High-energy ion-beam-induced phase separation in SiOx films -: art. no. 125329

The modification of the nanostructure of silicon suboxide (SiOx) films as a result of high-energy heavy-ion irradiation has been studied for the entire range 0.1 <= x < 2. The SiOx films have been obtained by radio-frequency magnetron sputter deposition. For 50 MeV Cu-63(8+) ions and an angle of incidence of 20 degrees with the plane of the surface, and for x >= 0.5, it takes a fluence of about 10(14)/cm(2) to reach a Si-O-Si infrared absorption spectrum, which is supposed to be characteristic for a Si-SiO2 composite film structure. For smaller x values, it takes a much larger fluence. The interpretation of the IR spectra is corroborated for the surface, region by results from x-ray photoelectron spectroscopy. The results present evidence for a mechanism, in which the phase separation takes place in the thermal spike, initiated by the energy deposited in many overlapping independent ion tracks. Such a process is possible since the suboxides fulfill the conditions for spinodal decomposition.