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Charge-controlled fixation of DNA molecules on silicon surface and electro-physical properties of Au–DNA–Si interface

Charge-controlled fixation of DNA molecules on silicon surface and electro-physical properties of Au–DNA–Si interface

Figure Legend: AFM images of silicon surfaces with fixed DNA ropes (a) and DNA mesh (b) and topographic profiles of these surfaces are presented in the figure.

Journal Reference

N.V. Bazlov, O.F. Vyvenko, P.A. Sokolov, N.A. Kas’yanenko, Yu V. Petrov.

Applied Surface Science, Volume 267, 2013, Pages 224-228.

V.A. Fok Institute of Physics, Saint-Petersburg State University, Ulyanovskaya 1, 198504 Saint-Petersburg, Russia

 

 

Abstract

Light-induced fixation of DNA molecules on silicon surface was done and electro-physical properties of Schottky diodes with DNA on interfaces were investigated. Thymus DNA molecules were deposited on silicon from a water solution. Fixed molecular structures were observed with helium ionic microscopy and atomic force microscopy and then they were covered with thermal sputtered gold film. Obtained structures Au–DNA–(n-Si) were examined with current–voltage and frequency dependent admittance measurements. In darkness immobilizing of molecules leaded to form DNA ropes with thickness up to 10 nm and distances between them about 1 mkm. Fixation under illumination resulted in forming of single DNA mesh with thickness about 1 nm and cell size about 100 nm. Presence of molecular mesh on interface leaded to increasing of charge density controlled by metal Fermi level and improved diode quality. Presence of molecular ropes resulted in increasing of charge density controlled by semiconductor. From the estimation of interface state density values the origin of the states at the interface between DNA and silicon substrate is suggested to be DNA phosphate groups contacting or being close to the substrate surface.

 

 

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