Abstract: An aluminum alloy ring (the outside diameter D.sub.1) which is an element of a rotary head cylinder, is inserted in a cavity (the inside diameter D.sub.2 >D.sub.1) of a fixed metal mold, with a clearance gap (D.sub.2 -D.sub.1) Then, the cavity of the fixed metal mold is closed by a movable metal mold, and the inner space of the aluminum alloy ring is filled with molten synthetic resin material. The filling resin is pressurized so that the aluminum alloy ring elastically expands until the outer diameter thereof D.sub.1 becomes exactly or almost equal to D.sub.2. After that, the filling synthetic resin material is cooled. Thus, the aluminum alloy ring and the synthetic resin material are integrated, resulting in a rotary head cylinder molding.

Abstract: The present invention relates to a method of forming a single crystalline magnesia spinel film on a single crystalline silicon substrate by the use of the vapor-phase epitaxial method.According to the method of the present invention, at first a first single crystalline magnesia spinel layer having a compositional ratio of magnesium maintained at a nearly stoichiometric compositional ratio is epitaxially grown in a vapor-phase on the single crystalline silicon substrate, and then a second single crystalline magnesia spinel layer having a compositional ratio of magnesium which decreases upward is epitaxially grown in a vapor-phase on the first single crystalline magnesia spinel layer. In the event that a Si film is grown on the single crystalline magnesia spinel film formed by the method of the present invention, out of atoms of Mg and Al taken in the Si film in the initial growth stage of the Si film, a concentration of Mg atoms which react more actively upon Si can be reduced.

Abstract: The present invention relates to a method for producing a semiconductor thin film, in which a single crystalline silicon film is grown on an insulative single crystalline substrate, such as a single crystalline sapphire substrate, by the molecular beam epitaxy method. Silicon molecular beams are irradiated onto the substrate under the conditions wherein a substrate temperature is kept at 700.degree. to 900.degree. C. and an intensity of the molecular beams is kept within a range from 1.times.10.sup.12 atoms/cm.sup.2 .multidot.sec to 1.times.10.sup.13 atoms/cm.sup.2 .multidot.sec to clean a surface of the substrate and then the intensity of the molecular beams is increased to form the single crystalline silicon film. Thus, the substrate can be cleaned without being defected.