Browsing by Author "Tan, Chia-Ying"

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Effect of Sensing Film Thickness on Sensing Characteristics of Dual-Gate Poly-Si Ion-Sensitive Field-Effect-Transistors
(2014-12-01)
Yen, Li-Chen
;
Tang, Ming-Tsyr
;
Tan, Chia-Ying
;
Pan, Tung-Ming
;
Chao, Tien-Sheng
We investigate the effect of sensing film thickness on the sensing characteristics of dual-gate (DG) poly-Si ion-sensitive field-effect transistors (ISFETs). The pH sensitivity (from 37.57 to 9.32 mV/pH) of the DG poly-Si ISFET device degrades with the increase in the sensing film thickness (from 20 to 120 nm), whereas hysteresis voltage (from 6.7 to 1.12 mV for a neutral to acid to alkaline to neural loop) and drift rate (from 13.47 to <3 mV/h at pH 7) improve accordingly. An improved hysteresis and drift phenomena are attributed to the reduction in top-gate capacitance of the sensing membrane, causing a smaller capacitive-coupling ratio (top-gate capacitance of sensing membrane to bottom-gate capacitance of tetraethylorthosilicate oxide).