| 摘要 |
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 mum. 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°. The thus obtained aluminum nitride single crystal layer 12, 13 has no clack formed therein, has an excellent piezo-electric property, and has a high propagating velocity for surface acoustic wave.
|
