Dependence of surface-compositional and angular distributions on the bulk composition in the sputtering of CuPt and CuNi alloys

Abstract

Under 1 keV Ar ion bombardment of CuPt and CuNi alloys at high fluence at low temperature, the depletion degree of the segregating species at the second surface layer, and the normalized sputtering yield ratios (non-segregating species/segregating species) in the near-normal direction (15°) and at oblique angles (75°), have been estimated by an improved kinetic BIGS (Bombardment-Induced Gibbsian Segregation) model. For both the bombarded CuPt and the bombarded CuNi alloys, calculations show that the depletion degree of the segregating species at the second surface layer is small when its bulk composition equals the extreme value, but this depletion degree becomes large when its bulk composition equals the intermediate value. Furthermore, the difference of the normalized sputtering yield ratio between 15° and 75° is small when the bulk composition of the segregating species equals the extreme value, but this difference becomes large when that of the segregating species equals the intermediate value.