Liquid-phase sensors using open-gate AlGaN/GaN high electron mobility transistor structure
Liquid-phase sensors using open-gate AlGaN/GaN high electron mobility transistor structure
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DOI：
10.1116/1.2214701
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发表时间：
2006-07-01
影响因子：
1.4
通讯作者：
Hashizume, Tamotsu
中科院分区：
文献类型：
--
作者：
Kokawa, Takuya;Sato, Taketomo;Hashizume, Tamotsu
研究了开栅AlGaN/GaN高电子迁移率晶体管（HEMT）结构在水溶液和极性液体中的液相传感特性。在去离子水中，开栅HEMT明显地表现出良好的漏极I-V特性，具有电流饱和和夹断行为，非常类似于典型的肖特基栅HEMT的I-V特性。我们观察到的转移曲线根据溶液中的pH值的变化，表示在AlGaN表面相应的电位变化的罚款平行移位。电位变化的灵敏度为57.5 mV/pH，非常接近于24 ℃下能斯特响应H+离子的理论值58.9 mV/pH。在低漏偏置区，漏电流随pH值线性下降。这也表明由于pH变化，AlGaN表面处的系统电势变化。本发明的开栅装置显示出对pH变化的快速响应和在固定pH值下的稳定操作。AlGaN表面的pH响应的一种可能的机制进行了讨论的羟基在AlGaN表面与H+在溶液中的平衡反应。人们还发现，该设备是相当敏感的变化，在静电边界条件的开放栅极区域暴露于极性液体。漏极电流随归一化液体偶极矩的增加而线性减小。(c)2006年美国真空学会。
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 degrees 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. (c) 2006 American Vacuum Society.