Stroboscopic X-Ray topography of surface acoustic wave devices

Abstract

Stroboscopic X-ray topography using the time structure of synchrotron radiation has been used to investigate 38 MHz lithium niobate, LiNB0(_3), surface acoustic wave devices. The methods of topography are discussed with particular reference to synchrotron radiation and stroboscopic techniques. Surface acoustic wave devices are described and relevant aspects of their performance are discussed. A detailed review is given of previous investigations of surface acoustic wave devices, including investigation of the contrast mechanism of the imaging of surface acoustic waves. Experimental evidence relating to the performance of surface acoustic wave devices and to the interaction of surface acoustic waves with defects such as grain boundaries is discussed; it is suggested that the use of ultrasonic wave propagation theory could allow grain boundaries to be considered as infinitely thin cracks. The effects of input voltage and incident X-ray wavelength are investigated. Computer programs are presented which simulate image positions for stroboscopic investigations of lithium niobate and Laue patterns for cubic and hexagonal crystals. An assessment is made of the perfection of crystals of lithium tetraborate, Li (_2) B (_4) O (_7) a possible future surface acoustic wave substrate material. Possibilities for future investigations are discussed.