Temperature dependence of surface roughening during homoepitaxial growth on Cu(001)

Abstract

X-ray scattering has been used to study the roughening of the Cu(001) surface during homoepitaxial growth, as a function of temperature. Between 370 and 160 K, the mean-square roughness ${\ensuremath{\sigma}}^{2},$ obtained from specular reflectivity data, was found to increase as a power law ${\ensuremath{\sigma}}^{2}={\ensuremath{\Theta}}^{2\ensuremath{\beta}}$ for coverages \ensuremath{\Theta}, ranging from 3 to 96 ML. The roughening exponent \ensuremath{\beta} was observed to depend on the temperature of the substrate: it monotonically increases with decreasing temperature from $\ensuremath{\beta}\ensuremath{\approx}\frac{1}{3}$ at $T=370\mathrm{K}$ to $\ensuremath{\beta}\ensuremath{\approx}\frac{1}{2},$ at $T=200\mathrm{K}.$ At 110 K a smoother growth re-enters in the presence of a large vacancy concentration in the deposited film.