A high-quality SiC single crystal and a method for producing such a SiC single crystal is provided. In the SiC single crystal, the threading dislocation density including screw dislocation, edge dislocation and micropipe defect is reduced. The method for producing the SiC single crystal according to a solution technique involves bringing an SiC seed crystal into contact with an SiC solution having a temperature gradient in which a temperature of the SiC solution is lower towards the surface of the SiC seed crystal. Growing an SiC single crystal includes setting the temperature gradient of the surface region of the SiC solution to 10 C/cm or below, bringing the (1-100) face of the SiC seed crystal into contact with the SiC solution, and growing an SiC single crystal on the (1-100) face of the seed crystal at a ratio (single crystal growth rate/temperature gradient) of less than 2010.sup.4 cm.sup.2/h.Math. C.

A high-quality SiC single crystal and a method for producing such a SiC single crystal is provided. In the SiC single crystal, the threading dislocation density including screw dislocation, edge dislocation and micropipe defect is reduced. The method for producing the SiC single crystal according to a solution technique involves bringing an SiC seed crystal into contact with an SiC solution having a temperature gradient in which a temperature of the SiC solution is lower towards the surface of the SiC seed crystal. Growing an SiC single crystal includes setting the temperature gradient of the surface region of the SiC solution to 10 C/cm or below, bringing the (1-100) face of the SiC seed crystal into contact with the SiC solution, and growing an SiC single crystal on the (1-100) face of the seed crystal at a ratio (single crystal growth rate/temperature gradient) of less than 2010.sup.4 cm.sup.2/h.Math. C.

There is provided a method of manufacturing a crystal substrate, including: preparing a first crystal body which is a substrate comprising a single crystal of group III nitride produced by a vapor phase method and having a first main surface, and in which c-plane of the single crystal is curved in a concave spherical shape with a predetermined curvature; and growing a second crystal body comprising a single crystal of group III nitride on the first main surface, in a mixed melt containing an alkali metal and a group III element.

Single crystals of the new semiconducting oxychalcogenide phase were synthesized using a novel crystal growth method. The crystals had low defects and homogeneous composition as characterized by single crystal X-ray diffraction and scanning electron microscopy, respectively. Heat capacity and resistivity measurements were in agreement with the calculated band structure calculations indicating semiconductivity, with a band gap of about 3 eV.

Single crystals of the new semiconducting oxychalcogenide phase were synthesized using a novel crystal growth method. The crystals had low defects and homogeneous composition as characterized by single crystal X-ray diffraction and scanning electron microscopy, respectively. Heat capacity and resistivity measurements were in agreement with the calculated band structure calculations indicating semiconductivity, with a band gap of about 3 eV.

Methods and apparatus for synthesizing diamond from a carbon solution are provided. A carbon solution comprising dissolved carbon and liquid solvent is positioned in a levitation volume. Levitation is facilitated by performing the methods in micro-gravity. The levitation volume can have a dissolution zone and a diamond growth zone at different temperatures, or the temperature of the levitation volume can be adjusted between different periods. Apparatus are provided with one or more levitation generators which define a levitation volume and temperature control systems and devices. Diamond materials having sizes and properties suitable for a variety of applications are also provided.

Methods and apparatus for synthesizing diamond from a carbon solution are provided. A carbon solution comprising dissolved carbon and liquid solvent is positioned in a levitation volume. Levitation is facilitated by performing the methods in micro-gravity. The levitation volume can have a dissolution zone and a diamond growth zone at different temperatures, or the temperature of the levitation volume can be adjusted between different periods. Apparatus are provided with one or more levitation generators which define a levitation volume and temperature control systems and devices. Diamond materials having sizes and properties suitable for a variety of applications are also provided.

In one embodiment, a method of producing an sp3 bonded C.sub.3N.sub.4 product includes contacting a starting material with a catalyst solvent in a reaction vessel, heating the reaction vessel to a temperature of 900? to 2000? C. under a pressure of 4 to 8 GPa, melting at least some of the catalyst solvent, and transforming at least some of the sp2 bonded C.sub.3N.sub.4 into sp3 hybridized C.sub.3N.sub.4. The starting material may include sp2 bonded C.sub.3N.sub.4. The catalyst solvent may be a solid at room temperature. In one example, the catalyst solvent is a carbo-nitride based catalyst solvent including a first compound having the chemical formula A.sub.xB.sub.yN.sub.z and a second compound having the chemical formula D.sub.qE.sub.rC.sub.s. In a second example, the catalyst solvent is a metal alloy based catalyst solvent including a compound having the chemical formula G.sub.xH.sub.y.

In one embodiment, a method of producing an sp3 bonded C.sub.3N.sub.4 product includes contacting a starting material with a catalyst solvent in a reaction vessel, heating the reaction vessel to a temperature of 900? to 2000? C. under a pressure of 4 to 8 GPa, melting at least some of the catalyst solvent, and transforming at least some of the sp2 bonded C.sub.3N.sub.4 into sp3 hybridized C.sub.3N.sub.4. The starting material may include sp2 bonded C.sub.3N.sub.4. The catalyst solvent may be a solid at room temperature. In one example, the catalyst solvent is a carbo-nitride based catalyst solvent including a first compound having the chemical formula A.sub.xB.sub.yN.sub.z and a second compound having the chemical formula D.sub.qE.sub.rC.sub.s. In a second example, the catalyst solvent is a metal alloy based catalyst solvent including a compound having the chemical formula G.sub.xH.sub.y.

It is provided a layer of a nitride of a group 13 element having a first main face and second main face. The layer of the nitride of the group 13 element includes a first void-depleted layer provided on the side of the first main face, a second void-depleted layer provided on the side of the second main face, and the void-distributed layer provided between the first void-depleted layer and second void-depleted layer.