Two-dimensional (2D) semiconductor materials, with their unique structures and physical properties, show enormous potential for next-generation electronic devices. However, the absence of dangling bonds on 2D semiconductor surfaces makes it challenging to deposit high-quality high-κ dielectric layers using conventional vapor-phase techniques such as atomic layer deposition (ALD), while simultaneously maintaining low defect-density interfaces. The scalable integration of high-κ materials on 2D semiconductors has thus remained a key bottleneck limiting the practical application of 2D devices.
Addressing this challenge, Prof. Liu Lei’s group at the School of Materials Science and Engineering, Peking University, together with collaborators, has developed a wet-chemistry-based approach to synthesize an amorphous high-κ (dielectric constant 42.9) copper-calcium titanate (CCTO) perovskite thin film. The team successfully integrated this material into 2D semiconductor devices, realizing a novel compute-in-memory prototype. The findings were recently published in Nature Communications (Nature Communications 16, 1482, 2025).
The researchers employed the Pechini method, a wet-chemistry-based route, to prepare transferable, self-supporting 2D amorphous CCTO films. In this process, metal ions are coordinated with citric acid to form chelates, followed by polymerization induced by ethylene glycol, creating a crosslinked network. Low-temperature baking removes solvents and organic residues, producing uniform amorphous CCTO films with finely controllable thickness. These films can be completely peeled from the growth substrate and transferred onto target substrates, forming heterostructures with 2D semiconductors (Figure 1).
Figure 1. Fabrication and Transfer of Two-Dimensional Amorphous CCTO Films.
The fabricated two-dimensional amorphous CCTO films exhibit a high dielectric constant of up to 42.9, with an equivalent oxide thickness (EOT) as low as 0.9 nm, meeting the gate dielectric requirements for advanced process nodes outlined by the International Roadmap for Devices and Systems (IRDS). 2D semiconductor devices using transferred CCTO films as the gate dielectric demonstrate excellent electrical performance: CCTO/MoS₂ devices achieve a subthreshold swing as low as 67 mV/dec, approaching the 60 mV/dec thermal limit, while exhibiting minimal hysteresis (~1 mV/(MV·cm⁻¹)).
In addition, the CCTO films are photoactive under visible light, enabling floating-gate operations in a simple field-effect transistor structure with optical write-in and electrical erase functionalities. This allows for reconfigurable logic operations, demonstrating the potential of these films for multifunctional 2D electronic devices.
Figure 2. High-Performance MoS₂ Field-Effect Transistors and Compute-in-Memory Devices Based on Two-Dimensional Amorphous High-κ Metal Oxide Gate Dielectrics.
This study marks the first application of wet-chemically synthesized high-κ amorphous metal oxide dielectrics in two-dimensional semiconductor devices. It not only overcomes the long-standing challenge of forming high-quality high-κ dielectrics on 2D materials using conventional methods, but also leverages the optical properties of amorphous thin films to integrate logic operations and data storage functionalities. The CCTO-based 2D semiconductor devices demonstrate low power consumption, high performance, and multifunctional integration, providing new strategies and approaches for the development of future 2D electronic systems. These advances are expected to accelerate the broader application of 2D semiconductor materials in high-performance computing, sensors, and logic circuits.
PhD student Zhixin Yao and postdoctoral researcher Huifeng Tian are the first authors of the paper, with Associate Professor Lei Liu from Peking University and Professor Junjie Guo from Taiyuan University of Technology serving as co-corresponding authors. Key collaborators include Professor Yong Soo Cho from Yonsei University, Professor Kaihui Liu and Professor Yanfeng Zhang from Peking University, and Researcher Lifen Wang from the Institute of Physics, Chinese Academy of Sciences. This work was supported by the Beijing Outstanding Young Scientists Fund, the National Key R&D Program of China, the National Natural Science Foundation of China, and the China Postdoctoral Science Foundation, among other funding programs.
DOI：https://www.nature.com/articles/s41467-025-56815-9
