藉由液相沉積法在接近室溫時成長一有效並且低成本的二氧化矽介電層在此篇論文中將被描述。此方法在溫度40℃時沉積速率大約為每小時55nm左右，並且可獲得較高的崩潰電場超過7.3MV/cm與較低的漏電流在電場為0.9MV/cm時約10-7A/cm2左右，並且二氧化矽成長在氮化鎵或氮化鋁鎵上的缺陷密度約為3×1011cm2eV-1。在此實驗中，我們將會用螺旋電子能譜分析儀和X射線光電子能譜分析儀量測氧化層的特性。除此之外，LPD法的自我校準與不易和外界產生反應可使元件的製造更便易。於是，用液相沉積法成長二氧化矽當作閘極介電層對於AlGaN/GaN異質接面金氧半場效電晶體將被驗證。在製程中，歐姆接觸所鍍的金屬為Ti/Al/Au (80nm/100nm/130nm)，而所得到的歐姆特性接觸阻抗為2.17×10-5 Ω－cm2。在蝕刻方面，本實驗採用光輔助化學濕式蝕刻(PEC)，並將原本的白金電極用氧化劑K2S2O8來取代。而在MOSHFET閘極尺寸長度為2 um、寬為100 um處，當Vgs=-4V, Vds=12V，我們所得到的轉導最佳約為53 mS/mm，而汲極最大電流約為650mA/mm。接著，我們將比較AlGaN/GaN MOSHFET 和 HFET兩種元件的特性，並且由MOSHFET，我們可獲得較小的漏電流，較大的閘極擺盪電壓和較寬且平的轉導範圍。

　　An efficient and low cost approach for depositing uniform silicon dioxide layers on GaN by liquid phase deposition (LPD) that is near room temperature will be described. The deposited rate of SiO2 is about 55nm/hr. at 40 ℃. Breakdown electric field as high as 7.3MV/cm and leakage current as low as 10-7A/cm2 at 0.9MV/cm for the deposited oxide layers can be achieved. The trap density of SiO2 on GaN or AlGaN is about 3×1011cm2eV-1. Auger Electron Spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) will be used to characterize the oxide properties. Self-align and self- passivation process of LPD can ease the device fabrication. AlGaN/GaN metal oxide semiconductor heterostructure field effect transistors (MOSHFETs) with liquid phase deposited SiO2 as the gate dielectric will be demonstrated. Ti/Al/Au (80nm /100nm/130nm) with a specific contact resistance of 2.17*10-5 Ω-cm2 can be achieved for source/drain ohmic contacts. Photo electrochemical wet etching with K2S2O8 (peroxydisulfate) as the oxidizing agent instead of the platinum electrode is used for device isolation. The best transconductance of AlGaN/GaN MOSHFET for gate length of 2um with 100um long in width is about 53 mS/mm at Vgs=-4V, Vds=12V and the maximum drain saturation current is 650 mA/mm. Comparison between the AlGaN/GaN MOSHFETs and heterostructure field effect transistors (HFETs) will also be made. Lower leakage current and larger gate swing voltage and flatter transconductances range can be seen in MOSHFETs.

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