CN117497649A - AlN intrinsic layer for deep ultraviolet light-emitting diode and preparation method thereof - Google Patents
AlN intrinsic layer for deep ultraviolet light-emitting diode and preparation method thereof Download PDFInfo
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- CN117497649A CN117497649A CN202311337103.2A CN202311337103A CN117497649A CN 117497649 A CN117497649 A CN 117497649A CN 202311337103 A CN202311337103 A CN 202311337103A CN 117497649 A CN117497649 A CN 117497649A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000004065 semiconductor Substances 0.000 claims abstract description 53
- 239000002131 composite material Substances 0.000 claims abstract description 49
- 230000035876 healing Effects 0.000 claims abstract description 37
- 239000000758 substrate Substances 0.000 claims abstract description 34
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 33
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000000463 material Substances 0.000 claims abstract description 24
- 229910005191 Ga 2 O 3 Inorganic materials 0.000 claims abstract description 21
- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical compound [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 claims abstract description 14
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims abstract description 14
- 229910001195 gallium oxide Inorganic materials 0.000 claims abstract description 13
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 23
- 229910021529 ammonia Inorganic materials 0.000 claims description 15
- 238000000137 annealing Methods 0.000 claims description 13
- 238000005121 nitriding Methods 0.000 claims description 13
- 239000007789 gas Substances 0.000 claims description 12
- 239000001257 hydrogen Substances 0.000 claims description 12
- 229910052739 hydrogen Inorganic materials 0.000 claims description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 11
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 11
- 229910001882 dioxygen Inorganic materials 0.000 claims description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 230000007423 decrease Effects 0.000 claims description 4
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 4
- 230000001788 irregular Effects 0.000 claims description 4
- 239000011295 pitch Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 2
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 claims 1
- 230000008646 thermal stress Effects 0.000 abstract description 6
- 238000005336 cracking Methods 0.000 abstract description 5
- 230000035882 stress Effects 0.000 abstract description 5
- 239000013078 crystal Substances 0.000 description 11
- 230000008569 process Effects 0.000 description 11
- 239000010408 film Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 6
- 229910052594 sapphire Inorganic materials 0.000 description 5
- 239000010980 sapphire Substances 0.000 description 5
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910002704 AlGaN Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 235000013312 flour Nutrition 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000005622 photoelectricity Effects 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/0004—Devices characterised by their operation
- H01L33/0008—Devices characterised by their operation having p-n or hi-lo junctions
- H01L33/0012—Devices characterised by their operation having p-n or hi-lo junctions p-i-n devices
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/12—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a stress relaxation structure, e.g. buffer layer
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Abstract
The invention provides an AlN intrinsic layer for a deep ultraviolet light-emitting diode and a preparation method thereof, wherein the preparation method comprises the following steps: first, in beta-Ga 2 O 3 Epitaxially growing a composite semiconductor layer with a whole layer structure on a substrate, epitaxially growing a first AlN layer on the composite semiconductor layer, epitaxially growing an AlN healing layer on the first AlN layer, and finally epitaxially growing a second AlN layer on the AlN healing layer, wherein the material of the composite semiconductor layer is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride; the composite semiconductor layer in the preparation method is equivalent to a stress release layer, the lattice structure of the composite semiconductor layer is gradually transited from an aluminum gallium oxide lattice structure to an aluminum nitride lattice structure, dislocation annihilation can be facilitated, dislocation density is reduced, thermal stress is released, cracking of an AlN film prepared later is prevented, and threading dislocation can be bent into a ring in the healing process of the AlN materialGradually annihilating, eventually reducing the dislocation density of the entire AlN intrinsic layer.
Description
Technical Field
The invention relates to the field of semiconductor photoelectricity, in particular to an AlN intrinsic layer for a deep ultraviolet light-emitting diode and a preparation method thereof.
Background
Among ultraviolet rays, light having a wavelength of 200nm to 350 nm is called deep ultraviolet rays. The deep ultraviolet light emitting diode has great application value in the fields of illumination, sterilization, medical treatment, printing, biochemical detection, high-density information storage, secret communication and the like because of the advantages of high efficiency, environmental protection, energy conservation, reliability and the like, which are incomparable with the common ultraviolet light emitting diode.
The material system of the deep ultraviolet LED is an AlGaN material, the most common substrate is sapphire, and an AlN intrinsic layer is usually grown on the substrate, and the AlGaN material is grown again. Wherein, the AlN intrinsic layer and the c-plane sapphire still have larger lattice mismatch, and a large amount of threading dislocation which penetrates upwards from the sapphire substrate can exist; meanwhile, due to the difference of the thermal expansion coefficients of the AlN intrinsic layer and the sapphire substrate, lattice deformation of the substrate and the epitaxial layer is not matched in the temperature raising and reducing process, so that cracks are generated on the epitaxial layer.
Therefore, the AlN intrinsic layer with high quality is the basis for preparing the high-performance deep ultraviolet light-emitting diode. Although the existing AlN growth technology has greatly advanced, how to solve the problems of poor growth quality and surface cracks caused by lattice mismatch and thermal mismatch of an AlN intrinsic layer and a substrate is still a current technical difficulty.
Disclosure of Invention
The invention aims to provide an AlN intrinsic layer for a deep ultraviolet light-emitting diode and a preparation method thereof, which are used for solving the technical problem that the dislocation density of the existing AlN intrinsic layer for the deep ultraviolet light-emitting diode is large.
In order to solve the technical problems, the invention provides a preparation method of an AlN intrinsic layer for a deep ultraviolet light-emitting diode, which comprises the following steps:
s10, at beta-Ga 2 O 3 Epitaxially growing a composite semiconductor layer with a whole layer structure on a substrate;
s20, epitaxially growing a first AlN layer on the composite semiconductor layer;
s30, epitaxially growing an AlN healing layer on the first AlN layer;
s40, epitaxially growing a second AlN layer on the AlN healing layer;
wherein, the material of the composite semiconductor layer is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride.
Preferably, before performing step S10, the method further comprises:
s101, beta-Ga in a reaction cavity of MOCVD equipment 2 O 3 Annealing the substrate;
s102, beta-Ga in the reaction chamber 2 O 3 The substrate is subjected to nitriding treatment.
Preferably, in the step S101, the temperature of the annealing treatment is higher than or equal to 1300 ℃, the time range of the annealing treatment is 5-60 min, and the gas atmosphere is hydrogen; in the step S102, the nitriding treatment is carried out at the temperature ranging from 1100 ℃ to 1400 ℃, the nitriding treatment time ranges from 1min to 60min, the gas atmosphere is mixed gas consisting of hydrogen and ammonia, and the ratio of the hydrogen to the ammonia ranges from 100:1 to 1:1.
Preferably, the step S10 specifically includes:
s103, simultaneously introducing an aluminum source and oxygen into the reaction cavity in a first time period;
s104, simultaneously introducing an aluminum source, ammonia gas and oxygen gas into the reaction cavity in a second time period;
s105, simultaneously introducing an aluminum source and nitrogen into the reaction cavity in a third time period.
Wherein, in any one of the steps S103 to S105, the flow rate of the aluminum source is in the range of 10SCCM to 10000SCCM.
Preferably, in the step S104, the ratio of the ammonia gas to the oxygen gas is greater than 0:1 and less than 1:0, and the ratio of the ammonia gas to the oxygen gas increases linearly with the increase of the growth time; the growth temperature of the composite semiconductor layer ranges from 500 ℃ to 1300 ℃, and the growth temperature of the composite semiconductor layer linearly decreases along with the increase of the growth time.
Preferably, in the step S20, the thickness of the first AlN layer ranges from 200nm to 4000nm, and the V/III ratio of the first AlN layer ranges from 2000 to 100000.
Preferably, the step S20 specifically includes:
s201, introducing an aluminum source into the reaction cavity in a fourth time period;
s202, introducing ammonia into the reaction cavity in a fifth time period;
s203, repeating the step S201 and the step S202 for a plurality of times to generate a first AlN layer.
Preferably, in the step S30, the AlN healing layer includes a plurality of air holes having irregular sizes and pitches, and the thickness of the AlN healing layer ranges from 100nm to 2000nm.
Preferably, in the step S30, the growth temperature of the first AlN layer is T1, the growth temperature of the AlN healing layer is T2, and the relationship between T1 and T2 satisfies: t1 is more than or equal to 900 ℃ and T2 is more than or equal to 1400 ℃.
Correspondingly, the invention also provides an AlN intrinsic layer for the deep ultraviolet light-emitting diode, which is prepared by adopting the preparation method of the AlN intrinsic layer for the deep ultraviolet light-emitting diode.
The beneficial effects of the invention are as follows: unlike the prior art, the present invention provides an AlN intrinsic layer for a deep ultraviolet light emitting diode and a method of preparing the same, which includes: first, in beta-Ga 2 O 3 Epitaxially growing a composite semiconductor layer with a whole layer structure on a substrate, epitaxially growing a first AlN layer on the composite semiconductor layer, epitaxially growing an AlN healing layer on the first AlN layer, and finally epitaxially growing a second AlN layer on the AlN healing layer, wherein the material of the composite semiconductor layer is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride; due to beta-Ga 2 O 3 The lattice mismatch between the crystal and AlN is only about 3%, and the preparation method is that firstly, beta-Ga 2 O 3 The composite semiconductor layer with the whole layer structure is epitaxially grown on the substrate, so that the crystal quality of the composite semiconductor layer can be effectively improved, wherein the material of the composite semiconductor layer is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride, the composite semiconductor layer is equivalent to a stress release layer, and the lattice structure of the composite semiconductor layer is composed of aluminum gallium oxideThe transition of the compound lattice structure to the aluminum nitride lattice structure is gradually beneficial to dislocation annihilation, reduces dislocation density, simultaneously releases thermal stress, prevents cracking of an AlN film prepared later, and then, in the process of growing a first AlN layer and an AlN healing layer on the composite semiconductor layer later, the threading dislocation can bend into a ring to annihilate gradually, so that the dislocation density of the whole AlN intrinsic layer is reduced finally, and the crystal quality of the AlN intrinsic layer is further improved.
Drawings
FIG. 1 is a process flow diagram of a method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode according to the embodiment of the invention;
FIG. 2 shows an AlN intrinsic layer in beta-Ga for a deep ultraviolet light emitting diode according to example 1 of the present invention 2 O 3 Schematic diagram of the film structure on the substrate.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.
The preparation method of the embodiment of the invention adopts MOCVD (metal organic chemical vapor deposition) equipment of the model Veeco K465i as growth equipment; wherein, high-purity H is adopted 2 Or high purity N 2 Or high purity H 2 And high purity N 2 High purity NH using the mixed gas of (2) as carrier gas 3 As a nitrogen source, trimethylgallium (TMGa) is used as a gallium source, trimethylaluminum (TMAL) is used as an aluminum source, and the pressure of a reaction cavity in MOCVD equipment is controlled to be 20-100 torr.
Referring to fig. 1, fig. 1 is a process flow chart of a preparation method of an AlN intrinsic layer for a deep-uv light emitting diode according to an embodiment of the present invention; FIG. 2 shows an AlN intrinsic layer in beta-Ga for a deep ultraviolet light emitting diode according to example 1 of the present invention 2 O 3 Schematic of the film structure on the substrate 10; wherein, the preparation method hasThe body comprises:
s10, at beta-Ga 2 O 3 A composite semiconductor layer 201 of an entire layer structure is epitaxially grown on the substrate 10.
Specifically, S10 further includes:
s101, providing a substrate 10, wherein the substrate 10 is beta-Ga 2 O 3 A material; beta-Ga 2 O 3 Is an emerging semiconductor material, and is commonly used in power electronic devices and detection devices. While beta-Ga 2 O 3 The lattice mismatch between the crystal and AlN is only about 3%, and the beta-Ga 2 O 3 The preparation cost of the monocrystal is obviously lower than that of AlN monocrystal, and the invention provides the preparation method of beta-Ga 2 O 3 An AlN film is epitaxially grown on the single crystal substrate 10, and the crystal quality of the AlN material can be improved.
Then, beta-Ga is processed in the reaction chamber of MOCVD equipment 2 O 3 The substrate 10 is subjected to an annealing treatment; wherein the temperature of the annealing treatment is more than or equal to 1300 ℃, the time range of the annealing treatment is 5-60 min, and the gas atmosphere is hydrogen; wherein, the annealing treatment under proper process conditions can be performed on the beta-Ga 2 O 3 The surface of the substrate 10 is baked to remove impurities and beta-Ga 2 O 3 The Ga in the substrate 10 undergoes suitable sublimation.
S102, beta-Ga in the reaction chamber 2 O 3 The substrate 10 is subjected to nitriding treatment; the nitriding treatment is carried out at 1100-1400 ℃ for 1-60 min in mixed gas comprising hydrogen and ammonia, and the ratio of the hydrogen to the ammonia is 100:1-1:1. Specifically, nitriding treatment is used for beta-Ga 2 O 3 A certain amount of nitrogen bonds are embedded in the surface of the substrate 10 to allow for better subsequent epitaxial growth.
After that, after the nitriding treatment, beta-Ga 2 O 3 The composite semiconductor layer 201 of the whole layer structure is epitaxially grown on the substrate 10, and the above process specifically includes:
s103, simultaneously introducing an aluminum source and oxygen into the reaction cavity in a first time period;
s104, simultaneously introducing an aluminum source, ammonia gas and oxygen gas into the reaction cavity in a second time period;
s105, simultaneously introducing an aluminum source and nitrogen into the reaction cavity in a third time period.
Wherein, in any one step from S103 to S105, the flow range of the aluminum source is 10 SCCM-10000 SCCM; the range of the first time period, the second time period and the third time period is 1 min-20 min.
In step S104, the ratio of the ammonia gas to the oxygen gas is greater than 0:1 and less than 1:0, and the ratio of the ammonia gas to the oxygen gas increases linearly with the growth time.
Specifically, the material of the composite semiconductor layer 201 corresponding to the composite semiconductor layer 201 is composed of aluminum gallium oxide, aluminum oxynitride, and aluminum nitride. By changing the ratio of the ammonia gas and the oxygen gas introduced into the reaction chamber from 0:1 to 1:0 (i.e. changing from full-through oxygen gas to full-through ammonia gas) along with the growth time, the lattice structure of the compound semiconductor layer 201 can be gradually transited from the aluminum gallium oxide lattice structure (part of Ga sublimates and exists in the reaction chamber in annealing treatment) to the aluminum nitride lattice structure, so that dislocation annihilation can be facilitated, dislocation density is reduced, thermal stress is released, and cracking of the AlN thin film prepared later is prevented.
In the embodiment of the present invention, the growth temperature of the composite semiconductor layer 201 ranges from 500 degrees celsius to 1300 degrees celsius, and the growth temperature of the composite semiconductor layer 201 decreases linearly with the increase of the growth time. Wherein the growth temperature of the compound semiconductor layer 201 linearly decreases with the increase of the growth time, which is beneficial to the release of the stress of the AlN thin film.
S20, epitaxially growing a first AlN layer 202 on the composite semiconductor layer 201.
Specifically, the step S20 specifically includes:
after the growth temperature in the reaction cavity is adjusted to 900-1400 ℃, a first AlN layer 202 is epitaxially grown on the composite semiconductor layer 201, and the first AlN layer 202 is made of AlN material; wherein the thickness of the first AlN layer 202 ranges from 200nm to 4000nm, and the V/III ratio of the first AlN layer 202 ranges from 2000 to 100000.
Specifically, the V/III ratio refers to the mole ratio of a V group source to a group source in a reaction cavity of MOCVD equipment in the epitaxial growth process, and a grown epitaxial layer can bring higher epitaxial lattice quality under the condition of high V/III ratio; on the contrary, if the epitaxial layer is grown under the condition of low V/III ratio, the epitaxial lattice quality of the grown epitaxial layer is poor, but a flat epitaxial lattice surface can be obtained.
Further, the first AlN layer 202 corresponds to an AlN intermediate-temperature growth layer, and is formed of beta-Ga 2 O 3 The transition between the substrate 10 and the second AlN layer 204 is effected.
In one embodiment of the present invention, the step S20 specifically includes:
s201, introducing an aluminum source into the reaction cavity in a fourth time period;
s202, introducing ammonia into the reaction cavity in a fifth time period;
s203, repeating the steps S201 and S202 a plurality of times to generate the first AlN layer 202.
The Al atoms can migrate better on the surface by alternately introducing the aluminum source and the ammonia gas, so that the two-dimensional growth of the AlN material is accelerated.
And S30, epitaxially growing an AlN healing layer 203 on the first AlN layer 202.
Specifically, the step S30 specifically includes:
heating or maintaining the temperature in the reaction cavity unchanged, and epitaxially growing an AlN healing layer 203 on the first AlN layer 202; the AlN healing layer 203 has a thickness ranging from 100nm to 2000nm; preferably, the AlN healing layer 203 includes a plurality of air holes with irregular size and interval, and the AlN healing layer 203 may be entirely free of air holes. Wherein, during the epitaxial growth of the AlN healing layer 203, the thermal stress accumulated in the AlN material during the growth process can be further and greatly released, and further the threading dislocation from the first AlN layer 202 can be greatly filtered.
Preferably, in step S30, the growth temperature of the first AlN layer 202 is T1, the growth temperature of the AlN healing layer 203 is T2, and the relationship between T1 and T2 satisfies: t1 is more than or equal to 900 ℃ and T2 is more than or equal to 1400 ℃; the growth temperature of AlN healing layer 203 is T2 greater than or equal to the growth temperature of first AlN layer 202 is T1, primarily because the higher the growth temperature, the faster the healing.
And S40, epitaxially growing a second AlN layer 204 on the AlN healing layer 203.
Specifically, S40 further includes:
epitaxially growing a second AlN layer 204 on the AlN healing layer 203; wherein, the growth temperature of the second AlN layer 204 is 1200-1500 ℃. The purpose of epitaxially growing the second AlN layer 204 on the AlN healing layer 203 is to obtain an AlN film with few dislocations and good crystal quality.
The technical scheme of the invention is further described with reference to specific embodiments.
Inventive example 1:
the preparation method of the AlN intrinsic layer for the deep ultraviolet light-emitting diode provided by the embodiment of the invention comprises the following steps:
s10, at beta-Ga 2 O 3 A composite semiconductor layer 201 of an entire layer structure is epitaxially grown on the substrate 10.
Specifically, S10 further includes:
s101, beta-Ga in a reaction cavity of MOCVD equipment 2 O 3 The substrate 10 is annealed, wherein the temperature of the annealing treatment is 1550 ℃, the annealing treatment time is 60min, and the gas atmosphere is hydrogen;
s102, beta-Ga in the reaction chamber 2 O 3 The substrate 10 is subjected to nitriding treatment, wherein the nitriding treatment temperature is 1350 ℃, the nitriding treatment time is 60min, the gas atmosphere is a mixed gas consisting of hydrogen and ammonia, and the ratio of the hydrogen to the ammonia is 2:1;
s103, simultaneously introducing an aluminum source and oxygen into the reaction cavity in a first time period;
s104, simultaneously introducing an aluminum source, ammonia and oxygen into the reaction cavity in a second time period, wherein the introducing ratio of the ammonia to the oxygen is more than 0:1 and less than 1:0, and the introducing ratio of the ammonia to the oxygen is linearly increased along with the increase of the growth time;
s105, simultaneously introducing an aluminum source and nitrogen into the reaction cavity in a third time period.
The material of the composite semiconductor layer 201 corresponding to the composite semiconductor layer 201 is composed of aluminum gallium oxide, aluminum oxynitride, and aluminum nitride; in any one of steps S103 to S105, the flow rate of the aluminum source is 1000SCCM; the total time of the first, second and third time periods is 10min. The growth temperature of the composite semiconductor layer 201 is linearly reduced from 1350 ℃ to 950 ℃, the oxygen flow is linearly reduced from 20000SCCM to 0 in the growth process, and the ammonia flow is linearly increased from 0to 15000SCCM; the thickness of the composite semiconductor layer 201 is 50nm.
S20, epitaxially growing a first AlN layer 202 on the composite semiconductor layer 201.
Specifically, the thickness of the first AlN layer 202 is 400nm, and the growth temperature is 1150 degrees celsius; in the growth process, an aluminum source (trimethylaluminum) and ammonia gas are alternately introduced, wherein the introduction time of the aluminum source is 10 seconds, and the introduction time of the ammonia gas is 5 seconds.
And S30, epitaxially growing an AlN healing layer 203 on the first AlN layer 202.
Specifically, the temperature of a reaction cavity in MOVCD equipment is maintained between 900 ℃ and 1400 ℃, an aluminum source and ammonia gas are introduced, the air pressure is 50torr, and the temperature is kept for 30 minutes; at this time, the AlN healing layer 203 contains air holes having irregular size and pitch, and the thickness of the AlN healing layer 203 is 800nm.
And S40, epitaxially growing a second AlN layer 204 on the AlN healing layer 203.
Specifically, the temperature of the reaction chamber in the MOVCD device is raised to 1350 ℃, and a second AlN layer 204 is epitaxially grown on the AlN healing layer 203, where the thickness of the second AlN layer 204 is 3000nm, to finally obtain an AlN intrinsic layer for a deep-uv light emitting diode as shown in fig. 2.
Comparative example:
s10, heating the sapphire substrate to 600 ℃ by using an MOCVD machine, and respectively introducing TMAL and NH under the pressure of 50Torr 3 And H with a flow rate of 5000sccm 2 Growing to form an AlN buffer layer with the thickness of 50nm, wherein the V/III ratio is 10000;
s20, heating the reaction chamber to 1350 ℃ by using an MOCVD machine, and respectively introducing the mixture under the pressure of 50TorrTMAL and NH 3 An AlN material layer having a thickness of 3000nm was grown, wherein the V/III ratio was 1000.
Further, XRD (X-ray diffraction) analysis was performed on the AlN intrinsic layers for deep-ultraviolet light emitting diodes prepared in example 1 of the present invention and comparative example, respectively, and the results are shown in table 1:
| sample of | (002) Flour with a plurality of grooves | (102) Flour with a plurality of grooves |
| Comparative example | 238 | 542 |
| Example 1 | 39 | 214 |
Table 1 results of rocking curve test of high resolution X-ray diffractometer
As is clear from Table 1, the half widths of the (002) plane and (102) plane rocking curves of the comparative example were 238/542arcsec, respectively, and the half widths of the (002) plane and (102) plane rocking curves of the present invention example 1 were 39/214arcsec, respectively.
From the above results, it is clear that the AlN material film grown in example 1 of the present invention has a significantly reduced half-width of the (102) plane rocking curve compared to the (102) plane rocking curve in the comparative example. The half-width of the (102) plane rocking curve has a larger correlation with the edge dislocation density in the material, and the lower the value of the half-width is, the lower the edge dislocation density in the material is, which is helpful to the improvement of the quantum efficiency of the deep ultraviolet light emitting diode;
meanwhile, the (002) plane rocking curve represents screw dislocation, and the half-width of the (002) plane rocking curve of the AlN material film grown in the embodiment 1 of the invention is obviously reduced compared with the half-width of the (002) plane rocking curve in the comparative example, which shows that the AlN intrinsic layer grown in the embodiment 1 of the invention has flat surface, no crack and higher growth quality.
According to the epitaxial growth method of the high-quality AlN intrinsic layer, the prepared composite semiconductor layer 201 with the whole structure is equivalent to a stress release layer, the lattice structure of the composite semiconductor layer is gradually transited from an aluminum gallium oxide lattice structure to an aluminum nitride lattice structure, dislocation annihilation can be facilitated, dislocation density is reduced, meanwhile, thermal stress is released, cracking of a subsequently prepared AlN film is prevented, meanwhile, in the healing process of a subsequent AlN material, threading dislocation can be bent into a ring to be annihilated gradually, and finally the dislocation density of the whole AlN intrinsic layer is reduced.
Correspondingly, the invention also provides an AlN intrinsic layer for the deep ultraviolet light-emitting diode, which is prepared by adopting the preparation method of the AlN intrinsic layer for the deep ultraviolet light-emitting diode.
Furthermore, the invention also provides an epitaxial wafer which contains the AlN intrinsic layer for the deep ultraviolet light-emitting diode. Preferably, the epitaxial wafer is obtained by sequentially growing an N-type ohmic contact layer, a multiple quantum well active region, a P-type electron blocking layer and a P-type ohmic contact layer on an AlN intrinsic layer for a deep ultraviolet light emitting diode.
The AlN intrinsic layer prepared by the invention has high crystal quality and no surface crack, so that the epitaxial wafer obtained on the basis of the invention has more usable area, thereby having high yield and higher brightness.
In summary, unlike the prior art, the present invention provides an AlN intrinsic layer for a deep-uv light emitting diode and a method for fabricating the same, which includes: first, in beta-Ga 2 O 3 A composite semiconductor layer 201 of a whole layer structure is epitaxially grown on a substrate 10, and then a first AlN layer 202 is epitaxially grown on the composite semiconductor layer 201, and again an AlN healing layer 203 is epitaxially grown on the first AlN layer 202,finally, a second AlN layer 204 is epitaxially grown on the AlN healing layer 203, wherein the material of the composite semiconductor layer 201 is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride; due to beta-Ga 2 O 3 The lattice mismatch between the crystal and AlN is only about 3%, and the preparation method is that firstly, beta-Ga 2 O 3 The composite semiconductor layer 201 with the whole layer structure is epitaxially grown on the substrate 10, so that the crystal quality of the composite semiconductor layer 201 can be effectively improved, wherein the material of the composite semiconductor layer 201 is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride, the composite semiconductor layer 201 is equivalent to a stress release layer, the lattice structure of the composite semiconductor layer 201 is gradually transited from the lattice structure of aluminum gallium oxide to the lattice structure of aluminum nitride, dislocation annihilation can be facilitated, dislocation density is reduced, meanwhile, thermal stress is released, cracking of an AlN film which is prepared later is prevented, and then, in the process of the first AlN layer 202 and the AlN healing layer 203 which are grown later on the composite semiconductor layer 201, threading dislocation can be bent into a ring to be annihilated gradually, so that the dislocation density of the whole AlN intrinsic layer is reduced finally, and the crystal quality of the AlN intrinsic layer is further improved.
It should be noted that, the foregoing embodiments all belong to the same inventive concept, and the descriptions of the embodiments have emphasis, and where the descriptions of the individual embodiments are not exhaustive, reference may be made to the descriptions of the other embodiments.
The foregoing examples merely illustrate embodiments of the invention and are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode, which is characterized by comprising the following steps:
s10, at beta-Ga 2 O 3 Epitaxial growth of a composite semiconductor layer of a monolithic structure on a substrate；
S20, epitaxially growing a first AlN layer on the composite semiconductor layer;
s30, epitaxially growing an AlN healing layer on the first AlN layer;
s40, epitaxially growing a second AlN layer on the AlN healing layer;
wherein the material of the composite semiconductor layer is composed of aluminum gallium oxide, aluminum oxynitride and aluminum nitride.
2. The method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 1, further comprising, before performing the step S10:
s101, carrying out beta-Ga in a reaction cavity of MOCVD equipment 2 O 3 Annealing the substrate;
s102, carrying out beta-Ga in the reaction cavity 2 O 3 The substrate is subjected to nitriding treatment.
3. The method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 2, characterized in that in the step S101, the temperature of the annealing treatment is 1300 ℃ or more, the time of the annealing treatment is 5 min-60 min, and the gas atmosphere is hydrogen; in the step S102, the temperature range of the nitriding treatment is 1100-1400 ℃, the time range of the nitriding treatment is 1-60 min, the gas atmosphere is a mixed gas consisting of hydrogen and ammonia, and the ratio of the hydrogen to the ammonia is 100:1-1:1.
4. The method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 2, wherein the step S10 specifically includes:
s103, simultaneously introducing an aluminum source and oxygen into the reaction cavity in a first time period;
s104, simultaneously introducing the aluminum source, ammonia gas and oxygen gas into the reaction cavity in a second time period;
s105, simultaneously introducing the aluminum source and nitrogen into the reaction cavity in a third time period.
Wherein, in any one of the steps S103 to S105, the flow rate of the aluminum source is in a range of 10SCCM to 10000SCCM.
5. The method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 4, wherein in step S104, the ratio of the ammonia gas to the oxygen gas is greater than 0:1 and less than 1:0, and the ratio of the ammonia gas to the oxygen gas increases linearly with the increase of the growth time; the growth temperature of the composite semiconductor layer ranges from 500 ℃ to 1300 ℃, and the growth temperature of the composite semiconductor layer linearly decreases along with the increase of the growth time.
6. The method of fabricating an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 4, wherein in step S20, the thickness of the first AlN layer ranges from 200nm to 4000nm and the V/III ratio of the first AlN layer ranges from 2000 to 100000.
7. The method for preparing an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 6, wherein the step S20 specifically includes:
s201, introducing the aluminum source into the reaction cavity in a fourth time period;
s202, introducing ammonia into the reaction cavity in a fifth time period;
and S203, repeating the step S201 and the step S202 for a plurality of times to generate the first AlN layer.
8. The method of fabricating an AlN intrinsic layer for a deep ultraviolet light emitting diode according to claim 1, wherein in the step S30, the AlN healing layer includes a plurality of air holes having irregular sizes and pitches, and the AlN healing layer has a thickness ranging from 100nm to 2000nm.
9. The method of claim 8, wherein in the step S30, the growth temperature of the first AlN layer is T1, the growth temperature of the AlN healing layer is T2, and the relationship between T1 and T2 satisfies: t1 is more than or equal to 900 ℃ and T2 is more than or equal to 1400 ℃.
10. An AlN intrinsic layer for a deep ultraviolet light emitting diode, characterized in that it is prepared by the preparation method of an AlN intrinsic layer for a deep ultraviolet light emitting diode as claimed in any one of claims 1 to 9.
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