本論文主要利用二氧化鈦絕緣層於n型鍺基板製備MIS結構，搭配各式的金屬來探討歐姆接觸之特性，其中鎢與二氧化鈦結合的MIS結構具備最低的蕭特基位能障，為74.6毫電子伏特。由於二氧化鈦的熱穩定性不佳，經過退火處理後容易有結晶現象發生，且結晶情況與絕緣層厚度有明顯的相依性。因此利用射頻濺鍍的氮電漿或原子層沉積的金屬先驅物如鋁(Al)、鉿(Hf)、鋯(Zr)元素於二氧化鈦絕緣層作為摻雜，觀察退火後電性之改善程度，發現沉積後氫氣退火(PDHA)能有效地改善電性表現，並確認金屬及氧化物之界面擴散對熱穩定性有顯著的影響。

In this thesis, a TiO2 insulator is used to fabricate MIS structure with various metal top layers on n-type Ge substrate to investigate the Ohmic contact characteristics. The combination of tungsten and TiO2 for MIS contact depicts the lowest barrier height about 74.6 meV. Nevertheless, all splits are easily crystallized after annealing process since the thermal stability of TiO2 is poor. Also, the crystalline phenomenon is dependent on the thickness of insulator. Therefore, one can observe the variations in the electrical characteristics after annealing by doping in TiO2 with nitrogen plasma of RF sputter or metal precursors of ALD, such as Al, Hf, and Zr elements. The characteristics are effectively improved after the PDHA process. Furthermore, there is a significant influence on thermal stability owing to the interlayer mixing between metal and oxide layers.

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