Distinguishing between dipoles and field effects in molecular gated transistors

Abstract

We combine Kelvin probe force microscopy and current-voltage measurements in order to characterize silicon-on-insulator bioFETs. The measurements were conducted on monolayer of (3-aminopropyl)-trimethoxysilane, which was deposited on ozone activated silicon oxide surface covering the transistor channel. The work function of the modified surface decreased by more than 2eV, and the threshold voltage measured on the same devices showed a very large increase (∼10V) following the chemical modification. A detailed analysis enables us to distinguish between electron affinity and field effects in such devices, and in molecular gated transistors in general.