Identifying the Mechanism of Biosensing with Carbon Nanotube Transistors

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• 作者：Iddo Heller ; Anne M. Janssens ; Jaan M&auml ; nnik ; Ethan D. Minot ; Serge G. Lemay ; Cees Dekker
• 刊名：Nano Letters
• 出版年：2008
• 出版时间：February 2008
• 年：2008
• 卷：8
• 期：2
• 页码：591 - 595
• 全文大小：195K
• 年卷期：v.8,no.2(February 2008)
• ISSN：1530-6992

文摘

Carbon nanotube transistors have outstanding potential for electronic detection of biomolecules in solution. The physical mechanism underlyingsensing however remains controversial, which hampers full exploitation of these promising nanosensors. Previously suggested mechanismsare electrostatic gating, changes in gate coupling, carrier mobility changes, and Schottky barrier effects. We argue that each mechanism hasits characteristic effect on the liquid gate potential dependence of the device conductance. By studying both the electron and hole conduction,the sensing mechanisms can be unambiguously identified. From extensive protein-adsorption experiments on such devices, we find thatelectrostatic gating and Schottky barrier effects are the two relevant mechanisms, with electrostatic gating being most reproducible. If thecontact region is passivated, sensing is shown to be dominated by electrostatic gating, which demonstrates that the sensitive part of ananotube transistor is not limited to the contact region, as previously suggested. Such a layout provides a reliable platform for biosensingwith nanotubes.