本論文在高阻值矽基板(111)上的氮化鋁鎵/氮化鎵試片製作出兩種不同閘極結構的元件，分別為傳統的蕭特基接觸以及金氧半閘極結構，並且探討兩種元件直流與高頻特性的影響。同時，本實驗也有委託公司代工目前製程發展較成熟的高電子遷移率電晶體與實驗室自行製作的元件進行比較。
在實驗室製作的閘極線寬0.5μm之元件中，於直流特性的部份，傳統高電子遷移率電晶體之飽和電流密度與最大轉導增益分別為1255mA/mm與278mS/mm而金氧半-高電子遷移率電晶體則為995mA/mm與206 mS/mm；在高頻特性部分，傳統的高電子遷移率電晶體之fT與fmax分別為10.2 GHz與20 GHz，受益於較高的直流轉導，二者數值皆高於金氧半-高電子遷移率電晶體的4.9 GHz與8.3 GHz。
由公司代工的試片，有著閘極線寬0.25 μm的元件，飽和電流密度與最大轉導增益分別為1.88A/mm與711mS/mm，明顯地比於實驗室自行製作的試片高上許多，而截止頻率與最大震盪頻率也是較高27.9GHz與 43.9GHz。

In this thesis, we fabricated and measured AlGaN/GaN HEMT and MOSHEMT on a high resistivity Si (111) substrate and compared their DC and RF characteristics. There are two types of gate structures to be studied: one is a traditional Schottky gate, and the other is a metal-oxide-semiconductor (MOS) gate. In this study, devices fabricated in the lab are also compared with devices fabricated through a foundry service.
For the DC characteristics of the devices fabricated in the lab, which features a gate length of 0.5 μm, the saturation current ID,sat density and the extrinsic maximum transconductance (Gm) of HEMT and MOS-HEMT are1.255 A/mm and 278 mS/mm, and 0.995 A/mm and 206 mS/mm, respectively. For high-frequency characteristics, HEMT shows a cutoff frequency fT of 10.2 GHz and a maximum oscillation frequency fmax of 20 GHz, which are also higher than the MOSHEMT’s values of 4.9 GHz and 8.3 GHz because of the higher transconductance.
For the devices through a foundry service with a gate length of 0.25 μm, the saturation current density and extrinsic maximum transconductance are 1.88A / mm and 711mS / mm respectively, which are significantly higher than the devices made in the lab. The cut-off frequency and maximum oscillation frequency reach 27.9GHz and 43.9GHz.

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