Liquid-Phase Sensors Using InN Ion Sensitive Field Effect Transistor Structure

• Main Authors: Lu, Yen-Sheng, 呂衍昇
• Other Authors: Yeh, J. Andrew
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/74558473038760431296

博士 === 國立清華大學 === 電子工程研究所 === 98 === Ion selective field effect transistor (ISFETs) based on single crystal indium nitride (InN) film have been demonstrated for detecting pH values, anions and polarity in liquids. Three kinds of InN ISFETs containing 10-nm-thick, 1-um-thick and 1.2 um, magnesium (Mg) doped InN have been investigated by electrolyte-gate-biased current-voltage (IDS-VGS) measurements. IDS-VGS characteristics reveal that the a-InN:Mg ISFETs have a large (~52%) current variation ratio at a gate bias of 0.3 V with respect to the unbiased one, which is higher than that from the undoped InN ISFETs (~18% and <0.1% for 10-nm and 1-�慆-thick –c-InN epilayers, respectively). The ultrathin InN and a-InN:Mg ISFETs can also function as pH sensor with a high sensitivity (58.25 mV/pH), a high resolution (0.05 pH), and a short response time(<10 s). For anion sensing applications, the positively charged donors on InN surfaces selectively adsorbed anions and built Helmholtz voltages near the InN/solution interface. The InN ISFETs reveal remarkable selectivity, response time, signal stability, and repeatability for chloride ions. Chemical response to polar liquids including methanol, IPA and acetone, etc, shows a linear relationship with the ratio of dipole moment to dielectric constant of the liquid.