Buitrago, E.; Fernández-Bolaños Badia, M.; Georgiev, Y. M.; Yu, R.; lotty, O.; Holmes, J. D.; Nightingale, A. M.; Guerin, H. M.; Ionescu, A. M.

2014

June

Sensors and Actuators, B: Chemical

Electrical characterization of high performance, liquid gated vertically stacked SiNW-based 3D FET biosensors

Published

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199

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A 3D vertically stacked silicon nanowire (SiNW) field effect transistor featuring a high density array offully depleted channels gated by a backgate and one or two symmetrical platinum side-gates through a liquid has been electrically characterized for their implementation into a robust biosensing system.The structures have also been characterized electrically under vacuum when completely surrounded by a thick oxide layer. When fully suspended, the SiNWs may be surrounded by a conformal high- gatedielectric (HfO2) or silicon dioxide. The high density array of nanowires (up to 7 or 8 × 20 SiNWs in thevertical and horizontal direction, respectively) provides for high drive currents (1.3 mA/m, normalizedto an average NW diameter of 30 nm at VSG = 3 V, and Vd = 50 mV, for a standard structure with 7 × 10 NWs stacked) and high chances of biomolecule interaction and detection. The use of silicon on insulatorsubstrates with a low doped device layer significantly reduces leakage currents for excellent Ion/Ioff ratios >10^6 of particular importance for low power applications. When the nanowires are submerged in a liquid,they feature a gate all around architecture with improved electrostatics that provides steep subthresholdslopes (SS < 75 mV/dec), low drain induced barrier lowering (DIBL < 20 mV/V) and high transconductances(gm> 10 S) while allowing for the entire surface area of the nanowire to be available for biomoleculesensing. The fabricated devices have small SiNW diameters (down to dNW∼ 15–30 nm) in order to be fullydepleted and provide also high surface to volume ratios for high sensitivities.

Amsterdam, The Netherlands

http://www.journals.elsevier.com/sensors-and-actuators-b-chemical/

10.1016/j.snb.2014.03.099