中国物理B ›› 2012, Vol. 21 ›› Issue (1): 17202-17202.doi: 10.1088/1674-1056/21/1/017202

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Effects of gate-buffer combined with a p-type spacer structure on silicon carbide metal–semiconductor field-effect transistors

宋坤, 柴常春, 杨银堂, 陈斌, 张现军, 马振洋   

  1. Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of Ministry of Education, School of Microelectronics, Xidian University, Xián 710071, China
  • 收稿日期:2011-07-15 修回日期:2011-09-16 出版日期:2012-01-15 发布日期:2012-01-20
  • 基金资助:
    Project supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 60725415), the National Natural Science Foundation of China (Grant No. 60606006), and the Pre-research Foundation of China (Grant No. 51308030201).

Effects of gate-buffer combined with a p-type spacer structure on silicon carbide metal–semiconductor field-effect transistors

Song Kun(宋坤), Chai Chang-Chun(柴常春), Yang Yin-Tang(杨银堂), Chen Bin(陈斌), Zhang Xian-Jun(张现军), and Ma Zhen-Yang(马振洋)   

  1. Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of Ministry of Education, School of Microelectronics, Xidian University, Xián 710071, China
  • Received:2011-07-15 Revised:2011-09-16 Online:2012-01-15 Published:2012-01-20
  • Supported by:
    Project supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 60725415), the National Natural Science Foundation of China (Grant No. 60606006), and the Pre-research Foundation of China (Grant No. 51308030201).

摘要: An improved structure of silicon carbide metal-semiconductor field-effect transistors (MESFET) is proposed for high power microwave applications. Numerical models for the physical and electrical mechanisms of the device are presented, and the static and dynamic electrical performances are analysed. By comparison with the conventional structure, the proposed structure exhibits a superior frequency response while possessing better DC characteristics. A p-type spacer layer, inserted between the oxide and the channel, is shown to suppress the surface trap effect and improve the distribution of the electric field at the gate edge. Meanwhile, a lightly doped n-type buffer layer under the gate reduces depletion in the channel, resulting in an increase in the output current and a reduction in the gate-capacitance. The structural parameter dependences of the device performance are discussed, and an optimized design is obtained. The results show that the maximum saturation current density of 325 mA/mm is yielded, compared with 182 mA/mm for conventional MESFETs under the condition that the breakdown voltage of the proposed MESFET is larger than that of the conventional MESFET, leading to an increase of 79% in the output power density. In addition, improvements of 27% cut-off frequency and 28% maximum oscillation frequency are achieved compared with a conventional MESFET, respectively.

关键词: silicon carbide, metal-semiconductor field-effect transistor, p-type spacer, gate-buffer

Abstract: An improved structure of silicon carbide metal-semiconductor field-effect transistors (MESFET) is proposed for high power microwave applications. Numerical models for the physical and electrical mechanisms of the device are presented, and the static and dynamic electrical performances are analysed. By comparison with the conventional structure, the proposed structure exhibits a superior frequency response while possessing better DC characteristics. A p-type spacer layer, inserted between the oxide and the channel, is shown to suppress the surface trap effect and improve the distribution of the electric field at the gate edge. Meanwhile, a lightly doped n-type buffer layer under the gate reduces depletion in the channel, resulting in an increase in the output current and a reduction in the gate-capacitance. The structural parameter dependences of the device performance are discussed, and an optimized design is obtained. The results show that the maximum saturation current density of 325 mA/mm is yielded, compared with 182 mA/mm for conventional MESFETs under the condition that the breakdown voltage of the proposed MESFET is larger than that of the conventional MESFET, leading to an increase of 79% in the output power density. In addition, improvements of 27% cut-off frequency and 28% maximum oscillation frequency are achieved compared with a conventional MESFET, respectively.

Key words: silicon carbide, metal-semiconductor field-effect transistor, p-type spacer, gate-buffer

中图分类号:  (Theory of electronic transport; scattering mechanisms)

  • 72.10.-d
73.20.At (Surface states, band structure, electron density of states) 85.30.De (Semiconductor-device characterization, design, and modeling)