應用於低電壓無線通訊之高效率砷化鎵功率金屬半導體場效電晶體之研究

Abstract

本實驗係以縮短汲極與源極間之距離來製造應用於低電壓無線通訊之 高效率砷化鎵功率金屬半導體場效電晶體(Power MESFET)。文中詳述了各 個製程步驟的技術，並藉著精確的製程控制達成優良的元件特性。 在 本論文中論及了此MESFET元件的直流與微波功率特性。一0.7μm×3.36 mm尺寸的元件具有飽和電流密度245.5 mA而其1.9 GHz、2.0 V操作下 有0.2 W的最大輸出功率，此時的功率效益高達66.0 %。此外，本論文亦 論及了元件的模型來模擬元件的直流及交流特性。最後亦比較兩種不同汲 極與源極距離(3 mm 與5 mm)的功率特性。證實較小的汲極與源極之距離 具有較佳之特性。 實驗的結果顯示以縮短汲極與源極間之距離來製造 的MESFET能提供高的功率效益。其亦在下一代的手攜式無線通訊應用方面 具有極大的發展潛力。 A high efficiency GaAs power MESFET for low voltage applications was developed in this research. The device is ideal for the hand-held phone applications for next generation wireless communication. The device was designed and processed with reduced drain-to-source spacing. A simple method was also used to simulate the device performance and fit the DC and RF characteristics observed. The DC characteristics of the MESFET were measured. The 0.7μm×3.36 mm device exhibited a saturation current density of 245.5 mA/mm (at VGS= 0 V) with a gate to drain breakdown voltage of 15 V. The maximum transconductance of the device was 145 mS/mm and the pinch-off voltage was -3.4 V. The knee voltage was 1.4 V and the effective knee voltage was as low as 0.5 V. The microwave power performance of the 0.7μm×3.36 mm device operating at 1.9 GHz and 2.0 V drain voltage demonstrated a maximum output power of 0.2 W with a 66.0 % power-added efficiency (PAE). These results indicate that the MESFET developed with reduced drain- to-source spacing is very useful for next generation wireless hand-held phone applications with low bias voltages.