat surface.
Compared with the prior art, the invention has the following beneficial effects:
according to the LED structure and the preparation method thereof, the P-type Al is formed in the preparation process of the LED structure x Ga 1-x The value of the growth pressure of the N layer is 100-300 torr, so as to improve the P-type Al x Ga 1-x The growth air pressure of the N layer accelerates the atom migration rate, is beneficial to combining V-shaped pits, so that the P-type Al x Ga 1-x The surface of the N layer facing away from the substrate is a flat surface, and P-type Al is formed under high air pressure x Ga 1-x The material crystal quality of the N layer is improved, and defects are reduced; said forming said P-type Al x Ga 1-x The growth temperature of the N layer is 850-1050 ℃ to increase the growth temperature, so that the P-type Al is formed x Ga 1-x The atomic mobility is increased when the N layer is formed, and the capability of merging V-shaped pits is enhanced; said forming said P-type Al x Ga 1-x The range of the growth rate of the N layer is 5A/s-30A/s, so as to reduce the P-type Al x Ga 1-x The growth rate of the N layer increases the effective migration time of atoms, so that the size of V-shaped pits is reduced, the V-shaped pits are combined, and the P-type Al is formed x Ga 1-x The surface of one side of the N layer, which faces away from the substrate, is a flat surface; p-type Al formed under the above growth conditions x Ga 1-x The N layer has higher quality, can be used as an electron blocking layer for blocking electron leakage, limits electrons to the quantum well active layer for compound luminescence, and overcomes the defects of P-type Al x Ga 1-x The problems of low doping efficiency of the N layer and insufficient hole injection are solved, and the output optical power of the InGaN/GaN-based LED structure is improved; and the atomic surface migration capacity can be enhanced by the measures of raising the growth temperature, slowing down the growth rate and the like, which is beneficial to the combination of V-shaped pits, thereby improving the antistatic capacity of the LED.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of an LED structure according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of another LED structure according to an embodiment of the present invention;
fig. 3 is a schematic flow chart of a method for manufacturing an LED structure according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of another method for manufacturing an LED structure according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an LED structure provided in the prior art.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Based on the description of the background art, the inventor finds that in the inventive process of the invention, al atoms show a lot of different properties compared with Ga atoms in the epitaxial growth process of the substrate surface, so that AlGaN material growth is obviously different from GaN material growth process, for example, parasitic reaction of Al atoms and ammonia gas is more serious in the MOCVD growth process, the surface diffusion length of the Al atoms is very small, and the like; therefore, alGaN materials have a plurality of difficulties in the growth process, such as poor material crystal quality, lattice mismatch, low Mg dopant activation rate and the like; therefore, how to improve the growth quality of the P-AlGaN layer is a technical problem to be solved by those skilled in the art.
Based on the above, the application provides an LED structure and a preparation method thereof, which can improve the growth quality of a P-AlGaN layer.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
An embodiment of the present invention provides an LED structure, referring to fig. 1, fig. 1 is a schematic diagram of an LED structure provided by the embodiment of the present invention, and in combination with fig. 1, the LED structure includes:
a substrate 1; a low-temperature gallium nitride layer 2 positioned on one side of the substrate 1, wherein the low-temperature gallium nitride layer 2 is provided with a first V-shaped pit; in a first direction A, a stress buffer layer 3, a quantum well active layer 4 and P-type Al which are sequentially positioned on one side of the low-temperature gallium nitride layer 2 away from the substrate 1 x Ga 1-x An N layer 5, in which the first direction a is perpendicular to the plane of the substrate 1 and is directed from the substrate 1 to the low-temperature gallium nitride layer 2, the stress buffer layer 3 has a second V-shaped pit, the quantum well active layer 4 has a third V-shaped pit, and the P-shaped Al x Ga 1-x The surface of the N layer 5 facing away from the substrate 1 is a planar surface.
Specifically, in the embodiment of the present invention, the substrate 1 includes, but is not limited to, a Si substrate or a PSS sapphire substrate or a SiC substrate; since the stress buffer layer 3 will further open the first V-shaped pit, the opening sizes of the first V-shaped pit, the second V-shaped pit and the third V-shaped pit are gradually increased In the first direction a, the first direction a is perpendicular to the plane of the substrate 1 and is directed to the low temperature gallium nitride layer 2 by the substrate 1, the stress buffer layer 3 provides buffer stress for the following quantum well active layer 4 by using a relatively low In component, and meanwhile, the stress buffer layer 3 is of a periodic well barrier structure, which is beneficial to current expansion; the projections of the bottom tips of the first V-shaped pit, the second V-shaped pit and the third V-shaped pit in the first direction a are overlapped, that is, the bottom tips of the first V-shaped pit, the second V-shaped pit and the third V-shaped pit are on the same straight line parallel to the first direction a; in addition, in the P-type Al x Ga 1-x In the N layer 5, x is more than or equal to 0 and less than or equal to 0.5; the P type Al x Ga 1-x The thickness of the N layer 5 in the first direction a may take any value within the range of 150nm to 250nm.
Optionally, in another embodiment of the present invention, the foregoing LED structure is further described, and referring to fig. 2, fig. 2 is a schematic diagram of another LED structure provided in an embodiment of the present invention, and in conjunction with fig. 2, the LED structure further includes:
in the first direction a, sequentially positioned with the substrate 1 facing the low sideAn AlN buffer layer 6, a three-dimensional nucleation layer 7, a two-dimensional merging layer 8 and an N-type gallium nitride layer 9 on one side of the gallium nitride layer 2; is positioned at the P-type Al x Ga 1-x The N layer 5 faces away from the P-type gallium nitride layer 10 on the side of the substrate 1.
Specifically, in the embodiment of the present invention, the three-dimensional nucleation layer 7 uses lattice mismatch between GaN and AlN as a driving force, and implements a three-dimensional island growth mode by deposition decomposition in a small ammonia atmosphere; and the two-dimensional merging layer 8 realizes a lateral growth mode by utilizing diffusion under the high-temperature large ammonia atmosphere, merges three-dimensional island shapes into a GaN plane, reduces dislocation density, and enables the low-temperature gallium nitride layer 2 to convert the dislocation density into a first V-shaped pit.
Optionally, in another embodiment of the present invention, a method for manufacturing an LED structure is further provided, referring to fig. 3, fig. 3 is a schematic flow chart of the method for manufacturing an LED structure provided in the embodiment of the present invention, and in conjunction with fig. 3, the method for manufacturing an LED structure includes:
s100: a substrate 1 is provided.
Specifically, in this step S100, the substrate 1 includes, but is not limited to, a Si substrate or a PSS sapphire substrate or a SiC substrate; in addition, the substrate 1 is required to be placed at the temperature with the value range of 900-1150 ℃ and H is introduced 2 A hydrogenation treatment is performed for 5 minutes to remove impurities, scratches, particles, etc. from the surface of the substrate 1.
S200: a low temperature gallium nitride layer 2 is formed on one side of the substrate 1, the low temperature gallium nitride layer 2 having a first V-shaped pit.
Specifically, in this step S200, as shown in fig. 2, the low-temperature gallium nitride layer 2 is located on one side of the substrate 1, and the low-temperature gallium nitride layer 2 has a first V-shaped pit, which in the embodiment of the present invention includes but is not limited to introducing TMGa and NH at a temperature ranging from 600 ℃ to 800 DEG C 3 、N 2 A low-temperature gallium nitride layer 2 is formed on one side of the substrate 1, and the thickness of the low-temperature gallium nitride layer 2 in the first direction a is in the range of 150nm-250nm.
S300: a stress buffer layer is sequentially formed on one side of the low-temperature gallium nitride layer 2 away from the substrate 13. Quantum well active layer 4 and P-type Al x Ga 1-x An N layer 5, the stress buffer layer 3 having a second V-shaped pit, the quantum well active layer 4 having a third V-shaped pit, the P-type Al x Ga 1-x The surface of the N layer 5 on the side facing away from the substrate 1 is a flat surface; wherein the P-type Al is formed x Ga 1-x The N layer 5 includes: forming the P-type Al under the conditions that the growth pressure is 100-300 torr, the growth temperature is 850-1050 ℃ and the growth rate is 5-30A/s x Ga 1-x N layer 5.
Specifically, in this step S300, as shown in fig. 2, the stress buffer layer 3 is of a periodic well barrier structure, the number of well barrier cycles of the stress buffer layer 3 may take any value within a range of 25-35, and forming the stress buffer layer 3 includes: forming a well layer of the stress buffer layer 3 at a temperature ranging from 700 ℃ to 850 ℃, forming a barrier layer of the stress buffer layer 3 at a temperature ranging from 800 ℃ to 1000 ℃, wherein the thickness of the stress buffer layer 3 in the first direction A can take any value ranging from 150nm to 250 nm; since the low-temperature gallium nitride layer 2 is provided with the first V-shaped pit, when the stress buffer layer 3 is formed, the stress buffer layer 3 covers the side wall of the first V-shaped pit, the thickness of the stress buffer layer 3 covering the first V-shaped pit is lower than that of the horizontal surface of the low-temperature gallium nitride layer 2 on the side away from the substrate 1, so as to form a second V-shaped pit of the stress buffer layer 3, and the second V-shaped pit penetrates through the stress buffer layer 3 and extends to the low-temperature gallium nitride layer 2; the quantum well active layer 4 is in a periodic well barrier structure, the number of well barrier cycles of the quantum well active layer 4 can take any value in a value range of 3-9, and forming the quantum well active layer 4 includes: forming a well layer of the quantum well active layer 4 at a temperature ranging from 700 ℃ to 850 ℃, forming a barrier layer of the quantum well active layer 4 at a temperature ranging from 800 ℃ to 1000 ℃, wherein the thickness of the quantum well active layer 4 in the first direction A can take any value within a range from 10nm to 16 nm; since the stress buffer layer 3 has the second V-shaped pit, the quantum well active layer 4 covers the quantum well active layer 4 when the quantum well active layer 4 is formedThe side wall of the second V-shaped pit, the thickness of the quantum well active layer 4 covering the second V-shaped pit is lower than the thickness of the horizontal surface covering one side of the stress buffer layer 3 away from the substrate 1, so as to form a third V-shaped pit of the quantum well active layer 4, and the third V-shaped pit penetrates through the quantum well active layer 4 and extends to the stress buffer layer 3; embodiments of the invention include, but are not limited to, forming the P-type Al by metal organic chemical vapor deposition x Ga 1-x N layer 5, the P type Al x Ga 1-x The doping element of the N layer 5 is Mg, and the P-type Al is formed x Ga 1-x In the case of the N layer 5, the doping concentration of Mg may be 1E19/cm 3 -2E20/cm 3 The value range of (2) takes any value; the P type Al x Ga 1-x The thickness of the N layer 5 in the first direction A can take any value in the range of 150nm-250nm, and the P-type Al is formed x Ga 1-x When the N layer 5 is filled, the third V-shaped pit is required to be filled, and the P-shaped Al is formed under the condition that the growth pressure is 100-300 torr, the growth temperature is 850-1050 ℃ and the growth rate is 5-30A/s x Ga 1-x N layer 5, which facilitates the incorporation of V-shaped pits under such growth conditions, thereby allowing the P-type Al to x Ga 1-x The surface of the N layer 5 facing away from the substrate 1 is a planar surface.
As can be seen from the above description, in the LED structure and the method for manufacturing the same according to the embodiments of the present invention, the P-type Al is formed during the manufacturing process of the LED structure x Ga 1-x The growth pressure of the N layer 5 is 100-300 torr to improve the P-type Al x Ga 1-x The growth air pressure of the N layer 5 accelerates the atom migration rate, is beneficial to combining V-shaped pits, so that the P-type Al x Ga 1-x The surface of the N layer 5 facing away from the substrate 1 is a flat surface, and P-type Al is formed under high pressure x Ga 1-x The material crystal quality of the N layer 5 is improved, and defects are reduced; said forming said P-type Al x Ga 1-x The growth temperature of the N layer 5 is 850-1050 ℃ to increase the growth temperature, so that the P-type Al is formed x Ga 1-x The atomic mobility becomes larger when the N layer 5 is formed, and the capability of merging V-shaped pits is enhanced; said forming said P-type Al x Ga 1-x The range of the growth rate of the N layer 5 is 5A/s-30A/s, so as to reduce the P-type Al x Ga 1-x The growth rate of the N layer 5 increases the effective migration time of atoms, so that the size of V-shaped pits is reduced, and the V-shaped pits are combined, so that P-type Al x Ga 1-x The surface of the N layer 5 on the side facing away from the substrate 1 is a flat surface; p-type Al formed under the above growth conditions x Ga 1-x The N layer 5 has higher quality, can be used as an electron blocking layer for blocking electron leakage, limits electrons to the quantum well active layer 4-domain composite luminescence, and overcomes the P-type Al x Ga 1-x The problems of low doping efficiency and insufficient hole injection of the N layer 5 are solved, and the output optical power of the InGaN/GaN-based LED structure is improved; and the atomic surface migration capacity can be enhanced by the measures of raising the growth temperature, slowing down the growth rate and the like, which is beneficial to the combination of V-shaped pits, thereby improving the antistatic capacity of the LED.
Optionally, in another embodiment of the present invention, the method for manufacturing an LED structure is further described, and referring to fig. 4, fig. 4 is a schematic flow chart of another method for manufacturing an LED structure according to an embodiment of the present invention, as shown in fig. 4, where the method for manufacturing an LED structure further includes:
s400: an AlN buffer layer 6, a three-dimensional nucleation layer 7, a two-dimensional merging layer 8 and an N-type gallium nitride layer 9 are sequentially formed on the side, facing the low-temperature gallium nitride layer 2, of the substrate 1.
Specifically, before forming the low-temperature gallium nitride layer 2 on one side of the substrate 1 in step S200, the method for manufacturing the LED structure further includes: an AlN buffer layer 6, a three-dimensional nucleation layer 7, a two-dimensional merging layer 8 and an N-type gallium nitride layer 9 are sequentially formed on one side of the substrate 1 facing the low-temperature gallium nitride layer 2; the embodiment of the invention comprises but is not limited to introducing TMAL and SiH at the temperature of 900-1150 DEG C 4 、NH 3 、H 2 、N 2 An AlN buffer layer 6 is formed on the side of the substrate 1 facing the low temperature gallium nitride layer 2, and the AlN buffer layer 6 has a thickness in the first direction AThe range is 5nm-50nm, wherein the molar ratio of Si to Al can take any value in the value range of 0.05-0.5; the embodiment of the invention comprises, but is not limited to, introducing NH at a temperature ranging from 800 ℃ to 1000 DEG C 3 、H 2 、N 2 A three-dimensional nucleation layer 7 is formed on the side of the AlN buffer layer 6 facing away from the substrate 1, wherein NH 3 The components can take any value in the value range of 30% -80%, and the time for forming the three-dimensional nucleation layer 7 can take any value in the value range of 0.5min-3 min; the embodiment of the invention comprises, but is not limited to, introducing NH at a temperature ranging from 900 ℃ to 1200 DEG C 3 、H 2 、N 2 A two-dimensional merging layer 8 is formed on the side of the three-dimensional nucleation layer 7 facing away from the AlN buffer layer 6, wherein NH 3 The components can take any value in the value range of 70% -100%, and the time for forming the two-dimensional merging layer 8 can take any value in the value range of 0.5min-3 min; the embodiment of the invention comprises but is not limited to introducing TMGa and SiH at the temperature of 900-1200 DEG C 4 、NH 3 、H 2 、N 2 And forming an N-type gallium nitride layer 9 on one side of the two-dimensional merging layer 8, which is far away from the three-dimensional nucleation layer 7, wherein the thickness of the N-type gallium nitride layer 9 in the first direction A is in a range of 1500nm-2500nm.
S500: at the P-type Al x Ga 1-x The side of the N layer 5 facing away from the substrate 1 forms a P-type gallium nitride layer 10.
Specifically, in step S300, the P-type Al is formed x Ga 1-x After the N layer 5, the method for preparing the LED structure further includes: at the P-type Al x Ga 1-x The side of the N layer 5 facing away from the substrate 1 is provided with a P-type gallium nitride layer 10; the embodiment of the invention comprises but is not limited to introducing TMGa and CP at the temperature of 800-1200 DEG C 2 Mg、NH 3 、H 2 、N 2 At the P-type Al x Ga 1-x The side of the N layer 5 facing away from the substrate 1 forms a P-type gallium nitride layer 10, wherein the doping concentration of Mg can be 1E19/cm 3 -4E20/cm 3 Any value in the range of the value of the P-type gallium nitride layer 10 in the first directionThe thickness of A is 200nm-600nm.
In order to make the effect of the embodiment of the invention more obvious, the LED structure formed by the preparation method of the invention is compared with the LED structure formed by the preparation method of the prior art:
comparative example: adopting equipment MOCVD, taking trimethylgallium TMGa and triethylgallium TEGa as Ga sources and ammonia gas NH 3 Is N source, TMIn is In source, TMAI is Al source, H 2 、N 2 The N-type doping source and the P-type doping source are respectively silane SiH 4 And a magnesium-dicyclopentadiene CP 2 Mg, using a graphite disk as a substrate carrier disk; introducing H at 1050 DEG C 2 Carrying out hydrogenation treatment on the sapphire substrate for 5min, and removing impurities, scratches, particles and the like on the surface of the sapphire substrate; introducing TMAL and SiH at 1000 DEG C 4 、NH 3 、H 2 、N 2 Growing an AlN buffer layer, wherein the thickness of the AlN buffer layer is 25nm, and the molar ratio of Si to Al is 0.2; introducing NH at 900 DEG C 3 、H 2 、N 2 Forming a three-dimensional nucleation layer, and realizing a three-dimensional island growth mode by using deposition decomposition in a small ammonia atmosphere by taking lattice mismatch between GaN and AlN as a driving force, wherein NH 3 The components are 20%, and the time for forming the three-dimensional nucleation layer is 1min; NH is introduced at 1100 DEG C 3 、H 2 、N 2 Forming a two-dimensional merging layer, realizing a lateral growth mode by diffusion under the high-temperature large ammonia atmosphere, merging three-dimensional island shapes into a GaN plane, and reducing dislocation density, wherein NH 3 The components are 80%, and the time for forming the two-dimensional merging layer is 2min; introducing TMGa and SiH at 1100 DEG C 4 、NH 3 、H 2 、N 2 Forming an N-type GaN layer in which SiH 4 Is 8E18/cm 3 The thickness of the N-type gallium nitride layer is 2000nm; introducing TMGa and NH at 650 DEG C 3 、N 2 Forming a low-temperature gallium nitride layer to convert dislocation density into V-shaped pits, wherein the thickness of the low-temperature gallium nitride layer is 200nm; into TEGa, TMIn, NH 3 、H 2 、N 2 A stress buffer layer is formed to further open the V-shaped pit,the stress is buffered by utilizing a relatively lower In component into a rear quantum well active layer, and the periodic well barrier structure is beneficial to current expansion, wherein the stress buffer layer comprises a 5nmInGaN/2nmGAN superlattice with 30 periods, the total thickness of the stress buffer layer is 210nm, the temperature for forming the well layer of the stress buffer layer is 800 ℃, and the temperature for forming the barrier layer of the stress buffer layer is 880 ℃; into TEGa, TMIn, siH 4 、NH 3 、H 2 、N 2 Forming a quantum well active layer, wherein H is not passed when forming a well layer of the quantum well active layer 2 Si is doped when forming a barrier layer of the quantum well active layer, the temperature when forming a well layer of the quantum well active layer is 780 ℃, the temperature when forming the barrier layer of the quantum well active layer is 900 ℃, the number of well barrier cycles of the quantum well active layer is 7, the total thickness of the quantum well active layer is 14nm, the thickness of the well layer of the quantum well active layer is 3nm, and the thickness of the barrier layer of the quantum well active layer is 11nm; at N 2 In the atmosphere, the growth pressure is 100torr, the growth temperature is 900 ℃, the growth rate is 20A/s, and the doping concentration of Mg is 5E19/cm 3 Under the condition of (5) introducing TMAl, TMGa, CP 2 Mg、NH 3 、H 2 Formation of P-type Al x Ga 1-x N layer to provide a high potential barrier to block electron leakage and regulate V pit growth and combination to regulate hole injection path, wherein x is 20%, P type Al x Ga 1-x The thickness of the N layer is 200nm; at 1050 ℃, the doping concentration of Mg is 1E20/cm 3 Down-feeding TMGa, CP 2 Mg、NH 3 、H 2 、N 2 Forming a P-type gallium nitride layer, wherein the thickness of the P-type gallium nitride layer is 400nm; cooling and annealing treatment is carried out, and the growth is finished; the LED structure formed by the preparation method of the prior art is tested and chip is manufactured, photoelectric parameter test is carried out through EL, as shown in FIG. 5, FIG. 5 is a schematic diagram of an LED structure provided in the prior art, and as can be obtained from FIG. 5, when the V-shaped pit is extended from the low-temperature gallium nitride layer to the P-shaped gallium nitride layer in the LED structure formed by the comparative example, the V-shaped pit has larger size, cannot be effectively combined, and a leakage channel is easy to form, so that the ESD performance is weak; and the V-shaped pit is higher than the potential barrier of the platform, so that holes cannot be injected into quanta from the V-shaped pitThe well active layer emits light, resulting in low luminous efficiency of the LED structure.
Examples: adopting equipment MOCVD, taking trimethylgallium TMGa and triethylgallium TEGa as Ga sources and ammonia gas NH 3 Is N source, TMIn is In source, TMAI is Al source, H 2 、N 2 The N-type doping source and the P-type doping source are respectively silane SiH 4 And a magnesium-dicyclopentadiene CP 2 Mg, using a graphite disk as a substrate carrier disk; introducing H at 1050 DEG C 2 Carrying out hydrogenation treatment on the sapphire substrate for 5min, and removing impurities, scratches, particles and the like on the surface of the sapphire substrate; introducing TMAL and SiH at 1000 DEG C 4 、NH 3 、H 2 、N 2 Growing an AlN buffer layer 6, wherein the thickness of the AlN buffer layer 6 is 25nm, and the molar ratio of Si to Al is 0.2; introducing NH at 900 DEG C 3 、H 2 、N 2 Forming a three-dimensional nucleation layer 7, and realizing a three-dimensional island growth mode by using deposition decomposition in a small ammonia atmosphere by taking lattice mismatch between GaN and AlN as a driving force, wherein NH 3 The components are 20%, and the time for forming the three-dimensional nucleation layer 7 is 1min; NH is introduced at 1100 DEG C 3 、H 2 、N 2 Forming a two-dimensional merging layer 8, realizing a lateral growth mode by diffusion under the atmosphere of high temperature and large ammonia gas, merging three-dimensional island shapes into a GaN plane, and reducing dislocation density, wherein NH 3 The components are 80%, and the time for forming the two-dimensional merging layer 8 is 2min; introducing TMGa and SiH at 1100 DEG C 4 、NH 3 、H 2 、N 2 Forming an N-type GaN layer 9 in which SiH 4 Is 8E18/cm 3 The thickness of the N-type gallium nitride layer 9 is 2000nm; introducing TMGa and NH at 650 DEG C 3 、N 2 Forming a low-temperature gallium nitride layer 2 to convert dislocation density into V-shaped pits, wherein the thickness of the low-temperature gallium nitride layer 2 is 200nm; into TEGa, TMIn, NH 3 、H 2 、N 2 The stress buffer layer 3 is formed to further open the V-shaped pit, buffer stress with a relatively low In composition for the subsequent quantum well active layer 4, while the periodic well barrier structure also facilitates current spreading, wherein the stress buffer layer 3 comprises 30 periods of 5nmInGaNThe total thickness of the stress buffer layer 3 is 210nm, the temperature of a well layer for forming the stress buffer layer 3 is 800 ℃, and the temperature of a barrier layer for forming the stress buffer layer 3 is 880 ℃; into TEGa, TMIn, siH 4 、NH 3 、H 2 、N 2 Forming a quantum well active layer 4, wherein H is not passed when forming a well layer of the quantum well active layer 4 2 Si is doped when forming the barrier layer of the quantum well active layer 4, the temperature when forming the well layer of the quantum well active layer 4 is 780 ℃, the temperature when forming the barrier layer of the quantum well active layer 4 is 900 ℃, the number of well barrier cycles of the quantum well active layer 4 is 7, the total thickness of the quantum well active layer 4 is 14nm, the thickness of the well layer of the quantum well active layer 4 is 3nm, and the thickness of the barrier layer of the quantum well active layer 4 is 11nm; at H 2 In the atmosphere, the growth pressure is 250torr, the temperature is 980 ℃, the growth rate is 10A/s, and the doping concentration of Mg is 5E19/cm 3 Under the condition of (5) introducing TMAl, TMGa, CP 2 Mg、NH 3 、H 2 Formation of P-type Al x Ga 1-x N layer 5 to provide a high potential barrier to block electron leakage and regulate V pit growth and combination to regulate hole injection path, wherein x is 20%, P type Al x Ga 1-x The thickness of the N layer 5 is 200nm; at a temperature of 1050 ℃, the concentration of Mg is 1E20/cm 3 Down-feeding TMGa, CP 2 Mg、NH 3 、H 2 、N 2 Forming a P-type gallium nitride layer 10, wherein the thickness of the P-type gallium nitride layer 10 is 400nm; cooling and annealing treatment is carried out, and the growth is finished; the LED structure formed by the preparation method of the invention is tested and chip is manufactured, and the photoelectric parameter test is carried out through EL, as shown in figure 2, the LED structure formed by the embodiment is compared with the LED structure formed by the comparative example, and the LED structure is in H 2 By increasing P-type Al under atmosphere x Ga 1-x The growth air pressure of the material in the N layer 5 can reduce point defects and improve the crystal quality of the material and the hollow concentration of the material; in the formation of P-type Al x Ga 1-x In the process of N layer 5, the migration capacity of the atomic surface can be enhanced by the measures of raising the growth temperature, slowing down the growth rate and the like, which is favorable for combining V-shaped pits, thereby improving the antistatic capacity of the LED and simultaneously forming P-type Al x Ga 1-x In the process of N layer 5The injection path of the holes is regulated and controlled by regulating the potential barrier sizes of the V-shaped pits and the platforms, so that the luminous efficiency is improved.
The above describes in detail an LED structure and a method for manufacturing the same, and specific examples are applied to illustrate the principles and embodiments of the present invention, and the above examples are only used to help understand the method and core idea of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include, or is intended to include, elements inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The preparation method of the LED structure is characterized by comprising the following steps of:
providing a substrate;
forming a low-temperature gallium nitride layer on one side of the substrate, wherein the low-temperature gallium nitride layer is provided with a first V-shaped pit;
sequentially forming a stress buffer layer, a quantum well active layer and P-type Al on one side of the low-temperature gallium nitride layer, which is away from the substrate x Ga 1-x An N layer, the stress buffer layer has a second V-shaped pit, the quantum well active layer has a third V-shaped pit, and the P-shaped Al x Ga 1-x The surface of one side of the N layer, which faces away from the substrate, is a flat surface;
wherein the P-type Al is formed x Ga 1-x The N layer comprises: forming the P-type Al under the conditions that the growth pressure is 100-300 torr, the growth temperature is 850-1050 ℃ and the growth rate is 5-30A/s x Ga 1-x And N layers.
2. The method of manufacturing an LED structure of claim 1, wherein the opening sizes of said first V-shaped pit, said second V-shaped pit and said third V-shaped pit are gradually increased in a first direction perpendicular to the plane of said substrate and directed from said substrate to said low temperature gallium nitride layer.
3. The method of manufacturing an LED structure according to claim 1, wherein prior to forming the low temperature gallium nitride layer, the method of manufacturing an LED structure further comprises:
and forming an AlN buffer layer, a three-dimensional nucleation layer, a two-dimensional merging layer and an N-type gallium nitride layer on one side of the substrate facing the low-temperature gallium nitride layer in sequence.
4. The method of manufacturing an LED structure of claim 1, further comprising:
at the P-type Al x Ga 1-x And forming a P-type gallium nitride layer on one side of the N layer, which is away from the substrate.
5. The method of manufacturing an LED structure according to claim 1, wherein, in the P-type Al x Ga 1-x In the N layer, x is more than or equal to 0 and less than or equal to 0.5.
6. The method of manufacturing an LED structure of claim 1, wherein said P-type Al is formed x Ga 1-x The N layer further includes:
the P-type Al is formed by adopting a metal organic chemical vapor deposition method x Ga 1-x And N layers.
7. The method of manufacturing an LED structure of claim 1, wherein said P-type Al x Ga 1-x The doping element of the N layer is Mg, and the P-type Al is formed x Ga 1-x When the N layer is formed, the doping concentration of Mg is 1E19/cm 3 -2E20/cm 3 。
8. The method of manufacturing an LED structure of claim 1, wherein said P-type Al x Ga 1-x The thickness of the N layer is 150nm-250nm.
9. The method of manufacturing an LED structure of claim 1, wherein said providing a substrate comprises:
a Si substrate or PSS sapphire substrate or SiC substrate is provided.
10. An LED structure, characterized in that it is prepared based on the method for preparing an LED structure according to any one of claims 1-9, comprising:
a substrate;
the low-temperature gallium nitride layer is positioned on one side of the substrate and is provided with a first V-shaped pit;
in a first direction, a stress buffer layer, a quantum well active layer and a P-type Al layer which are sequentially positioned on one side of the low-temperature gallium nitride layer, which is away from the substrate x Ga 1-x The N layer is perpendicular to the plane of the substrate in the first direction and is directed to the low-temperature gallium nitride layer by the substrate, the stress buffer layer is provided with a second V-shaped pit, the quantum well active layer is provided with a third V-shaped pit, and the P-shaped Al x Ga 1-x The surface of the N layer, which faces away from one side of the substrate, is a flat surface.
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