AlN epitaxial film on 6H-SiC(0001) using MOCVD for GHz-band SAW devices

Aluminum nitride (AlN)(0001) epitaxial films on 6H-silicon carbide (SiC)(0001) were successfully grown using metal-organic-chemical-vapor deposition (MO-CVD). Crack-free on the surface of AlN films were obtained without preannealing for removal of polishing-induced damage from the 6H-SiC(0001) substrate. The crack-free AlN films were grown at 1100°C under V-III ratio of 25000. A SAW device was fabricated on the AlN film using photolithography and reactive ion etching (RIE) techniques. The thickness of AlN film was 1.0 μm. The direction of SAW propagation was a-axis of AlN. The line and space of IDT was 0.6 μm. The center frequency was measured to be 2.747GHz. The phase velocity was calculated to be nearly equal 6600m/sec. The phase velocity in AlN(0001)/6H-SiC(0001) structure is larger than that of AlN(0001)/sapphire(0001) structure under same thickness and direction of SAW propagation.