Molecular Monolayers on CMOS for Nanoscale Chemical Sensors

该项目将与亚利桑那州立大学化学与生物化学系、电气工程系和固态电子研究中心合作，重点研究用于光学和化学传感的CMOS电路中可极化分子单层的制备和表征。所提出的基于fet的化学传感器的有效部分将是一个分子系统，它将在不同的极化状态之间切换。与每个状态相关联的不同的偶极子场会导致可以用电测量的阈值电压的差异。分子种类将通过自组装附着在分栅SOI MOSFET的栅极氧化物上。我们的团队将在真空或干氮等受控环境下，使用扫描探针显微镜技术（STM， AFM和导电尖端AFM）制造单层并对其进行表征。这些仪器将使更好地了解表面单层的分子结构成为可能。分子单层极化前后的表面电位将由数值模拟确定，这种表面电位反过来又与分子的偶极子场有关，并与CT-AFM测量确定的物理结构相关。通过将表面电位的测量与结构信息和分子模型相结合，我们将能够深入了解分子单层如何在氧化硅衬底上自组装，以及极化后它们的电子构型如何变化。将分子的物理结构与其相关的偶极子场联系起来的能力是我们提出的混合分子-半导体异质结的独特特征。化学、物理和电气工程的结合将为研究生和本科生提供在真正的跨学科环境中工作的机会。

The project will concentrate on the preparation and characterization of polarizable molecular monolayers designed into CMOS circuitry for optical and chemical sensing, in collaboration with the Departments of Chemistry and Biochemistry, and Electrical Engineering, and the Center for Solid State Electronics Research at Arizona State University. The active part of the proposed FET-based chemical sensors will be a molecular system that will be switchable between different polarization states. The different dipole fields associated with each state would lead to a difference in threshold voltage that could me measured electrically. The molecular species will be attached to the gate oxide of a split-gate SOI MOSFET by self-assembly. Our group will fabricate the monolayers and characterize them using scanning probe microscopy techniques - STM, AFM, and conducting-tip AFM - under a controlled environment, such as vacuum or dry nitrogen. These instruments will make it possible to better understand the molecular configuration of the surface monolayer. The surface potential before and after the molecular monolayer is polarized will be determined from numerical simulations this surface potential can in turn be related to the dipole filed of the molecule and correlated with the physical structure as determined by the CT-AFM measurements. By combining the measurements of the surface potential with structural information and molecular modeling we will be able to develop a thorough understanding of how the molecular monolayers self-assemble on oxidized silicon substrates, and how their electronic configuration changes after polarization. The ability to correlate the physical structure of the molecules with their associated dipole field is a unique feature of the hybrid molecular-semiconductor heterojunctions that we are proposing. The mix of chemistry, physics and electrical engineering will provide opportunities for graduate and undergraduate students to work in a truly interdisciplinary environment.