Abstract: The present GaN substrate can have an absorption coefficient not lower than 7 cm?1 for light having a wavelength of 380 nm and light having a wavelength of 1500 nm, an absorption coefficient lower than 7 cm?1 for at least light having a wavelength not shorter than 500 nm and not longer than 780 nm, and specific resistance not higher than 0.02 ?cm. Here, the absorption coefficient for light having a wavelength not shorter than 500 nm and not longer than 780 nm can be lower than 7 cm?1. Thus, a GaN substrate having a low absorption coefficient for light having a wavelength within a light emission wavelength region of a light-emitting device and specific resistance not higher than a prescribed value and being suitable for the light-emitting device is provided.

Abstract: The present GaN substrate can have an absorption coefficient not lower than 7 cm?1 for light having a wavelength of 380 nm and light having a wavelength of 1500 nm, an absorption coefficient lower than 7 cm?1 for at least light having a wavelength not shorter than 500 nm and not longer than 780 nm, and specific resistance not higher than 0.02 ?cm. Here, the absorption coefficient for light having a wavelength not shorter than 500 nm and not longer than 780 nm can be lower than 7 cm?1. Thus, a GaN substrate having a low absorption coefficient for light having a wavelength within a light emission wavelength region of a light-emitting device and specific resistance not higher than a prescribed value and being suitable for the light-emitting device is provided.

Abstract: Novel superconducting oxide material containing compound oxide having a composition represented by the formula:?(Tl.sub.1-x Bi.sub.x).sub.1-p .alpha..sub.p !.sub.q Sr.sub.y Ca.sub.z Cu.sub.v O.sub.win which ".alpha." is at least one element selected from a group consisting of In, Sn, Sb, Pb, Y and lanthanide elements and "x", "y", "z", "p", "q", "v" and "w" are numbers each satisfying respective range of 0.ltoreq.x.ltoreq.1.0, 0.5.ltoreq.y.ltoreq.4.0, 0.5.ltoreq.z.ltoreq.4.5, 0.ltoreq.p.ltoreq.0.6, 0.5.ltoreq..ltoreq.3.0, and 1.0.ltoreq.v.ltoreq.5.5.

Abstract: Herein disclosed are apparatuses for manufacturing compound semiconductor polycrystals comprising a pressure vessel, an upper shaft, a container for a first component fixed to the upper shaft, a heater around the container, a lower shaft, a susceptor and a crucible for charging a second component, a heater for the crucible and a communicating pipe for spatially connecting the container and the crucible optionally provided with a porous member at the lower extremity and/or a cylindrical member for confining a space over a part of the melt surface contained in the crucible from the remaining inner space of the vessel, the apparatuses permitting the substantial reduction of the reaction time and an improvement of the yield of the polycrystals due to the presence of the porous member and/or the cylindrical member separating the inner space of the vessel into two portions.

Abstract: Novel superconducting oxide material containing compound oxide having a composition represented by the formula:[(Tl.sub.1-x Bi.sub.x).sub.1-p .alpha..sub.p ].sub.q Sr.sub.y Ca.sub.z Cu.sub.v O.sub.win which ".alpha." is at least one element selected from a group consisting of In, Sn, Sb, Pb, Y and lanthanide elements and "x", "y", "z", "p", "q", and "v" are numbers each satisfying respective range of 0.1.ltoreq.x.ltoreq.0.5, 0.5.ltoreq.y.ltoreq.4.0, 0.5.ltoreq.z.ltoreq.4.5, 0.ltoreq.p.ltoreq.0.6, 0.5.ltoreq.q.ltoreq.3.0, and 1.0.ltoreq.v.ltoreq.5.5.

Abstract: In a process for pulling a crystal such as Si, Ge, GaAs, InP, GaP, InAs, AlAs, CdTe, CdSe, ZnTe, HgTe, MnTe, Gd.sub.3 Ga.sub.5 O.sub.12, Bi.sub.12 SiO.sub.20 and LiNbO.sub.3 from a raw material melt within a baffle plate whose bore diameter is gradually increased upward and which is arranged in such a manner that the melt inside and outside the baffle plate is in communication with each other through the small opening part at the end thereof, the baffle plate is moved relatively to the surface of the melt so as to increase the diameter of the melt surface inside the baffle plate with the increase of the diameter of the pulled crystal at the solid-liquid interface.

Abstract: In an apparatus for the Czochralsky growth of compound single crystals wherein a single crystal growing portion is provided in a sealed vessel whose opening part is sealed by a B.sub.2 O.sub.3 melt and which contains therein an atmosphere of a volatile element of the compound, at least the inner wall the sealed vessel is made of a material having a melting point of at least 1400.degree. C., selected from Group III-V compounds and oxides of Group III or V elements. Compound single crystals such as GaAs, GaP, InAs, InP, ZnS, ZnSe and CdS obtained by the use of this apparatus are free from contamination with silicon.

Abstract: An apparatus for pulling a single crystal by CZ method or LEC method is improved. To this end, the heater for heating the inside of the furnace is divided at least in the vicinity of the solid-liquid interface into at least two heaters. Using this apparatus, a single crystal with a decreased dislocation density can be obtained.

Abstract: A single crystal is prepared by drawing up a single crystal by the Czochralski process and cooling it at a temperature not lower than 600.degree. C. in vacuo. In this manner a single crystal having a dislocation density of 1.5.times.10.sup.4 cm.sup.2 or less is prepared.

Abstract: A modified liquid encapsulated Czockralski method for growing a single crystal of compound semiconductor is disclosed. This method uses two vessels. An inner vessel is filled with an inactive gas, a gas of an element of group V and optionally an impurity gas. The inner vessel encloses a crucible containing compound semiconductor material, an encapsulant material, and optionally an impurity element. An outer vessel is filled only with the inactive gas. The total pressure of the inner atmosphere is equal to or higher than that of the outer atmosphere. The partial pressure of the gas of the element of group V is larger than the dissociation pressure of the element of group V near the melting point of the compound semiconductor.

Abstract: A single-crystal boule pulling rod for pulling a boule from a melt utilizing the Czochralski method including a main pulling rod and a heat insulating layer surrounding the main pulling rod. The main pulling rod, which may be either bar-shaped or composed of two concentric pipes, is forcibly cooled. Preferably, a pipe made of molybdenum or stainless steel is provided around the heat insulating material.

Abstract: A process for preparing a single crystal comprising drawing up a single crystal by the Czochralski process and cooling it at a temperature not lower than 600.degree. C. at a reduced pressure or in vacuo, by which a single crystal having a dislocation density of 1.5.times.10.sup.4 cm.sup.2 or less is prepared.

Abstract: A process for manufacturing boron-doped GaAs single crystals which comprises preparing a mixture of boron, gallium and arsenic covered by a liquid B.sub.2 O.sub.3 encapsulant, melting the mixture, pulling up boron-doped GaAs crystals from the mixture melts in accordance with the LEC method, crushing those crystals into small pieces after removing the seed end therefrom, remelting those pieces in the presence of B.sub.2 O.sub.3, and pulling up single crystals from the mixture melts in accordance with the LEC method.