WS2@Pt之稀磁半導體之合成及其自旋催化與磁光研究

Abstract

本論文以二維過渡金屬硫化合物為研究核心，聚焦於二維二硫化鎢材料之可規模化成長與自旋驅動功能性開發。首先建立受限空間介質輔助化學氣相沉積策略，透過前驅物設計與基板前處理提升薄膜均勻性與再現性，實現高品質大面積二維二硫化鎢薄膜製備。在此基礎上，提出雙前驅物共同成長方法，使鉑以取代摻雜形式均勻嵌入二維二硫化鎢晶格且不形成團簇，維持單層結晶結構與材料品質。進一步發現鉑摻雜可誘發外延型二維稀磁半導體行為，使原本非磁性的鉑與二硫化鎢產生穩定鐵磁序並可延伸至室溫以上。圓偏振光致發光量測顯示摻雜後材料具顯著谷塞曼分裂，谷塞曼係數提升近兩個數量級，並對應高居禮溫度，第一原理計算指出其源自 Pt 5d 與 W 4d軌域雜化所導致之自旋極化態。除磁性研究外，本論文亦探討磁場與摻雜鉑的二硫化鎢在氫析出反應中的協同效應，證實外加磁場可降低界面電荷轉移阻抗並提升反應動力學，而鉑摻雜進一步改善導電性與氫吸附能障礙，整體提升電催化效率。最後以缺陷工程提出電子隱形策略，降低缺陷散射並提升光電元件表現。本研究建立從可大面積成長到自旋功能化之系統性路徑，為二維材料在自旋電子、磁控電催化與光電應用提供設計基礎。

This dissertation focuses on two-dimensional (2D) transition metal dichalcogenides, with an emphasis on the scalable growth of 2D tungsten disulfide (WS2) and the development of spin-driven functionalities. First, a confined-space, mediator-assisted chemical vapor deposition (CVD) strategy is established. By optimizing precursor design and substrate pretreatment, the film uniformity and reproducibility are significantly improved, enabling the fabrication of high-quality, large-area 2D WS2 films. Building on this platform, a dual-precursor co-growth approach is proposed, in which platinum (Pt) is uniformly incorporated into the WS2 lattice via substitutional doping without forming clusters, thereby preserving the monolayer crystalline structure and overall material quality. Furthermore, Pt doping is found to induce extrinsic two-dimensional dilute magnetic semiconductor behavior, leading to robust ferromagnetic ordering in an otherwise nonmagnetic Pt/WS2 system that persists above room temperature. Circularly polarized photoluminescence measurements reveal pronounced valley Zeeman splitting in the doped material, with a valley Zeeman coefficient enhanced by nearly two orders of magnitude and accompanied by a high Curie temperature. First-principles calculations attribute this phenomenon to spin-polarized states arising from strong hybridization between Pt 5d and W 4d orbitals. In addition to magnetism, this dissertation investigates the synergistic effects of an external magnetic field and Pt-doped WS2 on the hydrogen evolution reaction (HER). The results demonstrate that the applied magnetic field reduces interfacial charge-transfer resistance and enhances reaction kinetics, while Pt doping further improves electrical conductivity and optimizes hydrogen adsorption energetics, collectively boosting electrocatalytic performance. Finally, an electron-cloaking strategy based on defect engineering is proposed to suppress defect-induced scattering and enhance optoelectronic device performance. Overall, this work establishes a systematic pathway from scalable growth to spin-enabled functionality, providing a foundation for the design of 2D materials for spintronics, magnetically tunable electrocatalysis, and optoelectronic applications.