熱退火金/n型矽蕭特基侷域式表面電漿子共振感測器之製作與光電特性分析

Abstract

本研究聚焦於金/矽（Au/n-Si）金屬–半導體異質接面在不同介質環境下之光電特性與載子傳輸行為，透過理論推導、數值模擬與實驗驗證進行多層次分析。初步以傳輸矩陣法與米氏理論探討表面電漿共振與侷域式共振模態，並透過多物理場模擬分析空氣與水中場型分佈，揭示折射率與結構非對稱性之影響。 實驗方面，製作金/矽晶片並量測其電流–電壓特性，結果顯示經熱退火處理可有效提升導通性，使導通電流提升逾 200%。裝置於 850 奈米光源下展現穩定微安培等級光電流，並於溶液環境中驗證光響應隨折射率升高而下降，符合侷域式表面電漿子共振感測原理。 進一步引入甲基化與去甲基化 HOXB6 DNA 分子進行分子修飾，形成具偶極性之自組裝單層。其偶極場除促進熱載子注入、增強光電流外，亦可能降低界面缺陷密度，進一步改善元件導通與感測表現。 綜上所述，本研究成功建立電流型侷域式表面電漿子共振感測平台，具微型化與生醫感測潛力，未來可應用於穿戴式與智慧型感測元件之開發。

This study presents a systematic investigation of Au/n-Si metal–semiconductor heterojunctions for current-mode localized surface plasmon resonance (LSPR) sensing. Through theoretical modeling, numerical simulation, and experimental validation, we analyze how dielectric environment and surface modification affect optoelectronic properties. Using the transfer matrix method and Mie theory, we model SPR and LSPR characteristics and field distributions, revealing that water induces leaky modes while air enhances confinement. Experiments confirm diode-like behavior with enhanced current after thermal annealing. Under 850 nm illumination, the devices generate stable microampere-scale photocurrent. Refractive index sensing with DI water, NaCl, and glucose shows a decreasing trend in photocurrent as refractive index increases, consistent with LSPR mechanisms. Moreover, self-assembled monolayers of methylated and unmethylated HOXB6 DNA introduce interfacial dipoles aligned with the built-in electric field. Although Schottky barrier height slightly increases, the dipole-induced field assists hot carrier injection, enhancing photocurrent. DNA adsorption may also passivate interfacial defects. These results demonstrate the feasibility of integrating LSPR and Schottky barrier effects for label-free biosensing, with potential applications in wearable and miniaturized diagnostic platforms.