An underlying substrate including a seed crystal layer of a group 13 nitride, wherein projections and recesses repeatedly appear in stripe shapes at a principal surface of the seed crystal layer, and the projections have a level difference of 0.3 to 40 m and a width of 5 to 100 m, and the recesses have a bottom thickness of 2 m or more and a width of 50 to 500 m.

A method of producing a functional device has an etched gallium nitride layer and a functional layer having a nitride of a group 13 element. The method includes providing a body comprising a surface gallium nitride layer, performing a dry etching treatment of a surface of the surface gallium nitride layer to provide the etched gallium nitride layer using a plasma etching system comprising an inductively coupled plasma generating system, introducing an etchant during the dry etching treatment, the etchant consisting essentially of a fluorine-based gas, and forming the functional layer on a surface of the etched gallium nitride layer.

A synthetic single crystal diamond contains nitrogen atoms at a concentration of more than 600 ppm and 1500 ppm or less, and the nitrogen atoms do not include any isolated substitutional nitrogen atom.

A synthetic single crystal diamond contains nitrogen atoms at a concentration of more than 600 ppm and 1500 ppm or less, and the nitrogen atoms do not include any isolated substitutional nitrogen atom.

Alumina is generally used as an inorganic filler, while spinel, which is known to be lower in thermal conductivity than alumina, is used in applications such as gems, fluorescence emitters, catalyst carriers, adsorbents, photocatalysts and heat-resistant insulating materials, but not expected to be used as a thermally conductive inorganic filler. Thus, an object of the invention is to provide spinel particles having excellent thermal conductive properties. The invention relates to a spinel particle including magnesium, aluminum and oxygen atoms and molybdenum and having a [111] plane crystallite diameter of 220 nm or more.

Provided is a synthetic single crystal diamond containing nitrogen atoms at a concentration of more than 600 ppm and 1500 ppm or less. The Raman shift (cm.sup.1) of a peak in a primary Raman scattering spectrum of the synthetic single crystal diamond and the Raman shift (cm.sup.1) of a peak in a primary Raman scattering spectrum of a synthetic type IIa single crystal diamond containing nitrogen atoms at a content of 1 ppm or less satisfy the following expression (1):

0.10(1).

Provided is a synthetic single crystal diamond containing nitrogen atoms at a concentration of more than 600 ppm and 1500 ppm or less. The Raman shift (cm.sup.1) of a peak in a primary Raman scattering spectrum of the synthetic single crystal diamond and the Raman shift (cm.sup.1) of a peak in a primary Raman scattering spectrum of a synthetic type IIa single crystal diamond containing nitrogen atoms at a content of 1 ppm or less satisfy the following expression (1):

0.10(1).

A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. A normal line to the upper surface has an off-angle of 2.0 or less with respect to <0001> direction of the crystal of the nitride of the group 13 element.

Provided is a silicon-based molten composition including silicon, carbon, and a metal in which a solubility parameter (C.sub.si.sup.sol) defined by Equation (1) below is less than 0.37, wherein a SiC single crystal is formed by a solution method:
C.sub.si.sup.sol=AB+.sub.1.sub.2Equation (1)
in Equation (1) above, A is a first energy (A) of a first evaluation lattice including silicon atoms, a carbon atom, and metal atoms in a silicon crystal lattice including metals and carbons, B is a second energy (B) of a second evaluation lattice including silicon atoms and metal atoms in a silicon crystal lattice including metals, 1 is a constant of 5.422, and 2 is a constant of 9.097.

Provided is a silicon-based molten composition including silicon, carbon, and a metal in which a solubility parameter (C.sub.si.sup.sol) defined by Equation (1) below is less than 0.37, wherein a SiC single crystal is formed by a solution method:
C.sub.si.sup.sol=AB+.sub.1.sub.2Equation (1)
in Equation (1) above, A is a first energy (A) of a first evaluation lattice including silicon atoms, a carbon atom, and metal atoms in a silicon crystal lattice including metals and carbons, B is a second energy (B) of a second evaluation lattice including silicon atoms and metal atoms in a silicon crystal lattice including metals, 1 is a constant of 5.422, and 2 is a constant of 9.097.