Increase in surface-acoustic-wave velocity produced by ion implantation in quartz

An increase in the surface-acoustic-wave velocity, arising from surface-state modification, is reported for the first time. It was obtained by a 100 keV ion implantation on quartz substrates tested at a frequency of 180 MHz. 1H+, 4He+ 7Li+ 9Be+, 11B+ and 40A+ ions have been used. The flux is about 1016 ions/cm2 and the surface waves propagate faster on the implanted surface than on the unimplanted part, because a crystalline-to-amorphous transition is created by ion implantation. The greatest relative-velocity increase is measured using Li+ and He+ ion bombardment, and was found to be equal to 1.1% at 180 MHz. The insertion losses of the delay lines are not significantly changed by the implantation. A 1000 ¿ step height has been measured at the boundary of the implanted surface, as a consequence of the increase in volume of the implanted part.