Electronic sputtering of CuO films by high-energy ions

Abstract

We have studied the electronic sputtering, electronic and atomic structure modifications of CuO films under high-energy ion impact, for comparison with the other materials such as cuprite oxides (Cu2O) and further understanding of the electronic-excitation effects. It is found that the sputtering yields are much larger (by a factor of 100–1000) than those of the elastic collisions, confirming that the electronic excitations play a dominant role in the sputtering. The electronic sputtering yield Y of CuO is well fitted by Y=4.0Se1.08, Se being the electronic stopping power (keV/nm). This is exceptionally close to linear dependence on Se, in contrast to the super linear dependence for other oxides. The direct bandgap is determined to be 2.1(±0.1) eV for unirradiated films and no appreciable modification of the bandgap is observed by the 100MeV Xe ion impact. Disordering and lattice compaction were observed by the ion impact.