Self-organized nanoscale multilayer growth in hyperthermal ion deposition

Abstract

In the course of thin film growth by co-deposition of low energy mass selected carbon and metal (Au or Fe) ions, an effect of self-organization was found. Although carbon and metal ions were deposited quasi-simultaneously, a multilayer film structure of alternately metal-rich and metal-deficient layers was grown. The period of these layers is of the order of a few nanometers $(\ensuremath{\sim}6\text{\ensuremath{-}}20\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$, and the metal-rich layers consist of metallic nanocrystals. The multilayer formation process is discussed in comparison with earlier studies on $\mathrm{C}\ensuremath{-}\mathrm{Cu}$ and $\mathrm{C}\ensuremath{-}\mathrm{Ag}$ films with respect to the structural properties of small clusters of the different metals, the influence of sputtering yields, and the deposition parameters. For a variety of compound thin film materials we expect a multilayer structure to develop during simultaneous sputter deposition or ion beam deposition of the components. The suppositions for this scenario are: (a) the deposited elements are immiscible or there are immiscible phases of a compound material, (b) the sputtering yields of the film components imposed by the impinging species are in an appropriate range, and (c) one compound segregates at the surface.