Step roughness on vicinal Ag(111)

The roughness of steps on Ag(111) has been investigated using the tunnel microscope. At 300 K monatomic steps are rough with a roughness of the order of one atom diameter, while submonolayer steps caused by stacking faults or screw dislocations are always smooth. Monatomic steps become smooth when the temperature is lowered to 27 K. It is suggested that the observed roughness is caused by kink diffusion.