Characteristics of field-effect devices with gate oxide modification by DNA

Abstract

Current-voltage characterization was used to investigate the behavior of silicon field-effect devices with DNA solutions of various concentrations and molecular states deposited on the gate oxide. These devices were similar to conventional transistors but without gate metal, and no surface treatments or agents were used to immobilize the DNA. With increasing micromolar concentration, significant changes were produced in the device response. The current decreased with increasing ratios of double-to-single stranded populations produced by mixing complementary sequences, and by thermal denaturing. The device characteristics were reproducible. Modeling suggested a mechanism of modifications to the device carrier density induced by variations in the electrochemical properties of the DNA located within a charge screening length of the gate oxide surface. These results showed that field-effect devices may be useful for the real time monitoring of nucleic acids, without binding agents or label tags.