ANALYSIS OF THIN-FILMS WITH SLIGHTLY ROUGH BOUNDARIES

Technological procedures often produce thin films with rough boundarie s as for example, semiconductor films prepared by various chemical met hods. If roughness of the boundaries of the films is very small, i.e, if the rms values of the heights of boundary irregularities are equal to several nanometers, it is very difficult to carry out a detailed an alysis of the films. Spectroscopic ellipsometry and atomic force micro scopy represent two experimental techniques enabling us to determine s ome important parameters of these films (e.g. thickness) together with the main statistical quantities characterizing slight (nanometric) ro ughness of their boundaries. In this paper a method will be presented based on a combination of variable angle spectroscopic ellipsometry, s pectroscopic reflectometry and atomic force microscopy enabling us to determine the optical parameters and the most significant statistical parameters of the rough boundaries characterizing the slightly rough s ingle layers. Within the method the generalized Rayleigh-Rice theory p ublished elsewhere will be used for interpreting experimental data obt ained from both the optical techniques, i,e. variable angle spectrosco pic ellipsometry and spectroscopic reflectometry. The method will be i llustrated by presenting experimental results achieved by applying the method to slightly rough surfaces of single crystals of GaAs covered by very thin surface layers (i.e. by native oxide layers).