JP4883614B2 - Method for producing solid solution single crystal - Google Patents

Description

  The present invention relates to a method for producing a solid solution (mixed crystal) having a uniform composition and a single crystal structure with good reproducibility.

  Conventionally, a method called a “temperature gradient type zone melting method” has been proposed as one of the promising methods for producing a solid solution having a uniform composition and a single crystal structure (hereinafter simply referred to as “solid solution single crystal”). ing. This “temperature gradient type zone melting method” refers to a raw material that contacts a seed crystal by heating a raw material prepared so that a solute component having a low melting point has a high concentration on the seed crystal side together with a seed crystal under a relatively low temperature gradient. In this method, only a part of the melt is melted to form a melt zone, and the melt zone is sequentially moved to the raw material side to produce a single crystal that inherits the orientation of the seed crystal (performs crystal growth). This method is disclosed in Japanese Patent Laid-Open No. 2003-238287 (Patent Document 1).

JP 2003-238287 A

The conventional method has a problem that as the crystal growth progresses, the uniformity of the composition deteriorates or polycrystallization occurs in the grown crystal.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a solid solution (mixed crystal) single crystal capable of growing the solid solution (mixed crystal) single crystal with good reproducibility. To do.

The inventors firstly, during crystal growth, the melt in the molten zone generated by melting the solid raw material travels along the surface (side surface) of the remaining solid raw material remaining unmelted from the molten zone. By moving to the side, the surface of the solid raw material melts a lot and the interior of the solid raw material remains unmelted. As a result, the shape of the molten zone is deformed. We focused on the fact that the flatness of the growth interface is impaired and that the uniformity of the composition deteriorates and polycrystallization occurs in the grown crystal due to the deterioration of the flatness of the growth interface. .
Therefore, the present inventors attached a specific substance that prevents the melt in the melting zone generated by melting of the solid raw material to move on the surface of the remaining solid raw material to the surface of the solid raw material. If crystal growth is performed in this state, the inside of the solid raw material is melted by preventing the melt from moving from the melting zone generated by melting the solid raw material to the remaining solid raw material side during the crystal growth. As a result of the fact that the ratio and the ratio at which the surface of the solid material melts are almost the same, the inventors have found that the shape of the molten zone is maintained and the flatness of the growth interface is maintained, and the present invention has been created.
That is, the gist of the present invention is that the specific substance that prevents the melt produced by melting of the solid raw material from moving on the remaining solid raw material surface (side surface) is applied to the solid raw material surface (side surface). In the attached state, crystal growth is performed by the zone melting method using this solid raw material.

  According to the present invention, the specific substance that prevents the melt in the melting zone generated by melting of the solid raw material from remaining on the surface of the remaining solid raw material is attached to the surface of the solid raw material. In this case, by performing crystal growth, the molten liquid is prevented from moving from the molten zone to the residual solid raw material side through the surface of the residual solid raw material, resulting in deformation of the molten zone and this deformation. It is possible to prevent the crystal growth interface from being deformed. Therefore, it is possible to prevent compositional uniformity and polycrystallization during crystal growth caused by deformation of the crystal growth interface.

Hereinafter, embodiments of the present invention will be shown and the present invention will be described in more detail.
(Embodiment 1)
In the method for producing a solid solution single crystal according to the present embodiment, first, a raw material production step for producing a cylindrical raw material used in the crystal growth step is executed, and powder is formed on the surface of the cylindrical raw material produced by this raw material production step. At last, the zone melting method crystal growth step is performed using the columnar raw material to which the specific substance is adhered by this adhesion step, and the solid solution single crystal is manufactured. These three steps will be described in order.

First, the raw material production process will be described. In this raw material manufacturing step, first, In (indium), Ga (gallium), and As (arsenic) having a purity of 99.9999% are prepared, and In, which is weighed to have a composition of In _0.3 Ga _0.7 As, Ga and As are vacuum sealed in the quartz tube. The quartz tube is heated to about 1200 ° C. in an electric furnace to produce a melt having an In _0.3 Ga _0.7 As composition. Thereafter, the quartz tube is taken out of the electric furnace, immersed in water and rapidly cooled. Thereby, a cylindrical polycrystal having an average composition of In _0.3 Ga _0.7 As is synthesized.

  Thereafter, the polycrystalline body is vacuum-sealed in another quartz tube. The quartz tube is heated in a temperature gradient furnace to a high temperature portion of, for example, about 1200 ° C. and a low temperature portion of, for example, about 800 ° C. As a result, a temperature gradient of about 40 ° C./cm (measured value inside the core tube) is formed between the high temperature portion and the low temperature portion. That is, of the cylindrical polycrystalline body enclosed in the quartz tube, the portion located in the high temperature portion is heated to about 1200 ° C., and the portion located in the low temperature portion is heated to about 800 ° C. In the polycrystalline body, a temperature (concentration) gradient is formed from a portion located in the high temperature portion to a portion located in the low temperature portion. In such a state where a temperature gradient is formed, the cylindrical polycrystalline body enclosed in the quartz tube solidifies at a solidification rate of about 1 mm / h in one direction from the top surface (or bottom surface) to the bottom surface (or top surface). Be made. Regarding the InAs concentration distribution in the cylindrical polycrystal obtained in this way, the InAs concentration at the front end (near the top surface) grown in the initial stage of crystal growth was about 0.06 mol, and from this front end to the rear end of the crystal As it goes to the part (near the bottom), its InAs concentration becomes higher. Next, a portion having an InAs molar fraction of 0.06 to 0.10 is cut out as a raw material from the polycrystal obtained as described above. The raw material for the polycrystalline body having a cylindrical shape is manufactured by the raw material manufacturing process as described above.

  Secondly, the adhesion process will be described. In this adhesion step, the melt in the molten zone is transferred to the surface of the raw material when the zone melting method crystal growth step is performed on the side surface (surface) of the raw material (polycrystal) produced in the raw material production step. A specific substance that prevents melting of the surface more than inside the raw material is deposited. In this embodiment, a case where boron nitride powder, specifically, boron nitride powder having a particle size in the range of 10 to 25 μm is used as the specific substance will be described as an example.

  Specifically, first, for example, paper having an area sufficiently larger than the surface area of the columnar raw material prepared as described above is prepared. Boron nitride powder is spread on the surface of the paper. Next, the cylindrical raw material is placed with its side face in contact with the surface of the paper, and then rolled while being pressed. Thereby, boron nitride powder is adhered to the side surface of the cylindrical raw material. A raw material (polycrystal) in which boron nitride powder is adhered to the side surface is produced by the above-described adhesion process.

  Third, the zone melting method crystal growth step will be described. This zone melting method crystal growth step can be realized by using any crystal manufacturing apparatus well known to those skilled in the art. In this embodiment, the case where the crystal manufacturing apparatus disclosed in Japanese Patent Laid-Open No. 2003-238287 is used as an example will be described.

  FIG. 1 is a schematic diagram showing an outline of a crystal manufacturing apparatus used in the method for manufacturing a solid solution single crystal according to Embodiment 1 of the present invention. The crystal manufacturing apparatus 100 shown in FIG. 1 has a heating apparatus 101 that heats and melts a raw material inserted into a crystal growth container 105, and a rack and pinion that is engaged with a groove formed at one end of a support bar 103. The drive mechanism 102 that moves the crystal growth vessel 105 attached to the other end of the support rod 103 and the drive mechanism 102 operate by transmitting the power from the power source and operating the support rod 103. And a control mechanism 104 for controlling the movement of the crystal growth vessel 105. Specifically, the heating device 101 has a donut shape having a hollow portion extending in the central axis direction, and includes, for example, three heating portions 101a to 101c that are independently controlled to generate unique temperatures. Have. Under the control of the control mechanism 104, the crystal growth vessel 105 moves the hollow portion of the heating device 101 in the direction from the upper side to the lower side (arrow direction) on the paper surface to generate different temperatures 3 By sequentially facing the two heating units 101c to 101a, a temperature (concentration) gradient is formed in the raw material.

  FIG. 2 is a schematic diagram showing a cross-sectional view of crystal growth vessel 105 used in the method for producing a solid solution single crystal according to Embodiment 1 of the present invention. The crystal growth container shown in FIG. 2 mainly contains a boron nitride crucible 201 having a cylindrical region inside, a heat sink 202 for promoting single crystallization, and a crucible 201 and a heat sink 202 inside. It consists of a quartz container 203 for vacuum-sealing them.

  The outer diameter of the heat sink 202 is smaller than the inner diameter of the quartz container 203, and a gap 204 is formed between the heat sink 202 and the quartz container 203. In the crucible 201 made of boron nitride, that is, in a columnar region provided in the crucible 201, a GaAs seed crystal 205, InAs 206 as a melting zone forming material, and a small amount of arsenic 6 for adjusting the vapor pressure. ', A raw material (a raw material having a cylindrical shape and boron nitride powder attached to the side surface) 207 obtained through the above-described raw material preparation step and attachment step is inserted.

  It goes without saying that the outer diameter of the raw material 207 is processed to be smaller than the inner diameter of the crucible 201 so that the raw material 207 is accommodated in a cylindrical region provided inside the crucible 201. The ratio at which the outer diameter of the raw material 207 is made smaller than the inner diameter of the quartz container 203 depends on the diameter of the raw material 207. For example, when the outer diameter of the raw material 207 is 10 mm, the outer diameter of the raw material 207 A suitable difference from the inner diameter is about 0.4 mm. Thereby, the raw material 207 can be inserted into the crucible 201 without peeling off the boron nitride powder 208 adhering to the side surface of the cylindrical raw material 207.

Using the crystal manufacturing apparatus 100 and the crystal growth vessel 105 as described above, the following zone melting method crystal growth step is executed.
First, each of the heating units 101 c to 101 a is controlled so that a desired temperature gradient (here, 10 ° C./cm as an example) is formed at the crystal growth interface of the raw material 207, and the temperature distribution inside the heating apparatus 101. Is adjusted. Next, the crystal growth vessel 105 in which the raw material 207 is inserted is inserted into the hollow portion of the heating apparatus 101 via the drive mechanism 102 controlled by the control mechanism 104, and is disposed at a position facing the heating unit 101c. Is done.

When InAs 206 inserted into the crystal growth vessel 105 is heated and formed as a molten zone and reaches an equilibrium state, InAs has a concentration in the raw material 207 due to mutual diffusion of this InAs and GaAs in the raw material 207. It will be transported towards lower InAs. As a result, the InAs concentration of the InAs 206 at the interface with the seed crystal 205 gradually decreases. As a result, a single crystal having an In _0.3 Ga _0.7 composition that inherits the orientation of the seed crystal 205 grows.

As the transport of InAs to the raw material 207 proceeds, the melting zone moves in the direction toward the raw material 207 (upward), so the control mechanism 104 moves the crystal growth container 105 at a speed equal to the speed of this transport. The drive mechanism 102 is controlled to move in the arrow direction (downward). Thereby, the crystal growth interface of the raw material 207 and the heating unit (any one of 101 c to 101 a) that gives an intended temperature to the interface are kept facing each other. As a result, the temperature at the crystal growth interface of the raw material 207, that is, the InAs concentration is kept constant, whereby a single crystal having an In _0.3 Ga _0.7 composition grows.
A solid solution single crystal, that is, a solid solution having a uniform composition and a single crystal structure is manufactured by the zone melting method crystal growth step as described above.

Next, the effect obtained by the method for producing a solid solution single crystal according to the present embodiment will be described with reference to FIGS.
FIG. 3A is a schematic diagram showing the results of observing the growth interface and the melting interface in a raw material that has been rapidly cooled during crystal growth using the method for producing a solid solution single crystal according to Embodiment 1 of the present invention. . 3A, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG. 2, and detailed description thereof is omitted.
FIG. 3 (b) shows the result of observing the growth interface and the melting interface in the raw material that was rapidly cooled during crystal growth using the conventional manufacturing method under the same temperature environment as in FIG. 3 (a). It is a schematic diagram shown. In these drawings, a longitudinal section of a cylindrical sample, that is, a sample inserted into the crucible 201 shown in FIG. 2 is shown. However, FIG. 3B shows a longitudinal section of the sample when a cylindrical raw material without any powder attached to the side surface is inserted into the crucible as the raw material.

  In FIG. 3A (in FIG. 3B), the melting zone 301 (1) exists between the grown crystal 302 (2) and the raw material 207 (6). Of both ends of the melting zone 301 (1), the portion in contact with the growth crystal 302 (2) is the growth interface 303 (3), and the portion in contact with the raw material 207 (6) is the melting interface 304 (4). ).

  Referring to FIG. 3A, the growth interface 303 has a substantially flat shape. The shape of the melting interface 304 is slightly deformed around the surface of the sample and cannot be said to be completely flat, but it can be seen that the shape is almost flat around the central axis of the sample. On the other hand, referring to FIG. 3B, it can be seen that both the interfaces (growth interface 3 and melting interface 4) are U-shaped or V-shaped, and the vicinity of the surface rises toward the raw material 6 side.

  As shown in FIG. 3 (b), the inventors of the present invention have the reason that the growth interface 3 and the melting interface 4 have a U-shape or V-shape so as to rise toward the raw material 6 near the surface of the sample. As a result of the melt in 1 flowing along the surface of the raw material 6 and moving from the melting zone 1 to the raw material 6 side, the surface of the raw material 6 is melted more than the inside (in other words, the surface of the raw material is melted). We focused on the fact that the ratio of cracking is significantly larger than the ratio of melting the inside of the raw material). Therefore, as described above, the present inventors, if any substance is attached to the surface of the raw material 6, prevents the melt from moving from the melting zone 1 to the raw material 6, thereby causing the raw material 6 As a result of the fact that the rate at which the inside melts and the rate at which the surface of the raw material 6 melts are substantially the same, it has been found that the shape of the melt zone 1 is maintained and the flatness of the growth interface is also maintained. According to the present embodiment, by attaching boron nitride powder to the surface of the raw material 207, the molten material in the molten zone 301 is transmitted through the surface of the remaining raw material 207 and remains from the molten zone 301. As a result, the rate at which the melt melts the inside of the raw material 207 is substantially the same as the rate at which the surface melts, and as shown in FIG. The flatness of 304 is ensured.

FIG. 4 shows an axial InAs concentration distribution in a crystal manufactured using the method for manufacturing a solid solution single crystal according to Embodiment 1 of the present invention, and an InAs concentration distribution in a crystal manufactured using a conventional technique. It is a graph shown in comparison. In FIG. 4, the solid line 401 is the concentration distribution of the central axis portion of the crystal grown with the boron nitride powder attached, and the broken line 402 is 1 mm from the surface of the crystal grown with the boron nitride powder attached in the direction of the central axis. Concentration distribution of the advanced part, the one-dot chain line 404 is a crystal grown without attaching any powder, and the concentration distribution of the central axis part, the two-dot chain line 403 is a crystal grown without attaching any powder The density distribution of the part which advanced 1mm from the surface in the central axis direction is shown. In both cases, the sample was grown by moving the sample to the low temperature side at a moving speed of 0.22 mm / h, aiming at a uniform composition of In _0.3 Ga _0.7 As. Regarding the composition change of the method, there is almost no difference in concentration between the central axis portion and the portion proceeding in the direction of the central axis by 1 mm from the surface, and a composition with excellent uniformity is realized. This is because the flatness of the growth interface 303 and the melting interface 304 is ensured for the reasons described above. On the other hand, when grown without adhering any powder, the InAs concentration becomes higher as it grows, and the center axis portion 404 has a higher InAs concentration than the surface vicinity 403, resulting in a uniform composition. The quality has deteriorated. This is because the flatness of the crystal growth interface is deteriorated.

  FIG. 5A is a schematic diagram showing a result of observing a longitudinal section of a crystal grown using the method for producing a solid solution single crystal according to Embodiment 1 of the present invention. FIG. 5B is a schematic diagram showing a result of observing a longitudinal section of a crystal grown using a conventional manufacturing method under the same temperature environment as in FIG. In these drawings, the result of observing the grown crystal vertically or visually with respect to a cross section obtained by dividing the crystal in the direction of the central axis is schematically shown.

  The crystal grown by attaching boron nitride powder has a single crystal structure over the entire region, as shown in FIG. On the other hand, as for the crystal grown without adhering any powder, as shown in FIG. 5B, crystal grains 20 having different orientations grow from the middle. Although this crystal grain disappears once, when it grows about 3 mm, another crystal grain boundary 21 begins to grow, and finally a polycrystalline structure is formed. The polycrystalline structure is formed because the crystal growth interface 3 has a U-shaped or V-shaped shape as shown in FIG. As described above, according to the present embodiment, not only the uniformity of the composition distribution but also the ensuring of single crystallinity, the effect of growing by attaching the boron nitride powder is clear.

  In the present embodiment, the specific substance for preventing the melt in the melting zone from melting the raw material surface at a rate larger than the ratio of the melt in the melting zone transmitted through the raw material surface during crystal growth is used as a specific substance. Specifically, the case where boron nitride powder is used has been described, but the present invention is also applicable when a substance other than boron nitride powder is used as the specific substance. Specifically, according to the experimental results, it is preferable to use a substance having poor wettability with respect to the melt, that is, a substance having a contact angle with the melt of 90 ° or more as the specific substance.

  Further, in the present embodiment, as the most preferable form, the case where a boron nitride powder having a particle size of 10 to 25 μm within a range of a specific substance to be attached to the surface of the raw material has been described. Even when a boron nitride powder having a particle size in the range of 1 to 50 μm is used as the specific substance, the uniformity of composition distribution and single crystallinity can be satisfactorily ensured in the grown crystal.

  Further, regarding the amount of boron nitride powder to be adhered to the side surface of the columnar raw material, according to the experimental results, in order to ensure good uniformity of composition distribution and single crystallinity in the grown crystal, the surface area of the raw material, It is preferable to adhere boron nitride powder to at least 30% or more of the total area of the side surface.

(Embodiment 2)
In the present embodiment, the case where carbon (graphite) powder is used instead of boron nitride powder as the specific substance attached to the side surface of the raw material in Embodiment 1 will be described with reference to FIG. Hereinafter, the present embodiment will be described by focusing on matters different from those of the first embodiment described above, and detailed description of matters similar to those of the first embodiment will be omitted.

  FIG. 6 is a graph showing an axial InAs concentration distribution in a crystal manufactured using the method for manufacturing a solid solution single crystal according to Embodiment 2 of the present invention. In the present embodiment, after the carbon powder is deposited on the raw material by the same method as in the first embodiment in the above-described deposition step, the band described above under the same growth conditions as in the first embodiment. A crystal having a diameter of 10 mm is grown by performing a melt crystal growth process. According to the second embodiment, as shown in FIG. 6, a crystal with high composition uniformity can be obtained. It can be seen that the solid line 602 indicating the composition distribution in the central axis direction and the broken line 601 indicating the axial direction composition distribution in the portion proceeding from the surface toward the 1 mm central axis are in good agreement and show a uniform composition. Further, according to the experimental results, the single crystallinity can be satisfactorily ensured in the present embodiment as well as in the first embodiment.

  In the present embodiment, the case where carbon powder is used as the specific substance to be attached to the side surface of the raw material has been described. However, according to the experimental results, the specific substance includes aluminum nitride alone, carbon powder and boron nitride powder. Even in the case of using a mixture, a mixture of carbon powder and aluminum nitride powder, a mixture of boron nitride powder and aluminum nitride powder, a mixture containing these three powders, etc., uniformity of composition distribution and single crystallinity in the grown crystal Can be secured satisfactorily.

(Embodiment 3)
In the present embodiment, in Embodiment 1, a plate-shaped raw material is used instead of the columnar raw material, and a mixture of a specific substance (for example, boron nitride powder) and an organic solvent is used on the side surface of the raw material. Will be described. Hereinafter, the present embodiment will be described by focusing on matters different from those of the first embodiment described above, and detailed description of matters similar to those of the first embodiment will be omitted.

First, a plate-like GaAs raw material (for example, a thickness of 1.8 mm, a width of 9.6 mm, and a length of 50 mm) is prepared as a raw material.
Next, in the adhesion step described in the first embodiment, a mixture of boron nitride powder as a specific substance and an organic solvent is prepared, and this mixture is applied to a plate-like GaAs raw material. Specifically, boron nitride fine powder (particle size 5-10 μm) is dissolved in an organic solvent (butyl alcohol) and kneaded, and a mixture of paste boron nitride powder and organic solvent is a plate-like GaAs raw material. Is applied to the surface in the longitudinal axis direction by a brush. As a result, the boron nitride powder is simply retained on the side surface of the raw material by pressing (the first embodiment and the second embodiment), while being held in the paste-like organic solvent. Since it adheres to the side surface, it is more reliably prevented from peeling from the side surface of the raw material between this adhesion step and the next zone melting method crystal growth step.

  Next, in the zone melting method crystal growth step, the following are prepared as crystal growth containers. That is, the plate-shaped raw material described above is processed into a plate-like GaAs seed crystal (eg, thickness 1.95 mm, width 9.95 mm, length 10 mm), and InAs (eg, thickness 1.8 mm) 9.6mm wide, 15mm long), and inserted into a half-cylinder-shaped boron nitride crucible with a rectangular groove with a depth of 2mm and a width of 10mm. These are all inserted into a boron nitride cylinder and then vacuum-sealed in a quartz container to obtain a crystal growth container.

  This container is inserted into the heating device 101 (temperature gradient furnace) of the crystal manufacturing apparatus 100 shown in FIG. When the temperature around the container in the heating apparatus 101 rises to about 700 ° C., the organic solvent applied to the plate-like GaAs raw material is carbonized, and the boron nitride powder adheres to the raw material by the carbonized organic solvent. A state is formed. Specifically, the carbonized organic solvent is fixed to the side surface with the boron nitride powder sandwiched between the side surface of the GaAs raw material, and the boron nitride powder is then bonded to the side surface of the raw material by the carbonized organic solvent. It is kept in a state of being crimped to. In the present embodiment, in order to simplify the description, it is assumed that the step of carbonizing the organic solvent is performed in the zone melting method crystal growth step, that is, included in the zone melting method crystal growth step. However, the step of carbonizing the organic solvent can be considered as a step separate from the zone melting method crystal growth step.

  Thereafter, the heating device 101 is heated so that the interface temperature between the seed crystal and InAs is 1030 ° C. and the temperature gradient is about 10 ° C./cm to melt InAs, thereby forming a melting zone. Thereafter, as in Embodiment 1 described above, crystal growth is executed by moving the container to the low temperature side at a speed of 0.22 mm / h.

  Next, the effect obtained by the method for producing a solid solution single crystal according to the present embodiment will be described with reference to FIG. FIG. 7A is a schematic diagram showing a result of observing a growth interface and a melting interface in a raw material rapidly cooled during crystal growth using the method for producing a solid solution single crystal according to Embodiment 3 of the present invention. is there. FIG. 7B shows a result of observing a growth interface and a melting interface in a raw material rapidly cooled during crystal growth using a conventional manufacturing method under the same temperature environment as in FIG. 7A. It is a schematic diagram.

  In FIG. 7A (in FIG. 7B), the melting zone 701 (71) exists between the grown crystal 702 (72) and the raw material 703 (73). Of both ends of the melting zone 701 (71), the portion in contact with the growth crystal 702 (72) is the growth interface 704 (74), and the portion in contact with the raw material 703 (73) is the melting interface 705 (75). ).

  Referring to FIG. 7A, the crystal growth interface 704 and the melting interface 705 are both slightly concave, but it can be said that a substantially flat interface is formed. On the other hand, referring to FIG. 7B, a mixture of boron nitride powder and an organic solvent. The distortion of the crystal growth interface 74 and the melting interface 75 is obtained when the cylindrical sample used in the first embodiment is used (FIG. 3B). ))), And the width of the grown crystal becomes narrower as it grows. This is because the sample (raw material) was plate-like, and the penetration of the melt into the side surface was more noticeable than when a cylindrical sample (raw material) was used, and the plate-like sample (raw material). This is probably because the side surface is more easily melted as the volume is smaller than that of the columnar sample (raw material).

  In this embodiment, the case where a mixture of boron nitride powder and an organic solvent is applied to a plate-shaped raw material has been described. However, the shape of the raw material to which such a mixture is applied is not particularly limited. It goes without saying that even when such a mixture is applied to the columnar raw material described in Embodiments 1 and 2, uniformity of composition distribution and single crystallinity can be secured in the grown crystal.

  In this embodiment, the case where a mixture of a boron nitride powder and an organic solvent is applied to a raw material has been described. However, boron nitride powder and other substances (one or both of carbon powder and aluminum nitride) and organic It is also possible to use a mixture with a solvent. Also in this case, when the raw material is put into a heating device (temperature gradient furnace) and heated, the organic solvent is carbonized, and the boron nitride powder and the carbon powder are attached to the raw material by the carbonized organic solvent. Is formed.

  Rotating the specified material (for example, boron nitride powder, carbon powder, or a mixture thereof, etc.) on the paper surface while pressing the side surface of the raw material, and attaching the specific material to the side surface of the raw material Compared with Embodiment 1 and Embodiment 2, according to the present embodiment, since the mixture containing the specific substance and the organic solvent is applied to the side surface of the raw material, it is easily and reliably specified on the side surface of the raw material. A substance can be deposited. In addition, the specific substance is kept attached to the side surface of the raw material by an organic solvent after such coating, and after the start of crystal growth, the specific substance is carbonized fixed to the side surface of the raw material. It is held in a state where it is pressed against the side surface of the raw material by an organic solvent. Therefore, at the time when the crystal growth is actually progressing, the state in which the specific substance adheres to the portion of 30% or more of the surface area of the raw material, that is, the total area of the side surface is surely maintained. Uniformity of distribution and single crystallinity can be ensured more reliably.

(Embodiment 4)
In the present embodiment, a case where a plate-like raw material is used instead of a columnar raw material and an aluminum nitride powder is used instead of boron nitride powder as a specific substance to be attached to the surface of the raw material in Embodiment 1 will be described. To do. Hereinafter, with respect to the present embodiment, detailed description of matters similar to those of the above-described first to third embodiments is omitted.

  First, a plate-like Si raw material is prepared as a raw material. Next, in the attaching step described in the first embodiment, for example, paper having an area sufficiently larger than the surface area of the plate-like Si raw material is prepared. An aluminum nitride powder (for example, a particle size of about 50 μm) is spread on the paper. Thereafter, the four longitudinal axis side surfaces of the plate-like Si raw material are pressed in a state where the side surfaces are in contact with the surface of the paper, thereby attaching aluminum nitride to the four longitudinal axis surfaces of the raw material. .

Next, in the zone melting method crystal growth step, in order to grow a plate-like Si _0.5 Ge _0.5 crystal, the above-described plate-like Si raw material as a raw material, a Si single crystal as a seed crystal, and a molten zone forming material Using this Ge, a crystal growth vessel is prepared by the same method as described in the third embodiment. Thereafter, the heating condition of the heating device 101 (temperature gradient furnace) is such that the joint surface between the seed crystal Si and the molten zone forming material Ge is about 1100 ° C., and the temperature gradient in this temperature region is 10 ° C./cm. And the insertion position of the crystal growth vessel is adjusted. The temperature is maintained for 3 hours until the temperature becomes stable under this initial condition, and the crystal growth vessel is moved to the low temperature side at a constant speed at 0.27 mm / h.

FIG. 8 is a graph showing an axial SiGe concentration distribution in a crystal manufactured using the method for manufacturing a solid solution single crystal according to Embodiment 1 of the present invention. In FIG. 8, both the composition distribution 84 in the central axis direction and the axial composition distribution 85 in the portion proceeding from the surface toward the 1 mm central axis agree well, and a Si _0.5 Ge _0.5 crystal having excellent uniformity is obtained. I understand that. According to the experimental results, in the grown crystal, a single crystal that has inherited the orientation of the seed crystal has grown to the end. As described above, also in this embodiment, it is possible to ensure not only the uniformity of the composition distribution but also the single crystallinity in the grown crystal.

  As described above, according to the method for producing a solid solution single crystal according to the present invention, the melt in the melting zone generated by melting the solid raw material is prevented from moving on the surface of the remaining solid raw material remaining unmelted. In a state where a specific substance (preferably, a specific substance having poor wettability with respect to the melt, that is, a specific substance having a contact angle of 90 ° or more with respect to the melt) is attached to the surface of the solid raw material, By performing the growth, the melt is prevented from moving from the melting zone to the remaining solid raw material side through the surface of the remaining solid raw material, resulting in deformation of the melting zone and this deformation. It is possible to prevent the crystal growth interface from being deformed. Therefore, it is possible to prevent the compositional uniformity and polycrystallization in the crystal growth caused by the deformation of the crystal growth interface, so that a solid solution single crystal (that is, a solid solution having a uniform composition and a single crystal structure) can be obtained. It can be manufactured with good reproducibility.

  The method for producing a solid solution single crystal according to the present invention is not limited to the production of a specific material, and can be widely applied to the production of general solid solution single crystals. In particular, solid solutions of semiconductors such as InAs-GaAs and Si-Ge are required to have high quality and uniform composition when used for laser diode and integrated circuit device fabrication substrates. Therefore, the method for producing a solid solution single crystal according to the present invention is particularly suitable for producing a solid solution of a semiconductor such as InAs-GaAs or Si-Ge.

The schematic diagram which shows the outline of the crystal manufacturing apparatus used for the manufacturing method of the solid solution single crystal which concerns on Embodiment 1 of this invention. The schematic diagram which shows sectional drawing of the container 105 for crystal growth used for the manufacturing method of the solid solution single crystal which concerns on Embodiment 1 of this invention. (A) The schematic diagram which shows the result of having observed the growth interface and the fusion | melting interface in the raw material quenched rapidly during the crystal growth using the manufacturing method of the solid solution single crystal which concerns on Embodiment 1 of this invention. (B) A schematic view showing the result of observing the growth interface and the melting interface in a raw material that has been rapidly cooled during crystal growth using a conventional manufacturing method under the same temperature environment as in FIG. An axial InAs concentration distribution in a crystal manufactured using the method for manufacturing a solid solution single crystal according to Embodiment 1 of the present invention is shown in comparison with an InAs concentration distribution in a crystal manufactured using a conventional technique. Graph. (A) The schematic diagram which shows the result of having observed the longitudinal section of the crystal grown using the manufacturing method of the solid solution single crystal which concerns on Embodiment 1 of this invention. (B) A schematic view showing the result of observing a longitudinal section of a crystal grown using a conventional manufacturing method under the same temperature environment as in FIG. The graph which shows the axial direction InAs density | concentration distribution in the crystal manufactured using the manufacturing method of the solid solution single crystal which concerns on Embodiment 2 of this invention. (A) The schematic diagram which shows the result of having observed the growth interface and the fusion | melting interface in the raw material quenched rapidly during the crystal growth using the manufacturing method of the solid solution single crystal which concerns on Embodiment 3 of this invention. (B) The schematic diagram which shows the result of having observed the growth interface and the fusion | melting interface in the raw material rapidly cooled in the middle of the crystal growth using the conventional manufacturing method in the same temperature environment as the case of FIG. 7 (a). The graph which shows the SiGe density | concentration distribution of the axial direction in the crystal manufactured using the manufacturing method of the solid solution single crystal which concerns on Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Crystal manufacturing apparatus 101 Heating apparatus 102 Drive mechanism 103 Support rod 104 Control mechanism 105 Crystal growth container 201 Crucible 202 Heat sink 203 Quartz container 205 Seed crystal 206 InAs (melting zone forming material)
207 Raw material 208 Boron nitride powder (specific substance)

Claims (6)

Attaching a specific substance having a contact angle of 90 ° or more to the melt produced by melting the solid raw material to the surface of the solid raw material ;
A growth process for producing a solid solution single crystal by performing crystal growth by a zone melting method using the solid raw material to which the specific substance is attached;
A process for producing a solid solution single crystal comprising:   The said adhesion process includes the press process which adheres the said specific substance to the surface of the said solid raw material by pressing the surface of the said solid raw material with respect to the surface where the said specific substance was spread. A method for producing a solid solution single crystal. The attaching step includes an application step of applying a mixture containing the specific substance and an organic solvent to the surface of the solid raw material,
In the growth step, before the melt is generated by melting the solid raw material, the solid raw material coated with the mixture is heated to carbonize the organic solvent,
The method for producing a solid solution single crystal according to claim 1, further comprising a carbonization step in which the carbonized organic solvent is fixed to the surface and maintains the state where the specific substance is pressure-bonded to the surface.   The method for producing a single crystal solid solution according to any one of claims 1 to 3, wherein the specific substance is boron nitride, carbon, aluminum nitride, or a mixture containing at least two of them.   5. The method for producing a single crystal solid solution according to claim 1, wherein in the attaching step, the specific substance is attached to at least 30% or more of a surface area of the solid raw material. The method for producing a single crystal solid solution according to any one of claims 1 to 5 , wherein, in the attaching step, a powdery specific substance having a particle size in the range of 1 to 50 µm is attached to the surface of the solid raw material. .

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