Acoustic wave propagation in free standing CVD diamond: Influence of film quality and temperature

Acoustic wave propagation in high quality, free standing polycrystalline CV D diamond wafers has been studied using a laser ultrasonic technique. The i nfluence of wafer temperature in the range 30-250 degrees C on the propagat ion characteristics of Lamb waves has been assessed. Acoustic wave propagat ion characteristics showed little variation with temperature in the range m easured suggesting that CVD diamond material of the type studied here may b e suitable for the fabrication of acoustic wave devices operating at elevat ed temperatures. Material parameters extracted from the acoustic signal tog ether with SEM studies strongly suggest that void, microcrack and grain bou ndary density rather than sp(2) content most influence the propagation of l ow frequency Lamb waves in free standing CVD diamond films. (C) 1999 Elsevi er Science S.A. All rights reserved.