Abstract: Purpose: To provide a melt-moldable tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer with excellent durability without causing an excessive decrease of the melt flow rate and an increase of the perfluoro(alkyl vinyl ether) content. Solution means: A melt-moldable tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer, which is characterized in that in a parallel plate mode of a dynamic viscoelasticity measuring device, when the temperature is raised from ?40° C. to 200° C. at 5° C./min while fixing the measuring frequency to 1 Hz, the slope (? tan ?/?T) of the loss tangent (tan ?) measured between two arbitrary points in a range of 50-75° C. and at a temperature difference of 3° C. or higher is always in a range of 0.0005-0.0030, and its preparation method.

Abstract: Purpose: To provide a melt-moldable tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer with excellent durability without causing an excessive decrease of the melt flow rate and an increase of the perfluoro(alkyl vinyl ether) content. Solution means: A melt-moldable tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer, which is characterized in that in a parallel plate mode of a dynamic viscoelasticity measuring device, when the temperature is raised from ?40° C. to 200° C. at 5° C./min while fixing the measuring frequency to 1 Hz, the slope (? tan ?/?T) of the loss tangent (tan ?) measured between two arbitrary points in a range of 50-75° C. and at a temperature difference of 3° C. or higher is always in a range of 0.0005-0.0030, and its preparation method.

Abstract: A method for forming a SiC film having a wide optical energy gap and a high conductivity, which is capable of being stacked on a substrate of a large area uniformly. The SiC film is formed by supplying a material gas composed of monosilane gas, methane gas, diboran gas and hydrogen gas and having a hydrogen dilution ratio of about 144 and carbon mixing ratio of about 0.35, to the substrate, and supplying rf power of 60 to 270W(rf power density=80 to 350mW/cm.sup.2) under a gas pressure of 0.2 torr at a substrate temperature of 220.degree. C. The obtained film exhibits high dark-conductivity of 10.sup.-6 Scm.sup.-1 or more, and a Raman spectrum light thereof peaks at around 520 cm.sup.-1.