NANO.IL.

High Gain Transistor Based on Fully Depleted Silicon-On-Insulator Technology for Biosensing Applications

Ie Mei Bhattacharyya Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel

The development of high gain transistors is crucial for transducers in chemical or biological sensing applications. Double gate (DG) Silicon-On-Insulator (SOI) transistors, in which both the gates control the channel characteristics, offer attractive advantages such as near-ideal subthreshold slope and high transconductance. The active SOI thickness is an important parameter for the double gate transistor operation as it significantly influences electron charge density, threshold voltage and effective electron mobility. Electrostatic coupling between the front gate and the back gate voltages occurs in fully-depleted (FD) thin film SOI transistor and this facilitates precise tuning of the device parameters to achieve better performance in current, subthreshold slope, transconductance and speed; these directly affect the sensor dynamic range, sensitivity and limit of detection. Ultra-thin DG SOI transistors can operate in volume inversion regime to achieve higher gain (about 75%) due to high volume mobility and theoretical subthreshold swing (~60mV/decade). In this work, we numerically (Advanced TCAD by Synopsys) investigate a 100nm thin FD DG SOI transistors (1um long and 500nm wide channel) for biological sensing. The electrolyte and the reference electrode are simulated following Shoorideh and Chui 2014. We show the dependency of source-drain current (IDS) vs. reference electrode voltage (VREF) on both the back gate biasing and the SOI thickness. We show how the front interface transconductance and the front subthreshold swing are tuned accordingly. We also examine the possibility for volume inversion in solution-gate FD DG transistor.

Keywords: high gain transistor-based biosensing, Silicon-On-Insulator technology, electrolyte gate, ultra-thin double gate SOI transistors, fully depleted SOI.

Reference:

K. Shoorideh and C. O. Chui, “On the origin of enhanced sensitivity in nanoscale,” PNAS, vol. 111, no. 14, pp. 5111–5116, 2014.









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