Surface morphology evolution during electrodeposition of amorphous CoP films

We have used atomic force microscopy to measure the roughness of electrodeposited amorphous CoP as a function of length scale and film thickness. In contrast to the power law scaling usually observed for polycrystalline electrodeposited films in the absence of additives, the roughness decreases with increasing film thickness. For films grown on Au on glass substrates, the characteristic lateral feature size is ∼250 nm, independent of the CoP thickness. This is consistent with columnar growth. Films of thickness 4 μm have a saturation roughness of only ∼1 nm, which is less than that of the substrates.