| 摘要 |
PROBLEM TO BE SOLVED: To provide a substrate for a surface acoustic wave device in which an AIN film excellent in surface flatness and crystallinity is epitaxially grown on the surface of a C-faced sapphire base material by an MOCVD method, and a method for manufacturing this substrate, and a surface acoustic wave device using this substrate. SOLUTION: A sapphire base material 12 to be heated through a susceptor 13 is arranged at the center of a reaction tube 11, and an AIN film is grown by introducing trimethylaluminum gas and ammonia gas from one end of the reaction tube. In this case, the heating temperature of the base material is set to be almost 1,100 deg.C or over, and a V/II mol ratio is set to be almost 800 or below, and a film formation pressures is set to be almost 7-17 Torr. Thus, a substrate for a surface acoustic wave device is obtained, which is provided with excellent crystallinity having a half-value width of almost 90 arcsec or less in X ray rocking curve, with excellent flatness having an surface flatness Ra of 20Åor below, and with the deviation from the theoretical value of the propagating speed of surface acoustic waves reduced to almost 1.5 m/sec or below. |
