Power-law scaling during shadowing growth of nanocolumns by oblique angle deposition

The authors have investigated the power-law behaviors of various morphological parameters during the shadowing growth of ruthenium (Ru) nanocolumns by an oblique angle sputter deposition technique with substrate rotation. Particularly, wavelength and column number density were measured at different column heights (h). The exponents associated with the wavelength (pλ) and column number density (pn), correlated by the geometrical relationship pλ≈−12pn, were measured by atomic force microscopy to be ∼0.5 and ∼−1.0, respectively. Using a one-dimensional facet growth model based upon the principle of evolutionary selection under oblique angle deposition, they showed that the exponents associated with the column number density and wavelength can be predicted. The authors also illustrated that the exponent value associated with column number density originates from the competitive growth among columns that have different vertical growth rates. The simulated exponent values are independent of the shape of the facet, which indicates the universality of these power-law exponents.