ELECTRONIC SPUTTERING PROCESS OF SIO2 UNDER HEAVY-ION BOMBARDMENT

Secondary-ion yields have been measured for a SiO2 target bombarded by Ag ions at impact energies of 1.4-5.3 MeV, where the electronic and n uclear stopping powers compete with each other. Singly charged cluster ions as well as multiply charged monoatomic ions were observed. Domin ant species of the cluster ions were Si(SiO2)(x)(+), SiO(SiO2)(x)(+) a nd SiO2(SiO2)(x)(+). Oxygen rich positively charged species were not o bserved. All the cluster-ion yields were characterized by a power func tion of the electronic stopping power, of which exponent varies with c luster size. From this fact we can conclude that the cluster ions are produced directly through the collective process in the solid. (C) 199 8 Elsevier Science B.V.