本論文提出新型增強式三閘極氮化銦鋁/氮化鎵穿隧接面高電子遷移率電晶體。此高電子遷移率電晶體之設計包含源極蕭特基穿隧接面以及三閘極等結構，並且利用三閘極控制之穿隧接面使元件具有增強式之特性。此外，利用其高載子濃度以及高遷移率等特性，解決一般穿隧電晶體導通電流過低之情形。
本論文之元件皆以超音波噴塗熱裂解法製備高品質氧化鋁作為閘極介電層。為了確認氧化鋁介電層之化學元素成分組成、表面特性以及氧化層厚度，本論文採用X射線光電子能譜儀、原子力顯微鏡以及穿透式電子顯微鏡等方式進行量測與探討。此外，實驗中藉由製備不同閘-源重疊長度之原件，探究不同閘-源極重疊之距離對於元件整體電性表現之影響，實驗結果顯示重疊約為0.25微米之元件具有最佳電性表現。其元件具有以下特性，臨界電壓為 +1.8 V、開關電流比為 109、次臨界擺幅為 73 V/decade、導通電流約為 453 mA/mm、三端崩潰電壓為 560 V取自漏電流為 0.5 μA/mm時，所有特性與參考元件相比，均有相當明顯之提升。
此外，本論文也探討將上述結構應用在氮化銦鋁/氮化鎵與氮化鋁鎵/氮化鎵兩種磊晶結構上，比較其電性以及元件行為表現，實驗結果顯示時實踐在氮化銦鋁/氮化鎵上之元件具有較佳的輸出特性因為氮化銦鋁/氮化鎵具有較高濃度的二維電子氣，其關閉時之特性也較佳因為氮化銦鋁與氮化鎵晶格較為匹配。此外，本論文所提出之元件在熱穩定性以及低頻雜訊特性方面都具有不錯之表現。上述之特性均顯示本論文所提出之新型增強式三閘極於氮化銦鋁/氮化鎵穿隧接面高電子遷移率電晶體具有相當出色之性能且在高功率之應用具有相當的潛力。

In this thesis, we demonstrate an enhancement-mode tri-gate InAlN/GaN tunnel-junction high electron mobility transistor (TJ-HEMT). This kind of HEMT includes the designs of source Schottky tunnel-junction and tri-gate structure. It takes advantage of the tri-gate-controlled tunnel-junction to achieve an enhancement-mode device. Moreover, low turn-on current issues of conventional tunnel-junction transistors can be overcome due to the excellent carrier concentration and mobility of HEMTs.
Aluminium oxide (Al2O3) thin films deposited by using ultrasonic spray pyrolysis deposition (USPD) served as the gate dielectric of the proposed device. In order to investigate the composition of chemical elements, surface characteristics, and thickness of the Al2O3 dielectric layer, some material analyses were implemented such as X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Then, in order to characterize the influences of the gate overlapping with the Schottky source contact, we fabricated different devices with different overlapping length. The experiment results show the device with the partial overlap about 0.25 μm possessing the best performances. The device reveals a threshold voltage (VTH) of +1.8 V, an on-state/off-state ratio of 109, a subthreshold swing (SS) of 73 mV/decade, an on-state current (Ion) of 453 mA/mm, and a breakdown voltage of 560 V with a leakage current of 0.5 μA/mm. Compared with the reference device, all of the characteristics have been obviously improved.
The comparisons of InAlN/GaN and AlGaN/GaN epitaxy structures for our tri-gate TJ HEMTs were also investigated. The InAlN/GaN device shows better driving output and off-state performance due to the higher 2DEG density and the InAlN barrier lattice more matched to GaN active channel layer. Moreover, the proposed device shows the good thermal stability and low frequency noise characteristics. These results exhibit that the present novel enhancement-mode tri-Gate InAlN/GaN tunnel-junction HEMT with the excellent performances has great potential for high power device applications.

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