Heller Iddo, Janssens Anne M, Männik Jaan, Minot Ethan D, Lemay Serge G, Dekker Cees
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Nano Lett. 2008 Feb;8(2):591-5. doi: 10.1021/nl072996i. Epub 2007 Dec 28.
Carbon nanotube transistors have outstanding potential for electronic detection of biomolecules in solution. The physical mechanism underlying sensing however remains controversial, which hampers full exploitation of these promising nanosensors. Previously suggested mechanisms are electrostatic gating, changes in gate coupling, carrier mobility changes, and Schottky barrier effects. We argue that each mechanism has its 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 that electrostatic gating and Schottky barrier effects are the two relevant mechanisms, with electrostatic gating being most reproducible. If the contact region is passivated, sensing is shown to be dominated by electrostatic gating, which demonstrates that the sensitive part of a nanotube transistor is not limited to the contact region, as previously suggested. Such a layout provides a reliable platform for biosensing with nanotubes.
碳纳米管晶体管在溶液中生物分子的电子检测方面具有巨大潜力。然而，传感背后的物理机制仍存在争议，这阻碍了对这些有前景的纳米传感器的充分利用。先前提出的机制有静电门控、栅极耦合变化、载流子迁移率变化和肖特基势垒效应。我们认为，每种机制对器件电导的液栅电势依赖性都有其特征性影响。通过研究电子传导和空穴传导，可以明确识别传感机制。通过对此类器件进行广泛的蛋白质吸附实验，我们发现静电门控和肖特基势垒效应是两种相关机制，其中静电门控的可重复性最强。如果接触区域被钝化，传感显示主要由静电门控主导，这表明纳米管晶体管的敏感部分并不像先前认为的那样仅限于接触区域。这种布局为纳米管生物传感提供了一个可靠的平台。
