Abstract: An epitaxial wafer comprises a silicon substrate, a gettering epitaxial film formed thereon and containing silicon and carbon, and a main silicon epitaxial film formed on the gettering epitaxial film, in which the gettering epitaxial film has a given carbon atom concentration and carbon atoms are existent between its silicon lattices.

Abstract: In a separation method of a nitride semiconductor layer, a graphene layer in the form of a single layer or two or more layers is formed on a surface of a first substrate. A nitride semiconductor layer is formed on the graphene layer so that the nitride semiconductor layer is bonded to the graphene layer with a bonding force due to regularity of potential at atomic level at an interface therebetween without utilizing covalent bonding. The nitride semiconductor layer is separated from the first substrate with a force which is greater than the bonding force between the nitride semiconductor layer and the graphene layer, or greater than a bonding force between respective layers of the graphene layer.

Abstract: A uniform silicon carbide single crystal with either an n-type or a p-type conductivity. The crystal has a net carrier concentration less than 1015 cm?3 and a carrier lifetime of at least 50 ns at room temperature.

Abstract: The invention provides a doped semiconductor powder comprising nanocrystals of a group IV semiconductor and a rare earth element, the rare earth element being dispersed on the surface of the group IV semiconductor nanocrystals. The invention also provides processes for the preparation of the above doped semiconductor powder, and a composite material comprising a matrix in which is dispersed a doped semiconductor powder.