Title: Effect of Sensing Film Thickness on Sensing Characteristics of Dual-Gate Poly-Si Ion-Sensitive Field-Effect-Transistors
Authors: Yen, Li-Chen
Tang, Ming-Tsyr
Tan, Chia-Ying
Pan, Tung-Ming
Chao, Tien-Sheng
Department of Electrophysics
Keywords: Drift;dual-gate (DG);hysteresis;ion-sensitive field-effect transistor (ISFET);poly-Si;sensitivity
Issue Date: 1-Dec-2014
Abstract: 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).
URI: http://dx.doi.org/10.1109/LED.2014.2365478
ISSN: 0741-3106
DOI: 10.1109/LED.2014.2365478
Volume: 35
Issue: 12
Begin Page: 1302
End Page: 1304
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