三硫化二銻（Sb₂S₃）因其於非晶態與結晶態之間具有顯著之光學常數 對比，已被視為下一代相變光學元件之重要候選材料；然而，現有化學浴 沉積（Chemical Bath Deposition， CBD）法所製備之 Sb₂S₃ 薄膜文獻多以穿 透率、反射率與能隙分析為主，缺乏完整之折射率（n）與消光係數（k） 色散資料，限制其於精確光學設計之應用。本研究旨在以 CBD 法製備高 折射率低損耗之 Sb₂S₃ 光學等級薄膜，並建立其完整光學常數資料庫。 實驗採用 SbCl₃ 溶於丙酮與 Na₂S₂O₃ 作為前驅物，系統性地優化沉 積參數，包括反應溫度、沉積時間及基板前處理條件。研究發現室溫沉積 會導致反應速率過快，造成薄膜表面粗糙；經製程優化後，確立以 6 ~ 8 °C 低溫沉積 5 小時並配合 SnCl₂ 基板前處理為最佳製程條件，可獲得表 面平整且光學品質優良之非晶態薄膜。 在光學特性分析方面，本研究開發了基於 Tauc-Lorentz 模型之 MATLAB 橢偏儀擬合程式，並創新性地引入正規化均方誤差 （Normalized MSE）演算法，有效解決了傳統方法中 Ψ 與 Δ 權重不均 的問題，並透過 SiN 樣品驗證，證實此演算法能準確還原已知材料參 數。擬合結果顯示，非晶態 Sb₂S₃ 薄膜的折射率 n ≈ 2.33 ~ 2.43（@ 633 nm）、消光係數 k ≈ 0.26 ~ 0.28（@ 450 nm），光學能隙約為 2.09 ~ 2.15 eV，與文獻報導值（2.20 ± 0.05 eV）相符，且折射率落於本研究設定之 i 目標範圍（n ≈ 2.3 ~ 2.5）內，顯示 CBD 製程亦可達到接近真空製程之光 學品質。透過 Tauc plot 線性迴歸分析，判定該材料為間接能隙半導體， 此結論亦由光激發光（Photoluminescence， PL）量測中無明顯發光峰的結 果所佐證。 退火效應研究顯示，隨著退火溫度從 250°C 升至 300°C，薄膜發生 顯著的厚度收縮與相變，能隙從約 2.09 ~ 2.15 eV 降至約 1.44 eV，結晶 度達 93.77%，晶相鑑定為正交晶系 Sb₂S₃。然而，研究結果顯示，250°C 以上的退火會導致薄膜品質劣化。 綜合而言，本研究不僅成功優化了低溫 CBD 製程，更關鍵的是填補 了 CBD 法製備 Sb₂S₃ 薄膜之完整 n、k 色散資料缺口。本研究建立了一 套涵蓋『高品質製程、高精度擬合演算法與退火相變效應』之完整資料 庫，製得之薄膜折射率（n ≈ 2.33~2.43）已接近真空製程水準 （2.6~2.8），證明了低成本化學製程能提供精確的光學設計參數，為 Sb₂S₃ 於相變光學元件之實際應用奠定堅實的材料基礎。 關鍵詞：三硫化二銻、化學浴沉積、橢偏儀、Tauc-Lorentz 模型、光 學能隙、退火效應。;Antimony sulfide (Sb₂S₃) has emerged as a promising candidate for next generation phase-change photonic devices due to its significant optical contrast between amorphous and crystalline states. However， existing studies on chemical bath deposition (CBD)-fabricated Sb₂S₃ thin films primarily rely on transmittance， reflectance， and bandgap analyses， lacking complete refractive index (n) and extinction coefficient (k) dispersion data， which limits their direct application in precision optical design. This study aims to fabricate high refractive-index， low-loss optical-grade Sb₂S₃ thin films via CBD and establish a complete optical constants database. The experimental approach employs SbCl₃ dissolved in acetone and Na₂S₂O₃ as precursors， with systematic optimization of deposition parameters including reaction temperature， deposition time， and substrate pretreatment conditions. The investigation reveals that room-temperature deposition results in excessively rapid reaction rates， leading to rough film surfaces. Through process optimization， optimal fabrication conditions were established: low-temperature deposition at 6 ~ 8 °C for 5 hours with SnCl₂ substrate pretreatment， yielding amorphous films with smooth surfaces and excellent optical quality. For optical characterization， this research developed a MATLAB-based ellipsometry fitting program utilizing the Tauc-Lorentz model， innovatively incorporating a normalized mean square error (Normalized MSE) algorithm that effectively addresses the weight imbalance issue between Ψ and Δ parameters inherent in conventional methods. Validation through SiN samples confirmed the algorithm′s capability to accurately reproduce known material parameters. The measured refractive index is n ≈ 2.33–2.43 (at 633 nm)， and the extinction coefficient is k ≈ 0.26–0.28 (at 450 nm)， with an optical bandgap of iii approximately 2.09–2.15 eV， consistent with reported values (2.20 ± 0.05 eV). The achieved refractive index falls within the target range (n ≈ 2.3–2.5) of this study， demonstrating that CBD can deliver optical quality comparable to vacuum-based processes. Tauc plot analysis indicates that the material is an indirect bandgap semiconductor， further supported by the absence of distinct emission peaks in photoluminescence (PL) measurements. Annealing effect studies reveal that as the annealing temperature increases from 250°C to 300°C， the films undergo significant thickness contraction and phase transformation， with the bandgap decreasing from approximately 2.09 2.15 eV to about 1.44 eV and crystallinity reaching 93.77%. The crystalline phase was identified as orthorhombic Sb₂S₃. However， results indicate that annealing above 250°C leads to film quality degradation. In summary， this research not only successfully optimized the low temperature CBD process but， more critically， bridged the gap regarding the complete refractive index (n) and extinction coefficient (k) dispersion data of CBD-fabricated Sb₂S₃ thin films. By establishing a comprehensive database encompassing high-quality fabrication processes， high-precision fitting algorithms， and annealing phase-change effects， this study demonstrates that the fabricated films achieve a refractive index (n ≈ 2.33–2.43) approaching that of vacuum-based processes (2.6–2.8). This proves that low-cost chemical processes can provide precise optical design parameters， thereby laying a solid material foundation for the practical application of Sb₂S₃ in phase-change photonic devices.. Keywords: Antimony sulfide， Chemical bath deposition， Ellipsometry， Tauc-Lorentz model， Optical bandgap， Annealing effect
