Molecular Sensing on Chemically Modified Silicon Surfaces - From Gas Phase to Solution
Dr. Greg Lopinski
Steacie Institute For Molecular Sciences
National Research Council Canada
Abstract: On semiconductor surfaces, adsorption and reaction events that lead to charge re-distribution can alter the substrate conductivity through long- range electric field effects. These effects can be exploited to develop methods for electrically based chemical and biological sensing. Electrical transport measurements using hydrogen and alkyl monolayer terminated Silicon On Insulator (SOI) substrates have been used to observe large reversible field effects upon adsorption of polar molecular species from the gas phase. In particular, alkyl monolayer passivated SOI surfaces show a large reversible response to the prototypical electron acceptor Tetracyanoethylene (TCNE), suggesting that sensitive detection of high electron affinity compounds is possible. We will also discuss challenges and progress in using alkyl monolayers for biosensing applications, which requires stabilizing the electrical properties of the interface during extended exposures to aqueous buffer. Alkyl monolayers formed on the H-terminated surface are shown to be suitable gate dielectrics for biological field effect transistors (BioFETs).
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