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Liquid-phase sensors using open-gate AlGaN/GaN high electron mobility transistor structure
| Title: | Liquid-phase sensors using open-gate AlGaN/GaN high electron mobility transistor structure |
| Authors: | Kokawa, Takuya Browse this author | | Sato, Taketomo Browse this author →KAKEN DB | | Hasegawa, Hideki Browse this author | | Hashizume, Tamotsu Browse this author |
| Issue Date: | 25-Jul-2006 |
| Publisher: | AVS Science & Technology of Materials, Interfaces, and Processing |
| Journal Title: | Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures |
| Volume: | 24 |
| Issue: | 4 |
| Start Page: | 1972 |
| End Page: | 1976 |
| Publisher DOI: | 10.1116/1.2214701 |
| Abstract: | 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. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/14592 |
| Appears in Collections: | 量子集積エレクトロニクス研究センター (Research Center for Integrated Quantum Electronics) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 佐藤 威友
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