Optical control of polarization in ferroelectric heterostructures

“In the ferroelectric devices, polarization control is usually accomplished by application of an electric field.”* In the article “Optical control of polarization in ferroelectric heterostructures” Tao Li et al. demonstrate optically induced polarization switching in BaTiO3-based ferroelectric heterostructures utilizing a two-dimensional narrow-gap semiconductor MoS2 as a top electrode.

NANOSENSORS PPP-EFM PtIr coated AFM probes were used to perform the KPFM and PFM measurements mentioned in the article cited below.

Figure 1 from “Optical control of polarization in ferroelectric heterostructures”: Electrically induced polarization switching in the MoS2/BaTiO3/SrRuO3 junction. a, b PFM phase (a) and amplitude (b) images after application of a negative voltage pulse (−5 V, 0.5 s) to the MoS2 flake. The 12-u.c.-thick BTO film underneath the MoS2 flake is fully switched to the upward polarization, Pup. c, d PFM phase (c) and amplitude (d) images after application of several positive voltage pulses (+5 V, 0.5 s) to the MoS2 flake. BTO underneath the MoS2 flake is fully switched to downward polarization, Pdown. The polarization state of the bare BTO film (at the lower right corner) is not affected by the electrical bias. e, f The I–V characteristics of the same junction measured in the dark and during illumination. The tunneling current for the OFF state (Pup) is largely increased under illumination. Silicon AFM probes with Pt/Ir conductive coating and nominal stiffness of 3 N m−1 (PPP-EFM, NANOSENSORS) were used to perform the KPFM and PFM measurements.
Figure 1 from “Optical control of polarization in ferroelectric heterostructures”:
Electrically induced polarization switching in the MoS2/BaTiO3/SrRuO3 junction. a, b PFM phase (a) and amplitude (b) images after application of a negative voltage pulse (−5 V, 0.5 s) to the MoS2 flake. The 12-u.c.-thick BTO film underneath the MoS2 flake is fully switched to the upward polarization, Pup. c, d PFM phase (c) and amplitude (d) images after application of several positive voltage pulses (+5 V, 0.5 s) to the MoS2 flake. BTO underneath the MoS2 flake is fully switched to downward polarization, Pdown. The polarization state of the bare BTO film (at the lower right corner) is not affected by the electrical bias. e, f The I–V characteristics of the same junction measured in the dark and during illumination. The tunneling current for the OFF state (Pup) is largely increased under illumination

*Tao Li, Alexey Lipatov, Haidong Lu, Hyungwoo Lee, Jung-Woo Lee, Engin Torun, Ludger Wirtz, Chang-Beom Eom, Jorge Íñiguez, Alexander Sinitskii, Alexei Gruverman
Optical control of polarization in ferroelectric heterostructures
Nature Communications, volume 9, Article number: 3344 (2018)
DOI: https://doi.org/10.1038/s41467-018-05640-4

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Open Access:  The article “Optical control of polarization in ferroelectric heterostructures” by Tao Li et. Al. is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy

In their study “Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy” Kerstin Neuhaus, Giuliano Gregori and Joachim Maier show that “the combined polarization-KPFM method is able to produce consistent results for evaluation of room temperature chemical diffusion processes. In the future, a compilation of similar experiments with variation of temperature, humidity, gas surrounding etc. could also help to further study not only the role of the microstructure but also the influence of the environment on the polarization properties of other industrially relevant oxides.” *

“The samples were first mapped in the pristine state for reference. Subsequently, the sample was polarized with up to±5 V (with regard to the AFM tip) for up to 300 s. Directly after the end of the polarization experiment continuous surface potential mapping was started.”*

“For polarization and KPFM mapping, the samples were contacted with a silver paste back contact and Pt wire. The working contact for the polarization was an AFM tip (PPP-NCSTPt) with Pt coating, which was used simultaneously as probe during KPFM mapping (cf. Fig. 1).”*

Figure 1 from "Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy": Schematic of the experimental setup, NANOSENSORS PPP-NCST-Pt AFM probes were used
Figure 1 from “Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy”: Schematic of the experimental setup

*Kerstin Neuhaus, Giuliano Gregori, Joachim Maier
Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy
ECS Journal of Solid State Science and Technology,7 (8) P362-P368 (2018)
DOI: 10.1149/2.0011808jss

The article “Room Temperature Polarization Phenomena in Nanocrystalline and Epitaxial Thin Films of Gd-Doped Ceria Studied by Kelvin Probe Force Microscopy” by Neuhaus et. al. is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/.