本研究以溶膠凝膠法(sol–gel method)製備三氧化二鉻(Cr₂O₃)薄膜，並探討其於後段製程(Back End of Line, BEOL)薄膜電晶體(TFT)應用前之材料電性與界面特性。由於三氧化二鉻具有化學穩定性高、寬能隙、且理論上可作為P型氧化物半導體的特性，因此被視為具潛力的氧化物半導體。然而，其實際導電機制與缺陷行為尚未釐清，限制了其元件應用發展。
在實驗中，三氧化二鉻薄膜以溶膠凝膠法沉積於c軸藍寶石基板上，並藉由控制退火溫度調變其電洞濃度。金屬電極則以電子束蒸鍍(E-gun evaporation)製作。霍爾量測結果顯示，三氧化二鉻薄膜呈現P型導電特性，且載子濃度可隨退火條件有效控制。透過變溫電阻量測分析其導電機制，結果符合最鄰近躍遷(Nearest Neighbor Hopping, NNH)模式，所得活化能與室溫熱能相近，顯示載子於室溫下主要以熱激發方式在局域態間遷移。
進一步以三氧化二鉻薄膜與鋁電極形成蕭特基二極體進行電性分析。順向偏壓I–V 量測顯示極高的理想因子(n≫1)，且重複量測中出現明顯電流衰減，推測為鋁與三氧化二鉻界面生成氧化層(Al₂O₃)所致。該氧化層會妨礙空乏區形成，導致元件整流特性偏離理想蕭特基行為。另一方面，反向恢復電流測試結果顯示存在大量恢復電荷(Qrr)，結合變溫電阻量測結果可推論，三氧化二鉻薄膜中含有高密度局域態與陷阱態，能有效捕獲並釋放載子，影響整體載子傳輸與介面反應。
綜合以上結果，溶膠凝膠法製備之三氧化二鉻薄膜具有導電性與結構穩定性，但其電性明顯受缺陷態與界面氧化層影響。此現象顯示材料內部存在大量局域態與陷阱態，導致其載子傳輸以躍遷為主，並使蕭特基接面偏離理想行為。本研究結果為後續以三氧化二鉻作為BEOL可兼容薄膜電晶體主動層之前置研究提供了重要依據，未來若能進一步控制界面氧化與降低陷阱密度，預期可顯著提升其元件應用潛力。

This study investigates the electrical and defect characteristics of chromium oxide (Cr₂O₃) thin films prepared by a sol–gel process and analyzes their carrier transport behavior in Al/Cr₂O₃/Ni Schottky diodes. Owing to its tunable p-type conductivity and compatibility with low-temperature processing, Cr₂O₃ is a promising material for back-end-of-line (BEOL) electronic applications. The results show that the hole concentration increases with annealing temperature due to enhanced oxygen vacancy formation, which improves film conductivity. Temperature-dependent resistivity measurements reveal that the conduction follows the nearest-neighbor hopping (NNH) mechanism, indicating thermally activated carrier transport among localized states at room temperature. The forward I–V characteristics of the Schottky diodes can be analyzed using thermionic emission theory; however, the ideality factor is significantly larger than unity, suggesting that carrier transport is dominated by interfacial oxide formation and trap-assisted tunneling. Successive measurements show a gradual current decay, indicating interface degradation or trap filling effects. The reverse recovery measurement also exhibits a large recovery charge, implying the presence of deep traps capable of capturing and releasing carriers. These findings demonstrate that carrier transport in sol–gel-derived Cr₂O₃ is strongly influenced by traps and interfacial effects, providing important insights for process optimization and interface engineering in future BEOL-compatible p-type oxide semiconductors.

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