近年來，由層狀材料所組成之凡德瓦(van der Waals， vdW)異質結構已成為研究界面耦合效應與新穎量子態的重要平台。其中，金屬與拓樸絕緣體所形成之異質結構，由於界面兩側皆具有費米能階附近之電子態，因此可能產生顯著的電子結構重整化。然而，界面作用是否僅侷限於接觸層附近，或可進一步影響覆蓋層之電子結構，仍有待釐清。 本研究利用分子束磊晶(Molecular Beam Epitaxy， MBE)技術製備不同厚度之TiTe2成長於拓樸絕緣體Bi2Te3的vdW異質結構，並運用角解析光電子能譜(Angle-Resolved Photoemission Spectroscopy， ARPES)，系統性探討其電子結構與界面耦合效應。 在TiTe2/Bi2Te3異質結構中，我們從ARPES實驗結果觀察到明顯之界面電子結構重建，包括混成能隙開啟、新出現的能帶，以及電荷轉移現象。透過與理論團隊合作，第一原理計算之結果顯示，上述現象與界面耦合密切相關。其中，TiTe2厚度依賴量測結果發現，界面耦合效應並不僅侷限於異質界面，而可延伸至第二層TiTe2薄膜中。更有趣的是，即便TiTe2厚度增加至四層，其電子結構仍未恢復至TiTe2之本徵能帶結構，而是在第二層之後逐漸趨於穩定，顯示覆蓋層最終形成一種經界面重整化後之穩定電子態。 本研究結果顯示，TiTe2/Bi2Te3異質結構中存在顯著之有限深度界面耦合效應，其不僅改變局域界面附近之電子態，亦可進一步影響覆蓋層整體電子結構。此研究有助於理解金屬/拓樸絕緣體vdW異質結構中的界面電子行為，並為未來拓樸鄰近效應及相關二維量子元件之設計提供參考依據。;Van der Waals (vdW) heterostructures composed of layered materials have emerged as an important platform for investigating interfacial coupling effects and novel quantum states. In particular， heterostructures formed by metallic materials and topological insulators are expected to exhibit significant electronic structure renormalization due to the coexistence of electronic states near the Fermi level on both sides of the interface. However， whether such interfacial effects are confined to the contact layer or can further influence the electronic structure of the overlayer remains unclear. In this work， TiTe2/Bi2Te3 vdW heterostructures with different TiTe2 thicknesses were fabricated by molecular beam epitaxy (MBE)， where TiTe2 films were grown on the topological insulator Bi2Te3. Their electronic structures and interfacial coupling effects were systematically investigated using angle-resolved photoemission spectroscopy (ARPES). Pronounced interfacial electronic reconstruction was observed in the TiTe2/Bi2Te3 heterostructures， including the opening of a hybridization gap， the emergence of additional electronic bands， and signatures of charge transfer. In collaboration with a theoretical research group， first-principles calculations were performed and revealed that these phenomena are closely related to interfacial coupling. Thickness-dependent ARPES measurements further showed that the influence of interfacial coupling is not confined to the heterointerface itself but extends into the second layer. More interestingly， even when the TiTe2 thickness reaches to four layers， the electronic structure does not recover to the intrinsic band structure of TiTe2. Instead， it gradually evolves toward a stable interface-renormalized electronic state after the second layer. These results demonstrate the existence of a pronounced finite-depth interfacial coupling effect in the TiTe2/Bi2Te3 heterostructure. Such coupling not only modifies the electronic states near the interface but also influences the overall electronic structure of the overlayer. This study provides insight into the interfacial electronic behavior of metal/topological insulator vdW heterostructures and offers a useful reference for future investigations of topological proximity effects and the design of related two-dimensional quantum devices.
