Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
Nano Lett. 2013 May 8;13(5):1962-8. doi: 10.1021/nl304734g. Epub 2013 Apr 18.
A fundamental understanding of chemical sensing mechanisms in graphene-based chemical field-effect transistors (chemFETs) is essential for the development of next generation chemical sensors. Here we explore the hidden sensing modalities responsible for tailoring the gas detection ability of pristine graphene sensors by exposing graphene chemFETs to electron donor and acceptor trace gas vapors. We uncover that the sensitivity (in terms of modulation in electrical conductivity) of pristine graphene chemFETs is not necessarily intrinsic to graphene, but rather it is facilitated by external defects in the insulating substrate, which can modulate the electronic properties of graphene. We disclose a mixing effect caused by partial overlap of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of adsorbed gas molecules to explain graphene's ability to detect adsorbed molecules. Our results open a new design space, suggesting that control of external defects in supporting substrates can lead to tunable graphene chemical sensors, which could be developed without compromising the intrinsic electrical and structural properties of graphene.
对于开发下一代化学传感器而言，深刻理解基于石墨烯的化学场效应晶体管（chemFET）中的化学感测机制至关重要。在这里，我们通过将石墨烯 chemFET 暴露于供电子体和受电子体痕量气体蒸气，探索了负责调整原始石墨烯传感器气体检测能力的潜在感测模式。我们揭示了原始石墨烯 chemFET 的灵敏度（就电导率的调制而言）不一定是石墨烯固有的，而是由绝缘衬底中的外部缺陷促进的，该外部缺陷可以调节石墨烯的电子性质。我们揭示了由吸附气体分子的最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）的部分重叠引起的混合效应，以解释石墨烯检测吸附分子的能力。我们的研究结果开辟了新的设计空间，表明支撑衬底中外在缺陷的控制可以实现可调谐的石墨烯化学传感器，而无需牺牲石墨烯的固有电学和结构性质。
