Special CMSM Seminar No.304

The rise of two-dimensional (2D) semiconductors represents the next wave of innovation in semiconductor technology, offering new opportunities for scaling channel materials and rethinking device architectures beyond the limits of bulk silicon CMOS. However, despite considerable progress in n-type 2D materials, such as MoS2and WS2, the development of high-performance p-type counterparts remains significantly underdeveloped. A key challenge in identifying suitable p-type 2D semiconductors lies in the inherent difficulty of achieving stable valence band alignment, sufficient hole mobility, and reliable contact formation without introducing Fermi-level pinning or unintentional doping. Moreover, the performance of 2D devices is often compromised by degraded semiconductor/dielectric and semiconductor/electrode interfaces, especially when harsh fabrication steps or transfer processes are involved. These interfaces, though only a few atoms thick, play a decisive role in governing charge transport, threshold voltage stability, and scalability. In this talk, I will present our recent efforts in addressing these challenges by focusing on the epitaxy growth and integration of p-type 2D semiconductors, particularly for the direct growth of these materials on insulating substrates. This approach offers a practical pathway toward realizing high-performance complementary 2D logic while maintaining compatibility with back-end-of-line (BEOL) process constraints.

References
[1] Nature Nanotechnology 18, 1289 (2023).
[2] Nature Materials (2026).
https://doi.org/10.1038/s41563-026-02503-y
[3] Nature (2026) Accepted.

Ken-ichi Uchida
Research Center for Magnetic and Spintronic Materials
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