Electrostatic properties of molecular gated BioFETs

We combine Kelvin probe force microscopy and current-voltage measurements in order to characterize silicon-oninsulator biological field effect transistors. The measurements were conducted on monolayer of (3-aminopropyl)-trimethoxysilane, which was deposited on a plasma activated silicon oxide surface of the transistor channel. The work function of the modified silicon oxide decreased by more then 2 eV as a function of the chemical treatment time. The current-voltage measurements preformed on the same devices showed a very large decrease (~10 V) in the threshold voltage of the transistors following the chemical modification. A consequent increase of almost 3 orders of magnitude in the drain-source current was also observed. The (3-aminopropyl)-trimethoxysilane induced charge redistribution effects on the transistor channel surface are analyzed and discussed.