A group 13 nitride layer is composed of a polycrystalline group 13 nitride and is constituted by a plurality of monocrystalline particles having a particular crystal orientation approximately in a normal direction. The group 13 nitride comprises gallium nitride, aluminum nitride, indium nitride or the mixed crystal thereof. The group 13 nitride layer includes an upper surface and a bottom surface, and a full width at half maximum of a (1000) plane reflection of X-ray rocking curve on the upper surface is 20000 seconds or less and 1500 seconds or more.

A semiconductor wafer comprising single-crystal silicon has defined concentrations of oxygen, nitrogen and hydrogen; the semiconductor wafer further contains BMD seeds having a density averaged over the radius of not less than 110.sup.5 cm.sup.3 and not more than 110.sup.7 cm.sup.3; surface defects having a density averaged over the radius of not less than 1100 cm.sup.2; and BMDs, whose density is not lower than a lower limit of 510.sup.8/cm.sup.3. The semiconductor wafers are produced by a process which enables obtention of the required ranges of concentrations of oxygen, nitrogen, hydrogen, BMD seeds, and BMD's.

A free-standing substrate of a polycrystalline nitride of a group 13 element contains a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The polycrystalline nitride of the group 13 element is composed of gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. The free-standing substrate has a top surface and bottom surface. The free-standing substrate contains at least one of zinc and calcium. A root mean square roughness Rms at the top surface is 3.0 nm or less.

The present invention reduces warpage of a Group III nitride semiconductor crystal in a method for producing a Group III nitride semiconductor crystal on a seed substrate through a flux method. A Group III nitride semiconductor is grown so that the total Al amount at the interface is not more than 310.sup.14/cm.sup.2, and the total Si amount at the interface is not more than 510.sup.14/cm.sup.2. Here, the total amount at the interface refers to a total number of atoms per unit area of an interface between the grown Group III nitride semiconductor and the seed substrate. Thus, warpage can be reduced by growing a Group III nitride semiconductor through a flux method.

A method of growing an AlGaN semiconductor material utilizes an excess of Ga above the stoichiometric amount typically used. The excess Ga results in the formation of band structure potential fluctuations that improve the efficiency of radiative recombination and increase light generation of optoelectronic devices, in particular ultraviolet light emitting diodes, made using the method. Several improvements in UV LED design and performance are also provided for use together with the excess Ga growth method. Devices made with the method can be used for water purification, surface sterilization, communications, and data storage and retrieval.

A free-standing substrate of a polycrystalline nitride of a group 13 element is composed of a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The free-standing substrate has a top surface and a bottom surface. The polycrystalline nitride of the group 13 element is gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof and contains zinc at a concentration of 110.sup.17 atoms/cm.sup.3 or more and 110.sup.20 atoms/cm.sup.3 or less.

This disclosure provides a method and a device for manufacturing a semiconductor substrate. The method for manufacturing a semiconductor substrate comprises the following steps: heating a semiconductor material to a molten state to obtain a molten semiconductor material; thermally spraying the molten semiconductor material onto a baseplate by using a thermal spraying gun, then cooling to solidify the molten semiconductor material on the baseplate to obtain the semiconductor substrate. The disclosed method offers, when manufacturing the semiconductor substrate, high material utilization, low manufacturing cost, and the ability to manufacture larger semiconductor substrate, with controllable thickness and high purity, providing broad application prospects.

Photoactive silicon films may be formed by electrodeposition from a molten salt electrolyte. In an embodiment, SiO.sub.2 is electrochemically reduced in a molten salt bath to deposit silicon on a carbonaceous substrate.

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.

Graphene layers made of primarily sp2 bonded atoms and associated methods are disclosed. In one aspect, for example, a method of forming a graphite film can include heating a solid substrate under vacuum to a solubilizing temperature that is less than a melting point of the solid substrate, solubilizing carbon atoms from a graphite source into the heated solid substrate, and cooling the heated solid substrate at a rate sufficient to form a graphite film from the solubilized carbon atoms on at least one surface of the solid substrate. The graphite film is formed to be substantially free of lattice defects.