一、活動時間：2024年12月18日 (三) 13:00~14:30
二、活動地點：工學大樓1樓工學院第一會議室
三、講題：Materials Science and Engineering at the atomically thin limit
四、主講人： Vincent Tung(童俊智)教授

日本東京大學化學系統工程系 教授

University of California, Los Angeles (UCLA) Ph.D.

五、摘要：Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) representing the ultimate thickness scaling of channel materials provide a solution to tantalizingly push the limit of technology nodes in the sub-1-nm range. One key challenge with 2D semiconducting TMDs channel materials is the large-scale batch growth on insulating substrates with continuous single crystallinity, spatial homogeneity, and low defect density. Recent studies have claimed the epitaxy growth of wafer-scale, single-crystal 2D TMDs on C-plane sapphire substrate with deliberately engineered off-cut angles. It has been predominately postulated that exposed step edges break the energy degeneracy of nucleation and thus drive the seamless stitching of mono-oriented flakes. In this talk, I will show that a more dominant factor should be considered. The interaction of 2D TMD grains with the exposed oxygen-aluminum atomic plane establishes an energy-minimized 2D TMD-sapphire configuration. Reconstructing the surfaces of C-plane sapphire substrates to only a single type (symmetry) of atomic planes already guarantees the single-crystal epitaxy of monolayer TMDs without the aid of step edges. In addition, replacing S-vacancies with isovalent oxygen atoms suppresses the defect density by an order of magnitude. Electrical results also evidence the structural uniformity of the monolayers. Our new experimental findings elucidate the long-standing question that curbs the wafer-scale batch epitaxy of 2D TMDs single crystals, an essential step toward using 2D materials for future electronics. Experiments extended to other materials like perovskites also support the argument that the interaction with sapphire atomic surfaces is more dominant than the step edge docking.

六、聯絡人：永續發展與能源科技研究中心 邱小姐 分機:3744
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八、報名日期截止：2024年12月17日(二)
九、主辦單位：永續發展與能源科技研究中心
十、注意事項：
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