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Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

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タイトル: Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors
著者: Hashizume, Tamotsu 著作を一覧する
Ootomo, Shinya 著作を一覧する
Inagaki, Takanori 著作を一覧する
Hasegawa, Hideki 著作を一覧する
発行日: 2003年 8月 5日
出版者: AVS Science & Technology of Materials, Interfaces, and Processing
誌名: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures
巻: 21
号: 4
開始ページ: 1828
終了ページ: 1838
出版社 DOI: 10.1116/1.1585077
抄録: We have systematically investigated effects of plasma processing, formation of Si-based dielectrics, and formation of a thin Al2O3 film on the chemical and electronic properties of GaN and GaN/AlGaN heterostructure surfaces. The surface treatment in H2-plasma excited by electron-cyclotron-resonance (ECR) source, produced nitrogen-vacancy-related defect levels at GaN and AlGaN surfaces, while the ECR-N2-plasma treatment improved electronic properties of the surfaces. The deposition of a SiO2 film on GaN and AlGaN surfaces was found to induce high-density interface states, due to unexpected and uncontrollable oxidation reactions on the surfaces during the deposition process. In comparison, the SiNx/GaN passivation structure prepared by ECR-plasma assisted chemical vapor deposition showed good interface properties with the minimum Dit value of 1×1011 cm–2 eV–1. However, excess leakage currents governed by Fowler–Nordheim tunneling were observed in the SiNx/Al0.3Ga0.7N structure, due to a relatively small conduction band offset of 0.7 eV between SiNx and Al0.3Ga0.7N. A novel Al2O3-based passivation structure was proposed and fabricated by molecular beam deposition of Al and subsequent ECR O2-plasma oxidation. In situ x-ray photoelectron spectroscopy showed successful formation of the Al2O3 layer with a thickness of 3.5 nm and a large conduction band offset of 2.1 eV between Al2O3 and A0.3Ga0.7N. The GaN/AlGaN insulated-gate heterostructure field-effect transistors (IG HFETs) having the Al2O3-based passivation structure showed a good gate control of drain currents up to VGS = +3 V and achieved drain saturation current of 0.8 A/mm. The observed maximum gm value is 120 mS/mm. No current collapse was observed in the Al2O3 IG HFETs, indicating a remarkable advantage of the present Al2O3-based passivation structure.
資料タイプ: article
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 橋詰 保


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