臺灣博碩士論文加值系統

This study focuses on GaN heterostructure Schottky diodes with different geometries, aiming at achieving high breakdown voltage and high forward current. The AlGaN/GaN heterostrure devices are attractive due to their high mobility and high carrier density of two-dimensional electron gas at the AlGaN/GaN interface, which allows low on-state resistance of the devices. In this thesis, we design and fabricate the GaN Schottky diodes to have high forward current, high breakdown voltage, and low reverse recovery time. In GaN Schottky diodes with a buffer layer thickness of 2.4 μm, the measured breakdown voltage is higher than 900 V. The GaN diodes with a large area are also investigated to obtain a large output current. We propose of using vertical pads above the active region, which greatly increases the efficiency of area usage. We also design the circle-type testkeys to ensure the feasibility of the proposed ideas. The large-area AlGaN/GaN Schottky diode with a total size of 0.57 shows a forward current 1A (corresponding to a current density of ~ 0.18A/mm2) at an applied forward voltage of 2V after wire bonding. In reverse recovery tests, the GaN diode shows a very short switching time (trr) of only 21 ns.

目錄 v
表目錄 x
第1章 簡介 1
1.1. 前言 1
1.2. 論文架構 1
第2章 氮化鎵材料與異質結構蕭特基二極體 2
2.1. 氮化鎵材料特性 2
2.2. AlGaN/GaN 異質結構蕭特基二極體 3
2.2.1. 以AlGaN/GaN HEMT結構來製作GaN 蕭特基二極體 3
2.2.2. 元件結構 4
2.3. 2.4 μm與3.5 μm試片AlGaN/GaN蕭特基二極體製作 5
2.4. 本元件之設計考量 6
2.4.1. 尺寸設計 6
2.4.2. 元件設計 10
2.5. 崩潰路徑探討 15
2.6. 本章總結 16
第3章 元件製程與量測方法 17
3.1 20
3.1.1. 微影製程 21
3.1.2. 平臺隔離蝕刻(Mesa isolation etch) 22
3.2. 歐姆接觸(陰極製作) 23
3.2.1. 表面處理 23
3.2.2. 金屬蒸鍍 23
3.2.3. 剝離(Lift-off) 24
3.2.4. 快速熱退火(Rapid Thermal Annealing, RTA) 24
3.3. 蕭特基接觸(陽極製作) 25
3.4. 鈍化製程 25
3.5. 焊墊金屬（Bonding pad）製作 27
3.6. 結構封裝 27
3.7. 量測方法 29
3.7.1. Transfer Length Method (TLM) 29
3.7.2. 逆向恢復時間量測(Reverse recovery) 32
3.8. 本章總結 34
第4章 結果與討論 34
4.1. 試片結構 34
4.2. 元件直流特性分析與討論 35
4.3. 直流特性參數分析 46
4.4. 元件高壓特性分析與討論 47
4.5. 反向回復時間量測(Reverse recovery) 56
4.6. 本章結論 58
第5章 結論與未來工作 59

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