Chin. Phys. B ›› 2012, Vol. 21 ›› Issue (12): 126102-126102.doi: 10.1088/1674-1056/21/12/126102

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Sodium beta-alumina thin films as gate dielectrics for AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

田本朗, 陈超, 李言荣, 张万里, 刘兴钊   

  1. The State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electron Science and Technology of China, Chengdu 610054, China
  • 收稿日期:2012-04-20 修回日期:2012-06-04 出版日期:2012-11-01 发布日期:2012-11-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 50932002).

Sodium beta-alumina thin films as gate dielectrics for AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

Tian Ben-Lang (田本朗), Chen Chao (陈超), Li Yan-Rong (李言荣), Zhang Wan-Li (张万里), Liu Xing-Zhao (刘兴钊)   

  1. The State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electron Science and Technology of China, Chengdu 610054, China
  • Received:2012-04-20 Revised:2012-06-04 Online:2012-11-01 Published:2012-11-01
  • Contact: Liu Xing-Zhao E-mail:xzliu@uestc.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 50932002).

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摘要： Sodium beta-alumina (SBA) is deposited on AlGaN/GaN by using co-deposition process with using sodium and Al2O3 as the precursors. X-ray diffraction (XRD) spectrum reveals that the deposited thin film is amorphous. The binding energy and composition of the deposited thin film, obtained from the X-ray photoelectron spectroscopy (XPS) measurement are consistent with those of SBA. The dielectric constant of the SBA thin film is about 50. Each of the capacitance-voltage characteristics obtained at five different frequencies shows a high-quality interface between SBA and AlGaN. The interface trap density of metal-insulator-semiconductor high-electron-mobility transistor (MISHEMT) is measured to be (3.5～9.5)×1010 cm-2·eV-1 by the conductance method. The fixed charge density of SBA dielectric is on the order of 2.7×1012 cm-2. Compared with the AlGaN/GaN metal-semiconductor heterostructure high-electron-mobility transistor (MESHEMT), the AlGaN/GaN MISHEMT usually has a threshold voltage that shifts negatively. However, the threshold voltage of the AlGaN/GaN MISHEMT with using SBA as gate dielectric shifts positively from -5.5 V to -3.5 V. From XPS results, the surface valence-band maximum (VBM-EF) of AlGaN is found to decrease from 2.56 eV to 2.25 eV after the SBA thin film deposition. The possible reasons why the threshold voltage of AlGaN/GaN MISHEMT with the SBA gate dielectric shifts positively are the influence of SBA on surface valence-band maximum (VBM-EF), the reduction of interface traps and the effects of sodium ions, and/or the fixed charges in SBA on the two-dimensional electron gas (2DEG).

关键词: SBA, AlGaN/GaN, MESHEMT, MISHEMT

Abstract: Sodium beta-alumina (SBA) is deposited on AlGaN/GaN by using co-deposition process with using sodium and Al2O3 as the precursors. X-ray diffraction (XRD) spectrum reveals that the deposited thin film is amorphous. The binding energy and composition of the deposited thin film, obtained from the X-ray photoelectron spectroscopy (XPS) measurement are consistent with those of SBA. The dielectric constant of the SBA thin film is about 50. Each of the capacitance-voltage characteristics obtained at five different frequencies shows a high-quality interface between SBA and AlGaN. The interface trap density of metal-insulator-semiconductor high-electron-mobility transistor (MISHEMT) is measured to be (3.5～9.5)×1010 cm-2·eV-1 by the conductance method. The fixed charge density of SBA dielectric is on the order of 2.7×1012 cm-2. Compared with the AlGaN/GaN metal-semiconductor heterostructure high-electron-mobility transistor (MESHEMT), the AlGaN/GaN MISHEMT usually has a threshold voltage that shifts negatively. However, the threshold voltage of the AlGaN/GaN MISHEMT with using SBA as gate dielectric shifts positively from -5.5 V to -3.5 V. From XPS results, the surface valence-band maximum (VBM-EF) of AlGaN is found to decrease from 2.56 eV to 2.25 eV after the SBA thin film deposition. The possible reasons why the threshold voltage of AlGaN/GaN MISHEMT with the SBA gate dielectric shifts positively are the influence of SBA on surface valence-band maximum (VBM-EF), the reduction of interface traps and the effects of sodium ions, and/or the fixed charges in SBA on the two-dimensional electron gas (2DEG).

Key words: SBA, AlGaN/GaN, MESHEMT, MISHEMT

中图分类号:  (III-V and II-VI semiconductors)

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