Scanning tunneling microscopy as a tool to study surface roughness of sputtered thin films

A three-dimensional image of the surface roughness of four conducting iron-oxide Fe3O4 thin films was obtained using a scanning tunneling microscope. We obtain grain size and surface roughness of films deposited on Si(100) by reactive sputtering at different substrate temperatures. The apparent grain size lies between 10 and 50 nm, and depends on the substrate temperature and film thickness. We have also determined the scanning tunneling microscopy parameters (tip size and shape) to obtain ‘‘real’’ images (i.e., images without artifacts) of the films.