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首页> 外文期刊>Physical review >Annealing effects on electrical properties and defects of CaCu_3Ti_4O_(12) thin films deposited by pulsed laser deposition
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Annealing effects on electrical properties and defects of CaCu_3Ti_4O_(12) thin films deposited by pulsed laser deposition

机译：退火对脉冲激光沉积CaCu_3Ti_4O_（12）薄膜电学性质和缺陷的影响

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摘要

A systematic study was carried out to assess property changes in CaCu_3Ti_4O_(12) thin films upon annealing in air in order to evaluate the impact of oxygen vacancies on their colossal dielectric constant behavior. Highly preferentially oriented thin-film samples were deposited by pulsed laser deposition method at 720 ℃ in 200 mTorr oxygen. The as-deposited thin films show the typical feature of colossal dielectric constant. Annealing experiments were conducted at 480, 580, 620, and 680 ℃ with intermediate electrical measurements. The evolutions of the electrical properties (such as, dielectric constant, loss, resistance, etc.), defect concentration and activation energy, were observed with the increase in the annealing temperature. Capacitance-temperature results exhibited the double-plateau feature in the measuring temperature range, revealing two defect levels in the sample. The activation energy and concentration of these two defects were estimated at each annealed state. The sensitivity of these defects to oxygen atmosphere confirmed our previous conclusion about oxygen vacancies as the chemical origin of the colossal dielectric constant phenomenon in CaCu_3Ti_4O_(12). Numerical simulation to the capacitance response of a Schottky junction with two defects supports the experimental results. Annealing at 680 ℃ changed the sample from the colossal dielectric state into a normal dielectric state with a negative temperature coefficient of dielectric constant. In such a fully annealed state, the intrinsic dielectric properties of CaCu_3Ti_4O_(12) were observed. The abnormal increase in dielectric constant at low temperature may be attributed to the magnetodielectric coupling caused by magnetic ordering.
机译：进行了系统的研究，以评估在空气中退火后CaCu_3Ti_4O_（12）薄膜的性能变化，以评估氧空位对其巨大介电常数行为的影响。通过脉冲激光沉积法在720℃，200 mTorr氧气中沉积高度优先取向的薄膜样品。沉积的薄膜显示出巨大介电常数的典型特征。在480、580、620和680℃进行退火实验，并进行中间电学测量。随着退火温度的升高，观察到电性能（例如介电常数，损耗，电阻等），缺陷浓度和活化能的变化。电容-温度结果在测量温度范围内表现出双平稳的特征，揭示了样品中的两个缺陷水平​​。在每个退火状态下估计这两个缺陷的活化能和浓度。这些缺陷对氧气气氛的敏感性证实了我们先前关于氧空位作为CaCu_3Ti_4O_（12）中的巨大介电常数现象的化学起源的结论。带有两个缺陷的肖特基结电容响应的数值模拟支持了实验结果。 680℃退火将样品从巨大的介电状态变为具有负介电常数温度系数的正常介电状态。在这种完全退火的状态下，观察到CaCu_3Ti_4O_（12）的固有介电性能。低温下介电常数的异常增加可能归因于由磁有序引起的磁电耦合。

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  • 来源
    《Physical review》 |2010年第22期|P.224111.1-224111.9|共9页
  • 作者

    Guochu Deng; Paul Muralt;

  • 作者单位

    Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Ceramics Laboratory, Ecole Polytechnique Federate de Lausanne (EPFL), CH-1015 Lausanne, Switzerland;

    rnCeramics Laboratory, Ecole Polytechnique Federate de Lausanne (EPFL), CH-1015 Lausanne, Switzerland;

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  • 正文语种 eng
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  • 关键词

    dielectric loss and relaxation; impurity and defect levels; energy states of adsorbed species;

    机译：介电损耗和松弛;杂质和缺陷水平;吸附物质的能态;

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