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Si nanowire biosensors with lowest detection limit

A strong coupling between the liquid gate and back gate has been revealed and used for optimization of signal-to-noise ratio in Si NW FETs. The results reflect novel ways for improving sensitivity of the biosensors by designing devices with controlled channel position.

 

Si nanowire biosensors with lowest detection limitFigure 1. (a) Scanning electron microscopy (SEM) image of part of the silicon nanowire array FET sample in close vicinity of drain contact. The channel width of the single wire in array of 50 NW is 250 nm and length of each is 16 µm (b) Sketch of the experimental layout.

Publication:

Liquid and back gate coupling effect: towards biosensing with lowest detection limit.

Sergii Pud, Jing Li, Volodymyr Sibiliev, Mykhaylo Petrychuk, Valery Kovalenko, Andreas Offenhäusser, Svetlana Vitusevich

Abstract: We employ noise spectroscopy and transconductance measurements to establish the optimal regimes of operation for our in-house fabricated silicon nanowire field-effect transistors (Si NW FETs) sensors. A strong coupling between the liquid gate and back gate (the substrate) has been revealed and used for optimization of signal-to-noise ratio in sub-threshold as well as above-threshold regimes. Noise behavior  in regime of biased  back gate voltage is explained in frame of mobility fluctuations model whereas in the case of unbiased back gate the Si NW conducting channel behavior corresponds to number fluctuations one. Increasing the sensitivity of Si NW FET sensors above the detection limit has been predicted and proven by direct experimental measurements. We show that the effect can be used for tuning of the FET operation mode to increase the sensitivity of the fabricated biosensor structure by 50 %. The results reflect novel ways for improving sensitivity of the biosensors by designing devices with controlled channel position.

 

Nano Lett., 2014, 14 (2), pp 578–584 DOI: 10.1021/nl403748x

http://pubs.acs.org/doi/full/10.1021/nl403748x


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