COMPACTION OF TUNGSTEN-OXIDE FILMS BY ION-BEAM IRRADIATION

Evaporated amorphous tungsten oxide films with low densities, deposite d on different substrates, have been irradiated with various types of ions of different energies up to 30 MeV, and With fluences up to 10(18 ) cm-2. Compaction of the films up to nearly the bulk density was obse rved. No changes of the stoichiometry as determined by various ion-bea m analysis techniques were detectable. Raman measurements showed that ion-beam-modified films are also amorphous, but have a different micro structure from as-deposited films. The irradiated films have a higher refractive index than the as-deposited films. A low threshold for the compaction effect of a few times 10(12) ions cm-2 was found, leading t o the conclusion that one ion displaces more than 10(5) tungsten oxide molecules.