Atomic-scale insights into microstructural complexity of van der Waals ferroelectric CuInP2S6
Abstract
The rapid advancement of technology has positioned devices based on two-dimensional materials as a key solution to overcoming the limitations of traditional semiconductor materials. Among these, the ferroelectric compound CuInP2S6 (CIPS) has attracted significant attention for its multiple ferroelectric polarization states. However, its structural complexity, particularly its susceptibility to copper deficiency, presents notable challenges for further research. This study investigates copper-deficient CIPS (Cu: CIPS) to explore the structure–property relationship between ferroelectricity and structural composition at macroscopic and microscopic levels. Using spherical aberration-corrected scanning transmission electron microscopy, copper deficiency is shown to induce phase separation in CIPS, resulting in the coexistence of CIPS (Cc), CIPS (Cc′) (where the two layers experience a sliding displacement of 1/6b along the b-axis) and an In4/3P2S6 structure containing small amounts of Cu (Cu: IPS) structure. Moreover, the intermediate phase exhibits a lack of ferroelectric switching response in piezoelectric force microscopy measurements. This work elucidates the microstructural evolution of Cu: CIPS, identifies the mechanism underlying the failure of ferroelectric switching in CIPS, and provides valuable insights for advancing CIPS-based ferroelectric memory devices.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (9)
Jianwei Zhang
Biotech Drug Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences
Lei Yang
Yunzhe Zheng
Key Laboratory of Polar Materials and Devices (MOE), Shanghai Center of Brain-inspired Intelligent Materials and Devices, Department of Electronics, and Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University 1 , Shanghai 200241,
Ke Qu
Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, School of Information and Electronic Engineering
Qingfeng Zhu
Zhenzhong Yang
Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, School of Information and Electronic Engineering
Rong Huang
Ni Zhong
Chungang Duan
Key Laboratory of Polar Materials and Devices (MOE), School of Information and Electronic Engineering (School of Integrated Circuits Science and Engineering), East China Normal University, Shanghai, China.