SECONDARY-ION EMISSION FROM VARIOUS METALS AND THE SEMICONDUCTORS SI AND GAAS INDUCED BY MEGAELECTRONVOLT ION IMPACT

Experiments on secondary ions ejected from six UHV cleaned metals and from Si and GaAs have been performed with Cf-fission fragments both at Darmstadt and using the Tandem accelerator in Orsay. The energy and a ngular distributions measured for the metal ions by means of a time-of -flight technique are explainable by linear collision sputter theory, when an ionization term is included. Deviations from this theory indic ate contributions due to the electronic excitation of the collision-ca scade region around the nuclear track. Also, for the semiconductors, c ollisional sputtering seems to be the dominant process. Doping has no influence on the secondary ion yields.