Local C–V mapping for ferroelectrics using scanning nonlinear dielectric microscopy

Abstract

Detailed analysis of local polarization switching will promote the further development of a wide range of applications using ferroelectrics. Here, we propose a local C–V mapping technique using scanning nonlinear dielectric microscopy (SNDM) that enables visualization of dynamic ferroelectric switching behavior in real space. Using this method, C–V butterfly curves characteristic of ferroelectrics can be measured on a scanning probe microscopy platform with nanoscale resolution by virtue of the high capacitance-detection sensitivity of SNDM. This provides real-space mapping of the net switchable polarization, the switching voltage, and the local imprint with a short measurement time (e.g., 10 min or less for 256×256 pixels). Furthermore, the proposed method will be useful for study of the electric-field response of domain walls. In this paper, we present some examples of experiments with LiTaO3 single crystals and HfO2-based ferroelectric thin films and give an overview of what kind of evaluation is possible with the local C–V mapping technique.

High-precision local C–V mapping for ferroelectrics using principal component analysis

“…These observations are consistent with our previously reported results. 15) The introduction of a digitizer allowed these C-V curves to be resynthesized with greater accuracy than before because of the consideration of higher-order harmonics. When the harmonics used for resynthesis were truncated at the sixth order (N = 6), the C-V curves were blunted; by contrast, when harmonics up to 18ω (N = 18) were used, butterfly loops were obtained in which the steepness of the peaks was not impaired.…”

“…In the present study, we prepared a randomly oriented ferroelectric HfO 2 film 36) similar to that prepared in our previous study 15) because a sample with a large in-plane distribution is more convenient for the demonstrations. A 17.5 nm thick Y-doped HfO 2 (Y:HfO 2 ) film was deposited onto a Pt/TiO 2 /SiO 2 /Si substrate at room temperature using a pulsed laser deposition method, followed by annealing at 1000 °C for 10 s under a N 2 atmosphere.…”

“…a method based on measurement of the dielectric response (often referred to as a capacitancevoltage (C-V ) measurement), can also be used. In this context, we have recently proposed an alternative method 15) in which the local C-V curves are recorded using SNDM with nanoscale resolution. In this measurement mode, using the highly sensitive capacitance sensor incorporated into the probe unit of the SNDM system, we record local C-V curves at all image pixels during two-dimensional probe scanning.…”

Data-Driven Analysis of High-Resolution Hyperspectral Image Data Sets through Nanoscale Capacitance–Voltage Measurements to Visualize Ferroelectric Domain Dynamics

“…To address the measurement time problem, we have recently developed a local capacitance–voltage ( C – V ) mapping method using scanning nonlinear dielectric microscopy (SNDM), , which is a domain dynamics analysis method based on a measurement principle completely different than that of the PFM-based method. In local C – V mapping, the SNDM’s high-sensitivity capacitance sensor measures the capacitance change that occurs when a large-amplitude AC bias is applied to the sample through the scanning probe.…”

Nanoscale mapping to assess the asymmetry of local C–V curves obtained from ferroelectric materials

“…The present study demonstrates visualization of asymmetric domain switching in real space with high resolution using the local capacitance-voltage (C-V ) mapping method which was recently developed by our group. 13,14)…”