The provided by the disclosure is a SiC single crystal production method permitting suppression of temperature variation of a Si—C solution even in a case of long-time crystal growth. The SiC single crystal production method includes: a preparation step of preparing a production apparatus including a crucible, a seed shaft, and an internal lid; a formation step of heating the material in the crucible to form the Si—C solution; a growth step of bringing the seed crystal into contact with the Si—C solution to produce the Si—C single crystal on the seed crystal; an internal lid adjustment step of vertically moving one of the internal lid and the crucible relative to the other during the growth step to keep an amount of variation in vertical distance between the internal lid and the Si—C solution within a first reference range.

The provided by the disclosure is a SiC single crystal production method permitting suppression of temperature variation of a Si—C solution even in a case of long-time crystal growth. The SiC single crystal production method includes: a preparation step of preparing a production apparatus including a crucible, a seed shaft, and an internal lid; a formation step of heating the material in the crucible to form the Si—C solution; a growth step of bringing the seed crystal into contact with the Si—C solution to produce the Si—C single crystal on the seed crystal; an internal lid adjustment step of vertically moving one of the internal lid and the crucible relative to the other during the growth step to keep an amount of variation in vertical distance between the internal lid and the Si—C solution within a first reference range.

The present invention relates to a method and apparatus for growing sapphire single crystals, and more particularly to a method and apparatus for growing sapphire single crystals in which a high quality, long single crystal can be obtained within a short period of time upon the use of a long rectangular crucible and a long seed crystal extending in a c-axial direction. Use of the method and apparatus for growing sapphire single crystals according to the present invention can uniformly maintain the horizontal temperature at the inside of the crucible despite the use of a rectangular crucible, thereby obtaining a high-quality single crystal as well decreasing the possibility of a failure in the growth of the single crystal.

The present invention relates to a method and apparatus for growing sapphire single crystals, and more particularly to a method and apparatus for growing sapphire single crystals in which a high quality, long single crystal can be obtained within a short period of time upon the use of a long rectangular crucible and a long seed crystal extending in a c-axial direction. Use of the method and apparatus for growing sapphire single crystals according to the present invention can uniformly maintain the horizontal temperature at the inside of the crucible despite the use of a rectangular crucible, thereby obtaining a high-quality single crystal as well decreasing the possibility of a failure in the growth of the single crystal.

A production method according to an embodiment includes a formation step (S1), a first growth step (S2), a recovery step (S3), and a second growth step (S4). In the formation step (S1), a Si—C solution containing Si, Al and C is formed in a crucible. In the first growth step (S2), a seed shaft is moved down to bring a SiC seed crystal attached to the bottom edge of the seed shaft onto contact with the Si—C solution, and thereafter, an Al-doped p-type SiC single crystal is grown on the SiC seed crystal. After the first growth step (S2), the Al concentration in the Si—C solution is increased in the recovery step (S3). After the recovery step (S3), the Al-doped p-type SiC single crystal is further grown in the second growth step (S4).

A production method according to an embodiment includes a formation step (S1), a first growth step (S2), a recovery step (S3), and a second growth step (S4). In the formation step (S1), a Si—C solution containing Si, Al and C is formed in a crucible. In the first growth step (S2), a seed shaft is moved down to bring a SiC seed crystal attached to the bottom edge of the seed shaft onto contact with the Si—C solution, and thereafter, an Al-doped p-type SiC single crystal is grown on the SiC seed crystal. After the first growth step (S2), the Al concentration in the Si—C solution is increased in the recovery step (S3). After the recovery step (S3), the Al-doped p-type SiC single crystal is further grown in the second growth step (S4).

An apparatus for producing an SiC single crystal includes a crucible for accommodating an Si—C solution and a seed shaft having a lower end surface where an SiC seed crystal (36) would be attached. The seed shaft includes an inner pipe that extends in a height direction of the crucible and has a first passage. An outer pipe accommodates the inner pipe and constitutes a second passage between itself and the inner pipe and has a bottom portion whose lower end surface covers a lower end opening of the outer pipe. One passage of the first and second passages serves as an introduction passage where coolant gas flows downward, and the other passage serves as a discharge passage where coolant gas flows upward. A region inside the pipe that constitutes the introduction passage is to be overlapped by a region of not less than 60% of the SiC seed crystal.

An apparatus for producing an SiC single crystal includes a crucible for accommodating an Si—C solution and a seed shaft having a lower end surface where an SiC seed crystal (36) would be attached. The seed shaft includes an inner pipe that extends in a height direction of the crucible and has a first passage. An outer pipe accommodates the inner pipe and constitutes a second passage between itself and the inner pipe and has a bottom portion whose lower end surface covers a lower end opening of the outer pipe. One passage of the first and second passages serves as an introduction passage where coolant gas flows downward, and the other passage serves as a discharge passage where coolant gas flows upward. A region inside the pipe that constitutes the introduction passage is to be overlapped by a region of not less than 60% of the SiC seed crystal.

Provided are an SiC single-crystal ingot containing an SiC single crystal having a low threading dislocation density and low resistivity; an SiC single crystal; and a production method for the SiC single crystal. The SiC single crystal ingot contains a seed crystal and a grown crystal grown by a solution process in which the seed crystal is the base point, the grown crystal of the SiC single crystal ingot containing a nitrogen density gradient layer in which the nitrogen content increases in the direction of growth from the seed crystal.

Provided are an SiC single-crystal ingot containing an SiC single crystal having a low threading dislocation density and low resistivity; an SiC single crystal; and a production method for the SiC single crystal. The SiC single crystal ingot contains a seed crystal and a grown crystal grown by a solution process in which the seed crystal is the base point, the grown crystal of the SiC single crystal ingot containing a nitrogen density gradient layer in which the nitrogen content increases in the direction of growth from the seed crystal.