Revealing Fast Cu-Ion Transport and Enhanced Conductivity at the CuInP2S6-In4/3P2S6 Heterointerface

Marti Checa; Xin Jin; Ruben Millan-Solsona; Sabine M Neumayer; Michael A Susner; Michael A McGuire; Andrew O'Hara; Gabriel Gomila; Petro Maksymovych; Sokrates T Pantelides; Liam Collins

doi:10.1021/acsnano.2c06992

Revealing Fast Cu-Ion Transport and Enhanced Conductivity at the CuInP₂S₆-In_4/3P₂S₆ Heterointerface

ACS Nano. 2022 Sep 27;16(9):15347-15357. doi: 10.1021/acsnano.2c06992. Epub 2022 Aug 23.

Authors

Marti Checa¹, Xin Jin^{2

3}, Ruben Millan-Solsona^{4

5}, Sabine M Neumayer¹, Michael A Susner⁶, Michael A McGuire⁷, Andrew O'Hara², Gabriel Gomila^{4

5}, Petro Maksymovych¹, Sokrates T Pantelides^{2

8}, Liam Collins¹

Affiliations

¹ Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
² Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United States.
³ Institute of Physics and University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.
⁴ Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain.
⁵ Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain.
⁶ Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.
⁷ Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
⁸ Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States.

PMID: 35998341
DOI: 10.1021/acsnano.2c06992

Abstract

Van der Waals layered ferroelectrics, such as CuInP₂S₆ (CIPS), offer a versatile platform for miniaturization of ferroelectric device technologies. Control of the targeted composition and kinetics of CIPS synthesis enables the formation of stable self-assembled heterostructures of ferroelectric CIPS and nonferroelectric In_4/3P₂S₆ (IPS). Here, we use quantitative scanning probe microscopy methods combined with density functional theory (DFT) to explore in detail the nanoscale variability in dynamic functional properties of the CIPS-IPS heterostructure. We report evidence of fast ionic transport which mediates an appreciable out-of-plane electromechanical response of the CIPS surface in the paraelectric phase. Further, we map the nanoscale dielectric and ionic conductivity properties as we thermally stimulate the ferroelectric-paraelectric phase transition, recovering the local dielectric behavior during this phase transition. Finally, aided by DFT, we reveal a substantial and tunable conductivity enhancement at the CIPS/IPS interface, indicating the possibility of engineering its interfacial properties for next generation device applications.

Keywords: copper indium thiophosphate; ferroelectrics; ionic conductor; phase transition; piezoresponse force microscopy; scanning dielectric microscopy.