Evolution of ion-induced nano-dot patterns on silicon surface in presence of seeding materials

摘要

In this report, a comprehensive study on ion beam patterning of Si surface with simultaneous co-sputtering of stainless steel (SS) has been described. The experiment has been carried out using 500 eV energy Ar+ ion beam sputtering at normal ion incidence by varying the ion fluences. To explore the morphological details, different regions of the samples with respect to the distance from the SS target are probed using AFM and SEM techniques. For an ion fluence above 5 x 10(17) ions/cm(2), pronounced nano-dots appear on the surface and with a further increase of fluence up-to 5 x 10(18) ions/cm(2), coagulation and nucleation of the nano-dots occur leading to the formation of mound-like structures. Such a kind of patterning mechanism in the presence of metal impurity is governed by the recent theory put forward by Bradley. According to which the interplay between the irradiated surface and the surface impurity leads to the evolution of pronounced nanoscale patterns on the surface. The only required condition for such a mechanism is the formation of immobile chemical bonds on the surface, which in our case is reflected from the occurrence of FeSi2 bond revealed from XPS and TEM analysis.