An indium phosphide crystal substrate has a diameter of 100-205 mm and a thickness of 300-800 μm and includes any of a flat portion and a notch portion. In any of a first flat region and a first notch region, when an atomic concentration of sulfur is from 2.0×10.sup.18 to 8.0×10.sup.18 cm.sup.−3, the indium phosphide crystal substrate has an average dislocation density of 10-500 cm.sup.−2, and when am atomic concentration of tin is from 1.0×10.sup.18 to 4.0×10.sup.18 cm.sup.−3 or an atomic concentration of iron is from 5.0×10.sup.15 to 1.0×10.sup.17 cm.sup.−3, the indium phosphide crystal substrate has an average dislocation density of 500-5000 cm.sup.−2.

A method for producing the growth of a semiconductor material, in particular of type II-VI, uses a melt of the semiconductor placed in a sealed bulb under vacuum or under controlled atmosphere, the bulb being subjected to a sufficient temperature gradient for first maintaining the melt in the liquid state, then causing its progressive crystallization from the surface towards the bottom. The method further comprises an element capable of floating on the surface of the melt, and equipped with a substantially central bore, intended for receiving a seed crystal for permitting the nucleation leading to the preparation of a seed crystal, and also supporting the seed crystal above the melt while maintaining it in contact with the melt in order to permit the continued crystallization from the seed crystal by lowering the temperature gradient.

A method for producing the growth of a semiconductor material, in particular of type II-VI, uses a melt of the semiconductor placed in a sealed bulb under vacuum or under controlled atmosphere, the bulb being subjected to a sufficient temperature gradient for first maintaining the melt in the liquid state, then causing its progressive crystallization from the surface towards the bottom. The method further comprises an element capable of floating on the surface of the melt, and equipped with a substantially central bore, intended for receiving a seed crystal for permitting the nucleation leading to the preparation of a seed crystal, and also supporting the seed crystal above the melt while maintaining it in contact with the melt in order to permit the continued crystallization from the seed crystal by lowering the temperature gradient.

A process for growing a substrate (24) as a melt pool (28) solidifies beneath a molten slag layer (30). An energy beam (36) is used to melt a powder (32) or a hollow feed wire (42) with a powdered alloy core (44) under the slag layer. The slag layer is at least partially transparent (37) to the energy beam, and it may be partially optically absorbent or translucent to the energy beam to absorb enough energy to remain molten. As with a conventional ESW process, the slag layer insulates the molten material and shields it from reaction with air. A composition of the powder may be changed across a solidification axis (A) of the resulting component (60) to provide a functionally graded directionally solidified product.

Provided is a Ni-based single crystal superalloy containing 6% by mass or more and 12% by mass or less of Cr, 0.4% by mass or more and 3.0% by mass or less of Mo, 6% by mass or more and 10% by mass or less of W, 4.0% by mass or more and 6.5% by mass or less of Al, 0% by mass or more and 1% by mass or less of Nb, 8% by mass or more and 12% by mass or less of Ta, 0% by mass or more and 0.15% by mass or less of Hf, 0.01% by mass or more and 0.2% by mass or less of Si, and 0% by mass or more and 0.04% by mass or less of Zr, and optionally containing at least one element selected from B, C, Y, La, Ce, and V, with a balance being Ni and inevitable impurities.

A TiAl intermetallic compound single crystal material and a preparation method therefor are disclosed. The alloy composition of the material comprises Ti.sub.aAl.sub.bNb.sub.c(C, Si).sub.d, wherein 43≦b≦49, 2≦c≦10, a+b+c=100, and 0≦d≦1 (at. %).

An active laser medium for emitting a light beam by laser effect includes an X—F2-doped crystal, wherein X is a chemical element from the alkaline-earth family and F is fluorine. The crystal is doped with trivalent ions including: a first category of optically active dopant ions, in which each dopant ion is an ion of a first rare earth; and a second category of optically inactive dopant ions, referred to as buffer ions, in which each dopant ion is an ion of a rare earth different from the first rare earth. The second category of dopant ions has at least ions of a second rare earth and ions of a third rare earth, different from one another. The invention provides an active laser medium that can be used to obtain both a desired emission spectrum shape and a high thermal conductivity.

A method of fabricating at least one single-crystal alloy semiconductor structure. At least one seed, containing an alloying material, on a substrate for growth of at least one single-crystal alloy semiconductor structure is formed. At least one structural form, formed of a host material, on the substrate is crystallized to form the at least one single-crystal alloy semiconductor structure. The at least one structural form is heated such that the material of the at least one structural form has a liquid state. Also, the at least one structural form is cooled, such that the material of the at least one structural form nucleates at the least one seed and crystallizes as a single crystal to provide at least one single-crystal alloy semiconductor structure, with a growth front of the single crystal propagating in a main body of the respective structural form away from the respective seed.

Methods and devices for detecting incident radiation are provided. The methods and devices use high quality single-crystals of photoactive semiconductor compounds in combination with metal anodes and metal cathodes that provide for enhanced photodetector performance.

Disclosed in the present invention is a nonlinear optical crystal. The chemical formula of the nonlinear optical crystal is MHgGeSe.sub.4, M being selected from Ba or Sr. The nonlinear optical crystal has no symmetrical center, belongs to an orthorhombic crystal system, and has a space group Ama2. The nonlinear optical crystal is an infrared nonlinear optical crystal, and has the advantages of great nonlinear optical effect, wide light transmitting band, high hardness, good mechanical properties, breakage resistance, deliquescence resistance, easiness in processing and preserving, etc. Also disclosed in the present invention are a method for preparing the nonlinear optical crystal and application thereof.