Morphology evolution of thin Ni film on MgO(100) substrate

Abstract

Thin Ni films with various thicknesses were deposited onto the MgO(100) single crystal substrate at 400°C. The morphology measured by atomic force microscope shows an apparent correlation with the thickness. The initial 10 Å film is composed of small round Ni islands. In the 25 Å film, pinholes with narrow size distribution occur, which show local periodic distribution in some regions when the thickness of the film reaches 75 Å. The driving force for such a structure is attributed to the elastic strain energy. When the film is about 100 Å thick, the pinholes begin to disappear, due to filling by the late-coming atoms and covering of upper islands.