Impulsive stimulated scattering of surface acoustic waves on metal and semiconductor crystal surfaces

Impulsive stimulated scattering (ISS) is used to obtain the orientational d ependence of the velocity of surface acoustic waves (SAW) on single crystal metal and semiconductor surfaces. Mechanically polished surfaces of alumin um(111), nickel(100), and germanium(100) samples were examined, as well as a comparison of mechanically polished versus high vacuum sputtering/anneali ng of a Ni(100) surface. The ISS technique offers an accurate and robust me thod of obtaining surface acoustic velocities of metal and semiconductor cr ystalline surfaces without physical contact. The orientationally dependent ISS results on Ni(100) are compared with recent classical Brillouin scatter ing measurements, and with velocities calculated using bulk elastic constan t data. Finally, ISS measurements on tilted (i.e., lower symmetry surfaces) reveal coupling of the ISS excited SAW with bulk transverse modes. (C) 200 1 American Institute of Physics.