Contribution of anisotropic velocity distribution of recoil atoms to sputtering yields and angular distributions of sputtered atoms

Abstract

Abstract A modified Sigmund's formula is derived, based on the assumption that the transient phenomenon is dominant in low-energy sputtering, i.e., taking into account the anisotropy of the velocity distribution of recoil atoms near the surface. This modified Sigmund's formula is exactly coincident with Matsunami's empirical formula which includes the threshold effect of primary recoil atoms. The same approach is successfully applied to the analysis of the angular distribution of sputtered atoms and a simple formula is also obtained. This simple formula is shown to predict well both the heart-shaped distribution for normal incidence and preferential forward ejection of sputtered atoms for oblique incidence.