Physical properties of multilayer thin films of Ti-V and their hydrides studied by ion beam analysis methods

摘要

Titanium, titanium dioxide and vanadium oxide thin films, as well as V_2O_5/TiO_2 systems were deposited onto Si (111) substrates. For some samples, 1/3 of the surface was covered with palladium using molecular beam epitaxy. Chemical composition, density and layer thickness of the layers were determined by RBS. Samples have been charged with hydrogen 5 times (titanium films) and 3 times (vanadium oxide films) under pressure of 1 bar and at temperature of 300°C. Hydrogen depth profile was determined using Secondary Ion Mass Spectrometry (SIMS) and Nuclear Reaction Analysis (N-15 method). NRA measurements proved a higher hydrogen concentration in samples with partially covered top layers, than in samples without palladium indicating that palladium acts as a catalyst for hydrogen diffusion through the TiO_2 layer. RBS measurements showed reduction of V_2O_5 after each hydrogen charging, and VO_2 composition have been obtained after the third process. Further measurements, in particular hydrogen profiling, are in progress.