JP4041302B2 - Seed crystal for growing zinc oxide and its preparation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seed crystal for growing zinc oxide used for growing a single crystal of zinc oxide that can be used for industrial applications and a method for producing the same, and particularly suitable for obtaining a single crystal that is long in the c-axis direction. It is a seed crystal and its preparation method.
[0002]
[Prior art]
Conventionally, in semiconductor devices, semiconductor devices formed using amorphous silicon, polycrystalline silicon, or the like as a thin film material have been widely used. In recent years, zinc oxide (ZnO) has attracted attention as a thin film material. Semiconductor devices formed as thin film materials can be applied to existing semiconductor devices such as UV LEDs (Light Emitting Diodes), laser diodes (LDs), and transparent transistors, or research and development for new applications. It is being advanced.
[0003]
By the way, when manufacturing semiconductor devices, it is known that the quality of the thin film formed on the base substrate has a significant effect on its electrical characteristics, optical characteristics, reliability (lifetime), etc. The better the quality, the better the electrical and optical characteristics and reliability.
[0004]
For this reason, when producing a semiconductor device using ZnO as a thin film material, it is important to form a high-quality ZnO thin film without crystal defects on the base substrate.
Factors that determine the quality of the thin film include the difference in the lattice constant between the thin film material and the base substrate material. It is known that the smaller the difference in the lattice constant, the more the thin film without crystal defects can be formed. Note that the lattice constant indicates an arrangement interval of atoms regularly arranged in the crystal.
[0005]
For this reason, when a semiconductor device having a ZnO thin film is formed, a base substrate formed of sapphire or the like having a lattice constant relatively close to that of a ZnO single crystal has been used.
However, since the lattice constant differs between sapphire and a single crystal of ZnO by about 18%, in order to form a high-quality ZnO thin film on a base substrate formed of sapphire, it is necessary to form the thin film considerably thicker than usual. Because of the problem of profitability, there was no choice but to compromise with a certain level of quality industrially.
[0006]
Therefore, for example, in order to form an extremely high quality ZnO thin film on the base substrate at low cost, it is conceivable to form the base substrate with a single crystal of ZnO having the same lattice constant as that of the ZnO thin film. A ZnO single crystal having a size that can be used as a base substrate could not be grown.
In the growth of zinc oxide (ZnO) single crystals by the hydrothermal synthesis method, there is a problem that crystals grow selectively in the a-axis direction in the hexagonal crystal structure and hardly grow in the c-axis direction.
6A schematically showing the growth of the ZnO single crystal 30 centering on the seed crystal 3, and FIG. 6B depicting the crystal axis of the ZnO single crystal, as shown in FIG. When the seed crystal 3 cut into a rod shape parallel to the c-axis is used, when the crystals r1, r2, r3 grow by the growth in the a-axis direction, the available lengths in the c-axis direction are rather x1, x2, x3 Go reduced. That is, a single crystal exceeding the length of the initial seed crystal cannot be obtained.
[0007]
Therefore, in order to obtain a large ZnO single crystal in the c-axis direction, for example, according to Japanese Patent Laid-Open No. 6-12088, a plurality of seed crystals are brought into contact with each other so that the c-axis directions coincide with each other, and the contact portion is hydrothermally synthesized. There has been proposed a method of joining them by a method to form a long seed crystal.
As shown in the schematic view of the joined seed crystal 22 in FIG. 6C, a single ZnO single crystal is cut along the c-axis to cut out several seed crystals. Both end surfaces perpendicular to the c-axis are brought into contact with each other and fastened with a platinum wire 45, grown in a growth vessel, and joined and integrated by epitaxy.
If the c-axis direction and the + -direction are aligned during bonding, a seed crystal having a long c-axis can be obtained. At the same time, it is desirable to align the directions of the three a axes. X-ray analysis is used to measure and match the direction of the crystal axes.
The growth container used in the hydrothermal synthesis method and the growth status thereof will be described later.
[0008]
For example, as shown in FIG. 2C, as an example, two cleaved seed crystals 22a and 22b having a length of 7 mm along the c axis and a cross section perpendicular to the c axis of 3 × 1.5 mm coincide with the c axis. The seed wire 22 is bonded to the frame 61 of the crystal growth portion of the growth vessel and fixed to the frame 61 of the growth vessel by the platinum wire 62, so that the contact surface 41 is joined to form a single seed crystal 22. can get.
As a result of growing using this seed crystal 22, a crystal having a cross section of about 8 × 11 mm perpendicular to the c-axis and 14 mm in the c-axis direction is obtained. A crystal having a cross section perpendicular to the c-axis of about 8 × 11 mm is obtained.
Thus, by joining a plurality of seed crystals, a seed crystal having a length sufficient to obtain a practical crystal can be obtained.
[0009]
When the above-described seed crystal production operation is actually advanced, there is a tendency that some irregularities (direction mismatch) occur in the directions of the three a-axes at the time of contact of the seed crystal. As described above, it has been found that it is difficult to make the direction of the a-axis completely coincide with each other in the seed crystal bonding surface 41 even if careful use is made using X-ray analysis. It is difficult to avoid a mismatch (Δθ) between the directions of the a-axis 43 of the seed crystal 22a and the a-axis 43a of the seed crystal 22b as shown in the schematic diagram illustrating only the axis of FIG.
[0010]
When the seed crystal is grown by the hydrothermal synthesis method and the contact surfaces are bonded, the bonded surface generates a crystal defect region based on the mismatch of the a-axis. As schematically shown in FIG. 3B, when the solution crystallizes at the contact portion of the seed crystal, the mismatch of the a-axis at the contact surface locally affects the blade shape and the spiral shape. It is considered that a defect region that reaches the surface of the seed crystal by causing a transition is generated.
Even after the joining of the seed crystal contact portion is completed, even if a single crystal of ZnO is subsequently crystallized by a hydrothermal synthesis method and this single crystal is grown, this defect region does not disappear, and the three seed crystals Due to the mismatch in the direction of the a-axis, a concentric crystal defect region centering on the seed crystal grows from the joint portion of the seed crystal to the grown single crystal.
[0011]
[Problems to be solved by the invention]
As described above, when a concentric crystal defect region centered on the seed is formed at the seed crystal junction in the grown single crystal, the obtained single crystal includes a defect region for each length of the seed crystal. Thus, there is a problem that the grown single crystal has little industrial utility value.
Further, since the interval between the defect regions is the length of the initial seed crystal, there is a problem that a single crystal having a large interval between the defect regions cannot be obtained even if seed crystals are successively grown from the joined seed crystals.
[0012]
An object of the present invention is to supply a seed crystal in which a concentric crystal defect region centered on the seed does not occur in the grown single crystal at the junction of the seed crystal.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a seed crystal material in which the directions of a plurality of c- axes made of a single crystal of zinc oxide coincide with each other, and the a-axis directions substantially coincide with each other. a primary seed crystals bonded to a zinc oxide thin film of the above thickness of 2 to 4μm, which is deposited on the surface of the primary seed crystal, Tona is, the plurality of seed crystal material zinc oxide The zinc oxide thin film formed on the surface of the bonded primary seed crystal provides a seed crystal for growing zinc oxide formed by vapor phase growth .
[0014]
Furthermore, the present invention extends the c- axis of a seed crystal material that is aligned with the direction of a plurality of c- axes cut out from a single crystal of zinc oxide, and is joined so that the a-axis directions are substantially matched. Aligning the direction of the c-axis to the direction and making the a-axis direction substantially coincide with each other, abutting the abutment portion by epithermal growth by a hydrothermal synthesis method, and joining to form a primary seed crystal; a step of growing the following species of zinc oxide thin film of the above thickness of 2 to 4μm in vapor phase growth on the crystal surface, Tona is, the plurality of seed crystal material of zinc oxide and bonding the above primary seed crystal The zinc oxide thin film formed on the surface provides a method for producing a seed crystal for growing zinc oxide formed by vapor phase growth .
[0015]
A zinc oxide film is formed on the surface of a single crystal of zinc oxide by vapor phase growth to cover the crystal structure defects at the joint portion of the seed crystal material, so that the single crystal grown thereon does not have any defects. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Before describing the seed crystal, the outline of the hydrothermal synthesis method will be described with reference to FIG.
FIG. 2 is a diagram showing an example of a single crystal growth apparatus 51 using the single crystal growth vessel previously proposed by the present applicant.
[0017]
The single crystal growing apparatus 51 shown in FIG. 2 includes an autoclave 52 that can apply the temperature and pressure required for growing a ZnO single crystal by hydrothermal synthesis, and the inside of the autoclave 52. It is comprised from the growth container 60 accommodated and used for.
The autoclave 52 is covered with a lid 54 with a packing 57 sandwiched between a container body of the autoclave 52 made of, for example, high-strength steel mainly composed of iron, and fixed inside by a fixing portion 55. The structure is hermetically sealed.
[0018]
The growth container 60 that is accommodated and used in the autoclave 52 is formed of, for example, platinum (Pt) or the like, and the shape thereof is a substantially cylindrical container. And the bellows 70 which acts as a pressure adjustment part is attached to the upper part in the state which sealed the inside of the growth container 60. As shown in FIG.
[0019]
In such a single crystal growing apparatus 51, the ZnO seed crystal 3 is suspended using the frame 61 and the noble metal wire (platinum wire) 62 on the upper side in the growth vessel 60, and the raw material 66 is disposed on the lower side thereof. The seed crystal 3 is grown.
In this case, an internal baffle plate 64 that controls thermal convection is provided between the ZnO seed crystal 3 and the raw material 66, and the inside of the growth vessel 60 is divided into a melting region and a growth region by the internal baffle plate 64. It is delimited.
A plurality of holes are formed in the internal baffle plate 64, and the counter flow rate from the dissolution region to the growth region is controlled by the opening area of the baffle plate 64 determined by the number of holes. A temperature difference can be obtained.
[0020]
Then, a strong alkali solution such as sodium hydroxide (NaOH), calcium carbonate (Na 2 CO 3), potassium hydroxide (KOH), or the like is injected into the growth container 60 and transmitted between the autoclave 52 and the growth container 60. For example, a heat transfer solution 67 such as pure water is injected for heat, and the autoclave 52 is heated by the heaters 56, 56... A dissolved growth solution 71 is generated.
Then, the growth solution 71 is supplied to the growth region via the internal baffle plate 64 so that the ZnO seed crystal 3 is grown.
[0021]
Further, in the single crystal growing apparatus 51 shown in FIG. 2, an external baffle plate 65 is provided outside the growth vessel 60, and the convection outside the growth vessel 60 is restricted by the external baffle plate 65, so that the growth is performed. A temperature difference necessary for the growth of the ZnO seed crystal 3 is obtained between the regions in the container 60.
[0022]
In addition, a bellows 70 is provided as a pressure adjusting unit on the upper part of the growing container 60, and the internal pressure of the growing container 60 and the external pressure are balanced by the expansion and contraction of the bellows 70.
[0023]
Such a large single crystal growing apparatus 51 can carry out growth from a seed crystal to a ZnO single crystal by a hydrothermal synthesis method. A ZnO single crystal having a caliber size that can be used for industrial applications can be grown with almost no impurities mixed in the growth vessel 60.
If the seed crystal material 23a, 23b, 23c,... Is used only for joining the contact surfaces, the seed crystal-dedicated growth container 60 may be a small dedicated object.
[0024]
An example of the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram schematically showing an example of a method for forming a seed crystal of zinc oxide (ZnO) according to the present embodiment.
A single crystal of ZnO is a hexagonal crystal, and there are three a (1, 2, 3) axes that form an angle of 120 ° with respect to a c axis and a plane perpendicular to the c axis as crystal axes. . First, as shown in FIG. 1A, a ZnO single crystal thin plate 46 is cut out from a ZnO single crystal 40 so as to be parallel to the c-axis and one a-axis. Further, as shown in the perspective view of FIG. 5B, a plurality of ZnO seed crystal materials 23a, 23b,...
[0025]
The seed crystal materials 23a, 23b,... Are finished by polishing or the like on two surfaces perpendicular to the c-axis. Further, it is preferable that the other surfaces have substantially the same cross-sectional shape when the three a-axes are made coincident. For this purpose, it is convenient to cut out the seed crystal materials 23a, 23b,... From one ZnO single crystal 40, but a seed crystal material cut out from another single crystal may be combined. .
In the present embodiment, the seed crystal materials 23a, 23b,... Are drawn as rectangular shapes with a cross-sectional shape cut at right angles to the c-axis. However, the cross-sectional shape is, for example, a thin plate. Or a cylindrical shape.
[0026]
Next, as shown in FIG. 1 (c), a predetermined number of seed crystal materials 23a, 23b,... Are taken and the c-axis of the next material comes to the -c end of the c-axis. The direction is aligned, the joining surface 41 is brought into contact, and fixed by, for example, a method of binding with a platinum wire. Although three examples are shown in the figure, two or four or more may be contacted at the same time.
At this time, the three a-axis directions are aligned as much as possible. As mentioned above, X-ray analysis is used to measure and match the c-axis plus and minus directions with the a-axis direction.
The seed crystal materials 23a, 23b,... With aligned crystal axes are fixed to the crystal growth portion of the growth vessel by a hydrothermal synthesis method, and the contact surface (joint surface 41) is joined by epitaxy.・ Grow until integrated. The integrated seed crystal materials 23 a, 23 b,... Are called primary seed crystals 21.
[0027]
As shown in FIG. 1D, a ZnO film 2 is formed on the surface of the primary seed crystal 21 joined by the hydrothermal synthesis method by vapor phase epitaxy (VPE), which is one of the epitaxial growth methods. To do.
Although details will be described later, as schematically shown in FIG. 3A, the film formation state of the ZnO film 2, the crystal defect region due to some mismatch in the direction of the a-axis is eliminated as the number of thin films increases. To do.
Thus, the ZnO film 2 is formed until the crystal defect region of the contact portion 41 of the primary seed crystal 21 is eliminated, and the seed crystal 5 is obtained. Usually, when the thickness of the thin film is 2 to 4 μm, the surface of the ZnO film 2 formed on the seed crystal 5 is oriented with a sufficient number of defects industrially.
If the ZnO single crystal is grown again by the hydrothermal synthesis method using the deposited seed crystal 5, the length of the obtained single crystal in the c-axis direction is sufficiently long, and the crystal materials 23a, 23b ..,... Can be prevented from occurring due to a mismatch in the a-axis direction of the abutting portion 41.
[0028]
If the grown single crystal is sliced, it becomes a ZnO wafer, and a substrate having a size sufficient for industrial use can be obtained as a final product.
Of course, a single crystal may be mass-produced using a seed crystal cut out from the single crystal. In this case, if the primary seed crystal 21 is cut out so as not to include the crystal defect region in the central portion, it can be used as the seed crystal 5 without forming the ZnO film 2 on the surface by vapor deposition. The wafer formed from the obtained single crystal also does not include a crystal defect region at the center.
[0029]
Here, when the ZnO film 2 is formed on the surfaces of the seed crystal materials 23a, 23b, 23c,... Bonded by the hydrothermal synthesis method by the vapor phase growth method, the surface layer portion of the ZnO film 2 is formed on the surface layer portion. The reason why the influence of the defect generated at the joint is not explained.
[0030]
As described above, when ZnO single crystals are continuously grown by the hydrothermal synthesis method, when the direction mismatch of the directions of the three a axes of the seed crystals occurs, as described above, When a crystal defect region is likely to be formed in the a-junction portion and is subsequently grown by the hydrothermal synthesis method, the defect region expands concentrically as the crystal grows.
In the hydrothermal synthesis method, a solution of the same material as the single crystal is crystallized on the surface of the single crystal to form a single crystal. Although not necessarily theoretically exact, recrystallization occurs during the crystallization process, and the state of the surface of the seed crystal continues as the structure. Therefore, if there is a defect region on the surface of the seed crystal, the defect remains retained. There is a strong tendency to continue growing. Experimentally, it has not been confirmed that the defect region is reduced or disappears during the recrystallization process.
On the other hand, in the case of vapor phase generation, single crystals are deposited one by one on the surface of the substrate while taking the same crystal structure as the substrate. Since vapor-phase generation yields a highly crystalline ZnO thin film, the crystal structure of the thin film deposited on the surface layer of the seed crystal approaches a unique crystal structure for each layer.
[0031]
When vapor phase growth is performed using sapphire having a lattice constant relatively close to that of a single crystal of ZnO, the lattice constant differs between the sapphire and the single crystal of ZnO by about 18%. As the thickness increases, a fairly good ZnO thin film can be formed on the sapphire base substrate. Usually, it is said that the difference in lattice constant is preferably 15% or less, but depending on the thickness of the film formation, it is possible to obtain a thin film surface layer with few defects.
When forming a ZnO thin film on a single crystal plane of ZnO having the same lattice constant, if a thin film having a thickness of about 4 μm is formed, defects on the partial single crystal plane are covered and a surface layer having no defects is obtained.
[0032]
Description will be made with reference to FIG. 3A in which the vicinity of the crystal defect region 44 generated on the joint surface of the seed crystal materials 23a and 23b (which are already joined to form a primary seed crystal) is cut along a plane including the c-axis. To do. In the figure, ZnO deposited on the surfaces of the seed crystal materials 23a and 23b is shown as small squares, and (1), (2), (3)... Are sequentially deposited to form a ZnO thin film ( (The number of layers to be deposited is extremely compressed).
[0033]
In the first layer (1), the ZnO thin film is not deposited in the vicinity of the crystal defect region 44, and vacancies that are lattice defects are formed. In the second layer (2), the ZnO thin film penetrates from the end of the crystal defect region 44, and the interval between the vacancies near the crystal defect region 44 becomes narrow. In the third layer (3), the interval between lattice points near the crystal defect region 44 is further reduced.
The fourth layer (4) has almost normal lattice spacing, and the fifth and sixth layers (5) and (6) are normal layers and cover the defect area 44.
When a single crystal is grown from a surface with few defects by a hydrothermal synthesis method, a single crystal with few defects is obtained.
[0034]
The reason why the crystal defect region 44 is formed on the joint surface of the seed crystal due to the deviation in the a-axis direction is considered as follows. FIG. 3B is a schematic view of the crystal defect region 44 at the joint portion of the seed crystal material 23 (a, b) cut at a right angle to the c-axis and viewed from below.
In the figure, the arrangement inside the seed crystal material is omitted, and the growth is shown as the growth outside the seed crystal material 23. However, in the case of the hexagonal system, ZnO is arranged along the a axis. Accordingly, the seed crystal material 23a side is aligned and grown in the a-axis 43 direction, and the seed crystal material 23b side is grown in the a-axis 43a direction. In this way, the joining surface of the seed crystal material is joined while forming the spiral transition 47a over the entire contact surface of the seed crystal 23 (a · b). In practice, it may be considered that the polycrystals are not arranged in an orderly manner as shown in FIG.
[0035]
In addition, as shown in FIG. 4 by cutting perpendicularly to the c-axis to show a planar growth form of the crystal, the edge-shaped transition is caused by the growth of the crystal in two directions of the slightly inclined a-axis 43 and a-axis 43a. Sometimes it happens. Actually, the crystal defect region 44 includes a complex crystal defect, in which a spiral transition, an edge transition, and a polycrystalline state are irregularly mixed.
[0036]
As the ZnO film is formed by the vapor phase growth method, crystal defects on the bonding surface gradually decrease, but at the same time, the two a-axes 43 and 43a are gently connected.
FIG. 5 is a schematic diagram in which the change of the a-axes 43 and 43a is exaggerated by the degree of vapor deposition.
FIG. 2A shows a plane including the a-axis of the cylindrical seed crystal 23 (a, b) with hatching. The directions of the a-axes 43 and 43a slightly above and below the crystal defect region 44 are inconsistent. As the ZnO thin film 2 is formed, the a-axes 43 and 43a of the seed crystal are also extended in the same direction in the ZnO thin film 2 so as to form a straight line on the surface of the ZnO thin film 2.
[0037]
As shown in FIG. 5C, when the thickness of the ZnO thin film 2 is further increased, the crystal defect region 44 is gradually covered, but at this time, the a-axis direction is gradually changed in the vicinity of the crystal defect region 44. Connected smoothly.
When carefully aligned by X-ray analysis, the mismatch of the a-axis direction is negligible, and if the influence of the crystal defect region is removed, the performance as a single crystal is hardly adversely affected.
[0038]
In this way, a long c-axis seed crystal with few defects is obtained.
In order to obtain a longer seed crystal, the primary seed crystals 21, 21,... May be repeated from the single crystal having a long c-axis length obtained by the above procedure. However, matching the axial direction of the a-axis of the abutting portions of the primary seed crystals 21, 21,... With the required accuracy requires a considerable amount of work, so the number of abutting / joining points should be smaller. Good.
Once a ZnO single crystal having a length that can be expected to be mass-produced can be obtained, it is easy to keep a primary seed crystal of that length.
From the grown single crystal, a primary seed crystal 21 having a length necessary for growing a ZnO single crystal that can be used for industrial applications can be produced.
[0039]
Therefore, if a single crystal of ZnO is grown again from the primary seed crystal 21 by the hydrothermal synthesis method using the single crystal growth apparatus 51 shown in FIG. Moreover, it is possible to grow a ZnO single crystal having an aperture size that can be used for industrial applications.
Particularly, in this case, since the crystal defect region is not included in the seed crystal 21 used for growing the ZnO single crystal, a good quality ZnO wafer can be obtained from the ZnO single crystal.
[0040]
Therefore, if such a ZnO wafer is used as a base material and a ZnO thin film is formed on this base material, an extremely high quality ZnO thin film can be formed.
Therefore, if such a ZnO single crystal is used as a base material and a ZnO thin film is formed on this base material to produce a semiconductor device such as an ultraviolet LED, a laser diode, or a transparent transistor, the electrical / optical A semiconductor device having excellent characteristics and reliability can be realized.
[0041]
【The invention's effect】
As described above, the seed crystal for growing zinc oxide according to the present invention forms a zinc oxide thin film on the surface of a primary seed crystal obtained by joining a plurality of seed crystal materials made of a single crystal of zinc oxide. A single crystal grown as a seed crystal is not affected by the crystal defect region generated at the junction of the seed crystal material, and a good zinc oxide single crystal can be obtained. Then, by matching the directions of the a-axis and the three c-axes, there is an effect that a single crystal having industrially sufficient accuracy and size can be obtained.
Therefore, if a single crystal of zinc oxide is grown from such a seed crystal, it becomes possible to grow a single crystal of a size that can be used for an unprecedented industrial application.
[0042]
In addition, the process of growing a zinc oxide thin film on the surface of the primary seed crystal by using the epithermal growth of the contact part by hydrothermal synthesis method for joining a plurality of seed crystal materials cut out from a single crystal of zinc oxide. The method for producing a seed crystal for growing zinc oxide using phase growth has a great effect of guaranteeing both cost reduction and quality improvement of the obtained single crystal by properly using vapor phase growth and hydrothermal synthesis.
In addition, the thickness of the zinc oxide thin film covering the crystal defect region on the surface of the primary seed crystal is specified, and the establishment of a working standard has the effect of facilitating implementation.
[0043]
When this single crystal is used as the second seed crystal, the seed crystal necessary for growing a single crystal of a size that can be used for industrial applications can be supplied at low cost without requiring man-hours such as crystal axis alignment, Moreover, it is possible to always reproduce the necessary c-axis length seed crystal.
Therefore, the seed crystal formed once can be supplied in the future.
[0044]
Further, by repeating this method, a seed crystal having a required c-axis length can be obtained, so that it is possible to meet the demand for increasing the seed crystal length by introducing a large autoclave or the like.
Furthermore, since a high-quality ZnO single crystal can be obtained, it is a great effect that improvement in electrical and optical characteristics and reliability of semiconductor devices such as ultraviolet LEDs, laser diodes, and transparent transistors can be expected.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a method of forming a long seed crystal by joining contact surfaces of ZnO single crystals by a hydrothermal synthesis method.
FIG. 2 is a cross-sectional view of a single crystal growing apparatus used in a hydrothermal synthesis method.
FIG. 3 is a schematic diagram showing a thin film formation state by vapor phase growth in the vicinity of a crystal defect region of a seed crystal junction.
FIG. 4 is a schematic diagram showing the inside of a crystal defect region of a seed crystal junction.
FIG. 5 is a schematic diagram showing a state of change of the a-axis near the seed crystal joint.
FIG. 6 is a diagram for explaining a method of creating a seed crystal that is long in the c-axis direction.
[Explanation of symbols]
1, 20 base material, 2 ZnO film, 3, 5, 22 seed crystal, 21 primary seed crystal, 23 (a, b, c, ...) seed crystal material, 10, 30, 40 ZnO single crystal, 41 bonding surface, 42 c-axis, 43, 43a a-axis, 44 crystal defect region, 45 platinum wire,
1 thin plate of ZnO single crystal, 47 edge transition, 47a spiral transition, 51 single crystal growth device, 52 autoclave, 54 lid, 55 fixing part, 56 heater, 57 packing, 60 growth vessel, 61 frame, 62 platinum wire, 64 internal baffle plate, 65 external baffle plate, 66 raw material, 67 heat transfer solution, 70 bellows, 71 growth solution,

Claims (2)

A primary seed crystal in which a plurality of c- axis directions made of a single crystal of zinc oxide are aligned with each other, and a seed crystal material bonded in such a manner that the a-axis directions substantially match,
A zinc oxide thin film of the above thickness of 2 to 4μm, which is deposited on the surface of the primary seed crystal, Ri Tona,
A seed crystal for growing zinc oxide, wherein the zinc oxide thin film formed on the surface of the primary seed crystal to which the plurality of seed crystal materials of zinc oxide are joined is formed by vapor phase growth . The direction of the c- axis in the direction in which the c-axis is extended in the direction in which the c-axis is extended is aligned with the direction of a plurality of c- axes cut out from the zinc oxide single crystal and the a-axis direction substantially matches. Aligning and abutting substantially in the a-axis direction, epitaxy growing the abutting part by a hydrothermal synthesis method and joining to form a primary seed crystal;
Growing a zinc oxide thin film having a thickness of 2 to 4 μm or more on the primary seed crystal surface by vapor phase growth;
Tona is,
Preparation of a seed crystal for growing zinc oxide, characterized in that the zinc oxide thin film formed on the surface of the primary seed crystal where the plurality of seed crystal materials of zinc oxide are joined is formed by vapor phase growth. Method.

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