In the present invention, in producing a SiC single crystal in accordance with a solution method, a crucible containing SiC as a main component and having an oxygen content of 100 ppm or less is used as the crucible to be used as a container for a SiC solution. In another embodiment, a sintered body containing SiC as a main component and having an oxygen content of 100 ppm or less is placed in the crucible to be used as a container for a SiC solution. The SiC crucible and SiC sintered body are obtained by molding and baking a SiC raw-material powder having an oxygen content of 2000 ppm or less. SiC, which is the main component of these, serves as a source for Si and C and allows Si and C to elute into the SiC solution by heating.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer that suppresses diffusion of Zn from the free-standing substrate into the channel layer.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer that suppresses diffusion of Zn from the free-standing substrate into the channel layer.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of Al-doped GaN and suppresses diffusion of Zn from the free-standing substrate into the channel layer.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of Al-doped GaN and suppresses diffusion of Zn from the free-standing substrate into the channel layer.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of Al.sub.pGa.sub.1-pN (0.7p1) and suppresses diffusion of Zn from the free-standing substrate into the channel layer.

The present invention relates to a silicon-based molten composition for forming a SiC single crystal by a solution method, the composition containing silicon, carbon, and a metal satisfying 0.70Csisol1.510 with respect to a solubility parameter (Csisol) defined by the following Equation (1):

Csisol=AB+12Equation (1) wherein, A is first energy (A) of a first evaluation lattice containing silicon atoms, carbon atoms, and metal atoms, in a silicon crystal lattice containing the metal and the carbon; B is second energy (B) of a second evaluation lattice containing silicon atoms and metal atoms, in a silicon crystal lattice containing the metal; 1 is 5.422 as a constant value, and 2 is 9.097 as a constant value.

We provide methods and apparatus for preparing crystalline-clad and crystalline core optical fibers with minimal or no breakage by minimizing the influence of thermal stress during a liquid phase epitaxy (LPE) process as well as the fiber with precisely controlled number of modes propagated in the crystalline cladding and crystalline core fiber via precisely controlling the diameter of crystalline fiber core with under-saturated LPE flux. The resulting crystalline cladding and crystalline core optical fibers are also reported.

A seed crystal substrate 8 includes a base body 1 and a plurality of rows of stripe-shaped seed crystal layers 3 formed on the base body 1. An upper face 3a of the seed crystal layer 3 is (11-22) plane, a groove 4 is formed between the adjacent seed crystal layers 3, and a longitudinal direction of the groove 4 is a direction in which a c-axis of a crystal forming the seed crystal layer is projected on the upper face. A nitride of a group 13 element is formed on the seed crystal substrate.

A seed crystal substrate 8 includes a base body 1 and a plurality of rows of stripe-shaped seed crystal layers 3 formed on the base body 1. An upper face 3a of the seed crystal layer 3 is (11-22) plane, a groove 4 is formed between the adjacent seed crystal layers 3, and a longitudinal direction of the groove 4 is a direction in which a c-axis of a crystal forming the seed crystal layer is projected on the upper face. A nitride of a group 13 element is formed on the seed crystal substrate.