Using temperature to tune film roughness: Nonintuitive behavior in a simple system

Ag(100) homoepitaxy constitutes one of the simplest systems in which to stu dy thin-film growth. Yet we find that the roughness variation with temperat ure is extraordinarily complex. Specifically, as the deposition temperature is reduced from 300 to 50 K, the roughness of 35 monolayer films first inc reases, then decreases, then increases again. A transition from mound forma tion to self-affine (semifractal) growth occurs at similar to 135 K. The un derlying mechanisms are postulated. An atomistic model incorporating these mechanisms reproduces the experimental data quantitatively.