HIGHLY PREFERRED AL[111] FILMS FOR HIGH-FREQUENCY SURFACE-ACOUSTIC-WAVE DEVICES

Highly preferred AI[III] films suitable for high-frequency Surface Aco ustic Wave (SAW) devices have been deposited on an ultrathin metal und erlayer by means of an ion beam sputtering technique. The [111] textur e was obtained for Al underlayered with ultrathin metal films such as Y, Ti, V, Cr, Co, Ni and Cu, on a substrate that is being used for SAW devices. The region in which the texturing occurred was dependent on the metal element and the thickness of the underlayers. The [111] text ured films exhibited a very smooth film surface. The reason why the [1 11] texturing took place within the limited thickness range is discuss ed from the viewpoints of phenomenological wetting and a rotational sy mmetry mismatch between Al and metal underlayer texture.