Liquid-phase sensors using open-gate AlGaN/GaN high electron mobility transistor structure

• Kokawa, Takuya

• Sato, Taketomo

• Hasegawa, Hideki

• Hashizume, Tamotsu

抄録

Liquid-phase sensing characteristics of open-gate AlGaN/GaN high electron mobility transistor (HEMT) structures were investigated in aqueous solutions and polar liquids. In de-ionized water, the open-gate HEMT clearly showed good drain I-V characteristics with current saturation and pinch-off behavior, very similar to I-V characteristics of typical Schottky-gate HEMTs. We observed a fine parallel shift in the transfer curves according to change in the pH value in a solution, indicating the corresponding potential change at the AlGaN surface. The sensitivity for the potential change was 57.5 mV/pH, very close to the theoretical value of 58.9 mV/pH at 24 °C for the Nernstian response to H+ ions. In the low drain bias region, the drain current linearly decreased with the pH value. This also indicated a systematic potential change at the AlGaN surface due to pH change. The present open-gate device showed a fast response to the pH change and a stable operation at fixed pH values. A possible mechanism for the pH response of the AlGaN surface is discussed in terms of equilibrium reactions of hydroxyls at the AlGaN surface with H+ in a solution. It was also found that the device was quite sensitive to changes in the electrostatic boundary conditions of the open-gate area by exposure to polar liquids. The drain current linearly decreased with increasing normalized liquid dipole moment.

収録刊行物

• Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures

  Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures 24 (4), 1972-1976, 2006-07-25

  AVS Science & Technology of Materials, Interfaces, and Processing

詳細情報

• CRID: 1050282813955864832
• NII論文ID: 120000956602
• HANDLE: 2115/14592
• ISSN: 0734211X
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles