Morphological evolution of ion-sputtered Pd(001): Temperature effects

Abstract

We have investigated the kinetic effects on the morphological evolution of an Ar+-ion sputtered Pd(001) by in situ, real-time x-ray reflectivity and grazing-incidence small angle x-ray scattering measurements at various substrate temperatures. We find that surface roughness W and its associated growth exponent beta increase with T up to a certain temperature T-m. Beyond T-m, however, they decrease with increasing T. For T < T-m, surface roughening and coarsening kinetics are mostly driven by the deposition and diffusion of sputter-induced adatoms as reported in molecular beam epitaxial growth. When T is near T-m, however, vacancies rather than adatoms become the dominant surface species. Above T-m, the surface smoothing via adatom detachment and vacancy diffusion across step edges becomes effective.