Electrochemical potential gradients in Pb(Zr,Ti)O3 thin

Thin film PbZr0.55Ti0.45O3 (PZT) capacitors were observed to develop a de voltage offset when driven with an ac applied electric field. This voltage offset displayed a strong dependence on the ambient oxygen partial pressure, pO(2), of the atmosphere above the film, in addition to applied electric field and temperature dependencies. A scenario is proposed wherein a chemical potential gradient is established in the film, the magnitude of which is determined by the ambient pO(2). The subsequent redistribution of oxygen vacancies is thought to create the observed voltage offset. This hypothesis was supported by the observation of similar voltage offsets in compositionally graded PZT films. This effect shows promise for novel low-temperature oxygen sensing applications.