氮化鎵高功率元件串疊電路構裝設計與節能驅動控制特性研究

Abstract

氮化鋁鎵/氮化鎵高電子移導率電晶體是次世代功率元件的主要材料，適用於高功率以及高頻操作的電子元件。近年來具有高崩潰電壓、高電子遷移速率以及高電子飽和速度的氮化鎵材料在半導體產業大量的被討論，因氮化鎵材料具有上述各種優良特性，漸漸取代矽成為次世代的新興材料。本研究進行構裝設計之氮化鎵元件為本校材料系複合半導體實驗室所研製之常開型(normally-on) GaN-HEMT元件，常開型元件在電路上不適用現行閘極驅動元件，本研究將進行結合矽場效電晶體元件與常開型氮化鎵功率元件之串疊(cascode)電路特性分析，此GaN-HEMT/MOSFET cascode元件形成常閉型(normally-off)開關，可直接取代現行MOSFET功率元件。本研究提出串疊元件挑選之篩選條件，並分析各元件之電性特性與開關波形，最終運用在高效率直流升壓轉換器電路。利用氮化鎵電晶體串疊電路設計探討氮化鎵電晶體由normally-on元件轉換為normally-off元件，使氮化鎵電晶體電性特性表現更加優越，且可應用於高功率系統電子驅動。

Wide band gap power semiconductor is one of the important material for new power electronics device. AlGaN/GaN has many attractive material properties, such as wide band gap, high breakdown voltage, high critical breakdown field, high saturation electric drift velocity, high peak electron velocity and, high electron saturation velocity. The AlGaN/GaN HEMT devices in this study are operated in depletion mode, so it is a normally-on device. To easily apply depletion mode GaN HEMT in a power drive circuit design, a low voltage silicon MOSFET is in series to drive the GaN HEMT, which is known as cascode structure, this approach provides one of the simplest and fastest way to deliver a normally-off GaN product. This research studies the characteristics and operation principles of cascode GaN HEMT. Evaluations of GaN HEMT performance based on Boost converter under hard-switching and soft-switching conditions are proceeded in the study to evaluate the performance advantages of GaN/SiC power transistors in power conversion applications. Experimental results illustrate that GaN HEMT is superior than silicon MOSFET.