Momentum-imaging spectroscopy of secondary ions from GaN and SiC surfaces collided with highly charged ions at grazing angle

Three-dimensional momentum of sputtered ions were measured in coincidence with scattered Ar atoms in collisions between Arq+ (q = 3, 8, 11, and 14) and 6H-SiC and GaN surfaces at grazing-incidence angle (<0.5°). H+, H2+, Si+ and Ga+ ions were observed in time-of-flight-mass spectra. Sputtering yields of H+ and H2+ increased with increasing charge states of incident ions in proportion to q4. The momenta of these secondary ions emitted from the surfaces were intensively distributed to the direction of surface normal in spite of the grazing collisions. Almost no significant change among different q was found in the kinetic energy distributions of these secondary ions.