在本文中，藉由使用液相沉積法我們成功的將二氧化鈦氧化薄膜沉積於氮化鎵材料上，液相沉積法是一種相當便宜又容易使用的氧化層沉積技術，並且可於室溫下使用，沉積的速率約可達到每小時40奈米。為了分析液相沉積法所沉積之二氧化鈦薄膜，我們使用X光譜儀、歐傑電子分析儀、二次離子質譜儀與能量散佈分析儀來分析氧化層的化學組成成分和元素鍵結，掃描電子顯微鏡及原子力顯微鏡則用來觀察薄膜的表面狀態。當我們成長75奈米厚的氧化層時，氧化層漏電流密度可達到10-5A/cm2而電場約為0.2MV/cm，崩潰電場則可以達到1MV/cm以上。在經過高純度氮氣環境下的退火處理後，折射係數可增加至2.24，藉由X光繞射我們觀察到二氧化鈦氧化層由非晶相轉換至銳鈦礦及金紅石相且結晶顆粒增大，表面粗糙度也有所改善，我們也嘗試利用液相沉積法來成長二氧化鈦/二氧化矽雙層結構。在經過400℃退火處理後，二氧化鈦氧化層漏電流密度可達到10-5A/cm2而電場約為1MV/cm，崩潰電場則可以達到2.9MV/cm，在800℃退火處理後，最高的相對介電常數可以達到40.6。

TiO2 oxide has been deposited on GaN material through the liquid phase deposition method (LPD) which provides a low-cost and low-complex method in forming oxide layers at room temperature. The deposition rate is about 40nm/hr. Augar electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), second ion mass spectrometer (SIMS), and energy-dispersive spectrometer (EDS) are used to analyze chemical composition. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are likewise used to observe the surface of the LPD-TiO2 oxide. The leakage current is about 10-5A/cm2 at 0.2MV/cm and the breakdown field is more than 1MV/cm when the oxide thickness is 75nm. Upon annealing under an atmosphere of high purity N2, the refractive index increased significantly. It is observed that the crystal phase of TiO2 transformed from the amorphous to the anatase and rutile phases and the crystal size increased by X-ray diffraction (XRD). Moreover, surface roughness improved significantly after thermal treatment. We also attempted to deposit TiO2/SiO2 stack layer structure by LPD process. It is observed that the leakage current is about 10-5A/cm2 at 1MV/cm electric field and the breakdown field can reach 2.9MV/cm after annealing at 400℃ for 30 minutes. Furthermore, the highest relative dielectric constant is 40.6 after annealing at 800℃.

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