Fabrication and characterization of tetragonal and orthorhombic TeO 2 films

Single-phase tetragonal and mixed-phase tellurium oxide (TeO₂ ) films were fabricated by thermal evaporation and RF sputtering techniques. Crystallinity in the films with two structural phases was achieved by postdeposition annealing at 400°C of as-grown amorphous films of TeO₂ deposited at a substrate temperature of 100°C by thermal evaporation. RF sputtered as-grown amorphous film, deposited on room-temperature substrates, when annealed at 400°C showed the presence of a single tetragonal structural phase with high transparency. A higher annealing temperature in both the cases retained the single tetragonal phase, but with tellurium precipitation occurred in the film matrix. X-ray diffraction and transmission electron microscopy techniques were used to study the structural changes with postdeposition annealing. Electrical and optical characterization of the films are also reported