Charge distribution at interface and in bulk of YSZ thin films deposited on Si substrate

摘要

Charge distribution at the YSZ/Si interface and in the bulk of ZrO_2 + x.Y_2O_3 (x = 1.22, 2.39, 3.73 and 6.49 mol percent Y_2O_3) thin films were studied by the charge transient methods and the impedance spectroscopy. The smallest amount of mobile ionic charge for the film with 6.49mol percent Y_2O_3 was found, while the positive charge fixed at the YSZ/Si interface is almost the same for each of the investigated films. The currents flowing across the films were influenced by their phase compositions, mainly in the film with 6.49 mol Y_2O_3. The observed diode behaviour with the characteristic leakage current was present probably due to the absence of interface traps, capable to capture the mobile positive charge. The electrical conductivity as the function of yttria amount and phase composition indicates the presence of isolated oxygen vacancies as well as the associated point defects. The behaviour of electrical conductivity is in a relatively good agreement with that observed for the crystalline YSZ samples used as the targets at the deposition of investigated films by e-beam evaporation on the Si substrate.