title: Quantum size effect on adatom surface diffusion.
abstract: Using scanning tunneling microscopy, we demonstrate that the nucleation density of Fe islands on the surface of nanoscale Pb films oscillates with the film thickness, providing a direct manifestation of the quantum size effect on surface diffusion. The Fe adatom diffusion barriers were derived to be 204+/-5 and 187+/-5 meV on a 21 and 26 monolayer (ML) Pb film, respectively, by matching the kinetic Monte Carlo simulations to the experimental island densities. The effect is further illustrated by the growth of Fe islands on wedged Pb films, where the Fe island density is consistently higher on the odd-layer films than on the even-layer films in the thickness range of 11 to 15 ML.
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Ma
authors.forename: Lin
authors.initials: L
authors.lastname: Tang
authors.forename: Ze-Lei
authors.initials: ZL
authors.lastname: Guan
authors.forename: Ke
authors.initials: K
authors.lastname: He
authors.forename: Kang
authors.initials: K
authors.lastname: An
authors.forename: Xu-Cun
authors.initials: XC
authors.lastname: Ma
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Jia
authors.forename: Qi-Kun
authors.initials: QK
authors.lastname: Xue
authors.forename: Y
authors.initials: Y
authors.lastname: Han
authors.forename: Steve
authors.initials: S
authors.lastname: Huang
authors.forename: Feng
authors.initials: F
authors.lastname: Liu