拓樸絕緣體Bi2Se3奈米片經SiO2、TiO2 與Ag 修飾 後之材料性質變化探討;Exploration of the Changes in Material Properties of Topological Insulator Bi2Se3 Nanosheets after Surface Modification with SiO2, TiO2, and Ag

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Title:	拓樸絕緣體Bi2Se3奈米片經SiO2、TiO2 與Ag 修飾後之材料性質變化探討;Exploration of the Changes in Material Properties of Topological Insulator Bi2Se3 Nanosheets after Surface Modification with SiO2, TiO2, and Ag
Authors:	劉益如;Liu, Yi-Ru
Contributors:	化學工程與材料工程學系
Keywords:	拓樸絕緣體;硒化鉍奈米片;表面改質;Topological Insulators;Bismuth Selenide Nanosheet;Surface Modification
Date:	2025-08-26
Issue Date:	2025-10-17 11:41:11 (UTC+8)
Publisher:	國立中央大學
Abstract:	拓樸絕緣體（Topological Insulators, TIs）屬於具有特殊能帶結構的量子材料，其體態表現為絕緣，但在表面或邊界上卻存在受拓樸相保護的導電態。這些表面態因具自旋極化與無散射傳輸特性，使得電子能夠穩定地沿表面傳輸而不受雜質、缺陷或局部擾動干擾，展現出高度穩定性。此外，其表面電子結構對外在環境變化（如分子吸附、界面改質）具有高度響應性，因此在設計高靈敏度與高穩定性之感測器，尤其是生物感測器領域中，展現出極大應用潛力。然而，原始拓樸材料難以同時滿足感測器對靈敏度、穩定性與選擇性的多重需求，需透過表面改質技術加以強化。本研究以 Bi2Se3 奈米片為基礎，藉由表面改質技術將SiO2、TiO2 與銀等修飾層製備於奈米片表面，並結合多項表徵技術（XPS、XRD、SEM、UPS、UV-vis）確認改質層覆蓋成功且主體晶體結構完整。UPS 分析揭示各改質策略對表面態與能階分佈造成差異：SiO2 修飾呈現功函數下降與 VBM 上移，反映表面偶極效應；TiO2 與 Ag 修飾則因界面電荷重組導致功函數上升，藉由結構與能階角度初步分析界面互動對電子性質的調控潛能。 ;Topological insulators (TIs) are a class of quantum materials characterized by a unique band structure. While their bulk remains insulating, their surfaces or edges host topologically protected conductive states. These surface states exhibit spin polarization and dissipationless transport, allowing electrons to propagate stably along the surface without being scattered by impurities, defects, or local perturbations—offering exceptional stability. Moreover, the surface electronic structure of TIs is highly responsive to external stimuli such as molecular adsorption or interfacial modification, making them highly promising for the development of sensors that require both high sensitivity and stability, particularly in the field of biosensing. However, pristine topological materials often struggle to simultaneously fulfill the multifaceted requirements of sensitivity, stability, and selectivity demanded by advanced sensing applications, necessitating surface modification strategies to enhance their performance. In this study, Bi2Se3 nanosheets were employed as the base material. Surface modification was carried out using layers of SiO2, TiO2, and silver (Ag). Multiple characterization techniques—including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet photoelectron spectroscopy (UPS), and UV–visible spectroscopy (UV–vis)—were used to confirm the successful deposition of the modification layers and the preservation of the core crystalline structure. UPS analysis revealed that different surface modifications led to distinct changes in band structure: SiO2 modification resulted in a decreased work function and an upward shift of the valence band maximum (VBM), indicating the presence of a surface dipole effect; in contrast, TiO2 and Ag modifications induced an increase in work function, attributed to interfacial charge redistribution. These observations provide preliminary insight into the potential of interfacial engineering to tune the electronic properties of TIs from both structural and energy-level perspectives.
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