The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel.
ACS Nano. 2012 Jan 24;6(1):335-45. doi: 10.1021/nn203653h. Epub 2011 Dec 23.
Silicon nanowire field-effect transistors (Si NW FETs) have been used as powerful sensors for chemical and biological species. The detection of polar species has been attributed to variations in the electric field at the conduction channel due to molecular gating with polar molecules. However, the detection of nonpolar analytes with Si NW FETs has not been well understood to date. In this paper, we experimentally study the detection of nonpolar species and model the detection process based on changes in the carrier mobility, voltage threshold, off-current, off-voltage, and subthreshold swing of the Si NW FET. We attribute the detection of the nonpolar species to molecular gating, due to two indirect effects: (i) a change in the dielectric medium close to the Si NW surface and (ii) a change in the charged surface states at the functionality of the Si NW surface. The contribution of these two effects to the overall measured sensing signal is determined and discussed. The results provide a launching pad for real-world sensing applications, such as environmental monitoring, homeland security, food quality control, and medicine.
硅纳米线场效应晶体管（Si NW FET）已被用作化学和生物物种的强大传感器。由于与极性分子的分子门控作用，导致导电路径中的电场发生变化，从而检测到了极性物质。然而，迄今为止，对于 Si NW FET 对非极性分析物的检测还没有得到很好的理解。在本文中，我们通过实验研究了非极性物质的检测，并基于 Si NW FET 的载流子迁移率、电压阈值、关电流、关电压和亚阈值摆幅的变化来对检测过程进行建模。我们将非极性物质的检测归因于分子门控，这是由于两个间接效应：（i）靠近 Si NW 表面的介电介质的变化，以及（ii）Si NW 表面功能化的带电表面状态的变化。确定并讨论了这两种效应对整体测量传感信号的贡献。研究结果为实际传感应用提供了一个新的起点，例如环境监测、国土安全、食品质量控制和医学。
