Structure and AC conductivity of nanocrystalline Yttrium oxide thin films

Yttrium oxide (Y2O3) thin films were grown at substrate temperatures (Ts) ranging from room temperature (RT) to 500 °C and their structural and electrical properties were evaluated. The results indicate that Y2O3 films grown at RT-100 °C were amorphous (a-Y2O3). Y2O3 films began to show cubic phase (c-Y2O3) at Ts = 200 °C. The average grain size varies from 5 to 40 nm as a function of Ts. Room temperature ac electrical conductivity increases from 0.4 (Ω-m)− 1 to 1.2 (Ω-m)− 1 with increasing Ts from RT to 500 °C. The frequency dispersion of the electrical resistivity reveals the hopping conduction mechanism. Frequency dispersion of the electrical resistivity fits to the modified Debye's function, which considers more than one ion contributing to the relaxation process. The mean relaxation time decreases from 2.8 to 1.4 μs with increasing Ts indicating that the effect of microstructure of the Y2O3 films is significant on the electrical properties.