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、电气工程系以及固态电子研究中心合作，专注于设计用于光学和化学传感的 CMOS 电路中的可极化单分子层的制备和表征。 所提出的基于 FET 的化学传感器的活性部分将是一个可在不同偏振态之间切换的分子系统。 与每个状态相关的不同偶极子场会导致阈值电压的差异，我可以通过电测量来测量阈值电压。 分子物质将通过自组装附着到分栅 SOI MOSFET 的栅极氧化物上。 我们的小组将在受控环境（例如真空或干燥氮气）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构型成为可能。 单分子层极化之前和之后的表面电势将通过数值模拟确定，该表面电势又可以与分子的偶极场相关，并与通过 CT-AFM 测量确定的物理结构相关。 通过将表面电势的测量与结构信息和分子建模相结合，我们将能够全面了解单分子层如何在氧化硅基板上自组装，以及它们的电子构型在极化后如何变化。 将分子的物理结构与其相关的偶极场关联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.