Browsing by Author "Tang, Ming-Tsyr"

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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).
Improvement in pH Sensitivity of Low-Temperature Polycrystalline-Silicon Thin-Film Transistor Sensors Using H-2 Sintering
(2014-03-01)
Yen, Li-Chen
;
Tang, Ming-Tsyr
;
Chang, Fang-Yu
;
Pan, Tung-Ming
;
Chao, Tien-Sheng
In this article, we report an improvement in the pH sensitivity of low-temperature polycrystalline-silicon (poly-Si) thin-film transistor (TFT) sensors using an H-2 sintering process. The low-temperature polycrystalline-silicon (LTPS) TFT sensor with H-2 sintering exhibited a high sensitivity than that without H-2 sintering. This result may be due to the resulting increase in the number of Si-OH2+ and Si-O- bonds due to the incorporation of H in the gate oxide to reduce the dangling silicon bonds and hence create the surface active sites and the resulting increase in the number of chemical reactions at these surface active sites. Moreover, the LTPS TFT sensor device not only offers low cost and a simple fabrication processes, but the technique also can be extended to integrate the sensor into other systems.