臺灣博碩士論文加值系統

我們藉由極化工程提出了一個新穎的常關模式氮化鋁鎵/氮化鎵高電子遷移率場效電晶體。此研究最基本的概念是漸變阻擋層 ( barrier-layer ) 的鋁含量，由氮化鎵漸變至氮化鋁鎵，以減緩壓電極化對電子通道的影響，並使導電帶與費米能接重合部分減少，元件的閾值電壓移往正值，以利於常關模式的操作。此外，可以發現元件藉由操作氮化鋁鎵cap-layer的鋁含量，以及在氮化鎵緩衝層的頂部加入p型摻雜，可進一步調整直流電壓－電流特性。此項研究是基於元件的物理特性模擬，提供一個執行高效率常關模式氮化鎵高電子遷移率場效電晶體的方法。

We propose a novel normally-off AlGaN/GaN HEMT governed by the polarization engineering. The fundamental concept is to grade the Al-composition of barrier-layer from GaN to AlxGa1-xN, alleviating the impact of piezoelectric polarization on the 2-DEG and establishing the conduction-band profile well above the Fermi-energy. All of which leads to a positive shift for the threshold-voltage of the device, and benefits to the normally-off operation. Additionally, it is found that device’s DC transfer characteristics can be further modulated by simply adjusting the Al-composition of AlyGa1-yN cap-layer and the p-type doping concentration on the top of GaN buffer-layer. These findings based on the device’s physical simulation provide a guideline for the implementation of high-efficient normally-off AlGaN/GaN HEMTs.

致謝 VII
摘要 VIII
Abstract IX
第一章 緒論 1
1-1 前言 1
1-2 氮化鎵高電子遷移率場效電晶體 2
1-2-1 氮化鎵材料元件之發展 2
1-2-2 氮化鎵HEMT之應用 4
1-2-3 常關模式之氮化鎵HEMT 5
1-3 研究動機 7
1-4 論文架構 9
第二章 氮化鎵高電子遷移率電晶體元件特性回顧 11
2-1 極化效應 11
2-1-1 極化效應對GaN HEMT之影響 11
2-1-2 極化效應的計算 13
2-2 電子遷移率 17
2-3 衝擊離子化 18
2-4 閘極絕緣層 19
第三章 APSYS模擬軟體 21
3-1 APSYS模擬軟體之簡介 21
3-1-1 APSYS之應用 21
3-1-2 APSYS之功能 22
3-2 APSYS運作流程 22
3-2-1 輸入/輸出檔案 23
3-3 飄移－擴散模型 25
3-3-1 基礎方程式 25
3-3-2 SRH與歐傑複合 26
3-3-3 載子之統計 28
3-3-4 邊界條件 29
第四章 結構設定與模擬結果 32
4-1 結構參數設定 32
4-2 模擬結果與討論 33
第五章 結論 45
參考文獻 46
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