Growth and Characterization of III-Nitride on Si Substrates for High-Power Electronic Applications
Chang, Edward Yi
|關鍵字:||磊晶成長;氮化鎵;矽基板;功率電子;崩潰電壓;雙異質界面;高電子遷移率電晶體;epitaxy growth;GaN;Si substrate;power electronic;breakdown voltage;double heterostructure;HEMT|
第一部分，建立多重氮化鋁鎵緩衝層結構，以降低氮化鎵的差排密度，在1.2微米的氮化鎵磊晶層中，螺旋差排與刃差排密度分別為3.2×108 與 9.7×108 cm-2。其次，再藉由此多重氮化鋁鎵緩衝層的調變及圖樣化矽基板的應用，實現2.2微米無裂痕氮化鎵於矽基板上的成長，可大幅降低31%的薄膜應力，並將此結構運用在大尺寸圖樣化矽基板上，成功展示了第一顆在圖樣化矽基板上的功率元件，此元件崩潰電壓可達150伏特。
Owing to the distinctive material properties of GaN, GaN-based device exhibits superior characteristics on high breakdown voltage and high current. The integration of GaN and a large diameter Si substrate makes the GaN-on-Si device be a promising candidate for next-generation high-power applications. A global market of GaN-on-Si power electronics is steadily growing up through the commercialization of GaN-on-Si. To enhance device performances and further to meet the market demand, recent studies are focusing on the epitaxy growth and device fabrication to improve the breakdown voltage. This dissertation concentrates on the epitaxy growth technology of III-nitride on Si substrates by using metal organic chemical vapor deposition systems and the development of epitaxial structure with high breakdown voltage. The epitaxial quality is confirmed by the material analysis techniques and the device characterizations. In the first part, the multi-AlGaN buffer layer structure was used to reduce the dislocation density in GaN film. The screw and edge dislocation densities in the 1.2-μm-thick GaN film were 3.2×108 and 9.7×108 cm-2, respectively. Then the 2.2-μm-thick crack-free GaN films were obtained by patterning Si substrates and optimizing the multi-AlGaN layers. A 31% reduction of tensile stress for the GaN film was obtained. The first GaN power device fabricated on the large patterned Si substrate was successfully demonstrated. The breakdown voltage of the device was measured over 150 V. In the second part, a comprehensive study of AlGaN/GaN/AlGaN double heterostructure field effect transistor epitaxial structure was investigated. A high breakdown field and high bandgap AlGaN back barrier was used to prevent the leakage current. Compared with AlGaN/GaN single heterostructure field effect transistor structure, the device breakdown voltage can be improved from 130 V to higher than 200 V. Furthermore, a novel Al0.2Ga0.8N/GaN/Al0.1Ga0.9N double heterostructure grown on a Si substrate with the insertion of a LT-AlGaN interlayer was demonstrated. The effects of the LT-AlGaN interlayer on stress relaxation, dislocation reduction, and breakdown voltage enhancement were investigated. Compared with the traditional structures, the buffer breakdown voltage can be much improved to 600 V. By combining the advantages of the LT-AlGaN interlayer and double heterostructure, the innovation structure is an alternative epitaxial structure for high-power applications.
|Appears in Collections:||Thesis|