Molecular Monolayers on CMOS for Nanoscale Chemical Sensors

该项目将与化学、生物化学和电气工程系以及亚利桑那州立大学固态电子研究中心合作，重点研究设计成用于光学和化学传感的CMOS电路的可极化分子单分子膜的制备和表征。所提出的基于FET的化学传感器的活跃部分将是一个可以在不同偏振状态之间切换的分子系统。与每个状态相关的不同偶极场将导致阈值电压的不同，这可以用电学来测量。分子物种将通过自组装的方式附着在分裂栅SOI MOSFET的栅氧化层上。我们的团队将在受控环境(如真空或干氮气)下，使用扫描探针显微镜技术--扫描隧道显微镜、原子力显微镜和导电针尖原子力显微镜--来制备单分子膜并对其进行表征。这些仪器将使更好地了解表面单分子层的分子构型成为可能。分子单层极化前后的表面电势将由数值模拟确定，该表面电势又可以与分子的偶极场相关，并与CT-AFM测量确定的物理结构相关联。通过将表面电势的测量与结构信息和分子建模相结合，我们将能够深入了解分子单分子膜如何在氧化的硅衬底上自组装，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相关联的能力是我们提出的分子-半导体混合异质结的一个独特特征。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跨学科的环境中工作的机会。

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.