JP2008056562A - GaAs SINGLE CRYSTAL, AND METHOD AND APPARATUS FOR PRODUCING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a GaAs single crystal in which the carbon concentration at the upper end part is set to a target value can be produced in a short time even when high carbon concentration is required as the carbon concentration in the crystal. <P>SOLUTION: In the method, mixing of CO into a sealant melt is accelerated by supplying CO gas into a high pressure pulling furnace 11, then rotating an accommodated liquid raw material and a liquid sealant by rotating a crucible 12 and agitating the sealant melt by an agitation tool 21 before pulling the GaAs single crystal after a crystal raw material has been melted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for manufacturing a GaAs single crystal manufactured by a liquid sealing pulling method (hereinafter referred to as “LEC (Liquid Encapsulated Czochralski method) method”) and an apparatus for manufacturing the same.

  GaAs single crystals are widely used as substrate materials for high-speed, high-frequency devices such as field effect transistors (hereinafter referred to as “FET (Field Effect Transistor)” and integrated circuits (hereinafter referred to as “IC (Integrated Circuit)”). One of the methods for producing this GaAs single crystal is the LEC method, which is produced, for example, in the following manner.

  First, a crystal production material such as a crystal raw material or a sealant is accommodated in a crucible. Thereafter, the crucible is accommodated in a high pressure pulling furnace. Thereafter, the atmospheric gas in the furnace is replaced with Ar gas, and the pressure in the furnace is increased to a predetermined value with Ar gas. Then, the GaAs polycrystal is synthesized by heating the crystal manufacturing material accommodated in the crucible. Thereafter, further heating is performed to produce a raw material melt (GaAs melt). Thereafter, with the raw material melt covered with the sealant melt, the seed crystal is brought into contact with the surface of the raw material melt, and the seed crystal and / or the raw material melt is rotated (when both are rotated). Is rotated in the reverse direction.) A GaAs single crystal is produced by cooling and solidifying while pulling up. The above is an example of manufacturing a GaAs single crystal by the LEC method.

  In an apparatus for producing a GaAs single crystal by this LEC method, a heating element and a heat insulating material are disposed in a furnace. These are made of a carbon material such as graphite. In the apparatus using this carbon material, it was thought that carbon was mixed as an impurity in the manufactured GaAs single crystal. Carbon mixed in the crystal acts as a shallow acceptor. In this case, the level of the carbon concentration greatly affects the electrical characteristics of the GaAs single crystal and the activation rate after ion implantation.

  The electrical characteristics required for a GaAs substrate formed from a GaAs single crystal vary depending on the type of element in which the substrate is used. However, whatever element is used, it is desired that the GaAs single crystal that is the base of the GaAs substrate can be set uniformly and with good reproducibility without variation in the desired carbon concentration from the top to the bottom. .

  In the LEC method, it is considered that carbon in the GaAs single crystal is supplied from carbon monoxide (hereinafter referred to as “CO”) in the atmospheric gas in the furnace. Therefore, conventionally, during the crystal growth, by setting the CO concentration in the atmospheric gas in the furnace to a value corresponding to the target value of the carbon concentration in the crystal, the uniformity of the carbon concentration in the crystal and this It was designed to ensure uniformity and reproducibility.

  However, such a configuration has a problem that the carbon concentration in the GaAs single crystal becomes non-uniform, and the upper portion of the crystal becomes lower than the target value. This is considered because it takes several hours to several tens of hours until the carbon concentration in the raw material melt reaches the target value.

That is, since the CO gas in the furnace is taken into the raw material melt via an intermediate inclusion called a sealant melt, the carbon concentration in the raw material melt and the CO concentration in the furnace reach an equilibrium state. Takes several hours to tens of hours. Thereby, it takes several hours to several tens of hours until the carbon concentration in the raw material melt reaches the target value. As a result, in the above configuration, the carbon concentration in the crystal becomes lower than the target value in the upper part of the crystal.

  In order to solve this problem, the growth treatment of the GaAs single crystal may be started after the carbon concentration in the raw material melt reaches the target value.

  However, in such a configuration, when the time until the carbon concentration in the raw material melt reaches the target value is long, a new problem arises that the manufacturing time of the GaAs single crystal becomes long.

  In order to solve this problem, it is considered that the CO concentration in the furnace is made higher than the value corresponding to the target value of the carbon concentration in the GaAs single crystal until the carbon concentration in the raw material melt reaches the target value. .

However, even in such a configuration, when a high carbon concentration of, for example, 2.0E + 15 cm ⁻³ or more is required as the carbon concentration in the GaAs single crystal, the carbon concentration in the raw material melt becomes the target value. The time to reach will be several tens of hours. For this reason, a GaAs single crystal whose carbon concentration is set to a target value cannot be manufactured in a short time even in the upper part of the crystal.

  Therefore, the present invention provides a GaAs single crystal whose carbon concentration is set to a target value even in the upper part of the crystal even when a high carbon concentration is required as the carbon concentration in the GaAs single crystal. It aims at providing the manufacturing method and manufacturing apparatus which can be manufactured in time.

  In order to solve the above problems, the inventors of the present invention increase the frequency of indirect contact between the atmospheric gas in the furnace and the raw material melt by stirring the sealant melt, and in the GaAs single crystal. Even when a high carbon concentration is required as the carbon concentration, an attempt was made to shorten the time until the carbon concentration in the raw material melt was set to the target value. As a result of the experiment, according to such a configuration, even if a high carbon concentration is required as the carbon concentration in the GaAs single crystal, the carbon concentration in the raw material melt can be achieved to the target value in a short time. I understood.

  Therefore, the method for producing a GaAs single crystal according to the first means for solving the problem melts the crystal raw material and the sealing material accommodated in the crucible by heating in a furnace, and seals the raw material melt. A method of manufacturing a GaAs single crystal by bringing a seed crystal into contact with a raw material melt while being covered with a stopper melt, and cooling and solidifying the raw material melt while pulling it up. Then, before pulling up the GaAs single crystal, CO gas is supplied into the furnace, and in this state, the sealant solution is stirred to mix CO into the sealant melt.

  In the method according to the first means, the CO gas is supplied into the furnace after the crystal raw material is melted and before the GaAs single crystal is pulled up. In this state, the sealant melt is stirred. Thereby, the mixing of CO into the sealant melt is promoted. As a result, the movement of carbon from the sealant melt to the raw material melt by the reaction between the sealant melt containing CO and the raw material melt is promoted. Thereby, even if a high carbon concentration is required as the carbon concentration in the GaAs single crystal, the carbon concentration in the raw material melt is achieved to the target value in a short time. As a result, a GaAs single crystal in which the carbon concentration is set to the target value is also produced in a short time in the upper part of the crystal.

The method for producing a GaAs single crystal according to the second means is characterized in that, in the method according to the first means, the carbon concentration of the GaAs single crystal is 2.0E + 15 cm ⁻³ or more.

  In the GaAs single crystal manufacturing apparatus according to the third means, the crystal raw material and the sealing material accommodated in the crucible are melted by heating in a furnace, and the raw material melt is covered with the sealant melt. An apparatus for manufacturing a GaAs single crystal by bringing a seed crystal into contact with the raw material melt and cooling and solidifying the raw material melt while rotating the raw material melt. CO gas supply means for supplying gas, and stirring means for mixing CO into the sealant melt by stirring the sealant melt before the GaAs single crystal is grown after the crystal raw material is melted. It is provided with.

  In the apparatus according to the third means, a GaAs single crystal is manufactured using the method according to the first means. Thereby, even if a high concentration is required as the carbon concentration in the GaAs single crystal, a GaAs single crystal in which the carbon concentration is set to the target value is manufactured in a short time in the upper portion of the crystal.

The GaAs single crystal manufacturing apparatus according to the fourth means is similar to the method according to the second means in the apparatus according to the fourth means, and the carbon concentration of the GaAs single crystal is 2.0E + 15 cm ⁻³ or more. It is characterized by.

The GaAs single crystal according to the fifth means is manufactured by the LEC method, and the carbon concentration within 100 mm from the upper end of the crystal is 2.0E + 15 cm ⁻³ or more.

  In the GaAs single crystal according to the fifth means, a GaAs single crystal having a uniform carbon concentration from the top to the bottom of the single crystal can be obtained.

  As described in detail above, according to the GaAs single crystal manufacturing method and the GaAs single crystal manufacturing apparatus according to the first or second means, after the crystal raw material is melted, the GaAs single crystal is grown before the GaAs single crystal is grown. The sealant melt is stirred while supplying CO gas into the furnace. Thereby, even when a high carbon concentration is required as the carbon concentration in the crystal, a GaAs single crystal in which the carbon concentration in the upper part of the crystal is set to the target value can be manufactured in a short time.

  Further, according to the GaAs single crystal according to the fifth means, a GaAs single crystal having a uniform carbon concentration from the upper part to the lower part of the crystal can be obtained.

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

[1] First Embodiment [1-1] Configuration of GaAs Single Crystal Manufacturing Apparatus FIG. 1 is a cross-sectional view showing the configuration of a first embodiment of a GaAs single crystal manufacturing apparatus according to the present invention. is there. However, in the figure, in order to avoid complication of the figure, the oblique lines indicating the cross section are attached only to the high pressure pulling furnace.

  In the figure, 11 indicates a high-pressure pulling furnace, and 12 indicates a crucible. The crucible 12 is accommodated in a container 13 disposed inside the high pressure pulling furnace 11 after the crystal production material is stored outside the high pressure pulling furnace 11. As the crucible 12, for example, a crucible made of pBN (pyrolytic boron nitride) is used. In addition, examples of the crystal manufacturing material include a crystal raw material and a sealant. Ga and As are used as the crystal raw material.

The container 13 is made of, for example, graphite. The container 13 is supported by the crucible shaft 14 at the center. The crucible shaft 14 extends in the vertical direction. The crucible shaft 14 is rotated and driven by a rotary lift 15 disposed outside the high pressure pulling furnace 11. In this case, the crucible shaft 14 is always driven to rotate in the same direction.

  Around the container 13, a heater 16 for heating the crystal manufacturing material accommodated in the crucible 12 is disposed. The heater 16 is made of, for example, a carbon material such as graphite. A felt heat insulating material 17 is disposed around the heater 16 and above and below the container 12. The heat insulating material 17 is made of, for example, a carbon material such as graphite.

  Above the crucible 12 accommodated in the container 13, a crystal axis 18 for pulling up the GaAs single crystal is disposed. The crystal axis 18 is disposed coaxially with the crucible axis 14. A seed crystal 19 for determining the crystal orientation of the GaAs single crystal is attached to the lower end of the crystal axis 18. Further, the crystal axis 18 is driven to be rotated and driven up and down by a rotary lift mechanism 20 disposed outside the high pressure pulling furnace 11.

  Above the crucible 12, a stirring jig 21 for stirring the sealant melt is further provided. The stirring jig 21 is formed, for example, in a T shape, and has a stirring blade portion 211 and a stirring shaft 212. The stirring jig 21 is arranged such that the stirring blade portion 211 is positioned below and the stirring shaft 212 is parallel to the crystal axis 18. As a result, the stirring shaft 212 is positioned at a position displaced from the center of the crucible 12. The stirring jig 21 is rotated and driven by a rotary lifting mechanism 22 disposed outside the high-pressure pulling furnace 11. In this case, for example, the stirring jig 21 is driven to rotate alternately in the opposite direction at a predetermined cycle. In addition, since it can stir if the rotation of the crucible 12 is utilized, the stirring jig 21 may be structured such that it only moves up and down and does not rotate.

  A gas introduction pipe 23 for introducing pure Ar gas and CO gas into the furnace 11 is attached to the upper portion of the high pressure pulling furnace 11. An exhaust pipe 24 for discharging atmospheric gas in the furnace 11 is attached to the lower part of the high-pressure pulling furnace 11. A CO concentration meter 25 for measuring CO concentration is inserted into the exhaust pipe 24.

[1-2] Operation of GaAs Single Crystal Manufacturing Apparatus Next, the operation of the above-described GaAs single crystal manufacturing apparatus will be described.

  Before starting the production of the GaAs single crystal, as shown in FIG. 1, the crystal axis 18 and the stirring jig 21 are retracted upward.

  In this state, first, the crystal production material is accommodated in the crucible 13 outside the high-pressure pulling furnace 11. Next, the crucible 13 in which the crystal production material is accommodated is accommodated in the container 13 in the high-pressure pulling furnace 11. Next, the atmospheric gas in the furnace 11 is replaced with pure Ar gas, and the pressure in the furnace 11 is increased to a predetermined value.

  When the pressure in the furnace 11 is increased to a predetermined value, the crystal production material accommodated in the crucible 12 is heated by the heater 15. Thereby, the crystal raw material and the sealing agent are melted. As a result, a sealant melt and a raw material melt in which Ga and As are synthesized are formed. In this case, as shown in FIG. 2, the raw material melt 41 is positioned below the liquid sealant 42 because of the specific gravity. Thereby, the raw material melt 41 is covered with the sealant melt 42.

When the crystal raw material is melted, a predetermined amount of CO gas is mixed into the pure Ar gas in the furnace 11. However, the pressure in the furnace 11 is maintained at a predetermined value as it is. In this case, the CO concentration in the furnace 11 is set to a value corresponding to the target value of the carbon concentration in the raw material melt 41. When the CO concentration in the furnace 11 is set to the target value, the stirring jig 21 is driven downward by the rotary lifting mechanism 22. As shown in FIG. 3, the downward driving is performed until the stirring blade 211 is immersed in the sealant melt 42. When the stirring blade portion 211 is immersed in the sealant melt 42, the stirring jig 21 is rotationally driven by the rotary lifting mechanism 22.

Thereby, the sealing agent melt 42 is stirred. As a result, the mixing of CO in the atmospheric gas in the furnace 11 with respect to the sealant melt 42 is promoted. Thereby, the movement of carbon from the sealant melt 42 to the raw material melt 41 is promoted between the sealant melt 42 containing CO and the raw material melt 41. As a result, even if a high carbon concentration of, for example, 2.0E + 15 cm ⁻³ or higher is required as the carbon concentration in the crystal, the carbon concentration in the raw material melt 41 is set to the target value in a short time. .

  When the carbon concentration in the raw material melt 41 reaches the target value, the crystal shaft 18 is lowered by the rotary elevating mechanism 20 and the seed crystal 19 is brought into contact with the raw material melt 41. Next, the crystal shaft 18 is driven to rotate at a predetermined speed by the rotary elevating mechanism 20 and is driven to rise at a predetermined speed, for example. Further, the crucible 12 is rotationally driven by the rotary elevating mechanism 15. By these driving, the raw material melt 41 is rotated, for example, gradually while being rotated. Thereby, the raw material melt 41 is cooled and solidified. As a result, as shown in FIG. 4, the GaAs single crystal 43 is gradually grown.

  During the crystal growth, the CO concentration in the furnace 11 is gradually increased based on the segregation coefficient of carbon from the raw material melt 41 to the GaAs single crystal 43 and the solidification rate of the GaAs single crystal 43. This is for setting a uniform carbon concentration throughout the crystal.

  That is, when the GaAs single crystal 43 grows, the carbon in the raw material melt 41 is segregated toward the GaAs single crystal 43. Due to this segregation, in the configuration in which the CO concentration in the furnace 11 is set to a constant value during the growth of the GaAs single crystal 43, the carbon concentration in the raw material melt 41 gradually decreases as the GaAs single crystal 43 grows. As a result, the carbon concentration in the GaAs single crystal 43 gradually decreases from the upper part to the lower part.

  In contrast, during the growth of the GaAs single crystal 43, the CO concentration in the furnace 11 is gradually increased based on the segregation coefficient of carbon from the raw material melt 41 to the GaAs single crystal 43 and the solidification rate of the GaAs single crystal 43. According to the structure which raises, the fall of the carbon concentration in the raw material melt 41 is prevented. As a result, a GaAs single crystal 43 in which the carbon concentration is set uniformly over the entire region is obtained.

  The control for gradually increasing the CO concentration is also performed based on the measurement result of the CO concentration meter 25.

[1-3] Effects According to the embodiment described in detail above, the following effects can be obtained.

(1) First, according to the present embodiment, after the crystal raw material is melted and before the GaAs single crystal 43 is grown, the sealant melt 42 is stirred while supplying the CO gas into the furnace 11. The Thereby, mixing of CO with respect to the raw material melt 41 can be promoted. As a result, even if a high carbon concentration is required as the carbon concentration in the GaAs single crystal, a GaAs single crystal in which the carbon concentration is set to the target value in the upper portion of the crystal can be manufactured in a short time.

(2) Further, according to the present embodiment, when the sealant melt 42 is agitated, the agitation jig 21 is alternately rotated in the opposite direction. Thereby, the stirring efficiency of the sealing agent melt 42 can be increased.

(3) Furthermore, according to the present embodiment, when the sealant melt 42 is agitated, the crucible 12 is rotationally driven. Thereby, the stirring efficiency of the sealing agent melt 42 can be increased.

[2] Second Embodiment FIG. 4 is a cross-sectional view showing a configuration of a second embodiment of a GaAs single crystal manufacturing apparatus according to the present invention. In FIG. 4, components having substantially the same functions as those shown in FIG. 1 are given the same reference numerals, and detailed description thereof is omitted.

  In the previous embodiment, the case where the stirring jig 21 is provided at a position shifted from the crystal axis 18 has been described. On the other hand, in this embodiment, as shown in FIG. 4, the stirring jig 31 is provided coaxially with the crystal axis 18.

  FIG. 4 shows a case where the stirring jig 31 is composed of two L-shaped stirring members 311 and 312. These are provided so as to sandwich the crystal axis 18. Thereby, the stirring jig 31 is provided coaxially with the crystal axis 18. The agitating members 311 and 312 are driven to be lifted and lowered by the rotary lifting mechanism 32. The rotation raising / lowering mechanism 32 also has a function of rotating and raising / lowering the crystal axis 18. That is, the rotary lift mechanism 32 has the functions of the two rotary lift mechanisms 20 and 22 shown in FIG.

  Even in such a configuration, the sealant melt 42 can be agitated in substantially the same manner as in the previous embodiment, so that substantially the same effect as in this embodiment can be obtained.

[3] Third Embodiment FIG. 5 is a cross-sectional view showing a configuration of a third embodiment of a GaAs single crystal manufacturing apparatus according to the present invention. In FIG. 5, components having substantially the same functions as those shown in FIG. 1 are given the same reference numerals, and detailed description thereof is omitted.

  In the first and second embodiments, the case where the sealant melt 42 is stirred by rotating the stirring jigs 21 and 22 has been described. In other words, the case where the sealant melt 42 is stirred by moving the stirring jigs 21 and 22 has been described. On the other hand, in the present embodiment, the sealing material melt 42 is stirred while the stirring jig 33 is kept stationary.

  FIG. 5 shows a case where the stirring jig 33 is constituted by two baffle plates 331 and 332. These are attached to the heat insulating member 17 on the upper side via, for example, a heat shield member 34 so as to be positioned in the sealant melt 42.

  Even in such a configuration, the sealant melt 42 can be agitated by the baffle plates 331 and 332 as the container 13 rotates. Thereby, substantially the same effect as the previous embodiment can be obtained.

[4] Other Embodiments The three embodiments of the present invention have been described in detail above. However, the present invention is not limited to the embodiment described above.

(1) For example, in the previous embodiment, the case where the CO concentration in the furnace 11 is set to a value corresponding to the target value of the carbon concentration in the raw material melt 41 during the stirring period of the sealant melt 42. explained. However, the present invention may be set to a value larger than this corresponding value. According to such a configuration, the time for the carbon concentration in the raw material melt 41 to achieve the target value can be shortened from the previous embodiment.

(2) In the present invention, the CO concentration in the furnace 11 may be set to a value smaller than the corresponding value. Even with such a configuration, according to the present invention, the CO concentration in the sealant melt 42 can be made higher than the CO concentration in the furnace 11. Thereby, depending on the value of the CO concentration in the furnace 11, it is possible to shorten the time for the carbon concentration in the raw material melt 41 to achieve the target value.

(3) Further, according to the present invention, the CO concentration in the furnace 11 may be not only maintained at a constant value but also changed during the stirring period. For example, at the beginning of the agitation period, the CO concentration in the furnace 11 may be made higher than the corresponding value, and thereafter gradually lowered or kept at a constant value lower than the initial value. . According to such a configuration, after the carbon concentration in the raw material melt 41 is quickly raised to the vicinity of the target value, it can be gradually converged to the target value.

(4) In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

  Here, more specific examples of the present invention and comparative examples thereof will be described.

(1) Example In this example, first, a crystal production material (starting material) was placed in a crucible 12. In this case, Ga4000g and As4400g were accommodated as crystal raw materials. Moreover, the liquid sealing agent was accommodated as sealing agent. As this liquid sealant, B ₂ O ₃ having a water content of 200 ppm was accommodated. Thereafter, the crucible 12 was accommodated in a container 13 in the furnace 11. Thereafter, the atmosphere gas in the furnace 11 was replaced with pure Ar gas, and the pressure in the furnace 11 was increased to 37 kgf / cm ² or more with this pure Ar gas. Thereafter, the crystal manufacturing material was heated by the heater 16 to produce a sealant melt 42 and to synthesize Ga and As to produce a raw material melt (GaAs melt) 41. Thereafter, CO gas was introduced into the furnace 11 and the CO concentration in the furnace 11 was set to 10,000 ppm.

After that, the sealing blade melt 211 was stirred by immersing the stirring blade portion 211 of the stirring jig 21 in the sealing agent melt (B ₂ O ₃ melt) 42 and rotating it. In this case, in order to increase the stirring efficiency, the stirring jig 21 was alternately rotated in the opposite direction, and the crucible 12 was rotated at 5 to 50 rpm. By this stirring, the carbon concentration of the raw material melt 41 could be set to the target value. As a result, the time for setting the carbon concentration of the raw material melt 41 to the target value can be shortened from several hours to several tens of hours, compared with the case where stirring is not performed.

  Thereafter, the seed crystal 19 was lowered while the stirring jig 21 was retracted to the top, and brought into contact with the raw material melt 41. Thereafter, the seed crystal 19 was raised at 1 to 20 mm / hr, rotated at 3 to 10 rpm, and the crucible 12 was rotated at 5 to 50 rpm. As a result, a GaAs single crystal 43 having a diameter of 80 mm and a length of 260 mm was grown at a growth rate of 1 to 20 mm / hr. This GaAs single crystal 43 is shown in FIG.

In this case, the CO concentration in the furnace 11 was gradually increased during the growth of the crystal 43 so that a carbon concentration of 2 to 3E + 15 cm ⁻³ was set over the entire area of the GaAs single crystal 43.

FIG. 7 is a characteristic diagram showing the measurement result of the carbon concentration in the GaAs single crystal 43 manufactured according to this example. In FIG. 7, the horizontal axis indicates the distance from the upper end of the formed GaAs single crystal 34 (unit: mm), and the vertical axis indicates the carbon concentration (unit: ppm). The characteristic curve C2 shows the measurement result of the carbon concentration in the GaAs crystal 43. As illustrated, in this embodiment, a carbon concentration of about 2 to 3E + 15 cm ⁻³ is set over the entire area of the GaAs single crystal 31.

(2) Comparative Example This comparative example is substantially the same as the above-described example except that the stirring process is not performed and the reaction time is about four times longer than the above-described example.

FIG. 8 is a diagram showing the measurement result of the carbon concentration in the GaAs single crystal 43 manufactured according to this comparative example in the same manner as FIG. As shown in the figure, in this comparative example, the carbon concentration is lower than the target value at the upper part of the GaAs single crystal 43 (part from the upper end to about 100 mm) even though the reaction time is set to four times that of the example. It was. Thereby, in this comparative example, the GaAs single crystal 43 having a carbon concentration of 2 to 3E + 15 cm ⁻³ from the upper part to the lower part could not be obtained.

It is sectional drawing which shows the structure of 1st Embodiment of the manufacturing apparatus of the GaAs single crystal which concerns on this invention. It is a figure for demonstrating the stirring process in the 1st Embodiment of this invention. It is a figure for demonstrating the crystal growth process in the 1st Embodiment of this invention. It is sectional drawing which shows the structure of 2nd Embodiment of the manufacturing apparatus of the GaAs single crystal which concerns on this invention. It is sectional drawing which shows the structure of 3rd Embodiment of the manufacturing apparatus of the GaAs single crystal which concerns on this invention. It is a figure which shows the size of the GaAs single crystal manufactured by one Example of this invention. It is a characteristic view which shows the carbon concentration in the GaAs single crystal manufactured by one Example of this invention. It is a characteristic view which shows the carbon concentration in the GaAs single crystal manufactured by the comparative example compared with one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... High pressure pulling furnace 12 ... Crucible 13 ... Container 14 ... Crucible shaft 15,20,22,32 ... Rotary raising / lowering mechanism 16 ... Heater 17 ... Insulating material 18 ... Crystal shaft 19 ... Seed crystal 21,31,33 ... Stirring jig 23 ... Gas introduction pipe 24 ... Exhaust pipe 25 ... CO concentration meter

Claims (3)

Melting the crystal raw material and the encapsulant contained in the crucible by heating in a furnace, with the raw material melt covered with the encapsulant melt, bringing the seed crystal into contact with the raw material melt, A method of manufacturing a GaAs single crystal by cooling and solidifying while pulling up the raw material melt,
After the crystal raw material is melted and before pulling up the GaAs single crystal, carbon monoxide gas is supplied into the furnace, and in this state, the liquid raw material and the liquid sealing agent accommodated by rotating the crucible And rotate
A method for producing a GaAs single crystal, wherein the carbon monoxide gas is mixed into the sealant melt by providing a stirring jig in the liquid sealant and stirring. 2. The method for producing a GaAs single crystal according to claim 1, wherein a carbon concentration of the GaAs single crystal is 2.0E + 15 cm ⁻³ or more. The crystal raw material and the sealing material accommodated in the crucible are melted by heating in a furnace, and in a state where the raw material melt is covered with the sealant melt, the seed crystal is brought into contact with the raw material melt, An apparatus for producing a GaAs single crystal by cooling and solidifying while pulling up the raw material melt,
A carbon monoxide gas supply means for supplying a carbon monoxide gas into the furnace after the crystal raw material has melted;
Rotating means for rotating the crucible,
A crystal axis on which the seed crystal is disposed;
An apparatus for producing a GaAs single crystal, comprising: an agitation jig that agitates the sealing agent solution and mixes the carbon monoxide gas into the sealing agent solution independently of the crystal axis.

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