Micro and Nanosystems, Department of Mechanical and Process Engineering, ETH Zurich, CH-8092 Zurich, Switzerland.
Nanotechnology. 2010 May 7;21(18):185501. doi: 10.1088/0957-4484/21/18/185501. Epub 2010 Apr 14.
Carbon-nanotube-based field effect transistors (CNFETs) have been employed as highly sensitive chemical sensors. Often used as the sensor output signal, the gate threshold voltage (V(th)) is subject to concentration-dependent shifts upon exposure to target analytes. However, an unambiguous determination of the intrinsic V(th) is usually hampered by substantial hysteresis in CNFET gate characteristics. In this study we show that short gate voltage (V(gd)) pulses can be used for hysteresis reduction in CNFETs as chemical sensors, in particular for NO(2) detection. In the pulsed operation regime, even small shifts of V(th) upon sub-ppm NO(2) exposure remain resolvable. Furthermore, the hysteretic behaviour is systematically investigated by varying the pulse waveforms and timing parameters. Finally, we use an adapted hysteresis model for pulsed V(gd) and employ it to discuss the measurement data.
基于碳纳米管的场效应晶体管（CNFET）已被用作高灵敏度化学传感器。通常用作传感器输出信号的栅极阈值电压（V（th））在暴露于目标分析物时会发生与浓度相关的偏移。然而，由于 CNFET 栅极特性中存在显著的滞后现象，因此通常难以明确确定内在的 V（th）。在这项研究中，我们表明，短栅极电压（V（gd））脉冲可用于减少 CNFET 作为化学传感器的滞后，特别是用于检测 NO（2）。在脉冲操作模式下，即使在亚 ppm 的 NO（2）暴露下 V（th）的微小偏移仍然可以分辨。此外，通过改变脉冲波形和定时参数系统地研究了滞后行为。最后，我们使用了一个经过修正的脉冲 V（gd）滞后模型，并利用它来讨论测量数据。
