本論文主要研究不同閘汲極間距並應用超音波熱裂解噴霧法沉積摻雜氯離子及氟離子之氧化鋁於鰭式氮化鋁鎵/氮化鎵高電子遷移率場效電晶體之研究，並比較平面式結構與鰭式結構間的差異，以研究閘汲極間距對元件特性的影響並判斷出最佳的元件設計參數。
為了解超音波熱裂解噴霧法沉積摻雜氯離子及氟離子氧化鋁之氧化層組成，本論文中將採用化學分析電子光譜儀、穿透式電子顯微鏡、原子力顯微鏡來進行量測與探討。從化學分析電子光譜儀分析出的結果中可以證實氧化層中的化學成分組成為氧化鋁。穿透式電子顯微鏡的分析結果中觀察到超音波熱裂解噴霧法沉積之氧化鋁在鰭式通道的側壁部分仍保有良好的階梯覆蓋度及薄膜均勻度。採用原子力顯微鏡可以分析氧化層薄膜之粗糙度和均勻度，結果顯示未摻雜之氧化鋁粗糙度為0.95奈米、摻雜氯離子之氧化鋁粗糙度為0.9奈米、摻雜氟離子之氧化鋁粗糙度為1.05奈米。在設計方面，將鰭式結構應用進三-五族的元件中，相較於傳統型的結構，此作法能極大的降低次臨界導通對元件的不良影響、提升閘極對通道的控制能力，而三-五族自我加熱效應導致特性衰減的問題在此結構可獲得改善，另外我們發現鰭式結構可以提升二維電子雲的驅動量並進一步提升元件的閘極控制能力。 
在本論文中，蕭特基鰭式結構閾值電壓為-5.3伏特，未摻雜氧化鋁之鰭式結構閾值電壓為-5.7伏特、摻氯離子之氧化鋁鰭式結構閾值電壓為-3伏特、摻氟離子之氧化鋁鰭式結構閾值電壓為-4.5伏特，應用摻氯離子之氧化鋁可使閾值電壓往正偏移動約to 2.7伏特。基於三-五族材料多應用在高功率元件上，我們設計閘汲極為3μm、5μm、7μm三種不同的間距，在閘汲極為7μm會有最好的崩潰電壓表現但電流特性表現較差，而在閘汲極為3μm時，電流表現最佳但崩潰電壓則最差。此外，不同的閘汲極間距製作出的元件可以應用在不同的商業需求上。

This thesis proposed the investigation of different gate-drain spacings and the effects of halogen doping aluminum oxide (Al2O3) on the AlGaN/GaN fin structure high electron mobility transistors (HEMTs). Compared the difference between the planar structure and fin structure, we study the influence of gate drain spacings to find the best device characteristics.
In order to understand the composition of oxide layer doped with chloride ion and fluorine ion, we utilized the electron spectroscopy for chemical analysis (ESCA), transmission electron microscopy (TEM), atomic force microscopy (AFM) in the research. By the transmission electron microscope (TEM) analysis results, we observed that the thickness of aluminum oxide (Al2O3) deposited by the ultrasonic pyrolysis spray method still had good step coverage and film uniformity in the sidewall portion of the fin channels. The roughness and uniformity of the oxide film were analyzed by atomic force microscopy (AFM). The results showed that the un-doped Al2O3 had a roughness of 0.95 nm, the roughness of Al2O3 doped with chloride ions (Cl-) is 0.9 nm and the roughness of Al2O3 doped with fluorine ions (F-) is 1.05 nm.
The fin-type structure is applied to the III-V compound materials, which can greatly reduce the effect of the subthreshold swing and drain-induced barrier lowing (DIBL). In addition, we find that the fin-type structure can increase the driving force of the two-dimensional electron gas and further enhance the gate controllability of the devices. Furthermore, self-heating effect of the III-V compound materials will be improved by the fin structure.
In our research, the Schottky fin-type structure has a threshold voltage of -5.3 V, the fin-type structure with un-doped Al2O3 has a threshold voltage of -5.7 V, the fin-type structure with Al2O3:Cl has a threshold voltage of -3 V, and the fin-type structure with Al2O3:F has a threshold voltage of -4.5 V. The results show that the Al2O3:Cl and Al2O3:F can move the threshold voltage from -6V to -3V and -4.5V, respectively. Based on the application of III-V compound materials on high power devices, we designed three different length of gate-drain (LGD) =3,5,7 μm, the LGD of 7 μm will have the best performance of breakdown voltage, when the LGD is 3 μm, the current is the best, but the breakdown voltage is the worst. In addition, different gate-drain spacings can be applied on different device requirements.

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