本論文主要探討有機金屬化學氣相沉積法(Metal-Organic Chemical Vapor Deposition, MOCVD)成長之銳鈦礦(anatase)與金紅石(rutile)結構二氧化鈦(titanium dioxide; TiO2)奈米柱(nanorods)之光電導(photoconduction)效率及其物理機制。從環境變化光電導實驗發現其銳鈦礦與金紅石結構二氧化鈦奈米柱結構都具有共通的氧敏化光電導機制(oxygen-sensitized photoconduction mechanism)。在光功率相依的光電流反應實驗中，藉由計算代表材料本質光電導效率的歸一化增益(normalized gain)，發現銳鈦礦結構之歸一化增益高於金紅石結構約一個數量級，其歸一化增益在光強度0.016 W/m2下最高可達1.75×10-4 m2/V。進一步利用時間解析之光電導量測所獲得之載子活期，發現造成銳鈦礦結構二氧化鈦奈米柱具有較佳的光電導效率之原因並非來自於載子活期(lifetime)的差異，主要是由較高的遷移率(mobility)所造成。

We comparatively investigated the photoconduction (PC) efficiency and its physical mechanism of the anatase and rutile titanium dioxide (TiO2) nanorods with single-crystalline quality grown by cold-wall metal-organic chemical vapor deposition (MOCVD). The anatase TiO2 nanorods revealing similar oxygen-sensitized PC mechanism as the rutile ones has been confirmed by the environment-dependent PC measurement. The normalized gain which has the physical meaning of intrinsic PC efficiency has been defined and discussed for the as-grown TiO2 nanorods. It is found that the anatase TiO2 nanorods exhibit higher normalized gain for near one order of magnitude than the rutile phase. The optimal normalized gain of the anatase nanorods can reach 1.75×10-4 m2/V at the light intensity of 0.016W/m2. By the time-resolved PC measurement, the physical origin leading to the superior PC efficiency in anatase TiO2 nanorods in comparison to the rutile phase is proposed to be the probably higher electron mobility rather than carrier lifetime.

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