Abstract: A Group III nitride film is directly grown on a crystalline substrate along the C-axis of the substrate, and includes at least Al. The Group III nitride film has a hexagonal crystal system, and the lattice constant “c” of the c-axis of the Group III nitride film and the lattice constant “a” of the crystal face perpendicular to the main surface of the substrate satisfies the relation of “C>2.636a-3.232”.

Abstract: A method for fabricating a Group III nitride film is provided, including the steps of preparing a substrate, forming an underfilm and then forming the Group III nitride film on the underfilm. The underfilm is a Group III nitride comprising at least one Group III element and includes at least 50 atomic percent of elemental Al with respect to all of the Group III elements of the Group III nitride of the underfilm. The surface of the underfilm is contoured (concave-convex) and includes flat regions, and less than 50% of the underfilm surface is occupied by the flat regions.

Abstract: An epitaxial wafer includes a base material made of sapphire-SiC single crystal or the like, a III nitride underfilm including at least Al epitaxially grown on the base material and a GaN film, preferably having a thickness of 50 Å or more, formed on the underfilm. In fabricating III nitride films on the epitaxial wafer, the oxidized surface layer of the GaN film is removed through an etching process, and subsequently, another III nitride film is formed thereon.

Abstract: An AlxGayInzN(x+y+z=1,x,y,z≧0) film is epitaxially grown, for example to a thickness of about 1.0 &mgr;m, on a surface of a base material. A surface of the AlxGayInzN film opposing the base material is polished and thus, flattened to have a surface roughness Ra of less than 10 Å and a thickness of about 1.0 &mgr;m. A high crystallinity nitride film is interposed between the base material and the AlxGayInzN film.

Abstract: The back side space of a tubular member is evacuated by means of a pressure difference-creating means constructed of a pressure regulating chamber and a pump, and then, the pressure in the back side space of the tubular member is set to be tenth or below of the pressure in the front space of the tubular member. Then, a raw material gas is introduced and excited to generate a plasma raw material gas, which is introduced into the tubular member and onto an inner wall of the tubular member, efficiently commensurate with the pressure difference created by means of the pressure difference-creating means. As a result, a desired thin film is formed on the inner wall of the tubular member through the chemical reaction of the plasma raw material gas.

Abstract: The back side space of a mouth ring for forming a honeycomb-shaped green product is evacuated by means of a pressure difference-creating means constructed of a pressure regulating chamber and a pump, and then, the pressure in the back side space of the mouth ring is set to be tenth or below of the pressure in the front space of the mouth ring. Then, a raw material gas is introduced and excited to generate a plasma raw material gas, which is introduced into the mouth ring efficiently commensurate with the pressure difference created by means of the pressure difference-creating means. As a result, a thin film made of diamond or diamond-like carbon is made in the mouth ring in good quality.

Abstract: On a substrate made of e.g., sapphire single crystal is formed an Al underlayer having a crystallinity of 90 seconds or below in FWHM of X-ray rocking curve. Then, on the AlN underlayer is formed a buffer layer having a composition of AlpGaqIn1-p-qN (0≦p≦1, 0≦y≦q), and on the buffer layer is formed a GaN-based semiconductor layer group.

Abstract: A substrate is set on a susceptor installed in a reactor arranged horizontally. Then, a cooling jacket is provided at the opposite portion of the inner wall of the reactor to the susbtrate. By flowing a given cooling medium through the cooling jacket with a pump connected to the jacket, at least the opposite portion of the inner wall is cooled down, to inhibit the reaction between raw material gases introduced into the reactor. As a result, in fabricating a III-V nitride film, the film growth rate is developed and the crystal quality is developed.

Abstract: On a given substrate is formed an underfilm including a surface of concave-convex structure in which 50% or over is occupied by the flat region and made of a III nitride including 50 atomic percentages or over of Al element for all of the III elements constituting the III nitride. Then, a desired III nitride film is formed on the underfilm by a normal MOCVD method.

Abstract: In fabricating a semiconducting nitride film by a MOCVD method, a susceptor tray is employed. The susceptor tray is constructed of a base plate and an outer member detachable for the base plate. A substrate for the film to be formed is set in the recessed portion formed by disposing the outer member on the base plate.

Abstract: Strip-shaped ditches are formed on a sapphire substrate as a base material. Then, the sapphire substrate is set into a CVD chamber, and an AlxGayInzN (x+y+z=1,x>0,y,z≧0)film is epitaxially grown on the sapphire substrate so as to embed the ditches by a selective lateral epitaxial growth method. As a result, the AlxGayInzN film has low dislocation density areas on at least one of the concave portions and the convex portions of the strip-shaped ditches.

Abstract: At least one of the interior wall of a reactor and a susceptor installed in the reactor is coated with an AlaGabIncN (a+b+c=1, a>0) film, which is heated to about 1000° C. or over when a substrate is heated to a predetermined temperature so as to generate the MOCVD reaction between a III raw material gas and a V raw material gas. Therefore, the AlpGaqInrN (p+q+r=1) compound generated from the raw material gases is deposited on the coated AlaGablncN (a+b+c=1, a>0) film, and thus, particles composed of the AlpGaqlnrN compound are not almost created. As a result, the resulting AlxGaylnzN (x+y+z=1) film is not affected by the particles, and can have its desirable quality.

Abstract: A III nitride buffer film including at least Al element and having a screw-type dislocation density of 1×108/cm2 or below is formed on a base made of a sapphire single crystal, etc., to fabricate an epitaxial base substrate. Then, a III nitride underfilm is formed on the III nitride buffer film, to fabricate an epitaxial substrate.

Abstract: A III nitride film is directly grown on a crystalline substrate along the C-axis, and includes at least Al element. Then, the III nitride film has hexagonal crystal system, and the lattice constant “c” of the main axis and the lattice constant “a” of the crystal face perpendicular to the main surface satisfies the relation of “C>2.363a-3.232”.

Abstract: A base material made of C-faced sapphire single crystal is set on a susceptor installed in a reactor arranged horizontally. Then, a trimethylaluminum and an ammonia are introduced as raw material gases into the reactor and supplied onto the substrate, to form an AlN film. In this case, the temperature of the base material is set to 1100° C. or over, and the ratio (V raw material gas/III raw material gas) is set to 800 or below, and the forming pressure is set within a range of 7-17 Torr. As a result, the crystallinity of the AlN film is developed to 90 arcsec or below in FWHM of X-ray rocking curve, and the surface flatness of the AlN film is developed to 20 Å or below. Therefore, a substrate composed of the base material and the AlN film is preferably usable for an acoustic surface wave device, and if the substrate is employed, the deviation from the theoretical propagation velocity is set to 1.5 m/sec or below.

Abstract: A III nitride film including Al element is fabricated by a MOCVD method with monitoring the dew point of the reactor to be used in the MOCVD method. An organic metal vapor flown in the reactor, the dew point is preferably set to a temperature of −90° C. or below. Then, the film is fabricated.

Abstract: An epitaxial wafer has a base material made of sapphire-SiC single crystal or the like, a III nitride underfilm including at least Al element epitaxially grown on the base material and a GaN film, preferably having a thickness of 50 Å or over, formed on the underfilm. In a fabricating a III nitride films on the epitaxial wafer, the oxidized surface layer of the GaN film is removed through etching process, and subsequently, the III nitride film is formed.

Abstract: A sapphire single crystal wafer 11 having a diameter not less than two inches and having an off-angled surface which is obtained by rotating an R (1-102) surface about an axis in a negative direction by a given off-angle not less than 2° is introduced in a CVD apparatus. While the sapphire substrate is kept at a temperature of about 950° C., a buffer layer made of gallium nitride or aluminum-gallium nitride is first deposited with an average thickness of 0.1-0.2 &mgr;m, and then an aluminum nitride single crystal layer is deposited with an average thickness not less than 2 &mgr;m. The thus obtained aluminum nitride single crystal layer does not have a significant amount of cracks, has an excellent piezoelectric property, and has a high propagating velocity.

Abstract: A sapphire single crystal wafer 11 having a diameter not less than two inches and having an off-angled surface which is obtained by rotating an R (1-102) surface about a [11-20] axis by a given off-angle is introduced in a CVD apparatus, and a double-layer structure of first and second aluminum single crystal layers 12 and 13 is deposited on the off-angled surface of the sapphire single crystal wafer by MOCVD. The thus deposited aluminum single crystal layer 13 has (1-210) surface. The first aluminum nitride single crystal layer 12 serves as a buffer layer and has a thickness of 5-50 nm, and the second aluminum nitride single crystal layer 13 has a thickness not less than 1 &mgr;m. The off-angle is preferably set to a value not less than ±1°, much preferably a value ±2°, more preferably a value not less than −3°, and particularly preferable to a value within a range from −2°-+10°.

Abstract: A sapphire single crystal wafer 11 having a diameter not less than two inches and having an off-angled surface which is obtained by rotating an R (1-102) surface about a ?11-20! axis by a given off-angle is introduced in a CVD apparatus, and a double-layer structure of first and second aluminum single crystal layers 12 and 13 is deposited on the off-angled surface of the sapphire single crystal wafer by MOCVD. The thus deposited aluminum single crystal layer 13 has (1-210) surface. The first aluminum nitride single crystal layer 12 serves as a buffer layer and has a thickness of 5-50 nm, and the second aluminum nitride single crystal layer 13 has a thickness not less than 1 .mu.m. The off-angle is preferably set to a value not less than .+-.1.degree., much preferably a value .+-.2.degree., more preferably a value not less than -3.degree., and particularly preferable to a value within a range from -2.degree.-+10.degree..