Charge transport phenomena in porous ceramic PZT films are discussed. The leakage current has been found to be in PZT porous films is 1-1.5 orders higher than for the dense film throughout the whole bias voltage. In the low fields region (similar to 40-160 kV/cm) the main charge transport mechanism is the ohmic conductivity. Static (steady state) conductivity of porous PZT films is 1-2 orders higher than of dense film. The main possible charge transport mechanism in the high fields region (>= 160-180 kV/cm) is the space-charge-limited conduction.

The role of a change in the spontaneous polarization charge in the formation of negative differential conductance regions of the current-voltage characteristics of thin ferroelectric films has been determined. It has been shown that the polarization recovery current, which appears due to partial depolarization of a preliminarily polarized film, prevails over the intrinsic leakage current of the ferroelectric film in the coercive field region and corresponds to the Weibull distribution. The influence of polarization recovery current decreases with decreasing voltage sweep rate.

Исследовано влияние легирования лантаном пленок цирконата-титаната свинца (ЦТСЛ) на поляризационные свойства и токи утечки. Пленки Pb1 - xLax(Zr0.48Ti0.52)1 - x/4O3 с x = 0; 0.02; 0.05; 0.08 и 0.1 толщиной 240 нм сформированы золь-гель методом при температуре отжига 650°С на подложках со структурой Si SiO2 TiO2 Pt. Установлено, что при легировании La имеет место уменьшение остаточной поляризации и коэрцитивного поля. Пленки с x = 0.02 имеют приемлемые значения сегнетоэлектрических характеристик (7 мкКл/см2, 25 кВ/см) для их использования в сегнетоэлектрической памяти. Вольт-амперные характеристики пленок ЦТСЛ имеют две характерные области. В диапазоне слабых полей (до 80–90 кВ/см) ток утечки обусловлен преимущественно высоким сопротивлением обедненной области обратно смещенного барьера Шоттки на границе раздела электрод-сегнетоэлектрик, в результате чего величина тока утечки практически не зависит от содержания La. При превышении порогового напряжения происходит пробой барьера Шоттки, и в области сильных полей ток утечки определяется концентрацией свободных носителей в объеме пленки, зависящей от степени легирования La. При x = 0.02 ток утечки уменьшается приблизительно на два порядка по сравнению с нелегированной пленкой ЦТС. Дальнейшее увеличение содержания La сопровождается увеличением тока утечки в области сильных полей вследствие смены типа проводимости и увеличения концентрации носителей n-типа.

The influence of lanthanum doping of lead zirconate titanate films (PZTL) on their polarization properties and leakage currents is studied. The films of Pb1 − x La x (Zr0.48Ti0.52)1 − x/4O3 with x = 0, 0.02, 0.05, 0.08, and 0.1 and a thickness of 240 nm were produced using the sol-gel method at an annealing temperature of 650°C on the substrates with a Si-SiO2-TiO2-Pt structure. It is found that the residual polarization and the coercive field are weakened after doping with La. The films with x = 0.02 exhibit satisfactory ferroelectric characteristics (7 μC/cm2, 25 kV/cm) that make them suitable for use in ferroelectric memory. The current-voltage curves of PZTL films have two characteristic regions. In weak fields (up to 80–90 kV/cm), the leakage current is attributable primarily to the high resistance of the depletion region of the reverse-biased Schottky barrier at the electrode-ferroelectric interface, and the leakage current is thus practically independent of the La content. When the threshold voltage is exceeded, the Schottky barrier breakdown occurs, and the leakage current in strong fields is defined by the density of free carriers in the bulk of the film. This density depends on the La doping level. The leakage current at x = 0.02 is reduced by about two orders of magnitude compared to undoped PZT film. Further increases in the La content are accompanied by an increase in the leakage current in strong fields. This effect is attributed to a change in the conduction type and an increase in the density of n-type carriers.