Abstract: A method for producing a SiC single crystal having a large growth thickness of 10 mm or greater by a solution process is provided. This is achieved by a method for producing a SiC single crystal, wherein a SiC seed crystal substrate is contacted with a Si—C solution with a temperature gradient, in which the temperature decreases from the interior toward the surface, to grow a SiC single crystal, and wherein the temperature gradient in the surface region of the Si—C solution is increased at least once while the SiC single crystal is grown with the (000-1) face as the growth surface, to grow a SiC single crystal having a growth thickness of 10 mm or greater.

Abstract: 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.

Abstract: A region of an SiC solution in the vicinity of an SiC seed crystal is cooled while suppressing the temperature variation in a peripheral region of the SiC solution. An apparatus includes a seed shaft and a crucible for an SiC solution. The seed shaft has a lower end surface for attachment to an SiC seed crystal. The crucible comprises a main body, an intermediate cover, and a top cover. The main body includes a first cylindrical portion and a bottom portion at a lower end portion of the first cylindrical portion. The intermediate cover is within the first cylindrical portion and above the liquid level of the SiC solution in the main body. The intermediate cover has a first through hole for the seed shaft. The top cover is disposed above the intermediate cover and has a second through hole for the seed shaft to pass through.

Abstract: Provided is a method for producing SiC single crystals while maintaining a temperature gradient such that the temperature decreases from within an Si solution inside a graphite crucible toward the solution surface, with the SiC seed crystals that have contacted the solution surface serving as the starting point for crystal seed growth, wherein when the crystal growth surface of the SiC seed crystals, which serves as the starting point for SiC single crystal growth, contacts the solution surface, the height by which the solution rises to the side of the SiC seed crystals is within the range where the SiC single crystals that have grown from the crystal growth surface and the SiC single crystals that have grown from the side grow as one SiC single crystal unit.

Abstract: A manufacturing apparatus of a SiC single crystal which can suppress the generation of a polycrystal is provided. A jig (41) and a crucible (6) are accommodated in a chamber (1). A SiC solution (8) is housed in the crucible (6). The jig (41) includes a seed shaft (411) and a cover member (412). The seed shaft (411) can move up and down, and a SiC seed crystal (9) is attached to the lower surface thereof. The cover member (412) is attached to the lower end portion of the seed shaft (411). The cover member (412) is a housing which has an opening at its lower end, wherein the lower end portion of the seed shaft (411) is disposed in the cover member (412).

Abstract: A manufacturing apparatus for SiC single crystal has a control unit to control induction heating such that frequency f (Hz) of alternating current to be passed to the induction heating unit satisfies Formula (1); D1 (mm) is permeation depth of electromagnetic waves into a side wall of a crucible by the heating unit, D2 (mm) is permeation depth of electromagnetic waves into a SiC solution, T (mm) is thickness of the crucible side wall of the crucible, and R (mm) is crucible inner radius: (D1?T)×D2/R>1??(1) where, D1 is defined by Formula (2), and D2 by Formula (3): D1=503292×(1/(f×?c×?c))1/2??(2) D2=503292×(1/(f×?s×?s))1/2??(3); ?c is electric conductivity (S/m) of the sidewall, ?s is electric conductivity (S/m) of the SiC solution; ?c is relative permeability of the sidewall, and ?s relative permeability of the SiC solution.

Abstract: A method for manufacturing an n-type SiC single crystal, enables the suppression of the variation in nitrogen concentration among a plurality of n-type SiC single crystal ingots manufactured. A method includes the steps of: providing a manufacturing apparatus (100) including a chamber (1) having an area in which a crucible (7) is to be disposed; heating the area in which the crucible (7) is to be disposed and evacuating the gas in the chamber (1); filling, after the evacuation, the chamber (1) with a mixed gas containing a noble gas and nitrogen gas; heating and melting a starting material housed in the crucible (7) disposed in the area to produce a SiC solution (8) containing silicon and carbon; and immersing a SiC seed crystal into the SiC solution under the mixed gas atmosphere to grow an n-type SiC single crystal on the SiC seed crystal.

Abstract: A manufacturing method for a SiC single crystal film which allows stable growth of a SiC epitaxial film with a low doping concentration on a substrate with a diameter of at least 2 inches by the LPE method using a SiC solution in solvent of a melt includes an evacuation step in which the interior of a crystal growth furnace is evacuated with heating until the vacuum pressure at the crystal growth temperature is 5×10?3 Pa or lower prior to introducing a raw material for the melt into the furnace. Then, a crucible containing a raw material for the melt is introduced into the furnace, a SiC solution is formed, and a SiC epitaxial film is grown on a substrate immersed in the solution.

Abstract: A method capable of stably manufacturing a SiC single crystal in the form of a thin film or a bulk crystal having a low carrier density of at most 5×1017/cm3 and preferably less than 1×1017/cm3 and which is suitable for use in various devices by liquid phase growth using a SiC solution in which the solvent is a melt of a Si alloy employs a Si alloy having a composition which is expressed by SixCryTiz wherein x, y, and z (each in atomic percent) satisfy 0.50<x<0.68, 0.08<y<0.35, and 0.08<z<0.35, or ??(1) 0.40<x?0.50, 0.15<y<0.40, and 0.15<z<0.35.??(2) x, y, and z preferably satisfy 0.53<x<0.65, 0.1<y<0.3, and 0.1<z<0.3.

Abstract: A SiC single crystal wafer on which a good quality epitaxial film by suppressing defects derived from the wafer can be grown has an affected surface layer with a thickness of at most 50 nm and a SiC single crystal portion with an oxygen content of at most 1.0×1017 atoms/cm3. This SiC single crystal wafer is manufactured from a high purity SiC bulk single crystal obtained by the solution growth method using raw materials with an oxygen content of at most 100 ppm and a non-oxidizing atmosphere having an oxygen concentration of at most 100 ppm.

Abstract: To suppress 3D or convex growth and ensure a high flatness, an apparatus for producing an SiC single crystal includes: a container which holds an SiC solution, a portion for maintaining the solution in the container at a suitable temperature, a shaft having a lower end part acting as a portion for holding an SiC seed crystal in planar contact with an overall back surface of a crystal growth face and acting as a portion for cooling the SiC seed crystal, and a portion of the holding shaft for enabling an SiC single crystal to continuously grow at the crystal growth face by maintaining the crystal growth face brought into contact with the solution, a lower end part of the shaft having a portion for obtaining a uniform in-plane temperature distribution of the crystal growth face brought into planar contact, and a method for the same.

Abstract: A manufacturing method for a SiC single crystal film which allows stable growth of a SiC epitaxial film with a low doping concentration on a substrate with a diameter of at least 2 inches by the LPE method using a SiC solution in solvent of a melt includes an evacuation step in which the interior of a crystal growth furnace is evacuated with heating until the vacuum pressure at the crystal growth temperature is 5×10?3 Pa or lower prior to introducing a raw material for the melt into the furnace. Then, a crucible containing a raw material for the melt is introduced into the furnace, a SiC solution is formed, and a SiC epitaxial film is grown on a substrate immersed in the solution.

Abstract: A method capable of stably manufacturing a SiC single crystal in the form of a thin film or a bulk crystal having a low carrier density of at most 5×1017/cm3 and preferably less than 1×1017/cm3 and which is suitable for use in various devices by liquid phase growth using a SiC solution in which the solvent is a melt of a Si alloy employs a Si alloy having a composition which is expressed by SixCryTiz wherein x, y, and z (each in atomic percent) satisfy 0.50<x<0.68, 0.08<y<0.35, and 0.08<z<0.35, or??(1) 0.40<x?0.50, 0.15<y<0.40, and 0.15<z<0.35.??(2) x, y, and z preferably satisfy 0.53<x<0.65, 0.1<y<0.3, and 0.1<z<0.3.

Abstract: A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/?m and not more than 1500/?m, and with d002 being preferably not larger than 3.3650 ?, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500° C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500° C.

Abstract: A SiC single crystal is produced by the solution growth method in which a seed crystal attached to a seed shaft is immersed in a solution of SiC dissolved in a melt of Si or a Si alloy and a SiC single crystal is allowed to grow on the seed crystal by gradually cooling the solution or by providing a temperature gradient therein. To this method, accelerated rotation of a crucible is applied by repeatedly accelerating to a prescribed rotational speed and holding at that speed and decelerating to a lower rotational speed or a 0 rotational speed. The rotational direction of the crucible may be reversed each acceleration. The seed shaft may also be rotated synchronously with the rotation of the crucible in the same or opposite rotational as the crucible. A large, good quality single crystal having no inclusions are produced with a high crystal growth rate.

Abstract: A bulk silicon carbide single crystal of good crystalline quality which includes a minimized number of structural defects and is free from micropipe defects can be produced by crystal growth in a melt of an alloy comprising Si, C, and M (wherein M is either Mn or Ti) and having an atomic ratio between Si and M in which the value of x, when express as Si1-xMx, is 0.1?x?0.7 in the case where M is Mn or 0.1?x?0.25 in the case where M is Ti at a temperature of the melt which is below 2000° C. The C component is preferably supplied into the melt by dissolution of a graphite crucible which contains the melt such that the melt is free from undissolved C. One method of crystal growth is performed by cooling the melt after a seed substrate is immersed in the melt.

Abstract: A SiC single crystal is produced by the solution growth method in which a seed crystal attached to a seed shaft is immersed in a solution of SiC dissolved in a melt of Si or a Si alloy and a SiC single crystal is allowed to grow on the seed crystal by gradually cooling the solution or by providing a temperature gradient therein. To this method, accelerated rotation of a crucible is applied by repeatedly accelerating to a prescribed rotational speed and holding at that speed and decelerating to a lower rotational speed or a 0 rotational speed. The rotational direction of the crucible may be reversed each acceleration. The seed shaft may also be rotated synchronously with the rotation of the crucible in the same or opposite rotational as the crucible. A large, good quality single crystal having no inclusions are produced with a high crystal growth rate.

Abstract: A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/?m and not more than 1500/?m, and with d002 being preferably not larger than 3.3650 ?, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500° C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500° C.

Abstract: A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/?m and not more than 1500/?m, and with d002 being preferably not larger than 3.3650 ?, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500° C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500° C.

Abstract: A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/?m and not more than 1500/?m, and with d002 being preferably not larger than 3.3650 ?, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500° C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500° C.