Nickel was deposited on Ru(0001) in a vacuum chamber at a temperature of 295 K. The depositions were performed using both a continuous and an interrupted flux of Ni, up to the same coverage of 0.25 monolayer. The growth of Ni on Ru(0001) was studied by ultra-high vacuum scanning tunneling microscopy. It is shown that changing the deposition or the pause duration leads to a change of the dominant growth carriers in the postnucleation period, affecting thus the morphology of the obtained Ni/Ru(0001) surfaces. For a pause duration of 10 s, the saturation cluster density obtained by interrupted-flux deposition was two times higher than one obtained with continuous deposition, and increases with the number of periods. With further increase of the pause duration, the saturation cluster density decreased due to the formation of larger clusters, and might even fall below the value obtained for continuous deposition. (C) 2008 Elsevier B.V. All rights reserved.