Quantification of the Electromechanical Measurements by Piezoresponse Force Microscopy
Quantification of the Electromechanical Measurements by Piezoresponse Force Microscopy
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DOI：
10.1002/adma.202206237
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发表时间：
2022-10-21
影响因子：
29.4
通讯作者：
Gruverman, Alexei
中科院分区：
文献类型：
--
作者：
Buragohain, Pratyush;Lu, Haidong;Gruverman, Alexei
压电响应力显微镜(PFM)被广泛用于表征和探索铁电材料的纳米尺度性质。然而，由于各种外在和内在贡献的卷积，PFM信号的量化是具有挑战性的。虽然PFM幅度信号的量化已经受到相当大的关注，但还没有解决PFM相位信号的量化问题。正确校准的PFM相位信号可以提供关于局部压电系数符号的有价值的信息-这对于新兴的铁电材料来说是一个重要而不是微不足道的问题。在这项工作中，讨论了两种互补的方法来校准PFM相位信号。第一种方法基于已知独立测量的压电系数的标准参考样品，而第二种方法利用静电样品与悬臂梁的相互作用来确定寄生相位偏移。应用这些方法研究铁电HfO2基薄膜电容器的压电行为，发现纵向压电系数d(33，ef)的符号发生了有趣的变化。结果表明，HfO2基电容器的压电性对其厚度、电极和沉积方法具有内在的敏感性，并且可以表现出很大的变化，包括单个器件内d(33，ef)符号的变化。
Piezoresponse force microscopy (PFM) is widely used for characterization and exploration of the nanoscale properties of ferroelectrics. However, quantification of the PFM signal is challenging due to the convolution of various extrinsic and intrinsic contributions. Although quantification of the PFM amplitude signal has received considerable attention, quantification of the PFM phase signal has not been addressed. A properly calibrated PFM phase signal can provide valuable information on the sign of the local piezoelectric coefficient-an important and nontrivial issue for emerging ferroelectrics. In this work, two complementary methodologies to calibrate the PFM phase signal are discussed. The first approach is based on using a standard reference sample with well-known independently measured piezoelectric coefficients, while the second approach exploits the electrostatic sample-cantilever interactions to determine the parasitic phase offset. Application of these methodologies to studies of the piezoelectric behavior in ferroelectric HfO2-based thin-film capacitors reveals intriguing variations in the sign of the longitudinal piezoelectric coefficient, d(33,eff). It is shown that the piezoelectric properties of the HfO2-based capacitors are inherently sensitive to their thickness, electrodes, as well as deposition methods, and can exhibit wide variations including a d(33,eff) sign change within a single device.