JP2015182937A - Method of manufacturing gsgg monocrystal and method of manufacturing oxide garnet monocrystal film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a GSGG monocrystal in a Czochralski method capable of suppressing both facet growth and dislocation, and a method of manufacturing an oxide garnet monocrystal film capable of having pit formation suppressed in a liquid-phase epitaxial growth method.SOLUTION: A method of manufacturing a GSGG monocrystal is characterized in raising the GSGG monocrystal while maintaining a temperature gradient in an atmosphere up to 1 cm in a direction of lifting from a raw material melt surface in a raising furnace 1 at 7-14°C/cm and a temperature gradient in an atmosphere, exceeding 1 cm, up to 10 cm in the direction of lifting at 19-23°C/cm, and a method of manufacturing an oxide garnet monocrystal film is characterized in that the GSGG monocrystal obtained in the method of manufacturing the GSGG monocrystal is applied to a nonmagnetic garnet substrate.

Description

  The present invention relates to a method for producing a GSGG single crystal and a method for producing an oxide garnet single crystal film, and in particular, a method for producing a GSGG single crystal capable of suppressing both facet growth and dislocation, and an oxide capable of suppressing generation of pits. The present invention relates to a method for manufacturing a garnet single crystal film.

  An optical isolator has a Faraday rotator that rotates a polarization plane of incident light by applying a magnetic field. In recent years, an optical isolator is used not only in the field of optical communication but also in a fiber laser processing machine. It is becoming.

As the material of such a Faraday rotator used in an optical isolator, gadolinium scandium gallium garnet _{(Gd 5-x Sc x Ga} 3 O 12: GSGG) is a liquid phase epitaxial growth on a substrate made of single crystal obtained An oxide garnet single crystal film such as Rare-earth iron garnet (RIG) is known (see Non-Patent Document 1).

  However, pits having a diameter of several μm to several tens of μm are generated on the surface of the oxide garnet single crystal film obtained by liquid phase epitaxial growth on a substrate made of a GSGG single crystal manufactured by a conventional method. As a result, there is a problem of lowering the yield. It is known that the cause of generating pits on the surface of the oxide garnet single crystal film is dislocations inherent in the GSGG single crystal (nonmagnetic garnet single crystal) substrate (see Patent Documents 1 and 2).

  By the way, the GSGG single crystal constituting the nonmagnetic garnet single crystal substrate is conventionally manufactured by the Czochralski (CZ) method in which the seed crystal is brought into contact with the raw material melt and pulled up while rotating the seed crystal.

  And in the case of producing a single crystal by the CZ method, the occurrence of dislocation is caused by heat shock (heat shock during seeding) when the seed crystal is brought into contact with the raw material melt, temperature fluctuation during crystal growth, and the raw material. It depends on the temperature gradient in the atmosphere on the melt surface. For example, in the case of a silicon single crystal in which most of the dislocations are generated during seeding, in order to obtain a dislocation-free silicon single crystal, an operation called necking is performed to reduce the diameter of the crystal growth part after seeding, and temperature fluctuations during crystal growth are also observed. The temperature maintaining system in the growth furnace is configured so as to suppress the temperature gradient in the atmosphere on the surface of the raw material melt. Also, in compound semiconductors such as gallium arsenide (GaAs), in order to reduce dislocations, the above temperature gradient on the surface of the raw material melt during single crystal growth is kept gentle, and dislocations due to thermal stress are generated. It is considered effective to suppress (see Non-Patent Documents 2 to 3).

  Therefore, in order to suppress the dislocation of the GSGG single crystal, an attempt has been made to grow a GSGG single crystal by setting a gentle temperature gradient in the atmosphere on the surface of the raw material melt. The facet growth of the crystal plane becomes remarkable [for example, (211) the facet growth of the crystal plane becomes remarkable when grown in the <111> crystal orientation], there is a difference in the lattice constant between the facet portion and the off-facet portion. As a result, stress is generated at the boundary between the facet portion and the off-facet portion. As a result, a crack is generated in the grown GSGG single crystal, and the GSGG single crystal is twisted spirally during the growth of the GSGG single crystal, making it difficult to control the crystal shape. There was a problem.

  In order to suppress the facet growth at the time of crystal growth, when the transition from the crystal shoulder portion to the straight body portion is performed, the rotation speed of the seed crystal is controlled to make the growth interface flat from the convex state toward the raw material melt or Even if an interface inversion operation (see Patent Document 3) for inversion to a slightly convex state is performed, if the temperature gradient in the atmosphere on the surface of the raw material melt is set to be gentle (for example, 4 ° C./cm or less), facet growth is performed. It was difficult to suppress.

  Thus, when growing a GSGG single crystal by the Czochralski (CZ) method, it was extremely difficult to suppress both facet growth and dislocation.

JP-A-2005-314135 JP 2006-015424 A JP 2012-224516 A

Shintaro Miyazawa “Optical Crystal” 1995, Bafukan Takao Abe, Masahiko Kokima, Kenji Taniguchi “Silicon Crystals and Doping” 1986 Maruzen T. Kawase et. Al. "Low dislocation density 6-inch GaAs single crystals grown by VCZ method" 1992 Gallium Arsenide and Related Compounds 1992 Institute of Physics Conference Series Number 129, Institute of Physics Publishing, Bristol and Philadelphia

  The present invention has been made paying attention to such problems, and the object of the present invention is to provide a method for producing a GSGG single crystal capable of suppressing both facet growth and dislocation, and to suppress the generation of pits. An object of the present invention is to provide a method for producing an oxide garnet single crystal film.

  Therefore, in order to solve the above problems, the present inventors conducted the following technical analysis.

  First, conventional growth conditions by the Czochralski (CZ) method (heating conditions of the raw material melt, rotation and pulling conditions of the seed crystal, the reversal operation of the growth interface described in Patent Document 3, etc. are conventionally employed. While maintaining the condition by automatic control), the influence of the temperature gradient in the atmosphere on the surface of the raw material melt on the GSGG single crystal was investigated, and the conditions under which the facet growth and the occurrence of dislocation were prevented were investigated.

  As a result, when the temperature gradient in the atmosphere from the surface of the raw material melt up to 1 cm in the pulling direction and the temperature gradient in the atmosphere exceeding 1 cm and up to 10 cm in the pulling direction fall within a predetermined numerical range, both facet growth and dislocation are performed. It came to discover that it can be suppressed.

  Furthermore, the present inventors have found that a method for producing an oxide garnet single crystal film in which generation of pits is suppressed can be provided by obtaining a nonmagnetic garnet single crystal substrate from a GSGG single crystal in which both facet growth and dislocation are suppressed. .

That is, the first invention according to the present invention is:
In a method for producing a GSGG single crystal by the Czochralski method in which a seed crystal is brought into contact with a raw material melt in a crucible disposed in a crystal growth furnace and the seed crystal is pulled up while being rotated to grow a GSGG single crystal. ,
The temperature gradient in the atmosphere from the surface of the raw material melt in the crystal growth furnace to 1 cm in the pulling direction is 7 to 14 ° C./cm, and the temperature gradient in the atmosphere exceeding 1 cm and the pulling direction to 10 cm is in the range of 19 to 23 ° C./cm. The GSGG single crystal is grown while maintaining.

In addition, the second invention,
In the method for producing a GSGG single crystal according to the first invention,
The hot zone conditions in the pulling direction in the crystal growth furnace corresponding to the growth of the GSGG single crystal are set in advance, the position of the raw material melt surface in the pulling direction during crystal growth is measured, and the measured raw material melting Maintain the temperature gradient in the atmosphere from the surface of the raw material melt up to 1 cm in the pulling direction and the temperature gradient in the atmosphere up to 10 cm in the pulling direction within the above numerical range by adjusting to the hot zone conditions corresponding to the position data on the liquid surface. Features
The third invention is
In the method for producing a GSGG single crystal according to the first or second invention,
The crystal orientation on the surface of the seed crystal is <111>.

Next, the fourth invention is:
In the method for producing an oxide garnet single crystal film, wherein the oxide garnet single crystal film is grown on a nonmagnetic garnet substrate by a liquid phase epitaxial growth method,
The nonmagnetic garnet substrate is composed of a substrate made of a GSGG single crystal cut out from a GSGG single crystal grown by the method according to any one of the first to third inventions,
The fifth invention is:
In the method for producing an oxide garnet single crystal film according to the fourth invention,
The composition of the oxide garnet single crystal film is represented by (BiNdGd) ₃ Fe ₅ O ₁₂ .

According to the method for producing a GSGG single crystal according to the present invention,
While controlling the temperature gradient in the atmosphere up to 1 cm in the pulling direction from the surface of the raw material melt in the crystal growth furnace and the temperature gradient in the atmosphere up to 10 cm in the pulling direction while maintaining within a predetermined numerical range, By growing, a GSGG single crystal in which both facet growth and dislocation are suppressed can be produced.

Moreover, according to the method for producing an oxide garnet single crystal film according to the present invention,
Since a non-magnetic garnet substrate is composed of a substrate made of a GSGG single crystal cut out from a GSGG single crystal in which both facet growth and dislocations suppressed by the GSGG single crystal manufacturing method are suppressed, pits are generated. The suppressed oxide garnet single crystal film can be grown on a nonmagnetic garnet substrate by liquid phase epitaxial growth.

  For this reason, the yield of oxide garnet single crystal film can be improved by the absence of defective pits, and cracks and fine cracks also occur when the obtained oxide garnet single crystal film is cut into chips. This makes it difficult to improve the chip yield.

Explanatory drawing which shows schematic structure of the manufacturing apparatus used for the manufacturing method of the GSGG single crystal which concerns on this invention. Explanatory drawing which shows the crystal | crystallization top part and crystal | crystallization bottom part of the GSGG single crystal which concern on this invention. 1 is a photograph of a GSGG single crystal according to Example 1. FIG. The photograph of the GSGG single crystal which concerns on the comparative example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Manufacturing method of GSGG single crystal FIG. 1: is explanatory drawing which shows schematic structure of the manufacturing apparatus used for the manufacturing method of the gadolinium scandium gallium garnet (GSGG) single crystal which concerns on this invention.

  This manufacturing apparatus includes a growth furnace 1 for manufacturing a GSGG single crystal by a known Czochralski method. The structure of the growth furnace 1 will be briefly described. The growth furnace 1 includes a cylindrical chamber 2, a high-frequency coil 10 installed outside the chamber 2, and an iridium crucible arranged inside the chamber 2. 8. In addition, although the dimension of the said growth furnace 1 depends on the magnitude | size of the GSGG single crystal to manufacture, it is a diameter of about 0.6 m and height about 1 m as an example.

  Further, the growth furnace 1 is provided with two openings (not shown), and an inert gas, preferably argon gas, is supplied and discharged through these openings, so that a chamber 2 for crystal growth is provided. The inside is filled with an inert gas. In the growth furnace 1, a thermometer (thermocouple) (not shown) for measuring the temperature is installed below the bottom of the crucible 8.

  The high-frequency coil 10 is formed of a copper tube, and the electric power is controlled through a control unit (not shown) so that the crucible 8 is heated at a high frequency and the temperature is adjusted. Further, a heat insulating material 3 is disposed inside the chamber 2 inside the high frequency coil 10, and a hot zone 5 is formed by an atmosphere surrounded by the plurality of heat insulating materials 3.

  The temperature gradient of the hot zone 5 can be varied in a wide range depending on the shape and configuration (material) of the heat insulating material 3, and the shape and configuration of the heat insulating material 3 is designed according to the type of single crystal to be grown, and the appropriate hot zone A temperature gradient of 5 is formed. Further, the temperature gradient of the hot zone 5 can be finely adjusted by adjusting the relative position of the high-frequency coil 10 to the crucible 8. In addition, the said heat insulating material 3 is comprised with the refractory material of high melting | fusing point.

  The crucible 8 is formed in a cup shape, and the bottom thereof is disposed on the heat insulating material 3 and held by the heat insulating material 3. Further, on the upper side of the crucible 8, a pulling shaft 4 for holding and pulling the seed crystal and the grown GSGG single crystal is installed, and the pulling shaft 4 can be rotated around the axis.

  The crucible 8 is filled with the raw material, the crucible 8 is placed in the chamber 2 of the growth furnace 1 and heated by the high frequency coil 10 to melt the raw material, and then the seed crystal 6 is brought into contact with the raw material melt 9. The raw material melt 9 is sequentially crystallized on the lower side of the seed crystal by gradually lowering the temperature and simultaneously raising the pulling shaft 4 at the same time. Then, it is possible to grow the GSGG single crystal 7 having a desired diameter by adjusting the input power to the high frequency coil 10 in accordance with the conventional growth conditions. At this time, in order to suppress the occurrence of distortion due to facet growth, the “interface inversion operation” described in Patent Document 3 is performed to make the interface shape flat from convex. A series of temperature monitors for single crystal growth is performed by the thermometer (thermocouple).

Note that the raw material _{GSGG (Gd 5-x Sc x} Ga 3 O 12) crystal, gadolinium oxide (Gd ₂ O ₃₎ powder, scandium oxide (Sc ₂ O ₃₎ powder and gallium oxide (Ga ₂ O ₃₎ powder However, the mixing ratio of these raw material powders is determined by the composition of single crystals to be grown and the growth conditions.

  By the way, the manufacturing method of the GSGG single crystal according to the present invention is based on conventional growth conditions (conditions based on automatic control such as the raw material melt heating conditions, seed crystal rotation and pulling conditions, and the above interface reversal operation). ), The temperature gradient in the atmosphere from the surface of the raw material melt in the growth furnace 1 to 1 cm in the pulling direction is 7 to 14 ° C./cm, and the temperature gradient in the atmosphere exceeding 1 cm and 10 cm in the pulling direction is 19 to 23 ° C. It is characterized by growing a GSGG single crystal while maintaining it in the range of / cm.

  For this reason, “hot zone conditions” in the pulling direction in the growth furnace 1 corresponding to the growth of the GSGG single crystal 7 are set in advance. That is, since the raw material in the crucible 8 is consumed as the GSGG single crystal 7 grows, the position in the pulling direction on the surface of the raw material melt is lowered and the amount of the raw material melt in the crucible 8 is also reduced. For this reason, the temperature gradient in the atmosphere from the surface of the raw material melt to 1 cm in the pulling direction is 7 to 14 ° C./cm, exceeding 1 cm to 10 cm in the pulling direction in accordance with the displacement in the pulling direction on the surface of the raw material melt. It is necessary to obtain and set in advance a “hot zone condition” in the pulling direction in the growth furnace 1 in which the temperature gradient in the atmosphere is maintained within a range of 19 to 23 ° C./cm.

  When the “hot zone condition” is set in advance by a preliminary experiment, the temperature distribution in the hot zone 5 is measured as follows. That is, the raw material of the GSGG crystal is put into the crucible 8, and in this state, the thermocouple is attached to the pulling shaft 4 to which the seed crystal 6 is attached at the time of crystal growth, and the hot couple is gradually pulled up from the raw material surface while the hot couple is gradually pulled up. 5, the temperature in the pulling direction is recorded in sequence. However, since the “B thermocouple” is applied in the preliminary experiment, it is performed under the condition that the raw material in the crucible 8 does not melt.

  In addition, as a method of measuring the pulling direction position of the raw material melt surface during crystal growth, for example, a method of directly measuring with an optical sensor or the like, or measuring the weight of a GSGG single crystal grown with a weigh scale and crucible 8 The method of calculating | requiring the displacement of the raw material melt surface accompanying consumption of the raw material by calculation etc. is mentioned.

  In the GSGG single crystal manufacturing method according to the present invention, as described above, the temperature gradient in the atmosphere from the surface of the raw material melt in the growth furnace 1 to the pulling direction 1 cm and the temperature in the atmosphere exceeding 1 cm and the pulling direction 10 cm. The gradient is within a predetermined numerical range (the temperature gradient in the atmosphere from the raw material melt surface to 1 cm in the pulling direction is 7 to 14 ° C./cm, the temperature gradient in the atmosphere exceeding 1 cm and the pulling direction is 10 cm is in the range of 19 to 23 ° C./cm Since the GSGG single crystal 7 is grown while being managed so as to be maintained, the GSGG single crystal 7 in which both facet growth and dislocation are suppressed can be manufactured.

  By the way, compared with the case where the temperature gradient in the atmosphere on the raw material melt surface is gentle (for example, 4 ° C./cm or less), the temperature gradient in the atmosphere from the raw material melt surface to 1 cm in the pulling direction is 7 to 14 ° C./cm, The reason why the occurrence of the above-mentioned “facet growth” and “dislocation” is suppressed when the temperature gradient in the atmosphere exceeding 1 cm and up to 10 cm in the pulling direction is kept within the range of 19 to 23 ° C./cm is as follows. Etc. have guessed as follows.

  If the temperature gradient in the atmosphere on the surface of the raw material melt is gentle (for example, 4 ° C./cm or less), the space in which the temperature distribution fluctuates even with a temperature fluctuation of the same width during crystal growth compared to the case where the temperature gradient is tight. It is presumed that the area of interest increases and the axial symmetry of crystal growth tends to break, and as a result, crystal twisting is likely to occur. In addition, if the temperature gradient in the atmosphere on the surface of the raw material melt is gentle, a crystal plane that is easy to grow (facet growth surface) is likely to appear, whereas the above-mentioned temperature gradient is tight and has a shape corresponding to the melting point isotherm. It is speculated that facet growth is suppressed as a result of the formation of the liquid interface.

  The grown GSGG single crystal is taken out from the growth furnace 1 and subjected to an annealing process for removing thermal strain, and then processed into a nonmagnetic garnet substrate having a thickness conforming to the standard.

(2) Manufacturing Method of Oxide Garnet Single Crystal Film Next, an oxide garnet single crystal film such as (BiNdGd) ₃ Fe ₅ O ₁₂ which has a magneto-optic effect and is a material for a Faraday rotator is the GSGG single crystal. It is obtained by growing it on a nonmagnetic garnet substrate comprising:

  That is, a predetermined amount corresponding to the composition of the oxide garnet single crystal film is charged into a crucible together with a flux component, heated to about 1000 ° C. and melted, and then kept at a supercooling temperature of 800 to 950 ° C. An oxide garnet single crystal film is grown on a nonmagnetic garnet substrate made of crystals. At this time, the oxide garnet single crystal film grown on the nonmagnetic garnet substrate cut out from the GSGG single crystal without facet growth and dislocation does not easily generate pits. The crack defect when cutting out a 11 mm square chip is greatly reduced, and the Faraday rotator material can be obtained in high yield.

The raw material of the oxide garnet single crystal film represented by the composition formula (BiNdGd) ₃ Fe ₅ O ₁₂ includes bismuth oxide (Bi ₂ O ₃ ) powder, neodymium oxide (Nd ₂ O ₃ ) powder, gadolinium oxide (Gd). ₂ O ₃ ) powder and iron oxide (Fe ₂ O ₃ ) powder are applied, and the mixing ratio of these raw material powders is determined by the composition of the single crystal film to be grown and the growth conditions.

  Examples of the present invention will be specifically described below with reference to comparative examples.

[Example 1]
(Production of GSGG single crystal)
According to the “hot zone conditions” corresponding to the growth of the GSGG single crystal obtained in advance by a preliminary experiment, the temperature gradient in the atmosphere from the surface of the raw material melt to 1 cm in the pulling direction is 7 ° C./cm (range of 7 to 14 ° C./cm 1) Using the single crystal manufacturing apparatus shown in FIG. 1 under the condition that the temperature gradient in the atmosphere exceeding 1 cm and in the pulling direction up to 10 cm is 19 ° C./cm (in the range of 19 to 23 ° C./cm) According to the growing conditions, a GSGG single crystal having a diameter of 50 mm and a straight body length of 140 mm was grown.

  The obtained GSGG single crystal is free of facets and twists as shown in the photograph of FIG. 3, and is excellent in accuracy of a target diameter of ± 1 mm by an automatic diameter controller attached to the manufacturing apparatus of FIG. It was controlled and there were no cracks.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( A GSGG single crystal substrate: a non-magnetic garnet substrate) was obtained.

  When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, there was no dislocation.

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  It was confirmed by visual observation and microscopic observation that no pits exist in the oxide garnet single crystal film.

  Thereafter, when an 11 mm square chip was cut out from the obtained oxide garnet single crystal film, no crack or fine crack was generated, and an 11 mm square chip could be obtained with a yield of 100%.

[Example 2]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 10 ° C./cm (within a range of 7 to 14 ° C./cm). The temperature gradient is 20 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 70 mm. A GSGG single crystal was grown.

  The resulting GSGG single crystal is free from facets and twists, and is controlled well with an accuracy of the target diameter of ± 1 mm by an automatic diameter controller attached to the manufacturing apparatus shown in FIG. It was.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

  When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, there was no dislocation.

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  It was confirmed by visual observation and microscopic observation that no pits exist in the oxide garnet single crystal film.

  Thereafter, when an 11 mm square chip was cut out from the obtained oxide garnet single crystal film, no crack or fine crack was generated, and an 11 mm square chip could be obtained with a yield of 100%.

[Example 3]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 14 ° C./cm (within a range of 7 to 14 ° C./cm). The temperature gradient is 23 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the length of the straight body is 70 mm. A GSGG single crystal was grown.

  The resulting GSGG single crystal is free from facets and twists, and is controlled well with an accuracy of the target diameter of ± 1 mm by an automatic diameter controller attached to the manufacturing apparatus shown in FIG. It was.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

  When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, there was no dislocation.

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  It was confirmed by visual observation and microscopic observation that no pits exist in the oxide garnet single crystal film.

  Thereafter, when an 11 mm square chip was cut out from the obtained oxide garnet single crystal film, no crack or fine crack was generated, and an 11 mm square chip could be obtained with a yield of 100%.

[Comparative Example 1]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 4 ° C./cm (out of the range of 7 to 14 ° C./cm). The temperature gradient is 3 ° C./cm (outside the range of 19 to 23 ° C./cm), the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  As shown in the photograph of FIG. 4, twisting occurred in the upper part of the obtained GSGG single crystal, and the disturbance of the diameter control by the automatic diameter control device was large.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, 24 dislocations per 1 cm ² were observed.

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  Then, it was confirmed by visual observation and microscopic observation that pits exist in the oxide garnet single crystal film.

  Then, about the obtained oxide garnet single crystal film, when a chip of 11 mm square was cut out, defects due to cracks and fine cracks occurred, and the yield of the 11 mm square chip was 100%. Compared to 3, it was reduced to 78%.

[Comparative Example 2]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 4 ° C./cm (out of the range of 7 to 14 ° C./cm). The temperature gradient is 20 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  Twist occurred in the upper part of the obtained GSGG single crystal, and the disturbance of the diameter control by the automatic diameter control device was large.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, 63 dislocations were observed per cm ² .

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  Then, it was confirmed by visual observation and microscopic observation that pits exist in the oxide garnet single crystal film.

  Then, about the obtained oxide garnet single crystal film, when a chip of 11 mm square was cut out, defects due to cracks and fine cracks occurred, and the yield of the 11 mm square chip was 100%. Compared to 3, it was reduced to 67%.

[Comparative Example 3]
By the same method as in Example 1, the temperature gradient in the atmosphere from the raw material melt surface to the pulling direction 1 cm is 0.5 ° C./cm (outside the range of 7 to 14 ° C./cm), exceeding 1 cm and the pulling direction 10 cm. A GSGG with a diameter of 50 mm is used under the condition that the temperature gradient in the atmosphere is 0.7 ° C./cm (outside the range of 19 to 23 ° C./cm), using the single crystal manufacturing apparatus shown in FIG. An attempt was made to grow a single crystal.

  However, after the seed crystal was immersed in the melt, the seed crystal melted, and the crystal could not be grown.

[Comparative Example 4]
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 18 ° C./cm (out of the range of 7 to 14 ° C./cm). Using a single crystal manufacturing apparatus shown in FIG. 1 under a temperature gradient of 34 ° C./cm (within a range of 19 to 23 ° C./cm), and according to conventional growth conditions, a diameter of 50 mm and a straight body length of 110 mm A GSGG single crystal was grown.

  However, since cracks occurred in the GSGG single crystal, processing of the GSGG single crystal substrate was abandoned.

[Example 4]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction 1 cm is 7 ° C./cm (within a range of 7 to 14 ° C./cm), and in the atmosphere exceeding 1 cm and the pulling direction 10 cm. The temperature gradient is 23 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the length of the straight body is 70 mm. A GSGG single crystal was grown.

  The resulting GSGG single crystal is free from facets and twists, and is controlled well with an accuracy of the target diameter of ± 1 mm by an automatic diameter controller attached to the manufacturing apparatus shown in FIG. It was.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

  When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, there was no dislocation.

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  It was confirmed by visual observation and microscopic observation that no pits exist in the oxide garnet single crystal film.

  Thereafter, when an 11 mm square chip was cut out from the obtained oxide garnet single crystal film, no crack or fine crack was generated, and an 11 mm square chip could be obtained with a yield of 100%.

[Example 5]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 14 ° C./cm (within a range of 7 to 14 ° C./cm). The temperature gradient is 19 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 70 mm. A GSGG single crystal was grown.

  The resulting GSGG single crystal is free from facets and twists, and is controlled well with an accuracy of the target diameter of ± 1 mm by an automatic diameter controller attached to the manufacturing apparatus shown in FIG. It was.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

  When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, there was no dislocation.

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  It was confirmed by visual observation and microscopic observation that no pits exist in the oxide garnet single crystal film.

  Thereafter, when an 11 mm square chip was cut out from the obtained oxide garnet single crystal film, no crack or fine crack was generated, and an 11 mm square chip could be obtained with a yield of 100%.

[Comparative Example 5]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 6 ° C./cm (out of the range of 7 to 14 ° C./cm). The temperature gradient is 19 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  Twist occurred in the upper part of the obtained GSGG single crystal, and the disturbance of the diameter control by the automatic diameter control device was large.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, 63 dislocations were observed per cm ² .

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  Then, it was confirmed by visual observation and microscopic observation that pits exist in the oxide garnet single crystal film.

  Then, about the obtained oxide garnet single crystal film, when a chip of 11 mm square was cut out, defects due to cracks and fine cracks occurred, and the yield of the 11 mm square chip was 100%. Compared to 3, it was reduced to 67%.

[Comparative Example 6]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction 1 cm is 7 ° C./cm (within a range of 7 to 14 ° C./cm), and in the atmosphere exceeding 1 cm and the pulling direction 10 cm. The temperature gradient is 18 ° C./cm (outside the range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  Twist occurred in the upper part of the obtained GSGG single crystal, and the disturbance of the diameter control by the automatic diameter control device was large.

  Then, the obtained GSGG single crystal is held at 1600 ° C. in an air atmosphere for 40 hours and subjected to an “annealing process” for cooling to room temperature over 16 hours, and then processed to form a substrate made of GSGG single crystal ( GSGG single crystal substrate) was obtained.

When the GSGG single crystal substrate corresponding to the crystal top portion 11 and the crystal bottom portion 12 in FIG. 2 was observed with a polarizing microscope, 63 dislocations were observed per cm ² .

(Manufacture of oxide garnet single crystal film)
First, Bi ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Fe ₂ O ₃ as raw materials, and PbO and B ₂ O ₃ as fluxes are weighed, and predetermined amounts are put into a platinum crucible. The temperature was raised to 1100 ° C. to melt.

Next, after one surface of the GSGG single crystal substrate was placed so as to be immersed in the melt in the crucible, the GSGG single crystal substrate was epitaxially grown while rotating and indicated on the GSGG single crystal substrate by (BiNdGd) ₃ Fe ₅ O ₁₂ . An oxide garnet single crystal film was grown.

  Then, it was confirmed by visual observation and microscopic observation that pits exist in the oxide garnet single crystal film.

  Then, about the obtained oxide garnet single crystal film, when a chip of 11 mm square was cut out, defects due to cracks and fine cracks occurred, and the yield of the 11 mm square chip was 100%. Compared to 3, it was reduced to 67%.

[Comparative Example 7]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 14 ° C./cm (within a range of 7 to 14 ° C./cm). The temperature gradient is 24 ° C./cm (outside the range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  However, since cracks occurred in the GSGG single crystal, processing of the GSGG single crystal substrate was abandoned.

[Comparative Example 8]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to 1 cm in the pulling direction is 15 ° C./cm (out of the range of 7 to 14 ° C./cm). The temperature gradient is 23 ° C./cm (within a range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  However, since cracks occurred in the GSGG single crystal, processing of the GSGG single crystal substrate was abandoned.

[Comparative Example 9]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to the pulling direction of 1 cm is 6 ° C./cm (out of the range of 7 to 14 ° C./cm). The temperature gradient is 24 ° C./cm (outside the range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  However, since cracks occurred in the GSGG single crystal, processing of the GSGG single crystal substrate was abandoned.

[Comparative Example 10]
(Production of GSGG single crystal)
In the same manner as in Example 1, the temperature gradient in the atmosphere from the surface of the raw material melt to 1 cm in the pulling direction is 15 ° C./cm (out of the range of 7 to 14 ° C./cm). The temperature gradient is 18 ° C./cm (outside the range of 19 to 23 ° C./cm), and the single crystal manufacturing apparatus shown in FIG. 1 is used, and according to the conventional growth conditions, the diameter is 50 mm and the straight body length is 110 mm. A GSGG single crystal was grown.

  However, since cracks occurred in the GSGG single crystal, processing of the GSGG single crystal substrate was abandoned.

  Since an oxide garnet single crystal film having no pits is obtained by a liquid phase epitaxial method using the GSGG single crystal substrate according to the present invention, the oxide garnet single crystal film is used as an industrial Faraday rotator for an optical isolator. Have the availability of.

DESCRIPTION OF SYMBOLS 1 Growth furnace 2 Chamber 3 Heat insulating material 4 Lifting axis 5 Hot zone 6 Seed crystal 7 GSGG single crystal 8 Crucible 9 Raw material melt 10 High frequency coil 11 Crystal top part 12 Crystal bottom part

Claims (5)

In a method for producing a GSGG single crystal by the Czochralski method in which a seed crystal is brought into contact with a raw material melt in a crucible arranged in a crystal growth furnace and the seed crystal is pulled up while being rotated to grow a GSGG single crystal. ,
The temperature gradient in the atmosphere from the surface of the raw material melt in the crystal growth furnace to 1 cm in the pulling direction is 7 to 14 ° C./cm, and the temperature gradient in the atmosphere exceeding 1 cm and the pulling direction to 10 cm is in the range of 19 to 23 ° C./cm. A method for producing a GSGG single crystal, comprising growing a GSGG single crystal while maintaining the GSGG single crystal.   The hot zone conditions in the pulling direction in the crystal growth furnace corresponding to the growth of the GSGG single crystal are set in advance, the position of the raw material melt surface in the pulling direction during crystal growth is measured, and the measured raw material melting Maintain the temperature gradient in the atmosphere from the surface of the raw material melt up to 1 cm in the pulling direction and the temperature gradient in the atmosphere up to 10 cm in the pulling direction within the above numerical range by adjusting to the hot zone conditions corresponding to the position data on the liquid surface. The manufacturing method of the GSGG single crystal of Claim 1 characterized by these.   The method for producing a GSGG single crystal according to claim 1 or 2, wherein the crystal orientation on the surface of the seed crystal is <111>. In the method for producing an oxide garnet single crystal film, which is grown on a nonmagnetic garnet substrate by a liquid phase epitaxial growth method,
An oxide garnet single crystal film characterized in that the nonmagnetic garnet substrate is constituted by a GSGG single crystal substrate cut out from a GSGG single crystal grown by the method according to claim 1. Production method. _{5. The} method for producing an oxide garnet single crystal film according to claim 4, wherein the composition of the oxide garnet single crystal film is represented by (BiNdGd) ₃ Fe ₅ O ₁₂ .