The present invention provides a method including: a temperature raising step of raising a temperature in a crystal growing furnace with a silicon carbide raw material and a silicon carbide seed crystal arranged therein to a crystal growing temperature; a single crystal growing step of maintaining the crystal growing temperature and causing a silicon carbide single crystal to grow on the silicon carbide seed crystal; and a temperature lowering step of lowering the temperature in the crystal growing furnace from the crystal growing temperature to stop growth of the silicon carbide single crystal, in which the method further comprises, between the single crystal growing step and the temperature lowering step, a temperature lowering preparation step of maintaining the temperature in the crystal growing furnace at the crystal growing temperature and causing concentration of nitrogen gas in the crystal growing furnace to increase to be higher than concentration of nitrogen gas in the temperature raising step and in the single crystal growing step, and in which the concentration of the nitrogens gas in the crystal growing furnace in the temperature lowering step is higher than the concentration of the nitrogen gas in the temperature raising step and the single crystal growing step.

A manufacturing method for a group-III nitride crystal, the manufacturing method includes: preparing a seed substrate; increasing temperature of the seed substrate placed in a nurturing chamber; and supplying a group-III element oxide gas produced in a raw material chamber connected to the nurturing chamber by a connecting pipe and a nitrogen element-containing gas into the nurturing chamber to grow a group-III nitride crystal on the seed substrate, wherein a flow amount y of a carrier gas supplied into the raw material chamber at the temperature increase step satisfies following two relational equations (I) and (II), y<[1k*H(Ts)]/[k*H(Ts)j*H(Tg)]*j*H(Tg)*t (I), y1.58*10.sup.4*(22.4/28)S*F(N)/F(T) (II), wherein k represents an arrival rate to a saturated vapor pressure of a group-III element in the raw material chamber, Ts represents a temperature of the raw material chamber, Tg represents a temperature of the nurturing chamber, H(Ts) represents a saturated vapor pressure of the group-III element at the temperature Ts in the raw material chamber, H(Tg) represents a saturated vapor pressure of the group-III element at the temperature Tg in the nurturing chamber, j represents a corrective coefficient, t represents a sum of gas flow amounts flowing into the nurturing chamber from those other than the raw material chamber, S represents a cross-sectional area of the connecting pipe, F(N) represents a volumetric flow amount of the nitrogen element-containing gas supplied into the nurturing chamber, and F(T) represents a sum of volumetric flow amounts of gases supplied into the nurturing chamber from those other than the raw material chamber.

Provided is a method of producing a high purity molybdenum oxychloride by including means of sublimating and reaggregating a raw material molybdenum oxychloride in a reduced-pressure atmosphere, or means of retaining a gaseous raw material molybdenum oxychloride, which was synthesized in a vapor phase, in a certain temperature range, and thereby growing crystals to obtain a higher purity molybdenum oxychloride having a high bulk density and high hygroscopicity resistance.

A method for manufacturing a SiC single crystal reducing crystallinity degradation at a wafer central portion wherein a growth container surrounds a heat-insulating material with a top temperature measurement hole, a seed crystal substrate at an upper portion inside the container, and a silicon carbide raw material at a lower portion of the container and sublimated to grow a SiC single crystal on the seed crystal substrate. A center position hole deviates from a center position of the seed crystal substrate and moves to the periphery side of the center of the seed crystal substrate. A SiC single crystal substrate surface is tilted by a {0001} plane and used as the seed crystal substrate. The SiC single crystal grows with the seed crystal substrate directed to a normal vector of the seed crystal substrate basal plane parallel to the main surface and identical to the hole in a cross-sectional view.

An SiC volume monocrystal is processed by sublimation growth. An SiC seed crystal is placed in a crystal growth region of a growing crucible and SiC source material is introduced into an SiC storage region. During growth, at a growth temperature of up to 2,400 C. and a growth pressure between 0.1 mbar and 100 mbar, an SiC growth gas phase is generated by sublimation of the SiC source material and by transport of the sublimated gaseous components into the crystal growth region, where an SiC volume monocrystal grows by deposition from the SiC growth gas phase on the SiC seed crystal. A mechanical stress is introduced into the SiC seed crystal at room temperature prior to the start of the growth to cause seed screw dislocations present in the SiC seed crystal to undergo a dislocation movement so that seed screw dislocations recombine.

In a crystal growth apparatus and method, polycrystalline source material and a seed crystal are introduced into a growth ambient comprised of a growth crucible disposed inside of a furnace chamber. In the presence of a first sublimation growth pressure, a single crystal is sublimation grown on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a first gas that includes a reactive component that reacts with and removes donor and/or acceptor background impurities from the growth ambient during said sublimation growth. Then, in the presence of a second sublimation growth pressure, the single crystal is sublimation grown on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a second gas that includes dopant vapors, but which does not include the reactive component.

An apparatus for producing a Group-III nitride semiconductor crystal includes a raw material reaction chamber, a raw material reactor which is provided in the raw material reaction chamber and generates a Group-III element-containing gas, a board-holding member configured to hold a board in the raw material reaction chamber, a raw material nozzle configured to spray the Group-III element-containing gas toward the board, a nitrogen source nozzle configured to spray a nitrogen element-containing gas toward the board, in which, in a side view seen in a direction perpendicular to a vertical direction, a spray direction of the nitrogen source nozzle intersects with a spray direction of the raw material nozzle before the board, and a mixing part in which the Group-III element-containing gas and the nitrogen element-containing gas are mixed together is formed around the intersection as a center, a heater for heating the raw material reaction chamber, the raw material nozzle, the nitrogen source nozzle, and the board-holding member, and a rotation mechanism for rotating the board-holding member.

In various embodiments, controlled heating and/or cooling conditions are utilized during the fabrication of aluminum nitride single crystals and aluminum nitride bulk polycrystalline ceramics. Thermal treatments may also be utilized to control properties of aluminum nitride crystals after fabrication.

A method of processing a SiC single crystal includes a measuring step of measuring a shape of an atomic arrangement plane of the SiC single crystal along at least a first direction passing through a center in plan view and a second direction orthogonal to the first direction; and a surface processing step of processing a first plane serving as an attachment plane of the SiC single crystal, in which the surface processing step includes a grinding step of grinding the first plane, and in the grinding step, a difference is given to a surface state between the first plane and a second plane facing the first plane, and the atomic arrangement plane is flattened by Twyman's effect.

A method of measuring a SiC ingot includes a measuring step of measuring a curving direction of an atomic arrangement plane of a SiC single crystal at least along a first direction passing through a center in plan view and a second direction intersecting with the first direction to obtain a shape of the atomic arrangement plane; and a crystal growth step of performing crystal growth using the SiC single crystal as a seed crystal, in which in a case where the shape of the atomic arrangement plane measured in the measuring step is a saddle type, a crystal growth condition in the crystal growth step is set such that a convexity of a second growth front at the end of crystal growth becomes larger than a convexity of a first growth front when an amount of crystal growth in the center of the seed crystal is 7 mm.