Ion Selectivity Improvements of Niobium Oxide by Phase Modification

• Main Authors: Tzu Wen Chiang, 江資聞
• Other Authors: C. S. Lai
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/98133723306802206728

碩士 === 長庚大學 === 電子工程學系 === 102 === In this work, we use Niobium Oxide as a sensing membrane in electrolyte-insulator-semiconductor (EIS) structure. Hydrogen ion sensing characteristics in pH buffer solution were also discussed. IGZO thin film as sensing membrane in extended-gate field-effect-transistor (EGFET) was studied before IGZO thin film acts as semiconductor layer of LAPS structure. .The IGZO sensing membrane is using as the electrode of EGFET. pH value of pH buffer solution could be measured by this proposed EIS and EGFET. And then NbxOy/IGZO/ITO electrode/glass EIS structure was used to test pH value in pH buffer solution. In addition, some results of potassium and sodium ions sensing performance by changing the measurement frequency and AC amplitude were also presented. To improve the sensitivity and linearity of EIS structure in pH buffer solution, the sensing membrane surface with more hydrogen bonds generated by the increases of surface roughness per unit surface area; were treated by rapid temperature anneal process. The sensitivity rises to 60.7 mV/pH and linearity rises to 99.9 %. In the structure of NbxOy/IGZO/ITO electrode/glass, IGZO semiconductor layer is the sensing membrane of EGFET. The lattice composed and direction of lattice could be changed by RTA process. And oxygen flow rate was modified during sputtering. Thus we could have better performance with sensitivity rising from 41.54 m V/pH to 59.45 m V/pH, and linearity higher than 99%. In the NbxOy/IGZO/ITO electrode/glass of EIS structure, we preliminarily discuss the light transmittance of different wavelength, that photocurrent can be induced by light absorbed by IGZO semiconductor layer in LAPS structure. By using NbxOy/IGZO/ITO electrode/glass EIS structure, pH sensitivity can reach 60.58 mV/pH and 98.61% is obtained in linearity.