- Published as a Supplementary Cover article in ACS Nano: Securing a key technology for next-generation AI, aerospace, and ultra-low-power semiconductors

- Achieves ultra-low resistance approaching the quantum contact limit through precise plasma control

  The research team led by Professor Taewan Kim of the Intelligent Semiconductor Major, School of Advanced Fusion Studies at the University of Seoul, in collaboration with the team of Professor Hyo-Chang Lee of Korea Aerospace University, announced that their research paper, “Plasma Knowledge-Based Polymorphic Engineering for Two-Dimensional Semiconductor Contacts,” has been published as a Supplementary Cover article in ACS Nano (IF: 16.1, top 6% in JCR), a globally renowned journal in nanoscience.

  The research team systematized, for the first time in the world, a “plasma knowledge-based polymorphic process” technology capable of fundamentally resolving the high contact resistance issue that has hindered the commercialization of two-dimensional transition metal dichalcogenide (2D TMD) semiconductors. While conventional plasma processes have relied on empirical parameter tuning, the team quantitatively measured internal physical parameters such as plasma ion density and self-bias voltage and, based on these measurements, proposed a new process framework that enables precise control of kinetic ion energy flux.

  In particular, the research team selectively irradiated plasma ions onto semiconducting-phase (2H) MoTe₂ and WS₂, locally inducing the metallic 1T′ phase to realize a metal–semiconductor polymorphic junction (1T′/2H polymorphic interface) within a single material. Through this approach, they successfully formed ultra-low-resistance ohmic contacts that effectively eliminate the Schottky barrier between the metal electrode and the semiconductor.

  In terms of electrical characteristics, the team achieved a record-low contact resistance of 250.42 Ω·μm under on-state gate bias conditions in the polymorphic contact structure, and further reduced it to 122 Ω·μm in the polymorphic edge contact structure. This represents one of the lowest values reported to date for MoTe₂-based devices. As a result, the devices demonstrated a maximum on-current of 68.15 μA/μm, an electron mobility of 1.61 × 10⁴ cm²/V·s, an on/off ratio exceeding 10⁷, and an effective Schottky barrier height of approximately 0.28–0.405 meV, experimentally verifying performance approaching the quantum contact limit.

  In addition, this study confirmed that the same process strategy is effective not only for MoTe₂ but also for WS₂, demonstrating that the technology constitutes a generalizable contact process platform for 2D semiconductors rather than being limited to a specific material. It is therefore regarded as a key enabling technology with strong potential for extension to next-generation ultra-scaled CMOS, three-dimensional stacked semiconductors, and intelligent AI semiconductor systems.

  “This study is significant in that it transforms plasma processing from a ‘black box’ into a quantitatively understood scientific domain,” stated Professor Taewan Kim at the University of Seoul. “It presents a practical and manufacturing-friendly contact technology for the industrial-scale production of two-dimensional semiconductors and the realization of next-generation intelligent CMOS.”

▶ From left: Ji Won Heo (doctoral student, University of Seoul), Professor Hyo-Chang Lee (Korea Aerospace University), Professor Taewan Kim (University of Seoul).

  This research was conducted with support from the Materials Global Young Connect Program of the Ministry of Science and ICT and the National Research Foundation of Korea (NRF); the Convergence Research Program of the Ministry of Trade, Industry and Energy and the National Research Council of Science and Technology (NST); and the BK21 Program.

  This achievement is evaluated as a study that directly overcomes the physical limits of contact resistance in two-dimensional semiconductors and represents an important milestone toward accelerating the realization of next-generation AI, aerospace, and ultra-low-power semiconductor technologies.