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This dissertation presents an investigation into the electrical properties oftwo types of G4-DNA and several DNA-based molecules, targeting them ascandidates for molecular wires and devices. Atomic force microscopy (AFM) andelectrostatic force microscopy (EFM) comparison of co-deposited tetra- andintra-molecular G4-DNA reveals variations in morphology and differentsensitivity to the applied electric field, suggesting that the foldingorientation of the strands affects the molecular structure, i.e. either thetetrad unit or the tetrad-tetrad stacking or both, and therefore the chargemobility. Tetra-molecular G4-DNA is found to be twice as polarizable asintra-molecular G4-DNA, suggesting it has greater charge mobility. Thesepromising results motivated direct electrical transport measurements ontetra-molecular G4-DNA using a special conductive AFM setup, profiling theconductance along the molecule. Reproducible currents of tens to over 100 pAwere measured in many tetra-molecular G4-DNA molecules over distances rangingfrom tens to over 100 nm. The measured charge transport is compatible withlong-range thermally activated hopping between multi-tetrad segments. To formthe stationary electrical contact, a new variant of stencil lithography wasdeveloped, based on reversible electrostatic clamping, overcoming indeterminateblurring effects associated with the problem of metal penetration in standardmask patterning techniques. This method enabled to demonstrate full maskcompliance in scanning electron microscopy (SEM) and AFM measurements. Thepull-in instability was demonstrated inside an SEM chamber and was confirmed bya non-linear transient response computation. New mechanisms were proposed forthe replica formation and the blurring effect based on cluster evaporation andmobile source decay, explaining the ultimate resolution of the maskingtechnique and its limitations.

Development of novel electrical characterization methods and measurements of G4-DNA and DNA Derivatives