Molecular Monolayers on CMOS for Nanoscale Chemical Sensors

University Of Arizona, Tucson AZ

Investigators

Abstract

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.