True Reference Nanosensor Realized with Silicon Nanowires

Tarasov, A. and Wipf, M. and Bedner, K. and Kurz, J. and Fu, W. and Guzenko, V. A. and Knopfmacher, O. and Stoop, R. L. and Calame, M. and Schonenberger, C.. (2012) True Reference Nanosensor Realized with Silicon Nanowires. Langmuir, Vol. 28, H. 25. pp. 9899-9905.

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Official URL: http://edoc.unibas.ch/dok/A6070309

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Conventional gate oxide layers (e.g., SiO2, Al2O3, or HfO2) in silicon field-effect transistors (FETs) provide highly active surfaces, which can be exploited for electronic pH sensing. Recently, great progress has been achieved in pH sensing using compact integrateable nanowire FETs. However, it has turned out to be much harder to realize a true reference electrode, which while sensing the electrostatic potential - does not respond to the proton concentration. In this work, we demonstrate a highly effective reference sensor, a so-called reference FET, whose proton sensitivity is suppressed by as much as 2 orders of magnitude. To do so, the Al2O3 surface of a nanowire FET was passivated with a self-assembled monolayer of silanes with a long alkyl chain. We have found that a full passivation can be achieved only after an extended period of self-assembling lasting several days at 80 degrees C. We use this slow process to measure the number of active proton binding sites as a function of time by a quantitative,comparison of the measured nonlinear pH-sensitivities to a theoretical model (site-binding model). Furthermore, we have found that a partially passivated surface can sense small changes in the number of active binding sites reaching a detection limit of delta N-s approximate to 170 mu m(-2) Hz(-1/2) at 10 Hz and pH 3.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimentalphysik Nanoelektronik (Schönenberger)
UniBasel Contributors:Schönenberger, Christian and Tarasov, Alexey and Wipf, Mathias and Fu, Wangyang and Knopfmacher, Oren and Stoop, Ralph and Calame, Michel
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Chemical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:01 Mar 2013 11:14
Deposited On:01 Mar 2013 11:13

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