10479 results about "Crystallinity" patented technology

A semiconductor light-emitting element is provided which has a structure that does not complicate a fabrication process, can be formed in high precision and does not invite any degradation of crystallinity. A light-emitting element is formed, which includes a selective crystal growth layer formed by selectively growing a compound semiconductor of a Wurtzite type, a clad layer of a first conduction type, an active layer and a clad layer of a second conduction type, which are formed on the selective crystal growth layer wherein the active layer is formed so that the active layer extends in parallel to different crystal planes, the active layer is larger in size than a diffusion length of a constituent atom of a mixed crystal, or the active layer has a difference in at least one of a composition and a thickness thereof, thereby forming the active layer having a number of light-emitting wavelength regions whose emission wavelengths differ from one another. The element is so arranged that an electric current or currents are chargeable into the number of light-emitting wavelength regions. Because of the structure based on the selective growth, the band gap energy varies within the same active layer, thereby forming an element or device in high precision without complicating a fabrication process.

An object of the present invention is to provide a method for easily forming a polycrystalline semiconductor thin-film, such as polycrystalline silicon having high crystallinity and high quality, or a single crystalline semiconductor thin-film at inexpensive cost, the crystalline semiconductor thin-film having a large area, and to provide an apparatus for processing the method described above. In forming a polycrystalline (or single crystalline) semiconductor thin-film (7), such as a polycrystalline silicon thin-film, having high crystallinity and a large grain size on a substrate (1), or in forming a semiconductor device having the polycrystalline (or single crystalline) semiconductor thin-film (7) on the substrate (1), a method comprises forming a low-crystallization semiconductor thin-film (7A) on the substrate (1), and subsequently heating and cooling this low-crystallization semiconductor thin-film (7A) to a fusion, a semi-fusion, or a non-fusion state by flash lamp annealing to facilitate the crystallization of the low-crystallization semiconductor thin-film, whereby a polycrystalline (single crystalline) semiconductor thin-film (7) is obtained. A method for forming the semiconductor device and an apparatus for processing the methods are also disclosed.

This invention relates generally to low ethylene insertions into I-olefin polymers and processes for production of such polymers using unbridged fluxional metallocenes, primarily substituted aryl indenyl metallocenes, and more particularly to use of unbridged, fluxional, cyclopentadienyl or indenyl metallocene catalyst systems in methods of production of high melting point I-olefin homo- and co-polymers, particularly elastomeric crystalline and amorphous block homo- and co-polymers of I-olefins. The activity of fluxional unbridged metallocene polymerization catalysts containing at least one 2-arylindene ligand is increased 10x or more by the addition of small (typically 0.1-10 wt. %) amounts of ethylene to the polymerization system, which increase is termed the Polymerization Rate-Enhancement effect (PRE), which is measured in terms of an Ethylene Enhancement Factor (EEF) as a dimensionless ratio in the range of from about 1.1 to about 10 or above. The amount of ethylene included in the reaction system can be selected and controlled to be so small as to result in essentially minimal (<2 mole %) incorporation of ethylene units into the resulting elastomeric polymer and the molecular weight may be increased. Amounts of ethylene to generate the PRE effect may be greater than 0.1 wt. % and preferably range up to about 2 wt. %. However, if a polymer with more ethylene is desired, additional ethylene may be incorporated into the polymerization feed, including up to 10 to about 50 mole % based on olefin units. A second important aspect of this invention is the ability to use a PRE activity-enhancing amount of ethylene in an olefin polymerization without substantially affecting the physical properties of the elastomer. In a third important aspect of this invention, I-olefin elastomers are produced through incorporation of ethylene using unbridged fluxional catalyst systems which may not otherwise produce acceptable elastomeric homopolymers. This effect is termed the EPE effect, for Elastomeric Property-Enhancing effect. The EPE amount of ethylene required to produce such elastomers typically overlaps the PRE activity-enhancing amount. Incorporation of up to about 5 mole % or more of ethylene typically will produce an elastomeric polymer using such catalyst systems. Typical useful amounts of incorporated ethylene include about 1 to 3 mole %. Preferred polymers of this invention retain sufficient crystallinity to provide a high melting point (by DSC) of about 80° C., preferably above 100° C., including in the range of from about 120° C. to about 140° C. and above. Novel flexible alpha-olefin homo and copolymers having elongation in excess of 600% and substantially no retained force are disclosed.

The invention is an article comprising at least two layers, a low crystallinity layer and a high crystallinity layer. One or both layers is capable of being elongated so that a pre-stretched article is capable of being formed.

Methods of manufacturing polymeric intraluminal prostheses include annealing the polymeric material to selectively modify the crystallinity thereof. Annealing may be utilized to selectively modify various properties of the polymeric material of an intraluminal prosthesis, including: selectively increasing the modulus of the polymeric material; selectively increasing the hoop strength of the intraluminal prosthesis; selectively modifying the elution rate (increase or decrease) of a pharmacological agent subsequently disposed on or within the annealed polymeric material; selectively increasing / decreasing stress in the intraluminal prosthesis; and selectively modifying the polymeric material such that it erodes at a different rate.

This invention relates to high melting polyolefin copolymers suitable as thermoplastic elastomers and catalysts and methods for their synthesis. These elastomeric olefin copolymers are characterized by a mole fraction of crystallizable component Xc from about 30 to about 99%; low glass transition temperatures, below -20° C., and typically below -50° C.; melting points above about 90° C.; high molecular weights; a molecular weight distribution MW / Mn< / =10; and a narrow composition distribution between chains of < / =15%. The novel copolymers of the invention range from reactor blends to multiblock copolymers that can be sequentially fractionated into fractions of differing crystallinities, which fractions nevertheless show compositions of comonomers which differ by less than 15% from the parent polymer (reactor product). The invention also relates to a process for producing such copolymers by utilizing an unbridged, substituted or unsubstituted cyclopentadienyl metallocene catalyst that is capable of interconverting between states with different copolymerization characteristics, which interconversion is controlled by selecting the substituents of the cyclopentadienyl ligands so that the rate of interconversion of the two states is within several orders of magnitude of the rate of formation of a single polymer chain. Where ri>rf the polymer can be characterized as multiblock; where ri<rf, the result is a polymer blend and where ri / rf is close to 1, the resulting polymer is a mixture of blend and multiblock. The metallocene catalysts of the invention are able to interconvert between more than two states, with embodiments of four states being shown in FIG. 2.

A crystal growth 301 is carried out by diffusing a metal element, and a nickel element is moved into regions 108 and 109 which has been doped with phosphorus. An axis coincident with the moving directions 302 and 303 of the nickel element at this time is made to coincide with an axis coincident with the direction of the crystal growth, and a TFT having the regions as channel forming regions is manufactured. In the path of the region where nickel moved, since high crystallinity is obtained in the moving direction, the TFT having high characteristics can be obtained by this way.