The evolution of the average size l of the triangular Cu nanocrystals with the nominal deposition thickness d and deposition rate f. (a) The dependence between l and d. (b) The dependence between l and f. The dashed lines in (a) and (b) are the guides to the eye. Each data point represents an average value of over 13 nanocrystals and the error bars represent the standard errors of the mean values.