實驗透過分子束磊晶(Molecular Beam Epitaxy, MBE)成長單層Bi2Se3薄膜或雙層Bi2Se3/WS2薄膜，使用基板溫度370℃、鉍溫度450℃，調控流率比Bi：Se ~1:15。磊晶之後以臨場反射高能電子繞射儀(Reflection high-energy electron diffraction, RHEED)及原子力顯微鏡(Atomic Force Microscope, AFM)確認表面平整度；結構表徵以X光繞射儀(X-ray diffractometer, XRD)分析晶格結構以及X光反射率量測(X-ray reflectivity, XRR)計算樣品厚度；透過X射線光電子能譜 (hard X-ray Photonemission, HAXPES)確認元素組成。
透過自旋幫浦量測鐵磁共振(Ferromagnetic resonance, FMR)及自旋電壓，可以得到其樣品之有效阻尼係數(αeff)、飽和磁化率(Meff)和分離電壓訊號，加上四點電阻量測樣品片電阻(Rs)後，分別計算出自旋流J_c^2D 及電荷流 J_s^3D分析自旋流對電荷轉換效率。結果顯示，在單層Bi2Se3薄膜厚度由薄至厚呈現先略微降低再升高至飽和的變化。在薄膜厚度介於 6–8 nm 時，由於拓樸表面態尚未完全形成，薄膜內部上下表面態耦合效應仍存在，當薄膜厚度增加至10 nm 時，拓樸表面態已穩定，因此轉換效率出現明顯提升；薄膜厚度增加至12 nm 後，部分表面態轉換所產生的電荷流可能經由體態通道被分流，抑制整體轉換效率提升。雙層Bi2Se3/WS2薄膜相較單層Bi2Se3 效率將低，透過文獻以及相似系統實驗結果推測為雙層Bi₂Se₃/WS₂ 形成的完整的拓樸表面態所需厚度更高。轉換效率至10 nm仍為下降趨勢，直至10-12nm的轉換效率才有顯著提升。其中異質結構整體轉換效率低於單層拓樸絕緣體系統為拓樸表面態（Topological Surface States, TSS）與Rashba 效應（Rashba Effect）競爭。
拓樸表面態與介面因對稱性破缺所誘導的 Rashba 效應，兩者在動量空間（k-space）中雖然都具備自旋-動量鎖定特性，但在費米面附近的自旋性（Spin Helicity）方向是相反的。這種反向的自旋流在傳輸過程中產生了破壞性干涉（Destructive Interference），相互抵銷，導致整體的自旋轉換效率不增反減。綜上所述，本研究證明了高質量 TI/TMD 異質結構的可行性，更揭示了介面能帶工程在自旋電子元件設計中的關鍵角色。要提升基於拓樸材料的自旋軌道轉矩（SOT）元件效能，必須審慎選擇 TI 與 TMD 的搭配，避免 N-N 型介面帶來的自旋抵銷效應。未來在設計高效能 SOT-MRAM 或自旋邏輯元件時，建議朝向 P-N 型異質結構或調整能帶排列方向進行優化，以實現 Rashba 效應與拓樸表面態的加成作用（Constructive Interference），進而最大化自旋流的產生與傳輸效率。

High-quality monolayer Bi₂Se₃ films and Bi₂Se₃/WS₂ heterostructures were grown by molecular beam epitaxy and systematically characterized using structural, morphological, and spectroscopic techniques. Spin pumping combined with ferromagnetic resonance and spin-voltage measurements was employed to quantify the spin-to-charge conversion efficiency. Monolayer Bi₂Se₃ exhibits a nonmonotonic thickness dependence, with a pronounced enhancement at 10 nm due to the stabilization of topological surface states, followed by saturation caused by bulk shunting effects. In contrast, Bi₂Se₃/WS₂ heterostructures show reduced conversion efficiency and require a larger critical thickness for effective surface-state formation. This reduction is attributed to the competition between topological surface states and the interfacial Rashba effect, which possess opposite spin helicities and lead to destructive interference. These results highlight the importance of interfacial band engineering for optimizing spin–orbit torque devices based on topological insulator heterostructures.

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