臺灣博碩士論文加值系統

在高電子遷移率電晶體(high electron mobility transistors, HEMTs)中，透過三五族材料所組成的化合物半導體異質接面，產生高電子密度及遷移率，而GaN材料具有的高崩潰電場，更能使得HEMTs元件擁有超高頻、超高速、高功率等特性。
本研究是使用Sentaurus TCAD半導體模擬軟體，模擬AlGaN/GaN HEMTs元件特性，並優化崩潰電壓。本論文首先介紹模擬軟體使用的物理模型，接著介紹模擬元件時，各個步驟的設定。
本研究使用空乏型雙通道結構，先加入橋場板，崩潰電壓確實可以有效提升，但是閘極下方通道電場仍呈現明顯高峰，因此嘗試以四種方法加以改進：1.橋場板掘入、2.僅橋場板加入斜場板、3.僅閘極加入斜場板、4.閘極和橋場板均加入斜場板。比較結果之後發現「僅閘極加入斜場板」為最佳結構，崩潰電壓從最初結構的19V提升至最後優化的200V。

A high electron mobility transistor (HEMT) is composed of one or more III-V heterostructures. It has excellent performance with high electron density and mobility. This study focuses on optimizing the structure of an AlGaN/GaN HEMT to improve the breakdown voltage.
Sentaurus TCAD was used to simulate the characteristics of AlGaN/GaN HEMTs. This thesis firstly introduces the physical models and boundary conditions used in the TCAD. Next, parameter setting in each step of the device simulation is explained.
The study started with a depletion-mode double-channel AlGaN/GaN HEMT structure. A air-bridge field plate was added on the structure, which reduced the electric field at the gate. Because the peak electric field was still present, four approaches were applied separately: 1. a recessed air-bridge field plate; 2. an add-on slant field plate under the recessed air-bridge field plate, 3. a slant field plate at the gate only, and 4. slant field plates under both the gate and air-bridge field plate. The study found that the third approach was the most effective in reducing the peak electric field. It resulted in a breakdown voltage of 200 V, a significant improvement in contrast to the 19 V of the initial structure.

摘要 I
ABSTRACT II
致謝 III
目錄 IV
圖目錄 VI
表目錄 VIII
第一章 緒論 1
1-1前言 1
1-2 研究背景與研究目的 3
1-3 研究動機 3
1-4 論文架構 3
第二章 高電子遷移率電晶體元件原理與介紹 4
2-1 二維電子氣 4
2-2 異質接面極化效應 5
2-3 元件種類 9
2-4 空乏型改為增強型的方法 12
2-5 提升元件崩潰電壓 15
第三章 19
3-1 物理模型 19
3-1-1 基本電壓電流計算模型 20
3-1-2 半導體統計模型 21
3-1-3 復合模型 22
3-1-4 極化模型 23
3-1-5 遷移率模型 23
3-1-6 邊界條件 25
3-1-7 數值方法 26
3-1-8 圖形呈現 27
3-2 AlGaN/GaN HEMTs 元件模擬 27
3-2-1 AlGaN/GaN HEMTs 元件結構 28
3-2-2 建立元件網格 29
3-2-3 電極設定 29
3-2-4 極化效應模擬 30
3-2-5 模擬和量測曲線比較 33
第四章 結果與討論 34
4-1 定義崩潰電壓 34
4-2 元件初始結構 34
4-3 加入橋場板 37
4-4 第一種結構：橋場板掘入 38
4-5 第二種結構：橋場板下方加入斜場板 39
4-6 第三種結構：僅閘極加入斜場板 41
4-7 第四種結構：閘極和橋場板均加入斜場板 43
4-8 優化結構崩潰電壓 44
第五章 結論 48
參考文獻 49

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