DEPENDENCE OF SURFACE-COMPOSITIONAL AND ANGULAR-DISTRIBUTIONS ON THE BULK COMPOSITION IN THE SPUTTERING OF CU-PT AND CU-NI ALLOYS

Under 1 keV Ar ion bombardment of Cu-Pt and Cu-Ni alloys at high fluen ce at low temperature, the depletion degree of the segregating species at the second surface layer, and the normalized sputtering yield rati os (non-segregating species/segregating species) in the near-normal di rection (15 degrees) and at oblique angles (75 degrees), have been est imated by an improved kinetic BIGS (Bombardment-Induced Gibbsian Segre gation) model. For both the bombarded Cu-Pt and the bombarded Cu-Wi al loys, calculations show that the depletion degree of the segregating s pecies 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 degrees and 75 degrees is small when the bulk composition of the segregating species equals the extreme value, but this difference becomes large wh en that of the segregating species equals the intermediate value.