Angular dependence of sputtering yield of amorphous and polycrystalline materials

An analytical formula is developed for the evolution of angular dependence of sputtering yields by extending the theory of sputtering yield proposed by Sigmund. We demonstrate that the peak of sputtering yield at oblique incidence can be attributed to a balance between the increased energy deposited on the surface by incident ion which enhances the sputtering yield and the decreased depth travelled by recoil atom which reduces the sputtering yield. The predicted dependence of sputtering yield on the incident angle is in good agreement with experimental observations.