Swift heavy ion induced structural modifications in indium oxide films

Sub-stoichiometric indium oxide (InxOy) films were fabricated by electron-beam evaporation method. One set of films was irradiated with 120 MeV Ag9+ ions of varying fluences. Another set was thermally annealed and subsequently irradiated. Irradiation of the as-deposited InxOy films leads to a phase separation resulting in In and In2O3 and the formation of nanometer crystalline In clusters. The In cluster size is in the range of 35–45 nm. Elastic recoil detection analysis indicates a decrease in the O/In ratio with an increase in ion fluence, suggesting oxygen loss during irradiation. On the other hand, thermal annealing of the as-deposited InxOy films leads to a complete conversion into stoichiometric In2O3. The structure of the stoichiometric films is further resistant to irradiation. Preliminary electrical investigations indicate a decrease in the resistivity of the as-deposited sub-stoichiometric InxOy films with irradiation, but a very large increase after irradiation of the stoichiometric thermally annealed films. Thus, structural and electrical modifications induced by swift heavy ions depend upon the stoichiometry of the film.