CN117385468A - B-doped AlN single crystal and preparation method thereof - Google Patents
B-doped AlN single crystal and preparation method thereof Download PDFInfo
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- CN117385468A CN117385468A CN202311530332.6A CN202311530332A CN117385468A CN 117385468 A CN117385468 A CN 117385468A CN 202311530332 A CN202311530332 A CN 202311530332A CN 117385468 A CN117385468 A CN 117385468A
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- 239000013078 crystal Substances 0.000 title claims abstract description 47
- 238000002360 preparation method Methods 0.000 title abstract description 7
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims abstract description 25
- 238000000926 separation method Methods 0.000 claims abstract description 25
- 239000002994 raw material Substances 0.000 claims abstract description 22
- 229910052582 BN Inorganic materials 0.000 claims abstract description 21
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 20
- 239000002245 particle Substances 0.000 claims abstract description 14
- 238000010438 heat treatment Methods 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 125000006850 spacer group Chemical group 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 3
- 239000010937 tungsten Substances 0.000 claims description 3
- 230000008021 deposition Effects 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000002425 crystallisation Methods 0.000 abstract description 3
- 230000008025 crystallization Effects 0.000 abstract description 3
- 238000005204 segregation Methods 0.000 abstract description 3
- 238000000859 sublimation Methods 0.000 description 8
- 230000008022 sublimation Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 238000005192 partition Methods 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000000879 optical micrograph Methods 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000010897 surface acoustic wave method Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/38—Nitrides
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/002—Controlling or regulating
-
- 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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention belongs to the technical field of growth of aluminum nitride single crystals, and particularly relates to a B-doped AlN single crystal and a preparation method thereof. The preparation method of the B-doped AlN monocrystal comprises the following steps: designing a temperature zone separation sleeve in the crucible; so that the separation sleeve divides the bottom of the crucible into a low temperature area and a high temperature area; and (3) putting boron nitride polycrystalline particles into a low-temperature area inside the separation sleeve, filling an aluminum nitride raw material into a high-temperature area outside the separation sleeve, and then carrying out growth of the B-doped AlN monocrystal. By adopting the method, the doped B source and the AlN raw material can be sublimated at the same time without layering phenomenon, so that the B element can be uniformly distributed in the AlN single crystal without segregation or doped element enrichment phenomenon, the element doping is more uniform, the growth of the single crystal is not subjected to additional difficulty, and the B doped AlN single crystal with high crystallization quality and uniform doping is obtained by controlling the doping ratio of the B element and the Al element.
Description
Technical Field
The invention belongs to the technical field of growth of aluminum nitride single crystals, and particularly relates to a B-doped AlN single crystal and a preparation method thereof.
Background
AlN crystal is used as an extremely important ultra-wide band-gap semiconductor material, not only has an ultra-high band gap (6.2 eV), but also has high heat conductivity (3.2W cm -1 K -1 ) Excellent physical properties such as high resistivity and high surface acoustic velocity (5600-6000 m/s), and the like, and can be widely applied to lasers, high-power electronic devices, optoelectronic devices and surface acoustic wave devices. Currently, physical Vapor Transport (PVT) is a well-known efficient way to prepare large-size aluminum nitride single crystals, and the growth mechanism is mainly to sublimate AlN raw material in a high-temperature region below a crucible by an induction heating method, and then to transport the sublimated material to a low-temperature growth region by controlling pressure for growth of AlN crystals. The whole process is carried out in a closed nitrogen environment, and the temperature is higher than 2500 ℃, so that the AlN is difficult to realize effective doping of external gas in the growth process, but the doping of other elements is particularly critical in improving the overall performance of the AlN.
Boron nitride is one of the materials with the best heat conductivity at present, and if B element can be effectively doped into aluminum nitride crystals, the heat conductivity of aluminum nitride at high temperature can be effectively improved, but no report has been made at present at home to indicate that the effective intentional doping of AlN single crystals is realized, mainly because the sublimation temperature of AlN raw materials is above 2500 ℃, and doped elements are basically evaporated before the sublimation temperature of AlN is reached, so that the doping of external elements to AlN single crystals is difficult to realize.
Based on the above, how to realize effective doping of B element in the process of growing AlN single crystal by PVT method becomes the problem to be solved in the prior art for improving the crystal performance of AlN bulk.
Disclosure of Invention
Aiming at the defects of the prior art, in particular the difficult problem that the sublimation temperature of AlN raw materials is too high to realize effective doping of external elements, the invention provides a B-doped AlN single crystal and a preparation method thereof.
By adopting the method, the doped B source and the AlN raw material can be sublimated at the same time without layering phenomenon, so that the doped B element can be uniformly distributed in the AlN single crystal without segregation or doped element enrichment phenomenon, the element doping is more uniform, and the single crystal growth is not influenced.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
the invention provides a B-doped AlN single crystal, wherein the molar ratio of B to Al in the B-doped AlN single crystal is 1 (5-10).
The invention also provides a preparation method of the B-doped AlN monocrystal, which is grown by a PVT method and comprises the following steps:
(1) Designing a temperature zone separation sleeve in the crucible; the separation sleeve is hollow and consists of an upper cylindrical part and a lower round table part; the bottom radius of the cylindrical part is the same as the upper bottom radius of the round table part and is 1/3 of the radius of the crucible, and the lower bottom radius of the round table part is 4/5 of the radius of the bottom of the crucible; the height of the round table part is the same as that of the cylindrical part, and is 1/5 of that of the crucible;
(2) Placing the separation sleeve at the center of the bottom of the crucible, placing boron nitride polycrystal particles into the separation sleeve, and filling aluminum nitride raw materials outside the separation sleeve, wherein the height of the aluminum nitride raw materials is less than 4/5 of the height of the separation sleeve; the inside of the separation sleeve is a low temperature area, and the outside of the separation sleeve is a high temperature area;
(3) Placing aluminum nitride seed crystal on the top of the crucible, and sealing the crucible;
(4) Placing the crucible in an AlN heating furnace, and setting a low crucible position, wherein a radial gradient of more than 20 ℃ exists at the bottom of the crucible under the low crucible position; and (3) vacuumizing the crucible, filling nitrogen, heating to grow, and obtaining the B-doped AlN monocrystal after the growth is finished, wherein the growth temperature of the deposition surface is 2200-2250 ℃.
Preferably, in step (1), the material of the partition sleeve is tungsten metal.
Preferably, in the step (2), the mass ratio of the boron nitride polycrystalline particles to the aluminum nitride raw material is 1 (8.2-16.4) so as to ensure that the molar ratio of B to Al in the obtained B-doped AlN single crystal is 1 (5-10).
It is further preferred that in step (2), the mass ratio of boron nitride polycrystalline particles to aluminum nitride feedstock is 1:16.4.
Preferably, in the step (2), the grain size of the boron nitride polycrystal grains is 1-3mm.
Further preferably, in the step (2), the particle diameter of the boron nitride polycrystal particles is 2.+ -. 0.5mm.
Preferably, in the step (4), the position of 1/2 of the height of the crucible coincides with the center of the coil.
In the invention, the aluminum nitride raw material is an aluminum nitride raw material which can be directly used for AlN single crystal growth after multiple times of impurity removal.
Preferably, in the step (4), the heating furnace is a resistance furnace.
Preferably, the time of growth in step (4) is 40-60 hours.
The invention has the following beneficial technical effects:
(1) By adopting the method provided by the invention, the doped B source and the AlN raw material can be sublimated at the same time without layering phenomenon, so that the B element can be uniformly distributed in the AlN single crystal without segregation or doped element enrichment phenomenon, the element doping is more uniform, and the growth of the single crystal is not difficult to be additionally caused.
(2) According to the invention, the B doped AlN single crystal with high crystallization quality and uniform doping is obtained by controlling the doping ratio of B element and Al element, and the thermal conductivity of the crystal below 1000 ℃ is obviously higher than that of the pure AlN single crystal.
Drawings
FIG. 1 is a schematic view showing the internal structure of a crucible according to example 1 of the present invention;
wherein 1 is a crucible; 2 is a separation sleeve; 3 is AlN raw material; 4 is BN raw material; and 5 is seed crystal.
Fig. 2 is a cross-sectional view of a spacer sleeve according to embodiment 1 of the present invention.
Fig. 3 is an optical micrograph of an AlN ingot grown after boron doping in example 1 of the present invention.
Fig. 4 shows an AlN ingot grown after boron doping in example 1 of the present invention.
FIG. 5 is a photograph of crystals grown in comparative example 1 of the present invention.
FIG. 6 is a photograph of crystals grown in comparative example 2 of the present invention.
FIG. 7 is a photograph of crystals grown in comparative example 3 of the present invention.
Detailed Description
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Example 1
A method for growing B-doped AlN single crystals by a PVT method comprises the following steps:
1) Selecting a cylindrical tungsten crucible with the bottom radius dimension of 150mm (the height of 125 mm) to grow the B-doped AlN monocrystal; the temperature zone separation sleeve in the crucible is designed, and the separation sleeve is hollow and consists of a cylindrical part above and a round table part below.
The radius size of the lower bottom of the round table part is 4/5 of the radius of the bottom of the crucible, namely 120mm.
The bottom radius of the cylindrical part is the same as the upper bottom radius of the circular truncated cone part, and is 1/3 of the radius of the crucible, namely 50mm.
The height of the round platform part is 25mm, and the height of the cylindrical part is 25mm.
2) Placing a partition sleeve at the center of the bottom of the crucible, and adding 10g of boron nitride polycrystal particles into the partition sleeve; 164g of aluminum nitride growth raw material is added into the high-temperature area outside the separation sleeve, so that the molar ratio of BN to AlN at the raw material is ensured to be 1:10.
3) And placing an aluminum nitride seed crystal on the top of the crucible, and sealing the crucible.
4) The crucible is placed in an AlN hearth, 1/2 of the height of the crucible is reduced to a low crucible position overlapped with the center of a heating coil of the resistance furnace, and a radial gradient at 25 ℃ exists at the bottom of the crucible. And (3) vacuumizing the crucible, filling nitrogen, heating to grow at 2200-2250 ℃ for 48h, and cooling to obtain the uniformly doped B-doped AlN single crystal.
The sublimation point of the boron nitride single crystal is 20-50 ℃ lower than that of the aluminum nitride single crystal, boron nitride can be used as an ideal doping source of aluminum nitride due to the small difference of the sublimation points of the boron nitride single crystal and the aluminum nitride can be effectively improved in heat conductivity due to the high heat conductivity of the boron nitride. Because the heating source in the temperature field of the resistance method is arranged outside the crucible, the crucible can be effectively separated into a low-temperature area and a high-temperature area by the heat insulation effect of the separation sleeve under the low crucible position; because the sublimation point of boron nitride is lower, the sublimation point of aluminum nitride is higher, and the simultaneous sublimation can be realized by placing boron nitride in a low-temperature area and aluminum nitride in a high-temperature area. FIG. 1 is a schematic view of the internal structure of a crucible; FIG. 2 is a schematic view of the construction of the spacer sleeve; FIG. 3 is a micrograph of an AlN ingot grown from doped boron nitride, showing that the B doped ingot does not affect the integrity of the AlN bulk structure, and does not cause large scale lattice abrupt changes; fig. 4 is a graphical representation of a B-doped ingot showing overall yellow color, with a slow growth rate of the doped ingot, but also a uniform growth, without delamination.
Comparative example 1
The difference from example 1 is that the doping ratio is 1: as shown in FIG. 5, 164g of AlN material and 33g of BN material were charged, and a single crystal was not formed, and a large amount of polycrystal appeared on the surface, resulting in poor growth quality.
Comparative example 2
The difference from example 1 is that the doping ratio is 1:15 g of AlN raw material and 6.66g of gBN raw material were charged, and the growth was not different from that of pure AlN as shown in FIG. 6, and the doping amount of B was too small to have a substantial doping effect.
Comparative example 3
Compared to example 1, the difference is that no spacer sleeve is used, alN and BN are mixed according to 1:10 proportion, and the growth condition is shown in fig. 7, and the boron nitride has a low melting point, is easily sublimated and attached to the surface of the AlN seed crystal in the early stage, so that the crystal is layered, the content of B in a lower layer area in the figure is higher, the content of B in a subsequent upper layer area is less, the doping is uneven, and the crystallization quality is poor.
Claims (10)
1. A B-doped AlN single crystal is characterized in that the molar ratio of B to Al in the B-doped AlN single crystal is 1 (5-10).
2. The method for producing a B-doped AlN single crystal according to claim 1, characterized by being grown by PVT, comprising the steps of:
(1) Designing a temperature zone separation sleeve in the crucible; the separation sleeve is hollow and consists of an upper cylindrical part and a lower round table part; the bottom radius of the cylindrical part is the same as the upper bottom radius of the round table part and is 1/3 of the radius of the crucible, and the lower bottom radius of the round table part is 4/5 of the radius of the bottom of the crucible; the height of the round table part is the same as that of the cylindrical part, and is 1/5 of that of the crucible;
(2) Placing the separation sleeve at the center of the bottom of the crucible, placing boron nitride polycrystal particles into the separation sleeve, and filling aluminum nitride raw materials outside the separation sleeve, wherein the height of the aluminum nitride raw materials is less than 4/5 of the height of the separation sleeve; the inside of the separation sleeve is a low temperature area, and the outside of the separation sleeve is a high temperature area;
(3) Placing aluminum nitride seed crystal on the top of the crucible, and sealing the crucible;
(4) Placing the crucible in an AlN heating furnace, and setting a low crucible position, wherein a radial gradient of more than 20 ℃ exists at the bottom of the crucible under the low crucible position; and (3) vacuumizing the crucible, filling nitrogen, heating to grow, and obtaining the B-doped AlN monocrystal after the growth is finished, wherein the growth temperature of the deposition surface is 2200-2250 ℃.
3. The method of claim 2, wherein in step (1), the spacer sleeve is made of tungsten metal.
4. The method according to claim 2, wherein in the step (2), the mass ratio of the boron nitride polycrystalline particles to the aluminum nitride raw material is 1 (8.2 to 16.4).
5. The method according to claim 4, wherein in the step (2), the mass ratio of the boron nitride polycrystalline particles to the aluminum nitride raw material is 1:16.4.
6. The method according to claim 2, wherein in the step (2), the boron nitride polycrystal particles have a particle diameter of 1 to 3mm.
7. The method according to claim 6, wherein in the step (2), the particle diameter of the boron nitride polycrystal particles is 2.+ -. 0.5mm.
8. The method according to claim 2, wherein the heating furnace in step (4) is a resistance furnace.
9. The method according to claim 8, wherein in the step (4), the crucible height 1/2 coincides with the center of the coil of the resistance furnace.
10. The method according to claim 2, wherein the time of the growth in step (4) is 40 to 60 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311530332.6A CN117385468A (en) | 2023-11-16 | 2023-11-16 | B-doped AlN single crystal and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311530332.6A CN117385468A (en) | 2023-11-16 | 2023-11-16 | B-doped AlN single crystal and preparation method thereof |
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| CN117385468A true CN117385468A (en) | 2024-01-12 |
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| CN202311530332.6A Pending CN117385468A (en) | 2023-11-16 | 2023-11-16 | B-doped AlN single crystal and preparation method thereof |
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- 2023-11-16 CN CN202311530332.6A patent/CN117385468A/en active Pending
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