Extrinsic contributions to the apparent thickness dependence of the dielectric constant in epitaxial Pb(Zr,Ti)O3 thin films
Extrinsic contributions to the apparent thickness dependence of the dielectric constant in epitaxial Pb(Zr,Ti)O3 thin films
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DOI：
10.1103/physrevb.75.224113
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发表时间：
2007-06
影响因子：
3.7
通讯作者：
L. Pintilie;I. Vrejoiu;D. Hesse;G. LeRhun;M. Alexe
中科院分区：
文献类型：
--
作者：
L. Pintilie;I. Vrejoiu;D. Hesse;G. LeRhun;M. Alexe
分析了外延$Pb（Zr，Ti）O 3 $（PZT）薄膜的介电常数随厚度的变化规律，以及非本征因素对介电常数的影响.结果表明，测量电容的频率依赖性可以通过包含肖特基接触的含陷阱电容的等效电路来最好地模拟。的介电常数的厚度依赖性，使用平面电容器的公式计算，似乎是一个外在的效果，由于在金属-铁电-金属结构中的界面现象。PZT材料的本征介电常数似乎与厚度无关，并且具有约30\char21{}40的低值。这更接近于从拉曼测量或从铁电性的量子理论估计的值。厚度的独立性也证明了piezoresponse力显微镜测量。陷阱的存在证明了在subgap波长的光伏效应的存在。
The problem of the thickness dependence of the dielectric constant, as well as the extrinsic contributions to its value, is analyzed for the case of epitaxial $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$ (PZT) thin films. It is shown that the frequency dependence of the measured capacitance is best simulated by an equivalent circuit incorporating the trap-containing capacitance of a Schottky contact. The thickness dependence of the dielectric constant, calculated using the formula of a plane capacitor, appears to be an extrinsic effect due to the interface phenomena in the metal-ferroelectric-metal structure. The intrinsic dielectric constant of the PZT material seems to be thickness independent and of low value of about 30\char21{}40. This is closer to the values estimated from Raman measurements or from quantum theories of ferroelectricity. The thickness independence is also proven by piezoresponse force microscopy measurements. The presence of traps is evidenced by the presence of a photovoltaic effect at subgap wavelengths.