本論文主要在低阻值矽 (111) 基板上進行氮化鋁鎵/氮化鎵高電子遷移率場效電晶體的製作，並探討不同緩衝層結構之元件直流與動態/暫態電性。實驗之磊晶試片於MOCVD腔體中採用不同的長晶條件成長緩衝層與氮化鎵層，研究不同緩衝層與氮化鎵層磊晶品質對製作成元件後之崩潰電壓與電流崩塌的效應。 本實驗在製作電晶體前，先對磊晶試片做一系列的材料分析與探討，其中藉由光激發致螢光頻譜 (PL) 儀探討兩種長晶條件下所成長的緩衝層之YL/BE ratio，也利用二次離子質譜儀解析磊晶結構的摻雜離子縱深對應，並有X射線繞射儀量測磊晶。 低YL/BE ratio、高XRD半高寬值與低碳摻雜濃度的磊晶所製作之元件擁有較高水平崩潰電壓、高垂直崩潰電壓及高三端元件崩潰電壓。接續為了降低元件漏電流，而製作金氧半場效電晶體並探討其直流電性。 本實驗針對蕭特基閘極場效電晶體與金氧半場效電晶體進行暫態量測分析，實驗結果指出structure B磊晶 (低YL/BE ratio、高XRD半高寬值與低碳摻雜濃度的磊晶) 的元件於高偏壓與高電場作用下，電流崩塌效應均明顯降低。此外觀察個別元件在施予不同偏壓後的回復狀況，並再搭配改變溫度的方式以探討個別對應的陷阱活化能階位置。 ;This study investigates the DC and transient performance of AlGaN/GaN high electron mobility transistors with different buffer layers, which were deposited on the low-resistivity Si (111) substrate. Based on the distinct buffer layers and i-GaN layer, we investigated the device breakdown characteristics and current collapse phenomenan. The main targets of this thesis is to analyze the device performance that correlated to the quality of buffer layers. For the evaluation of the epitaxial layer’s quality, photoluminescence(PL) spectroscopy was used to study the YL/BE ratio that corresponds to different buffer layers, followed by the secondary ion mass spectroscopy and XRD measurement. The epitaxial layers with lower YL/BE ratio, higher XRD FWHM, and lower Carbon concentration can result in high horizontal and vertical material breakdown and device breakdown voltages. In order to suppress the gate leakage current, the devices with MIS structure has been fabricated and the gate leakage characteristic were improved. In this study, the transient measurements to analyze the performance of schottky and MIS HEMTs have been carried out. According to the experiments, the results indicate the epilayers with low YL/BE ratio, higher XRD FWHM, and lower Carbon concentration have significiently suppressed the current collapse effect when the devices were operated at high stress and high electric field.