Influence of metal-ferroelectric contacts on the space charge formation in ferroelectric thin film capacitors

Fast 704 MHz Ferroelectric Tuner for Superconducting Cavities

“…It is also clearly seen that if one starts at a bias of 15 kV/cm (or above), then increases the bias and then comes back to the 15 kV/cm bias again, the value of dielectric constant is nearly the same, as opposed to the case when one tries to start (and come back) to any bias voltages below 15 kV/cm. This is in a sound agreement with other research on ferroelectric materials, albeit not in a bulk shape but a form of thin films [16].…”

Suppression of slow capacitance relaxation phenomenon in Pt/Ba0.3Sr0.7TiO3/Pt thin film ferroelectric structures by annealing in oxygen atmosphere

“…This threshold voltage level depends on the FE films and electrode material, their quality, and fabrication method used. 8,9 The nature of switching kinetics in ferroelectric structures at temperatures lower than the Curie temperature (T < T c ) is rather well determined, 10-12 however, the explanation of slow relaxation processes at T > T c is not entirely clear.…”

“…8,13,14 It has been demonstrated that the slow relaxation processes in BSTO structures are connected with oxygen vacancies, which commonly exist in oxide films. 7,8,13 So, it can be concluded that one way to suppress the slow relaxation process in these films is to decrease the concentration of oxygen vacancies by annealing in an oxygen atmosphere. Nowadays, a high-temperature annealing operation is often used to increase the structure quality and improve the electrical properties of FE films.…”

“…This residual capacitance phenomenon has a threshold nature (see, for example, Ref. 8), which appears only when the applied pulsed voltage is bigger than a threshold voltage level (V > V th ; at V < V th , the DC ¼ 0). This threshold voltage level depends on the FE films and electrode material, their quality, and fabrication method used.…”

“…However, when a unipolar voltage pulse is applied, the response of the FE film based metal/FE/metal (M/FE/M) capacitor structures become ambiguous. This is because, besides the fast response process (soft mode response, <1 ns), there are slow relaxation processes, which cause up to 20% of the capacitance value to relax (i.e., return to initial state after the pulse duration) for a time s $ 10 3 s. [5][6][7][8] The oscillogram (Fig. 1) demonstrates the typical response of a FE varactor on a rectangular voltage pulse.…”