ABSTRACT
A number of electronic and magnetic properties of a thin film depend upon the roughness of its surface and its interfaces with other films. At the levels of roughness involved in semiconductor and magnetic thin films, x-ray scattering is the only nondestructive technique for measurement of the interface roughness of buried interfaces. For surfaces, scanning probe microscopy (SPM) methods work well for measurement of the topological roughness, provided that the length scale of the roughness is not large. In the case where the in-plane correlation length of the roughness is greater than a few tens of nanometers, the SPM data may be severely truncated if long scan ranges are not employed. Specular x-ray reflectivity is the most commonly used method, but there is no information on interface structure parallel to the interface, and the full interface width is measured. To obtain data more directly comparable with, for example, atomic force microscopy, it is necessary to distinguish between the roughness and the grading of an interface, and this can be done by measurement of the diffuse scatter at low angles. Interface roughness can also be deduced from the shape of the tails of the diffraction peak in a Bragg reflection. This is rarely used but can be helpful in certain cases.
