Surface morphology of thin Cu films grown on magnesium oxide (100)

Copper films were epitaxially grown on MgO(001) with a thickness of 50 nm e mploying molecular beam epitaxy, Depending on the growth temperature and gr owth rate different sizes of Cu islands can be achieved. The island size in creases with substrate temperature from about 30 nm at 320 K up to about 10 0 nm at 420 K; at higher temperatures, the size does not change significant ly. At a substrate temperature of 420 K, a higher growth rate resulted in s maller island sizes due to the enhanced nucleation density. The island size is closely related to the in-plane correlation length derived through a sc aling analysis fi sm scanning probe microscopy images of the surface. The r oughness exponent ct for a sample is calculated as the slope of the rms rou ghness as a function of the scanning probe microscopy image scan size. Valu es of ct between 0.7 and 0.95 were found for scan sizes smaller than the is land size. At larger scan sizes, the rms value saturates and does not depen d significantly on the scan size.