Influence of the co-deposited metal content in the formation dynamics of silicon nanodot patterns produced by low-energy ion beam sputtering

Poster presented at International Symposium on Nanoscale Pattern Formation at Surfaces, which took place in Copenhagen (Denmark) in 2013.In this work, we report on the effect of the metal nature (Fe or Mo) and content in the formation dynamics of silicon nanodot patterns induced by normal-incidence lowenergy ion beam sputtering (IBS) under metal co-deposition. The simultaneous source of metal atoms is controlled by partially covering the target with a metal mask during the irradiation. In this way, the metal incorporation rate is tuned by changing the relative area uncovered by the mask and, obviously, the (residual and stationary) metal content increases by covering a larger area of the target. Atomic force microscopy (AFM) imaging of the resulting patterns shows that the formation dynamics is faster as the metal incorporation rate increases. In addition, the asymptotic pattern parameters (roughness and characteristic wavelength) are also determined by such rate, being larger for higher metal incorporation. Interestingly, as extracted from the analysis of the AFM images, highly-ordered patterns are obtained for the Mo case. This fact suggests that the metal nature plays an important role in IBS nanopatterning with metal co-deposition. Finally, we have also studied the early stages of the irradiation process in order to get an insight on the existence of a metal content threshold for pattern formation. This study has been made on both flat and rough silicon targets to assess the influence of the initial target morphology on the pattern formation and dynamics