NONDESTRUCTIVE IN-SITU ANALYSIS OF INTERFACE PROCESSES AND THIN-FILM GROWTH

The growth of polyamic acid films on polycrystalline gold substrates w as monitored with second harmonic generation (SHG). Pyromellitic dianh ydride (PMDA), 4,4'-oxydianiline (ODA) and 4,4'-diaminodiphenyl disulf ide (DAPS) served as monomers. Depending on the diamine the second har monic signal behaves very differently both during formation of the pol ymerimetal interface and the subsequent film growth. The experimental data are quantitatively described by a theoretical model which relates the SH signal to the orientation of the molecules. The model shows th at the shape of the thickness dependent second harmonic signal yields structural information about the film and hence, demonstrates that SHG can be applied as a technique to analyse the growth of thin films.