本實驗主要探討熱退火溫度對於二氧化鈦(Titanium dioxide, TiO2)與氧化鋅(Zinc oxide, ZnO)的影響, 光電導效率及表面物理機制. 利用定義歸一化增益(Γn), 去除實驗參數的貢獻, 分別探討TiO2與ZnO之光電導效率. 可以發現將TiO2奈米管熱退火750oC後, 其光電導效率比原始的TiO2奈米管光電導效率約高了100倍, 推測原因為熱退火提供能量使得內部結晶性變得更好, 以至於電子在內部傳輸的阻力減少, 使得光電導效率提升. 在ZnO的部分, 光電導效率也與溫度有著相依的關係, 隨著熱退火的溫度越高, 原本的混亂多晶相會轉變為有序的多晶相, 且由於ZnO只擁有單一晶相, 所以當其結晶性越好時, 光電導效率也會隨之提升. 另外, 觀察藉由環境變化之光電導量測去探討奈米線之氧分子效應, 結果顯示金屬氧化物的光電流於氧氣下減少的機制與氧化物半導體的氧敏化機制相同, 真空環境下的光電流高於氧氣環境下的光電流, 其原因為氧氣分子的吸附會捕捉奈米線表面的電子而變成帶負電的氧負離子, 導致光電流下降, 所以在氧分子減少時, 光電流就會上升.

In this thesis, we investigated the relationship of the annealing temperature with the photoconduction efficiency and physical mechanism of titanium dioxide and zinc oxide. The normalized gains, which determine the intrinsic photoconduction efficiencies, were defined and compared in two kinds of metallic oxide. By excluding the contributions of experimental parameters, our results indicated the magnitude of normalized gains of TiO2 nanowire (NW) for post-annealed TiO2 NW was one hundred times higher than pristine TiO2 NW. This could be due to the crystalline could be enhanced by the annealing procedure. Therefore, the photoconduction efficiency increased with the decreasing of the resistance. Meanwhile, the photoconduction efficiency of ZnO also had the same relationship with annealing temperature. The crystalline of ZnO changed from disordered polycrystalline to ordered polycrystalline, and therefore increased the photoconduction efficiency. Besides, the molecular effect of TiO2 NW and ZnO NW were investigated by the environmental dependent photoconductivity measurement. In vacuum, the photocurrent was higher than in oxygen due to the oxygen molecular capture the electrons and absorbed on the surface of oxide semiconductor. The research exhibited that the result consistent with the mechanism of oxide semiconductor.

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